The Effect of Body Postural Changes on the Relationship Between Pulmonary Tissue and Rib Deformation: A Study Based on High-Resolution CT and 3D Reconstruction

The Effect of Body Postural Changes on the Relationship Between Pulmonary Tissue and Rib Deformation: A Study Based on High-Resolution CT and 3D Reconstruction | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The Effect of Body Postural Changes on the Relationship Between Pulmonary Tissue and Rib Deformation: A Study Based on High-Resolution CT and 3D Reconstruction Maodan Chen, Yang Huang, Zhiping Huang, Wenfei Zhu, Zewei Li, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6416423/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Background: The accurate localization of pulmonary nodules is significantly influenced by body positional changes, which also have a profound impact on lung morphology. As the body position changes, alterations in lung morphology are closely associated with shifts in the thoracic cage structure. However, the relationship between rib morphology and pulmonary tissue deformation has not been thoroughly explored. This study aims to investigate the relationship between lung tissue deformation and rib movement during the transition from the supine to the left lateral decubitus position. To achieve this, we employed computed tomography (CT) imaging and three-dimensional (3D) reconstruction techniques. Methods: Eleven healthy male volunteers received high-resolution CT scans in both the supine and left lateral decubitus positions. Lung volumes and morphological characteristics were assessed using 3D reconstruction software. Simulated pulmonary nodules were created, and the distances between the centroids of these nodules and the rib centerline coordinates were measured. Paired t-tests were conducted to evaluate the differences in lung volume, morphology, and rib deformation between the two positions. Results: In the left lateral decubitus position compared to the supine position, significant increases were observed in the volumes of the right upper lobe, right lower lobe, and total right lung, while the right middle lobe exhibited no significant change. Lung height and hemidiaphragm height showed significant increases, whereas lung width and depth remained relatively stable. The deformation relationships between the right upper and middle lobes and the ribs were minimal, with a maximum variation of 13 mm. In contrast, significant differences were identified between the right lower lobe and the ribs, with a maximum discrepancy of 27 mm. Conclusion: The transition from the supine to the left lateral decubitus position has a significant impact on lung volumes and morphological parameters, especially in the right lower lobe. The relationship between pulmonary tissue deformation and rib movement is relatively consistent in the right upper and middle lobes, but substantial differences are observed in the right lower lobe. These discrepancies are likely due to a combination of increased lung volume, lobar sliding, and rib deformation. Supine position Left lateral decubitus Rib deformation Lung tissue deformation CT scan Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Accurate localization of pulmonary nodules is essential for early detection and effective therapeutic intervention in lung cancer [ 1 ]. To improve the success rates of video-assisted thoracoscopic surgery (VATS) and reduce the need for open thoracotomies, various preoperative localization techniques have been developed [ 2 ]. The increasing use of high-resolution chest CT has significantly enhanced the detection of lung nodules [ 3 ]. Currently, the clinical standard for lung nodule localization involves a multimodal approach, combining preoperative CT-guided techniques—such as methylene blue injection, sclerosing agent injection, or hook wire placement—with advanced technologies like bronchscopic assistance, 3D printing, robotic assistance, 3D reconstruction, and augmented reality (AR) [ 4 , 5 ]. For small nodules (< 1 cm), those located deep within the pleura, or those with ground-glass or subsolid features, CT-guided needle localization is often the preferred method in many hospitals [ 6 ]. However, in most hospitals, this localization is not performed intraoperatively in real-time but preoperatively under conscious sedation, with a significant waiting period between localization and surgery. This not only increases patient anxiety and pain but also poses risks such as pneumothorax, bleeding, air embolism, and detachment of the localization needle [ 7 , 8 ]. Several intraoperative pulmonary nodule localization techniques have been explored and implemented, including electromagnetic navigation bronchoscopy (ENB), intraoperative ultrasound localization, and fluorescent thoracoscopy [ 4 , 9 – 11 ]. Each method has its unique advantages and limitations. For example, electromagnetic navigation bronchoscopy (ENB) is limited by its high cost and complex procedures. Intraoperative ultrasound localization, which is appreciated for its radiation-free and cost-effective features, faces challenges in localizing pulmonary nodules smaller than 1 cm or those with ground-glass opacity (GGO) features, due to the reflection and scattering of ultrasound waves by air within the lung tissue, which affects the penetration and signal quality of the ultrasound. Fluorescent thoracoscopy, while advantageous in some aspects, requires specialized fluorescent thoracoscopy equipment and struggles with deep-seated nodule localization and delineating the margins of pure ground-glass opacity nodules due to limited fluorescence penetration [ 4 ]. To address these challenges, ongoing research aims to improve localization accuracy, reduce procedural complications, optimize surgical workflows, and enable real-time localization during surgery. Although with the continuous updates of imaging equipment and software, as well as the emergence of hybrid operating rooms equipped with CT, intraoperative real-time CT-guided localization of pulmonary nodules has been implemented in many institutions and has achieved significant improvements in precision and safety [ 12 ], changes in the patient's intraoperative position can cause shifts in the relative anatomical position of the nodule and the chest wall, often necessitating multiple repeated CT scans to further confirm the location of the nodule [ 13 ]. Moreover, many institutions do not have hybrid operating rooms equipped with CT scanners. Therefore, further optimization is needed to develop more simplified and timely methods for pulmonary nodule localization. Specifically, there is an urgent need for a straightforward localization technique that can be directly implemented in the operating room. Given the complexities of pulmonary nodule localization, several factors must be considered, including nodule size, location, morphology, body position variations, and the relationship with surrounding structures [ 14 , 15 ]. Changes in body position can significantly impact pulmonary morphology, which in turn affects nodule localization. As body position changes, the ribs shift, altering their position and angle, potentially affecting the trajectory and depth of the puncture needle. Pulmonary tissue moves in coordination with the thoracic cage, with the direction of lung deformation aligning with that of the rib cage. Therefore, the interplay between lung and rib deformation across different body positions may influence both surgical planning and execution. Using rib position for the localization of pulmonary nodules appears to be a promising approach. However, while preliminary studies have begun to characterize patterns of pulmonary deformation under various body positions [ 14 ], the relationship between rib and pulmonary deformation remains poorly understood. This study aims to collect and analyze CT data in both the supine and left lateral decubitus positions to elucidate the relationship between pulmonary tissue and rib deformation across different body positions. Materials and methods Study population This prospective study was conducted from April to May 2024, with approval obtained from the Ethics Committee of Zhujiang Hospital, Southern Medical University. Written informed consent was obtained from all participants. A total of 11 healthy male volunteers were recruited based on predefined inclusion criteria. Participants were excluded if they had a history of smoking, diabetes, hypertension, dyslipidemia, significant pulmonary disease, trauma, prior surgery, or any current symptoms. Multi-detector row computed tomography (MDCT) was performed on all participants. Pulmonary anatomical and morphological measurements were extracted in both two-dimensional (2D) and three-dimensional (3D) formats from the MDCT datasets, followed by comprehensive analysis. CT acquisition High-resolution CT (HRCT) scans were performed on all participants in both the supine and left lateral decubitus positions (Fig. 1 a, 1 b). In the left lateral decubitus position, a 10-cm cushion was placed under the armpit to replicate the surgical setup. The scans were conducted using a 256-slice multidetector CT scanner (Brilliance iCT, Philips, Amsterdam, The Netherlands) during full inspiration. The scanning parameters were as follows: Tube voltage: 120 kVp Tube current: 100–180 mAs Slice thickness: 1.0 mm Slice reconstruction interval: 0.5 mm Pixel matrix: 512 × 512 Window width: -1024 to 3071 HU The scanning field of view extended from the shoulders to the abdomen, covering the full skin contour and thoracic bones. The procedure was supervised by senior radiologists and thoracic surgeons to ensure accurate body positioning, thereby maintaining data integrity and comparability. All scans were performed by the same radiologist on the same day to ensure consistency. Lung and Lobe Volume Measurements In this study, we utilized Smart Vision 3DVWorks medical imaging software (Shenzhen Yitu Intelligent Technology Co., Ltd.) to conduct 3D volumetric assessments of the lungs and their respective lobes in our cohort. The software's advanced image processing capabilities enabled the automatic extraction of left and right lung images, identification of lobar bronchi, and precise delineation of fissures (Fig. 2 a, 2 b). To ensure the accuracy of segmentation, two experienced thoracic surgeons, each with over five years of clinical experience, independently reviewed the lobar segmentation results. In cases where the automated identification of interlobar fissures was suboptimal, manual adjustments to the segmentation were made by the surgeons. To enhance the reliability of the findings, pulmonary volume measurements for all 11 volunteers were cross-validated through independent assessments by both surgeons. Subsequently, we performed a comparative analysis of volumetric differences in the right lung and its lobes between the supine and left lateral decubitus positions. Lung Morphology Quantified Using 2D Imaging CT imaging was used to comprehensively assess the morphological parameters of the right lung, with measurements obtained along the three principal anatomical axes: Lung width (axial plane) The maximum distance from the inner to the outer edge of the lung, measured at the midline plane of the seventh thoracic intervertebral disc (Fig. 3 a). Lung height (coronal plane) The vertical distance from the pulmonary apex to the most cephalic superior point of the hemidiaphragm, measured on the coronal plane corresponding to the position of the pulmonary apex (Fig. 3 b). Lung depth (sagittal plane) The maximum anteroposterior distance between the anterior and posterior borders of the lung, measured on the sagittal CT scan (Fig. 3 c). Hemidiaphragmatic width (coronal plane) The distance between the lateral and medial attachment points of the diaphragm (Fig. 3 b). Hemidiaphragmatic height (coronal plane) The vertical distance from the apex of the diaphragm to the line that marks the hemidiaphragmatic width (Fig. 3 b). Protocol for Investigating the Interrelationship Between Rib and Lung Pulmonary Tissue Deformation After acquiring the imaging data, DICOM-formatted images were processed using 3DVWorks software to reconstruct the lung tissue and rib structures (Fig. 4 a). Subsequently, the open-source software package ParaView (Kitware Inc., Clifton Park, NY) was used to align and fit the ribs and lung tissue in both the supine and left lateral decubitus positions, with the sternum serving as a reference point (Fig. 4 b- 4 d). The sternum, which remains unchanged in size or shape regardless of body position, helped minimize alignment errors. This methodology enabled the investigation of the deformation relationship between the ribs and lung tissue during positional changes. In the next phase of this study, the intersection points between pulmonary subsegments and their branching vessels were identified as reference centers for analysis (Fig. 5 a). The Sphere tool in 3DVWorks was then used to simulate pulmonary nodules, thereby modeling localized pathological structures (Fig. 5 b, 5 c). Spherical structures with a radius of 5 mm were placed in lung tissue regions adjacent to the anterior, lateral, and posterior ribs to simulate pulmonary nodules. The precise localization of these vascular intersections was verified by two experienced thoracic surgeons to ensure consistency and minimize variability, thereby enhancing the scientific rigor and accuracy of the research. In the advanced phase of this study, a 3D reconstruction of the cortical bone segment of the right ribs was performed in two distinct positions. The central axis of the ribs was subsequently delineated using the 3DVWorks software. Based on the original CT scan data of the participants, the central axis of each rib was divided into four equal segments, resulting in the identification of five key coordinate points: the rib head, posterior rib, lateral rib, anterior-lateral rib, and anterior rib (Fig. 5 d). Further analysis of the central axis and coordinate points was performed in 3DVWorks software. Pulmonary nodules were simulated in three lung regions—upper, middle, and lower—comprising 6, 5, and 10 nodules, respectively. The distances from the centroid of each pulmonary nodule to the corresponding coordinate points along the central axis of the adjacent ribs were measured (Fig. 5 e, 5 f), and statistical analysis was conducted. Statistical Analysis Continuous variables that followed a normal distribution were expressed as mean ± standard deviation (SD). Paired t-tests were employed to compare the volumes of the right lung and individual lobes between the supine and lateral decubitus positions, to assess changes in two-dimensional (2D) linear indices, and to evaluate differences in the distances from pulmonary nodules to their corresponding ribs. A P-value of less than 0.05 was considered to indicate statistical significance. All statistical analyses were performed using SPSS software (version 27.0; IBM SPSS Corp., Armonk, NY, USA). Result The clinical characteristics of the participants are summarized in Table 1 . The study population was predominantly male, with a mean age of 27.82 ± 6.66 years, a mean height of 172.36 ± 6.87 cm, and a mean weight of 67.81 ± 9.13 kg. The mean body mass index (BMI) was 22.83 ± 2.96. Table 1 Participants characteristics Demographic variables average ± SD or n range Number of participants (n) 11 Sex Male 11 Age (years) 27.82 ± 6.66 23–45 Height(cm) 172.36 ± 6.87 165–185 Weight(kg) 67.81 ± 9.13 50–78 Body mass index 22.83 ± 2.96 18.37–27.18 The lung volumes and 2D linear indices are summarized in Table 2 . No significant difference was observed in the volume of the right middle lobe between the supine and left lateral decubitus positions (503.29 ± 178.42 mL vs. 436.12 ± 144.56 mL, P = 0.251). However, significant increases were found in the right upper lobe volume (934.38 ± 267.12 mL vs. 996.52 ± 212.26 mL, P = 0.043), the right lower lobe volume (1258.31 ± 368.41 mL vs. 1496.47 ± 247.27 mL, P = 0.012), and the total right lung volume (2653.03 ± 604.18 mL vs. 2930.43 ± 507.67 mL, P = 0.012) in the left lateral decubitus position compared to the supine position. Table 2 Lung volume and 2D linear indices Supine position Average ± SD (Range) Left lateral decubitus position Average ± SD (Range) Ratio of volume in supine position to that in supine position Average ± SD (Range) P value Right lung volume (ml) Upper lobe 934.38 ± 267.122 (558.73-1389.70) 996.52 ± 212.26 (688.26-1326.42) 0.93 ± 0.10 (0.7–1.05) 0.043 Middle lobe 503.29 ± 178.42 (283.13-922.96) 436.12 ± 144.56 (141.88-648.469) 1.28 ± 0.67 (0.85–2.73) 0.251 Lower lobe 1258.31 ± 368.41 (661.74-1796.99) 1496.47 ± 247.27 (141.88-648.469) 0.84 ± 0.17 (0.85–2.73) 0.012 Total lung 2653.03 ± 604.18 (1566.74-3692.81) 2930.43 ± 507.67 (1864.3-3763.28) 0.90 ± 0.09 (0.76–1.06) 0.004 Linear indices (mm) Lung width 124.35 ± 8.79 127.60 ± 7.79 0.132 Lung height 221.24 ± 36.35 236.20 ± 28.93 0.048 Lung depth 159.73 ± 27.11 165.84 ± 20.16 0.358 Hemidiaphragm width 115.56 ± 14.15 109.76 ± 11.09 0.153 Hemidiaphragm height 37.426 ± 4.85 44.44 ± 7.34 0.003 In terms of linear indices, significant increases were observed in lung height (221.24 ± 36.35 mm vs. 236.20 ± 28.93 mm, P = 0.048) and hemidiaphragm height (37.43 ± 4.85 mm vs. 44.44 ± 7.34 mm, P = 0.03) in the left lateral decubitus position compared to the supine position. In contrast, no significant differences were found in lung width (124.35 ± 8.79 mm vs. 127.60 ± 7.79 mm, P = 0.132), lung depth (221.24 ± 36.35 mm vs. 165.84 ± 20.16 mm, P = 0.358), or hemidiaphragm width (115.56 ± 14.15 mm vs. 109.76 ± 11.09 mm, P = 0.153) between the supine and left lateral decubitus positions. Table 3 presents a comparative analysis of the distances from pulmonary nodules to ribs across the upper, middle, and lower lobes of the right lung in both the supine and left lateral decubitus positions. Measurements for the lower lobe were excluded for two subjects due to inconsistencies in the depth of inspiration. Table 3 Measurement of nodule-to-rib in the upper, middle and lower lobes of lungs in supine and left lateral decubitus positions 95% Confidence Interval of the Difference Supine position minus left side position Costal parenchymal bone Supine position (mm) Left lateral decubitus (mm) Mean ± SD Lower Upper Lower Upper P Right upper lobe Caput costae 84.84 ± 27.48 83.75 ± 28.35 1.09 ± 3.74 0.17 2.01 -6.1 10.11 0.021 Posterior lateral rib 73.34 ± 35.49 73.99 ± 35.54 -0.65 ± 3.42 -1.49 0.19 -13 9.56 0.128 Lateral rib 55.53 ± 25.42 56.88 ± 25.09 -1.35 ± 3.49 -2.21 -0.49 -12.79 6.58 0.003 Anterolateral rib 65.58 ± 33.86 66.53 ± 34.30 -0.95 ± 4.01 -1.94 0.03 -11.45 9.37 0.058 Anterior rib 95.17 ± 95.17 96.13 ± 48.13 -0.95 ± 3.91 -1.91 0.01 -12.17 11.58 0.052 Right middle lobe Caput costae 139.79 ± 20.26 137.68 ± 21.18 2.11 ± 2.82 1.35 2.87 -3.54 8.01 <0.001 Posterior lateral rib 139.62 ± 30.97 139.62 ± 31.22 0.471 ± 2.139 -0.11 1.05 -4.08 6.94 0.108 Lateral rib 91.01 ± 33.40 91.31 ± 33.64 -0.3 ± 2.46 -0.97 0.36 -5.48 5.7 0.368 Anterolateral rib 50.03 ± 20.02 51.31 ± 19.52 -1.29 ± 3.46 -2.22 -0.35 -8.56 5.5 0.008 Anterior rib 53.25 ± 32.36 54.66 ± 33.37 -1.41 ± 2.4 -2.05 -0.76 -7.47 3.58 <0.001 Right lower lobe Caput costae 91.31 ± 40.50 95.78 ± 41.15 -4.47 ± 5.49 -5.62 -3.33 -18.41 4.5 <0.001 Posterior lateral rib 75.68 ± 45.65 82.12 ± 47.42 -6.44 ± 6.82 -7.86 -5.02 -25.37 5.63 <0.001 Lateral rib 55.9 ± 26.43 59.08 ± 28.08 -3.19 ± 8.260 -4.91 -1.47 -27.07 14.46 <0.001 Anterolateral rib 74.98 ± 34.72 70.55 ± 33.47 4.43 ± 8.00 2.76 6.09 -18.55 24.22 <0.001 Anterior rib 116.98 ± 45.26 109.32 ± 45.64 7.66 ± 7.19 6.17 9.16 -3.77 27.93 <0.001 Figure 6 shows box plots illustrating the distances between pulmonary nodules and the centerline coordinates of each rib, providing a visual representation of the positional changes in rib-nodule distances. In the right upper lobe, a significant decrease of 1.09 ± 3.74 mm in the distance to the rib head (caput costae) was observed when transitioning from the supine to the left lateral decubitus position (p = 0.021), with the 95% confidence interval (CI) ranging from − 6.1 mm to 10.11 mm. No significant change was detected in the posterior lateral ribs, with a negligible increase of -0.65 ± 3.42 mm (p = 0.128, 95% CI: -1.49 mm to 0.19 mm). A slight but statistically significant increase of -1.35 ± 3.49 mm was identified in the lateral ribs (p = 0.003, 95% CI: -2.21 mm to -0.49 mm). Non-significant changes were observed in the anterolateral ribs (increase: -0.95 ± 4.01 mm, p = 0.058) and in the anterior ribs (increase: -0.95 ± 3.91 mm, p = 0.052). In the right middle lobe, a modest but statistically significant decrease of 2.11 ± 2.82 mm was observed in the distance to the rib head (caput costae) (p < 0.001, 95% CI: 1.35 mm to 2.87 mm). No significant changes were detected in the posterior lateral or lateral ribs. The posterior lateral ribs showed a slight decrease of 0.47 ± 2.14 mm (p = 0.108), while the lateral ribs demonstrated a negligible increase of -0.30 ± 2.46 mm (p = 0.368). In contrast, significant increases were identified in the anterolateral and anterior ribs, measuring − 1.29 ± 3.46 mm (p = 0.008, 95% CI: -2.22 mm to -0.35 mm) and − 1.41 ± 2.4 mm (p < 0.001, 95% CI: -2.05 mm to -0.75 mm), respectively. In the right lower lobe, significant changes were observed across various rib regions. The distance to the rib head (caput costae) exhibited a significant increase of -4.47 ± 5.49 mm (p < 0.001, 95% CI: -5.62 mm to -3.33 mm). Similarly, the posterior lateral rib showed a significant increase of -6.44 ± 6.82 mm (p < 0.001, 95% CI: -7.86 mm to -5.02 mm), and the lateral ribs demonstrated a significant increase of -3.19 ± 8.26 mm (p < 0.001, 95% CI: -4.91 mm to -1.47 mm). In contrast, significant decreases were identified in the anterolateral and anterior ribs. The anterolateral region decreased by 4.43 ± 8.00 mm (P < 0.001, 95% CI: 2.76 mm to 6.09 mm), while the anterior region demonstrated a more pronounced decrease of 7.66 ± 7.19 mm (P < 0.001, 95% CI: 6.17 mm to 9.16 mm). Discussion The study demonstrated significant changes in pulmonary volume and morphology as subjects transitioned from the supine to the left lateral decubitus position. Specifically, the volumes of the right upper lobe, right lower lobe, and the total right lung significantly increased in the left lateral decubitus position. In contrast, the volume of the right middle lobe decreased, although this change was not statistically significant. Notably, the right lower lobe exhibited a significantly greater volumetric change compared to the right upper and middle lobes. These findings are consistent with the research of Yamada et al. [ 15 , 16 ], who documented alterations in pulmonary volume associated with the transition from the supine to the upright posture. These differences are potentially attributable to gravitational forces and the associated reconfiguration of the thoracic structure during postural changes. The lower lobes experience greater volume changes than the upper lobes during respiration due to the gravitational effects on lung recoil [ 17 – 19 ]. According to Yamada et al., the greater volume change observed in the lower lobes is attributed to the descent of the diaphragm in the standing position relative to the supine position, which allows greater expansion of the lower lobes. However, our study found that the increase in lung volume in the left lateral decubitus position is associated with a marked increase in the height of the right lung, potentially resulting from lung stretching and gravitational redistribution. This leads to the reorganization of dependent lung tissue. In our study, the elevation of the right hemidiaphragm was significantly increased in the left lateral decubitus position, which may limit lung volume expansion. This elevation is likely due to the compression of alveoli on the dependent side during the lateral decubitus position, leading to increased airway pressure and reduced dynamic compliance [ 20 – 22 ]. Additionally, we observed an increase in lung height without significant changes in lung width or depth. This finding aligns with the observations of Little et al. [ 23 ], further validating the predictable pattern of pulmonary morphological shifts during the transition from the supine to the left lateral decubitus position. Existing literature suggests that prone and forward-leaning positions during ventilation can significantly improve oxygenation indices and reduce ventilation-perfusion mismatch [ 24 – 27 ]. Patients with acute respiratory distress syndrome (ARDS) exhibit a significant reduction in tidal volume in the dorsal regions when positioned supine [ 28 ]. The prone position is recognized as an effective pulmonary protective maneuver, potentially reducing ventilator-associated lung injury [ 29 ]. Shin et al. [ 30 ] elucidated the underlying mechanisms using quantitative CT scan analysis. However, definitive evidence regarding the mechanisms by which the lateral decubitus position improves oxygenation remains limited. Our study provides critical evidence of a significant increase in arterial oxygen partial pressure (PaO2) and the oxygenation index (PaO2/FiO2) associated with the lateral decubitus position. In cases of right-sided atelectasis, the left lateral decubitus position is hypothesized to improve respiratory function and potentially expedite the resolution of atelectasis, though further investigation is needed. It is noteworthy that the left lateral decubitus position could also precipitate atelectasis in the left lung [ 31 ]. In respiratory gating registration and validation, structures with minimal deformation, such as the spine, trachea, and carina, are commonly selected as fiducial points [ 13 , 32 , 33 ]. Metrics such as the Jacobian determinant, anisotropy deformation index, and plate-rod index have been used to quantify local parenchymal deformation [ 13 , 34 ]. These methods have facilitated significant advancements, including the work by Alvarez et al. [ 13 ], which highlights morphological alterations in lung lobes resulting from intraoperative patient positioning changes. The sternum, due to its morphological stability across different body positions, was used as a reference for registration and calibration, with pulmonary deformation analyzed using Paraview software. Registration fitting was performed on the ribs and lungs of 11 subjects, revealing a consistent pattern of lung deformation during the transition from the supine to the left lateral decubitus position. This deformation was characterized by anterior, lateral, and inferior displacement of lung tissue. These findings are consistent with those of Alvarez et al., who observed significant displacement in the anterior and basal lung regions adjacent to the sternum and diaphragm. However, our findings highlight the posterior and basal areas of the lung. Notably, the anterior portion of the lung exhibited significantly less displacement than the posterior portion, indicating that posterior deviation is not predominantly due to forward lung rotation. Instead, this deviation appears to result from an increase in lung volume, elevation in lung height, and caudal expansion of the lung surface. Nevertheless, the potential influence of peripheral forward rotation on this difference cannot be disregarded. Jahani et al. [ 35 ] demonstrated that, due to its lower elasticity and higher compliance, lung tissue at lower lung volumes undergoes greater deformation, with the upper and middle lobes reaching full expansion earlier than the lower lobes. This finding supports the idea that greater deformation of the lower lung indirectly contributes to the significantly smaller anterior displacement of the lung compared to the posterior portion. Additionally, five points along the centerline of each rib were connected, and the resulting direction and magnitude of rib deformation after registration were observed (Fig. 7 ). The lateral deformation observed in our study may be associated with the use of axillary pads to simulate surgical positioning. Despite the lack of quantitative data on the extent of lung deformation, the registration and fitting process enabled the identification of general trends in lung morphological changes. In this study, systematic observation and analysis revealed that the morphological changes during the transition from the supine to the left lateral decubitus position are consistent with rib deformation. However, the existing literature lacks a definitive explanation of the specific deformities involved. To address this gap, a novel quantitative methodology was introduced to investigate the intricate interplay between pulmonary tissue and rib mechanics. To accurately simulate pulmonary nodules, we constructed nodules with a diameter of 1 cm, centered at the subsegmental bronchi or their branching vessels. This placement reflects the close association between pulmonary nodules and blood vessels [ 36 , 37 ]. This approach effectively reproduces the deformation characteristics of ground-glass opacity (GGO) and normal pulmonary tissues. However, discrepancies may arise in the deformation patterns of solid nodules [ 38 ]. The interplay between lung tissue and rib deformation was quantified by measuring the distances from the centroids of the simulated pulmonary nodules to the central rib axes at various coordinate points. Given that the overall length of the ribs remains fixed across different body positions, with changes occurring only in their shape and orientation, this method of deformation analysis using the bisected rib centerline is considered reliable. The findings suggest that the deformation disparities between the right upper and right middle lobes of the lung are minimal during positional changes. Specifically, no statistically significant differences were observed in the distances from the right upper lobe nodule to the posterior lateral, anterolateral, and anterior ribs. Although statistically significant differences were identified in the distances from the caput costae and lateral rib to the pulmonary nodule, these differences were minor, with an average of less than 2 millimeters and a maximum of 13 millimeters. In the right middle lobe, no statistically significant differences were observed in the distances from the posterior lateral rib and lateral rib to the pulmonary nodule. In contrast, while statistically significant differences were identified in the distances from the caput costae, anterolateral rib, and anterior rib to the pulmonary nodule, these differences were also minor, with an average of approximately 2 millimeters and a maximum of less than 9 millimeters. The differences observed in the caput costae and lateral rib may be attributable to the effect of the axillary pad. In the right lower lobe, statistically significant differences were observed in the distances from pulmonary nodules to the ribs, with considerable variations, including a maximum discrepancy of 27 millimeters. The study concludes that, after transitioning from the supine to the left lateral decubitus position, the deformation of the right upper and middle lobes relative to the ribs is generally consistent, although some localized differences are observed. However, the differences in rib deformation in these areas are relatively minor. In contrast, the deformation of the right lower lobe relative to the ribs shows significant differences. The observed differences in the right upper lobe are likely due to an increase in lung volume and interference from the subpleural pad. The variations in the middle lobe are primarily attributed to a reduction in lung volume and the effect of the axillary pad. The disparities in the right lower lobe are mainly driven by a combination of increased lung volume, lobar sliding, and rib deformation. Study Limitations and Future Perspectives This study has several limitations. First, the sample size is relatively small, and only male participants were included, which may limit the generalizability of the findings. Future research should aim to increase the sample size and include participants of different genders and age groups to enhance the applicability of the results. Additionally, while this study primarily focused on the impact of positional changes on pulmonary morphology, future investigations should consider other factors, such as the respiratory cycle and changes in pleural pressure, which may also influence lung deformation. Despite these limitations, the findings provide a valuable scientific foundation for the potential application of virtual reality technology in localizing pulmonary nodules using preoperative supine CT scans. Future research could further explore how these data can be leveraged to optimize surgical planning, reduce complications, and improve surgical efficiency. Furthermore, these findings could be integrated into robot-assisted surgery and augmented reality technologies to enhance the precision of pulmonary nodule localization. Conclusions In summary, significant changes in lung volume and morphology were observed during the transition from the supine to the left lateral decubitus position. Specifically, the volume of the right upper lobe, right lower lobe, and the entire right lung significantly increased in the left lateral decubitus position, while the volume of the right middle lobe showed no significant variation. Notably, the volume change in the right lower lobe was substantially greater than that in the right upper and middle lobes. This study quantified the relationship between lung tissue and rib deformation by simulating pulmonary nodules and measuring the distances from their centroids to various coordinate points along the rib centerline. During positional changes, the deformation differences between the right upper lobe and the ribs, as well as between the right middle lobe and the ribs, were relatively minor. In contrast, the deformation relationship between the right lower lobe and the ribs showed significant differences. These discrepancies are likely attributable to a combination of increased lung expansion volume, lobar sliding, and rib deformation. Declarations Ethics approval and consent to participate All the study protocols were conducted in accordance with the ethical guidelines of the Declaration of Helsinki. This study was approved by the Ethics Committee of Zhujiang Hospital, Southern Medical University and was conducted in accordance with the regulations of the Ethics Committee of Zhujiang Hospital, Southern Medical University. Informed consent was obtained from all recruited participants. Consent for publication Not applicable. Competing interests The authors declare no competing interests. Funding: This study was supported in part by the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2023A1515012587), Shenzhen Scientific and Technology Program Grant (Grant No. JCYJ20220531100614032), and Shenzhen Medical Research Fund (Grant No. D2402006). Author Contribution MC, HL, and HL contribured to study design, imaging evaluation, and manuscript editing. WZ, ZL, and ZH contribured to provision of study materials or patients. YH, BR, and YW contribured to data collection and analysis. FZ, YW, AND HL contribured to data interpretation. All authors reviewed the manuscript. Acknowledgements Not applicable. Data Availability The raw datasets used during the current study are available from the cor responding author on reasonable request. References Hsu HH, Shen CH, Tsai WC et al. Localization of nonpalpable pulmonary nodules using CT-guided needle puncture. World J Surg Oncol. 2015;13:248. Published 2015 Aug 15. 10.1186/s12957-015-0664-9 Park CH, Han K, Hur J, et al. Comparative Effectiveness and Safety of Preoperative Lung Localization for Pulmonary Nodules: A Systematic Review and Meta-analysis. Chest. 2017;151(2):316–28. 10.1016/j.chest.2016.09.017 . Zhou G, Chen X, Niu B, et al. Intraoperative localization of small pulmonary nodules to assist surgical resection: A novel approach using a surgical navigation puncture robot system. Thorac Cancer. 2020;11(1):72–81. Wang Y, Chen E. Advances in the localization of pulmonary nodules: a comprehensive review. J Cardiothorac Surg. 2024;19(1):396. 10.1186/s13019-024-02911-8 . Published 2024 Jun 27. 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Prone position ameliorates lung elastance and increases functional residual capacity independently from lung recruitment. Intensive Care Med Exp. 2015;3(1):55. 10.1186/s40635-015-0055-0 . Ubolnuar N, Tantisuwat A, Mathiyakom W, Thaveeratitham P, Kruapanich C. Effect of pursed-lip breathing and forward trunk lean positions on regional chest wall volume and ventilatory pattern in older adults: An observational study. Med (Baltim). 2022;101(4):e28727. 10.1097/MD.0000000000028727 . Puybasset L, Cluzel P, Chao N, Slutsky AS, Coriat P, Rouby JJ. A computed tomography scan assessment of regional lung volume in acute lung injury. The CT Scan ARDS Study Group. Am J Respir Crit Care Med. 1998;158(5 Pt 1):1644–55. 10.1164/ajrccm.158.5.9802003 . Galiatsou E, Kostanti E, Svarna E, et al. Prone position augments recruitment and prevents alveolar overinflation in acute lung injury. Am J Respir Crit Care Med. 2006;174(2):187–97. 10.1164/rccm.200506-899OC . Shin KM, Choi J, Chae KJ et al. Quantitative CT-based image registration metrics provide different ventilation and lung motion patterns in prone and supine positions in healthy subjects. Respir Res. 2020;21(1):254. Published 2020 Oct 2. 10.1186/s12931-020-01519-5 David P, Pompeo E, Fabbi E, Dauri M. Surgical pneumothorax under spontaneous ventilation-effect on oxygenation and ventilation. Ann Transl Med. 2015;3(8):106. 10.3978/j.issn.2305-5839.2015.03.53 . Al-Mayah A, Moseley J, Velec M, Hunter S, Brock K. Deformable image registration of heterogeneous human lung incorporating the bronchial tree. Med Phys. 2010;37(9):4560–71. 10.1118/1.3471020 . van der Weide L, van Sörnsen de Koste JR, Lagerwaard FJ, et al. Analysis of carina position as surrogate marker for delivering phase-gated radiotherapy. Int J Radiat Oncol Biol Phys. 2008;71(4):1111–7. 10.1016/j.ijrobp.2007.11.027 . Ruhaak J, Polzin T, Heldmann S, et al. Estimation of Large Motion in Lung CT by Integrating Regularized Keypoint Correspondences into Dense Deformable Registration. IEEE Trans Med Imaging. 2017;36(8):1746–57. 10.1109/TMI.2017.2691259 . Jahani N, Yin Y, Hoffman EA, Lin CL. Assessment of regional non-linear tissue deformation and air volume change of human lungs via image registration. J Biomech. 2014;47(7):1626–33. 10.1016/j.jbiomech.2014.02.040 . Gao F, Li M, Ge X, et al. Multi-detector spiral CT study of the relationships between pulmonary ground-glass nodules and blood vessels. Eur Radiol. 2013;23(12):3271–7. 10.1007/s00330-013-2954-3 . Zhao B, Wang X, Sun K, et al. Correlation Between Intranodular Vessels and Tumor Invasiveness of Lung Adenocarcinoma Presenting as Ground-glass Nodules: A Deep Learning 3-Dimensional Reconstruction Algorithm-based Quantitative Analysis on Noncontrast Computed Tomography Images. J Thorac Imaging. 2023;38(5):297–303. 10.1097/RTI.0000000000000731 . Weiss E, Wijesooriya K, Dill SV, Keall PJ. Tumor and normal tissue motion in the thorax during respiration: Analysis of volumetric and positional variations using 4D CT. Int J Radiat Oncol Biol Phys. 2007;67(1):296–307. 10.1016/j.ijrobp.2006.09.009 . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 29 Jun, 2025 Reviewers invited by journal 11 Jun, 2025 Editor invited by journal 22 May, 2025 Editor assigned by journal 06 May, 2025 Submission checks completed at journal 03 May, 2025 First submitted to journal 03 May, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6416423","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":470536432,"identity":"88e7df44-18d6-4a5f-94b6-524819e563be","order_by":0,"name":"Maodan Chen","email":"","orcid":"","institution":"Zhujiang Hospital, Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Maodan","middleName":"","lastName":"Chen","suffix":""},{"id":470536433,"identity":"06405b3e-8c8d-4b5e-b8de-373a68cd55d3","order_by":1,"name":"Yang Huang","email":"","orcid":"","institution":"Zhujiang Hospital, Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yang","middleName":"","lastName":"Huang","suffix":""},{"id":470536434,"identity":"f3fc60af-0b16-4f07-a14d-75294c40d9cf","order_by":2,"name":"Zhiping Huang","email":"","orcid":"","institution":"Zhujiang Hospital, Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Zhiping","middleName":"","lastName":"Huang","suffix":""},{"id":470536435,"identity":"7f5bd966-d50b-4191-9815-81453e331655","order_by":3,"name":"Wenfei Zhu","email":"","orcid":"","institution":"Zhujiang Hospital, Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Wenfei","middleName":"","lastName":"Zhu","suffix":""},{"id":470536436,"identity":"19483196-ab8b-4850-86f6-55eb323f4a6d","order_by":4,"name":"Zewei Li","email":"","orcid":"","institution":"Zhujiang Hospital, Southern Medical 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University","correspondingAuthor":true,"prefix":"","firstName":"Hui","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2025-04-10 04:53:30","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6416423/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6416423/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":84721188,"identity":"80eeff23-8189-43e6-aea2-013762fc7873","added_by":"auto","created_at":"2025-06-16 15:07:23","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1671357,"visible":true,"origin":"","legend":"\u003cp\u003eCT scans were performed on subjects in both the supine and left lateral decubitus positions. \u003cstrong\u003e(a)\u003c/strong\u003e In the supine position, subjects underwent a conventional CT scan with their arms raised above their head and holding a deep inspiratory breath. \u003cstrong\u003e(b) \u003c/strong\u003eIn the left lateral decubitus position, the arms were positioned laterally, and a deep inspiratory breath-hold was similarly maintained.To replicate the surgical setup, a 10-cm cushion was placed beneath the armpit.\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-6416423/v1/04aaa7e53dadc6c2492b63ab.png"},{"id":84722527,"identity":"ec202bfb-37d8-44ba-ad13-54e82a9cfc1a","added_by":"auto","created_at":"2025-06-16 15:15:23","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1199579,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative segmentation and volumetric assessments of the lung lobes in a subject. The color coding is as follows: red indicates the right upper lobe, yellow indicates the right middle lobe, brown indicates the right lower lobe, blue indicates the left upper lobe, and purple indicates the left lower lobe. \u003cstrong\u003e(a) \u003c/strong\u003eVolumetric assessment of the right lung in the supine position.\u003cstrong\u003e (b)\u003c/strong\u003e Volumetric assessment of the right lung in the left lateral decubitus position.\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-6416423/v1/503c0d7c5363a5c968af9928.png"},{"id":84722526,"identity":"1e6bc6b8-b9ca-4140-9111-b6563f391ee4","added_by":"auto","created_at":"2025-06-16 15:15:23","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1985683,"visible":true,"origin":"","legend":"\u003cp\u003e2D Linear indices of the three principal anatomical axes. \u003cstrong\u003e(a)\u003c/strong\u003e Lung width is measured as the distance from the inner edge to the outer edge of the lung, indicated by the solid red line on the axial plane at the centroid of the seventh thoracic intervertebral disc. The red dot marks the centroid of the seventh thoracic disc. \u003cstrong\u003e(b) \u003c/strong\u003eLung height is defined as the vertical distance from the lung apex to the highest point of the diaphragmatic dome in the coronal CT plane (upper arrow). Hemidiaphragmatic width is measured laterally between the lateral and medial attachment points of the diaphragm (lower arrow). Hemidiaphragmatic height is the perpendicular distance from the apex of the diaphragm to the line marking the hemidiaphragmatic width (middle arrow). \u003cstrong\u003e(c) \u003c/strong\u003eLung depth is defined as the maximum anteroposterior distance between the anterior and posterior edges of the lung in the sagittal CT plane.\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-6416423/v1/a51319a1e5f54bd65b1e95ab.png"},{"id":84722528,"identity":"cce8f0c6-5132-4053-aa13-03c4d0891642","added_by":"auto","created_at":"2025-06-16 15:15:23","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1936715,"visible":true,"origin":"","legend":"\u003cp\u003e3D reconstruction and positional alignment of lung tissue and ribcage. In the visualizations, the ribcage and lung tissue in the supine position are shown in light blue, while those in the left lateral decubitus position are depicted in transparent brown. The deformation of the lung closely follows that of the ribcage, with significant anterior, lateral, and inferior displacement of the lung tissue observed when transitioning from the supine to the left lateral decubitus position. \u003cstrong\u003e(a)\u003c/strong\u003e 3D reconstruction of lung tissue and ribcage.\u003cstrong\u003e (b)\u003c/strong\u003e Anterior view.\u003cstrong\u003e (c) \u003c/strong\u003eRight lateral view. \u003cstrong\u003e(d) \u003c/strong\u003ePosterior view.\u003c/p\u003e","description":"","filename":"Fig.4.png","url":"https://assets-eu.researchsquare.com/files/rs-6416423/v1/ab1ca1856adf20cf8e53aeab.png"},{"id":84721194,"identity":"3eb3cf50-9c9d-462d-8ccc-d1ec4556cf21","added_by":"auto","created_at":"2025-06-16 15:07:23","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1967921,"visible":true,"origin":"","legend":"\u003cp\u003eReconstruction of pulmonary nodules, ribs, and the rib centerline. \u003cstrong\u003e(a) \u003c/strong\u003eA 1-cm diameter nodule is marked using the intersection of pulmonary subsegments or branch vessels as the central point (supine view shown on the left, left lateral view shown on the right). \u003cstrong\u003e(b, c) \u003c/strong\u003eVisualization of the right rib and simulated pulmonary nodules. \u003cstrong\u003e(d)\u003c/strong\u003eIllustration of the process of dividing the central axis of ribs 2-11 on the right into four segments, creating five coordinate points. \u003cstrong\u003e(e, f) \u003c/strong\u003eMeasurement of distances from pulmonary nodules in the upper, middle, and lower lung regions to the five division points on the adjacent ribs.\u003c/p\u003e","description":"","filename":"Fig.5.png","url":"https://assets-eu.researchsquare.com/files/rs-6416423/v1/12dcd385f88a1162e00795a9.png"},{"id":84722529,"identity":"dba21efd-3221-4cec-b58f-9b3700b82c71","added_by":"auto","created_at":"2025-06-16 15:15:23","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":405916,"visible":true,"origin":"","legend":"\u003cp\u003eBox plots showing the distances between pulmonary nodules and the centerline coordinates of each rib. Color-coded by body positions (supine: blue; left lateral decubitus: dark green). The x-axis represents the rib coordinate points, while the y-axis indicates the corresponding distances.\u003c/p\u003e","description":"","filename":"Fig.6.png","url":"https://assets-eu.researchsquare.com/files/rs-6416423/v1/b5acc8287f87b1dfa3606729.png"},{"id":84722531,"identity":"54dbd917-cba4-4190-8c8c-24f912a2e46f","added_by":"auto","created_at":"2025-06-16 15:15:23","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":3272422,"visible":true,"origin":"","legend":"\u003cp\u003eVisualization of rib deformation during positional change. After connecting the corresponding coordinate points along the centerline of each rib and performing fitting, the direction and magnitude of rib deformation were clearly observed as the body transitions from the supine to the left lateral decubitus position. Six sets of images were used to observe rib deformation from different angles.\u003c/p\u003e","description":"","filename":"Fig.7.png","url":"https://assets-eu.researchsquare.com/files/rs-6416423/v1/a3b870a6950c45e6c20f0d67.png"},{"id":84723893,"identity":"e894c803-8b98-496e-bf59-e93cd6193b82","added_by":"auto","created_at":"2025-06-16 15:31:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":12344169,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6416423/v1/0ce380ff-f1ee-47e6-bfe9-9b94c5331d76.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Effect of Body Postural Changes on the Relationship Between Pulmonary Tissue and Rib Deformation: A Study Based on High-Resolution CT and 3D Reconstruction","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAccurate localization of pulmonary nodules is essential for early detection and effective therapeutic intervention in lung cancer [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. To improve the success rates of video-assisted thoracoscopic surgery (VATS) and reduce the need for open thoracotomies, various preoperative localization techniques have been developed [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The increasing use of high-resolution chest CT has significantly enhanced the detection of lung nodules [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Currently, the clinical standard for lung nodule localization involves a multimodal approach, combining preoperative CT-guided techniques\u0026mdash;such as methylene blue injection, sclerosing agent injection, or hook wire placement\u0026mdash;with advanced technologies like bronchscopic assistance, 3D printing, robotic assistance, 3D reconstruction, and augmented reality (AR) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. For small nodules (\u0026lt;\u0026thinsp;1 cm), those located deep within the pleura, or those with ground-glass or subsolid features, CT-guided needle localization is often the preferred method in many hospitals [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. However, in most hospitals, this localization is not performed intraoperatively in real-time but preoperatively under conscious sedation, with a significant waiting period between localization and surgery. This not only increases patient anxiety and pain but also poses risks such as pneumothorax, bleeding, air embolism, and detachment of the localization needle [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSeveral intraoperative pulmonary nodule localization techniques have been explored and implemented, including electromagnetic navigation bronchoscopy (ENB), intraoperative ultrasound localization, and fluorescent thoracoscopy [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Each method has its unique advantages and limitations. For example, electromagnetic navigation bronchoscopy (ENB) is limited by its high cost and complex procedures. Intraoperative ultrasound localization, which is appreciated for its radiation-free and cost-effective features, faces challenges in localizing pulmonary nodules smaller than 1 cm or those with ground-glass opacity (GGO) features, due to the reflection and scattering of ultrasound waves by air within the lung tissue, which affects the penetration and signal quality of the ultrasound. Fluorescent thoracoscopy, while advantageous in some aspects, requires specialized fluorescent thoracoscopy equipment and struggles with deep-seated nodule localization and delineating the margins of pure ground-glass opacity nodules due to limited fluorescence penetration [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. To address these challenges, ongoing research aims to improve localization accuracy, reduce procedural complications, optimize surgical workflows, and enable real-time localization during surgery.\u003c/p\u003e \u003cp\u003eAlthough with the continuous updates of imaging equipment and software, as well as the emergence of hybrid operating rooms equipped with CT, intraoperative real-time CT-guided localization of pulmonary nodules has been implemented in many institutions and has achieved significant improvements in precision and safety [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], changes in the patient's intraoperative position can cause shifts in the relative anatomical position of the nodule and the chest wall, often necessitating multiple repeated CT scans to further confirm the location of the nodule [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Moreover, many institutions do not have hybrid operating rooms equipped with CT scanners. Therefore, further optimization is needed to develop more simplified and timely methods for pulmonary nodule localization. Specifically, there is an urgent need for a straightforward localization technique that can be directly implemented in the operating room.\u003c/p\u003e \u003cp\u003eGiven the complexities of pulmonary nodule localization, several factors must be considered, including nodule size, location, morphology, body position variations, and the relationship with surrounding structures [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Changes in body position can significantly impact pulmonary morphology, which in turn affects nodule localization. As body position changes, the ribs shift, altering their position and angle, potentially affecting the trajectory and depth of the puncture needle. Pulmonary tissue moves in coordination with the thoracic cage, with the direction of lung deformation aligning with that of the rib cage. Therefore, the interplay between lung and rib deformation across different body positions may influence both surgical planning and execution.\u003c/p\u003e \u003cp\u003eUsing rib position for the localization of pulmonary nodules appears to be a promising approach. However, while preliminary studies have begun to characterize patterns of pulmonary deformation under various body positions [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], the relationship between rib and pulmonary deformation remains poorly understood. This study aims to collect and analyze CT data in both the supine and left lateral decubitus positions to elucidate the relationship between pulmonary tissue and rib deformation across different body positions.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003e This prospective study was conducted from April to May 2024, with approval obtained from the Ethics Committee of Zhujiang Hospital, Southern Medical University. Written informed consent was obtained from all participants. A total of 11 healthy male volunteers were recruited based on predefined inclusion criteria. Participants were excluded if they had a history of smoking, diabetes, hypertension, dyslipidemia, significant pulmonary disease, trauma, prior surgery, or any current symptoms. Multi-detector row computed tomography (MDCT) was performed on all participants. Pulmonary anatomical and morphological measurements were extracted in both two-dimensional (2D) and three-dimensional (3D) formats from the MDCT datasets, followed by comprehensive analysis.\u003c/p\u003e \u003cp\u003eCT acquisition\u003c/p\u003e \u003cp\u003eHigh-resolution CT (HRCT) scans were performed on all participants in both the supine and left lateral decubitus positions (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). In the left lateral decubitus position, a 10-cm cushion was placed under the armpit to replicate the surgical setup. The scans were conducted using a 256-slice multidetector CT scanner (Brilliance iCT, Philips, Amsterdam, The Netherlands) during full inspiration. The scanning parameters were as follows:\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTube voltage: 120 kVp\u003c/p\u003e \u003cp\u003eTube current: 100–180 mAs\u003c/p\u003e \u003cp\u003eSlice thickness: 1.0 mm\u003c/p\u003e \u003cp\u003eSlice reconstruction interval: 0.5 mm\u003c/p\u003e \u003cp\u003ePixel matrix: 512 × 512\u003c/p\u003e \u003cp\u003eWindow width: -1024 to 3071 HU\u003c/p\u003e \u003cp\u003eThe scanning field of view extended from the shoulders to the abdomen, covering the full skin contour and thoracic bones. The procedure was supervised by senior radiologists and thoracic surgeons to ensure accurate body positioning, thereby maintaining data integrity and comparability. All scans were performed by the same radiologist on the same day to ensure consistency.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eLung and Lobe Volume Measurements\u003c/h3\u003e\n\u003cp\u003eIn this study, we utilized Smart Vision 3DVWorks medical imaging software (Shenzhen Yitu Intelligent Technology Co., Ltd.) to conduct 3D volumetric assessments of the lungs and their respective lobes in our cohort. The software's advanced image processing capabilities enabled the automatic extraction of left and right lung images, identification of lobar bronchi, and precise delineation of fissures (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). To ensure the accuracy of segmentation, two experienced thoracic surgeons, each with over five years of clinical experience, independently reviewed the lobar segmentation results. In cases where the automated identification of interlobar fissures was suboptimal, manual adjustments to the segmentation were made by the surgeons. To enhance the reliability of the findings, pulmonary volume measurements for all 11 volunteers were cross-validated through independent assessments by both surgeons. Subsequently, we performed a comparative analysis of volumetric differences in the right lung and its lobes between the supine and left lateral decubitus positions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eLung Morphology Quantified Using 2D Imaging\u003c/h3\u003e\n\u003cp\u003eCT imaging was used to comprehensively assess the morphological parameters of the right lung, with measurements obtained along the three principal anatomical axes:\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eLung width (axial plane)\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe maximum distance from the inner to the outer edge of the lung, measured at the midline plane of the seventh thoracic intervertebral disc (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eLung height (coronal plane)\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe vertical distance from the pulmonary apex to the most cephalic superior point of the hemidiaphragm, measured on the coronal plane corresponding to the position of the pulmonary apex (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb).\u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eLung depth (sagittal plane)\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe maximum anteroposterior distance between the anterior and posterior borders of the lung, measured on the sagittal CT scan (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec).\u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eHemidiaphragmatic width (coronal plane)\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe distance between the lateral and medial attachment points of the diaphragm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb).\u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eHemidiaphragmatic height (coronal plane)\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe vertical distance from the apex of the diaphragm to the line that marks the hemidiaphragmatic width (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb).\u003c/p\u003e \u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eProtocol for Investigating the Interrelationship Between Rib and Lung Pulmonary Tissue Deformation\u003c/h3\u003e\n \u003cp\u003eAfter acquiring the imaging data, DICOM-formatted images were processed using 3DVWorks software to reconstruct the lung tissue and rib structures (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea). Subsequently, the open-source software package ParaView (Kitware Inc., Clifton Park, NY) was used to align and fit the ribs and lung tissue in both the supine and left lateral decubitus positions, with the sternum serving as a reference point (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb-\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed). The sternum, which remains unchanged in size or shape regardless of body position, helped minimize alignment errors. This methodology enabled the investigation of the deformation relationship between the ribs and lung tissue during positional changes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn the next phase of this study, the intersection points between pulmonary subsegments and their branching vessels were identified as reference centers for analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). The Sphere tool in 3DVWorks was then used to simulate pulmonary nodules, thereby modeling localized pathological structures (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb, \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec). Spherical structures with a radius of 5 mm were placed in lung tissue regions adjacent to the anterior, lateral, and posterior ribs to simulate pulmonary nodules. The precise localization of these vascular intersections was verified by two experienced thoracic surgeons to ensure consistency and minimize variability, thereby enhancing the scientific rigor and accuracy of the research.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn the advanced phase of this study, a 3D reconstruction of the cortical bone segment of the right ribs was performed in two distinct positions. The central axis of the ribs was subsequently delineated using the 3DVWorks software. Based on the original CT scan data of the participants, the central axis of each rib was divided into four equal segments, resulting in the identification of five key coordinate points: the rib head, posterior rib, lateral rib, anterior-lateral rib, and anterior rib (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed). Further analysis of the central axis and coordinate points was performed in 3DVWorks software.\u003c/p\u003e \u003cp\u003ePulmonary nodules were simulated in three lung regions—upper, middle, and lower—comprising 6, 5, and 10 nodules, respectively. The distances from the centroid of each pulmonary nodule to the corresponding coordinate points along the central axis of the adjacent ribs were measured (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ee, \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ef), and statistical analysis was conducted.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eContinuous variables that followed a normal distribution were expressed as mean ± standard deviation (SD). Paired t-tests were employed to compare the volumes of the right lung and individual lobes between the supine and lateral decubitus positions, to assess changes in two-dimensional (2D) linear indices, and to evaluate differences in the distances from pulmonary nodules to their corresponding ribs. A P-value of less than 0.05 was considered to indicate statistical significance. All statistical analyses were performed using SPSS software (version 27.0; IBM SPSS Corp., Armonk, NY, USA).\u003c/p\u003e \u003c/div\u003e "},{"header":"Result","content":"\u003cp\u003eThe clinical characteristics of the participants are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The study population was predominantly male, with a mean age of 27.82 ± 6.66 years, a mean height of 172.36 ± 6.87 cm, and a mean weight of 67.81 ± 9.13 kg. The mean body mass index (BMI) was 22.83 ± 2.96.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eParticipants characteristics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDemographic variables\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eaverage ± SD or n\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003erange\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of participants (n)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27.82 ± 6.66\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23–45\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight(cm)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e172.36 ± 6.87\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e165–185\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight(kg)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67.81 ± 9.13\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50–78\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBody mass index\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22.83 ± 2.96\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.37–27.18\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe lung volumes and 2D linear indices are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. No significant difference was observed in the volume of the right middle lobe between the supine and left lateral decubitus positions (503.29 ± 178.42 mL vs. 436.12 ± 144.56 mL, P = 0.251). However, significant increases were found in the right upper lobe volume (934.38 ± 267.12 mL vs. 996.52 ± 212.26 mL, P = 0.043), the right lower lobe volume (1258.31 ± 368.41 mL vs. 1496.47 ± 247.27 mL, P = 0.012), and the total right lung volume (2653.03 ± 604.18 mL vs. 2930.43 ± 507.67 mL, P = 0.012) in the left lateral decubitus position compared to the supine position.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"±\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"±\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"±\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLung volume and 2D linear indices\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSupine position \u003c/p\u003e \u003cp\u003eAverage ± SD (Range)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLeft lateral decubitus position\u003c/p\u003e \u003cp\u003eAverage ± SD (Range)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRatio of volume in supine position to that in supine position \u003c/p\u003e \u003cp\u003eAverage ± SD (Range)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight lung volume (ml)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUpper lobe\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e934.38 ± 267.122 (558.73-1389.70)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e996.52 ± 212.26 (688.26-1326.42)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e0.93 ± 0.10 (0.7–1.05)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.043\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMiddle lobe\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e503.29 ± 178.42 (283.13-922.96)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e436.12 ± 144.56 (141.88-648.469)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e1.28 ± 0.67 (0.85–2.73)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.251\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLower lobe\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e1258.31 ± 368.41 (661.74-1796.99)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e1496.47 ± 247.27 (141.88-648.469)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e0.84 ± 0.17 (0.85–2.73)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.012\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal lung\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e2653.03 ± 604.18 (1566.74-3692.81)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e2930.43 ± 507.67 (1864.3-3763.28)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e0.90 ± 0.09 (0.76–1.06)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLinear indices (mm)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLung width\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e124.35 ± 8.79\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e127.60 ± 7.79\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.132\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLung height\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e221.24 ± 36.35\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e236.20 ± 28.93\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.048\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLung depth\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e159.73 ± 27.11\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e165.84 ± 20.16\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.358\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHemidiaphragm width\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e115.56 ± 14.15\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e109.76 ± 11.09\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.153\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHemidiaphragm height\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e37.426 ± 4.85\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e44.44 ± 7.34\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIn terms of linear indices, significant increases were observed in lung height (221.24 ± 36.35 mm vs. 236.20 ± 28.93 mm, P = 0.048) and hemidiaphragm height (37.43 ± 4.85 mm vs. 44.44 ± 7.34 mm, P = 0.03) in the left lateral decubitus position compared to the supine position. In contrast, no significant differences were found in lung width (124.35 ± 8.79 mm vs. 127.60 ± 7.79 mm, P = 0.132), lung depth (221.24 ± 36.35 mm vs. 165.84 ± 20.16 mm, P = 0.358), or hemidiaphragm width (115.56 ± 14.15 mm vs. 109.76 ± 11.09 mm, P = 0.153) between the supine and left lateral decubitus positions.\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e presents a comparative analysis of the distances from pulmonary nodules to ribs across the upper, middle, and lower lobes of the right lung in both the supine and left lateral decubitus positions. Measurements for the lower lobe were excluded for two subjects due to inconsistencies in the depth of inspiration.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMeasurement of nodule-to-rib in the upper, middle and lower lobes of lungs in supine and left lateral decubitus positions\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e95% Confidence Interval of the Difference\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eSupine position minus left side position\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCostal parenchymal bone\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSupine position\u003c/p\u003e \u003cp\u003e(mm)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLeft lateral decubitus (mm)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean ± SD\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eLower\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eUpper\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eLower\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eUpper\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight upper lobe\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCaput costae\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84.84 ± 27.48\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e83.75 ± 28.35\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.09 ± 3.74\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.17\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.01\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-6.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e10.11\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.021\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePosterior lateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e73.34 ± 35.49\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e73.99 ± 35.54\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.65 ± 3.42\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-1.49\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.19\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-13\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.56\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.128\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55.53 ± 25.42\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e56.88 ± 25.09\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-1.35 ± 3.49\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-2.21\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.49\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-12.79\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e6.58\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterolateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65.58 ± 33.86\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66.53 ± 34.30\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.95 ± 4.01\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-1.94\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-11.45\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.37\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.058\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterior rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e95.17 ± 95.17\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96.13 ± 48.13\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.95 ± 3.91\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-1.91\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-12.17\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e11.58\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.052\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight middle lobe\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCaput costae\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e139.79 ± 20.26\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e137.68 ± 21.18\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.11 ± 2.82\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.35\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.87\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-3.54\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e8.01\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePosterior lateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e139.62 ± 30.97\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e139.62 ± 31.22\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.471 ± 2.139\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.11\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.05\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-4.08\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e6.94\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.108\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e91.01 ± 33.40\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e91.31 ± 33.64\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.3 ± 2.46\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.97\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.36\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-5.48\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.368\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterolateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50.03 ± 20.02\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51.31 ± 19.52\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-1.29 ± 3.46\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-2.22\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.35\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-8.56\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.008\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterior rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53.25 ± 32.36\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54.66 ± 33.37\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-1.41 ± 2.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-2.05\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.76\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-7.47\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e3.58\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight lower lobe\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCaput costae\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e91.31 ± 40.50\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95.78 ± 41.15\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-4.47 ± 5.49\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-5.62\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-3.33\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-18.41\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e4.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePosterior lateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75.68 ± 45.65\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e82.12 ± 47.42\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-6.44 ± 6.82\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-7.86\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-5.02\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-25.37\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5.63\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55.9 ± 26.43\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59.08 ± 28.08\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-3.19 ± 8.260\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-4.91\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-1.47\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-27.07\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e14.46\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterolateral rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74.98 ± 34.72\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e70.55 ± 33.47\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.43 ± 8.00\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.76\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.09\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-18.55\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e24.22\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterior rib\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e116.98 ± 45.26\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e109.32 ± 45.64\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.66 ± 7.19\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.17\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9.16\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-3.77\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e27.93\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e shows box plots illustrating the distances between pulmonary nodules and the centerline coordinates of each rib, providing a visual representation of the positional changes in rib-nodule distances.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cp\u003eIn the right upper lobe, a significant decrease of 1.09 ± 3.74 mm in the distance to the rib head (caput costae) was observed when transitioning from the supine to the left lateral decubitus position (p = 0.021), with the 95% confidence interval (CI) ranging from − 6.1 mm to 10.11 mm. No significant change was detected in the posterior lateral ribs, with a negligible increase of -0.65 ± 3.42 mm (p = 0.128, 95% CI: -1.49 mm to 0.19 mm). A slight but statistically significant increase of -1.35 ± 3.49 mm was identified in the lateral ribs (p = 0.003, 95% CI: -2.21 mm to -0.49 mm). Non-significant changes were observed in the anterolateral ribs (increase: -0.95 ± 4.01 mm, p = 0.058) and in the anterior ribs (increase: -0.95 ± 3.91 mm, p = 0.052).\u003c/p\u003e\u003cp\u003eIn the right middle lobe, a modest but statistically significant decrease of 2.11 ± 2.82 mm was observed in the distance to the rib head (caput costae) (p \u0026lt; 0.001, 95% CI: 1.35 mm to 2.87 mm). No significant changes were detected in the posterior lateral or lateral ribs. The posterior lateral ribs showed a slight decrease of 0.47 ± 2.14 mm (p = 0.108), while the lateral ribs demonstrated a negligible increase of -0.30 ± 2.46 mm (p = 0.368). In contrast, significant increases were identified in the anterolateral and anterior ribs, measuring − 1.29 ± 3.46 mm (p = 0.008, 95% CI: -2.22 mm to -0.35 mm) and − 1.41 ± 2.4 mm (p \u0026lt; 0.001, 95% CI: -2.05 mm to -0.75 mm), respectively.\u003c/p\u003e\u003cp\u003eIn the right lower lobe, significant changes were observed across various rib regions. The distance to the rib head (caput costae) exhibited a significant increase of -4.47 ± 5.49 mm (p \u0026lt; 0.001, 95% CI: -5.62 mm to -3.33 mm). Similarly, the posterior lateral rib showed a significant increase of -6.44 ± 6.82 mm (p \u0026lt; 0.001, 95% CI: -7.86 mm to -5.02 mm), and the lateral ribs demonstrated a significant increase of -3.19 ± 8.26 mm (p \u0026lt; 0.001, 95% CI: -4.91 mm to -1.47 mm). In contrast, significant decreases were identified in the anterolateral and anterior ribs. The anterolateral region decreased by 4.43 ± 8.00 mm (P \u0026lt; 0.001, 95% CI: 2.76 mm to 6.09 mm), while the anterior region demonstrated a more pronounced decrease of 7.66 ± 7.19 mm (P \u0026lt; 0.001, 95% CI: 6.17 mm to 9.16 mm).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe study demonstrated significant changes in pulmonary volume and morphology as subjects transitioned from the supine to the left lateral decubitus position. Specifically, the volumes of the right upper lobe, right lower lobe, and the total right lung significantly increased in the left lateral decubitus position. In contrast, the volume of the right middle lobe decreased, although this change was not statistically significant. Notably, the right lower lobe exhibited a significantly greater volumetric change compared to the right upper and middle lobes.\u003c/p\u003e \u003cp\u003eThese findings are consistent with the research of Yamada et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], who documented alterations in pulmonary volume associated with the transition from the supine to the upright posture. These differences are potentially attributable to gravitational forces and the associated reconfiguration of the thoracic structure during postural changes. The lower lobes experience greater volume changes than the upper lobes during respiration due to the gravitational effects on lung recoil [\u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. According to Yamada et al., the greater volume change observed in the lower lobes is attributed to the descent of the diaphragm in the standing position relative to the supine position, which allows greater expansion of the lower lobes.\u003c/p\u003e \u003cp\u003eHowever, our study found that the increase in lung volume in the left lateral decubitus position is associated with a marked increase in the height of the right lung, potentially resulting from lung stretching and gravitational redistribution. This leads to the reorganization of dependent lung tissue.\u003c/p\u003e \u003cp\u003eIn our study, the elevation of the right hemidiaphragm was significantly increased in the left lateral decubitus position, which may limit lung volume expansion. This elevation is likely due to the compression of alveoli on the dependent side during the lateral decubitus position, leading to increased airway pressure and reduced dynamic compliance [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Additionally, we observed an increase in lung height without significant changes in lung width or depth. This finding aligns with the observations of Little et al. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], further validating the predictable pattern of pulmonary morphological shifts during the transition from the supine to the left lateral decubitus position.\u003c/p\u003e \u003cp\u003eExisting literature suggests that prone and forward-leaning positions during ventilation can significantly improve oxygenation indices and reduce ventilation-perfusion mismatch [\u003cspan additionalcitationids=\"CR25 CR26\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Patients with acute respiratory distress syndrome (ARDS) exhibit a significant reduction in tidal volume in the dorsal regions when positioned supine [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. The prone position is recognized as an effective pulmonary protective maneuver, potentially reducing ventilator-associated lung injury [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Shin et al. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] elucidated the underlying mechanisms using quantitative CT scan analysis. However, definitive evidence regarding the mechanisms by which the lateral decubitus position improves oxygenation remains limited. Our study provides critical evidence of a significant increase in arterial oxygen partial pressure (PaO2) and the oxygenation index (PaO2/FiO2) associated with the lateral decubitus position. In cases of right-sided atelectasis, the left lateral decubitus position is hypothesized to improve respiratory function and potentially expedite the resolution of atelectasis, though further investigation is needed. It is noteworthy that the left lateral decubitus position could also precipitate atelectasis in the left lung [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn respiratory gating registration and validation, structures with minimal deformation, such as the spine, trachea, and carina, are commonly selected as fiducial points [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Metrics such as the Jacobian determinant, anisotropy deformation index, and plate-rod index have been used to quantify local parenchymal deformation [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. These methods have facilitated significant advancements, including the work by Alvarez et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], which highlights morphological alterations in lung lobes resulting from intraoperative patient positioning changes.\u003c/p\u003e \u003cp\u003eThe sternum, due to its morphological stability across different body positions, was used as a reference for registration and calibration, with pulmonary deformation analyzed using Paraview software. Registration fitting was performed on the ribs and lungs of 11 subjects, revealing a consistent pattern of lung deformation during the transition from the supine to the left lateral decubitus position. This deformation was characterized by anterior, lateral, and inferior displacement of lung tissue.\u003c/p\u003e \u003cp\u003eThese findings are consistent with those of Alvarez et al., who observed significant displacement in the anterior and basal lung regions adjacent to the sternum and diaphragm. However, our findings highlight the posterior and basal areas of the lung. Notably, the anterior portion of the lung exhibited significantly less displacement than the posterior portion, indicating that posterior deviation is not predominantly due to forward lung rotation. Instead, this deviation appears to result from an increase in lung volume, elevation in lung height, and caudal expansion of the lung surface. Nevertheless, the potential influence of peripheral forward rotation on this difference cannot be disregarded.\u003c/p\u003e \u003cp\u003eJahani et al. [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] demonstrated that, due to its lower elasticity and higher compliance, lung tissue at lower lung volumes undergoes greater deformation, with the upper and middle lobes reaching full expansion earlier than the lower lobes. This finding supports the idea that greater deformation of the lower lung indirectly contributes to the significantly smaller anterior displacement of the lung compared to the posterior portion.\u003c/p\u003e \u003cp\u003eAdditionally, five points along the centerline of each rib were connected, and the resulting direction and magnitude of rib deformation after registration were observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The lateral deformation observed in our study may be associated with the use of axillary pads to simulate surgical positioning. Despite the lack of quantitative data on the extent of lung deformation, the registration and fitting process enabled the identification of general trends in lung morphological changes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn this study, systematic observation and analysis revealed that the morphological changes during the transition from the supine to the left lateral decubitus position are consistent with rib deformation. However, the existing literature lacks a definitive explanation of the specific deformities involved. To address this gap, a novel quantitative methodology was introduced to investigate the intricate interplay between pulmonary tissue and rib mechanics.\u003c/p\u003e \u003cp\u003eTo accurately simulate pulmonary nodules, we constructed nodules with a diameter of 1 cm, centered at the subsegmental bronchi or their branching vessels. This placement reflects the close association between pulmonary nodules and blood vessels [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. This approach effectively reproduces the deformation characteristics of ground-glass opacity (GGO) and normal pulmonary tissues. However, discrepancies may arise in the deformation patterns of solid nodules [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. The interplay between lung tissue and rib deformation was quantified by measuring the distances from the centroids of the simulated pulmonary nodules to the central rib axes at various coordinate points. Given that the overall length of the ribs remains fixed across different body positions, with changes occurring only in their shape and orientation, this method of deformation analysis using the bisected rib centerline is considered reliable.\u003c/p\u003e \u003cp\u003eThe findings suggest that the deformation disparities between the right upper and right middle lobes of the lung are minimal during positional changes. Specifically, no statistically significant differences were observed in the distances from the right upper lobe nodule to the posterior lateral, anterolateral, and anterior ribs. Although statistically significant differences were identified in the distances from the caput costae and lateral rib to the pulmonary nodule, these differences were minor, with an average of less than 2 millimeters and a maximum of 13 millimeters.\u003c/p\u003e \u003cp\u003eIn the right middle lobe, no statistically significant differences were observed in the distances from the posterior lateral rib and lateral rib to the pulmonary nodule. In contrast, while statistically significant differences were identified in the distances from the caput costae, anterolateral rib, and anterior rib to the pulmonary nodule, these differences were also minor, with an average of approximately 2 millimeters and a maximum of less than 9 millimeters. The differences observed in the caput costae and lateral rib may be attributable to the effect of the axillary pad. In the right lower lobe, statistically significant differences were observed in the distances from pulmonary nodules to the ribs, with considerable variations, including a maximum discrepancy of 27 millimeters.\u003c/p\u003e \u003cp\u003eThe study concludes that, after transitioning from the supine to the left lateral decubitus position, the deformation of the right upper and middle lobes relative to the ribs is generally consistent, although some localized differences are observed. However, the differences in rib deformation in these areas are relatively minor. In contrast, the deformation of the right lower lobe relative to the ribs shows significant differences.\u003c/p\u003e \u003cp\u003eThe observed differences in the right upper lobe are likely due to an increase in lung volume and interference from the subpleural pad. The variations in the middle lobe are primarily attributed to a reduction in lung volume and the effect of the axillary pad. The disparities in the right lower lobe are mainly driven by a combination of increased lung volume, lobar sliding, and rib deformation.\u003c/p\u003e\n\u003ch3\u003eStudy Limitations and Future Perspectives\u003c/h3\u003e\n\u003cp\u003eThis study has several limitations. First, the sample size is relatively small, and only male participants were included, which may limit the generalizability of the findings. Future research should aim to increase the sample size and include participants of different genders and age groups to enhance the applicability of the results. Additionally, while this study primarily focused on the impact of positional changes on pulmonary morphology, future investigations should consider other factors, such as the respiratory cycle and changes in pleural pressure, which may also influence lung deformation.\u003c/p\u003e \u003cp\u003eDespite these limitations, the findings provide a valuable scientific foundation for the potential application of virtual reality technology in localizing pulmonary nodules using preoperative supine CT scans. Future research could further explore how these data can be leveraged to optimize surgical planning, reduce complications, and improve surgical efficiency. Furthermore, these findings could be integrated into robot-assisted surgery and augmented reality technologies to enhance the precision of pulmonary nodule localization.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, significant changes in lung volume and morphology were observed during the transition from the supine to the left lateral decubitus position. Specifically, the volume of the right upper lobe, right lower lobe, and the entire right lung significantly increased in the left lateral decubitus position, while the volume of the right middle lobe showed no significant variation. Notably, the volume change in the right lower lobe was substantially greater than that in the right upper and middle lobes.\u003c/p\u003e \u003cp\u003eThis study quantified the relationship between lung tissue and rib deformation by simulating pulmonary nodules and measuring the distances from their centroids to various coordinate points along the rib centerline. During positional changes, the deformation differences between the right upper lobe and the ribs, as well as between the right middle lobe and the ribs, were relatively minor. In contrast, the deformation relationship between the right lower lobe and the ribs showed significant differences. These discrepancies are likely attributable to a combination of increased lung expansion volume, lobar sliding, and rib deformation.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003e All the study protocols were conducted in accordance with the ethical guidelines of the Declaration of Helsinki. This study was approved by the Ethics Committee of Zhujiang Hospital, Southern Medical University and was conducted in accordance with the regulations of the Ethics Committee of Zhujiang Hospital, Southern Medical University. Informed consent was obtained from all recruited participants.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eCompeting interests\u003c/strong\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis study was supported in part by the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2023A1515012587), Shenzhen Scientific and Technology Program Grant (Grant No. JCYJ20220531100614032), and Shenzhen Medical Research Fund (Grant No. D2402006).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eMC, HL, and HL contribured to study design, imaging evaluation, and manuscript editing. WZ, ZL, and ZH contribured to provision of study materials or patients. YH, BR, and YW contribured to data collection and analysis. FZ, YW, AND HL contribured to data interpretation. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe raw datasets used during the current study are available from the cor responding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHsu HH, Shen CH, Tsai WC et al. Localization of nonpalpable pulmonary nodules using CT-guided needle puncture. World J Surg Oncol. 2015;13:248. Published 2015 Aug 15. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12957-015-0664-9\u003c/span\u003e\u003cspan address=\"10.1186/s12957-015-0664-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark CH, Han K, Hur J, et al. 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Int J Radiat Oncol Biol Phys. 2007;67(1):296\u0026ndash;307. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.ijrobp.2006.09.009\u003c/span\u003e\u003cspan address=\"10.1016/j.ijrobp.2006.09.009\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-medical-imaging","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmim","sideBox":"Learn more about [BMC Medical Imaging](http://bmcmedimaging.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmim/default.aspx","title":"BMC Medical Imaging","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Supine position, Left lateral decubitus, Rib deformation, Lung tissue deformation, CT scan","lastPublishedDoi":"10.21203/rs.3.rs-6416423/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6416423/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e The accurate localization of pulmonary nodules is significantly influenced by body positional changes, which also have a profound impact on lung morphology. As the body position changes, alterations in lung morphology are closely associated with shifts in the thoracic cage structure. However, the relationship between rib morphology and pulmonary tissue deformation has not been thoroughly explored. This study aims to investigate the relationship between lung tissue deformation and rib movement during the transition from the supine to the left lateral decubitus position. To achieve this, we employed computed tomography (CT) imaging and three-dimensional (3D) reconstruction techniques.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e Eleven healthy male volunteers received high-resolution CT scans in both the supine and left lateral decubitus positions. Lung volumes and morphological characteristics were assessed using 3D reconstruction software. Simulated pulmonary nodules were created, and the distances between the centroids of these nodules and the rib centerline coordinates were measured. Paired t-tests were conducted to evaluate the differences in lung volume, morphology, and rib deformation between the two positions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eIn the left lateral decubitus position compared to the supine position, significant increases were observed in the volumes of the right upper lobe, right lower lobe, and total right lung, while the right middle lobe exhibited no significant change. Lung height and hemidiaphragm height showed significant increases, whereas lung width and depth remained relatively stable. The deformation relationships between the right upper and middle lobes and the ribs were minimal, with a maximum variation of 13 mm. In contrast, significant differences were identified between the right lower lobe and the ribs, with a maximum discrepancy of 27 mm.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eThe transition from the supine to the left lateral decubitus position has a significant impact on lung volumes and morphological parameters, especially in the right lower lobe. The relationship between pulmonary tissue deformation and rib movement is relatively consistent in the right upper and middle lobes, but substantial differences are observed in the right lower lobe. These discrepancies are likely due to a combination of increased lung volume, lobar sliding, and rib deformation.\u003c/p\u003e","manuscriptTitle":"The Effect of Body Postural Changes on the Relationship Between Pulmonary Tissue and Rib Deformation: A Study Based on High-Resolution CT and 3D Reconstruction","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-16 15:07:18","doi":"10.21203/rs.3.rs-6416423/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"191139879493958742629608388000974777202","date":"2025-06-30T03:39:46+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-11T11:52:30+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-05-22T05:54:24+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-06T04:53:21+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-03T05:38:05+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Medical Imaging","date":"2025-05-03T05:36:57+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-medical-imaging","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmim","sideBox":"Learn more about [BMC Medical Imaging](http://bmcmedimaging.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmim/default.aspx","title":"BMC Medical Imaging","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c33e489d-a33f-450c-a91f-4944f6624666","owner":[],"postedDate":"June 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-06-16T15:07:18+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-16 15:07:18","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6416423","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6416423","identity":"rs-6416423","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}