Evaluation of Image Quality of Temporal Maximum Intensity Projection and Average Intensity Projection of Adaptive 4D Spiral CT Scans: A Phantom Study

Evaluation of Image Quality of Temporal Maximum Intensity Projection and Average Intensity Projection of Adaptive 4D Spiral CT Scans: A Phantom Study | 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 Article Evaluation of Image Quality of Temporal Maximum Intensity Projection and Average Intensity Projection of Adaptive 4D Spiral CT Scans: A Phantom Study Hiroki Horinouchi, Toshinori Sekitani, Tatsuya Nishii, Noriyuki Negi, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5148491/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Adaptive four-dimensional (4D) spiral computed tomography (CT) scans facilitate the acquisition of volume perfusion data for organs or long-range vessels but optimizing image quality and reducing noise while minimizing radiation doses remains challenging. Thus, image-processing techniques such as temporal maximum intensity projection (MIP) and average intensity projection (AIP) are crucial in this context. This ex vivo study aimed to compare image noise, spatial resolution, and vessel diameter measurements between temporal MIP and AIP images with those of conventional CT images using phantoms. Three phantoms were scanned with equivalent radiation doses using single helical and adaptive 10-phase 4D spiral scans using a third-generation dual-source CT scanner. Temporal MIP and AIP images of 4D CT scans were generated by summing varying numbers of phases, incorporating automatic motion correction with non-rigid registration and a noise reduction algorithm. The CT values and image noise of the temporal MIP and AIP images were compared to conventional CT images. The task transfer function (TTF) was calculated using static phantoms. Vessel diameters of the phantoms for each image dataset were evaluated using motion phantoms. Temporal AIP images showed comparable CT values with those of the reference image, whereas the CT values of the temporal MIP images were significantly higher than those of the reference images (P < .01). The image noise of temporal AIP images with six or more phases was equal to or lower than that of the reference images. In contrast, temporal MIP images exhibited consistently high noise levels regardless of the number of summed phases. The TTF of temporal AIP images was comparable to that of the reference CT images. However, the TTF of temporal MIP images gradually decreased as the number of summed phases increased. No significant differences were observed in vessel diameter measurements among the three groups or with varying numbers of summed phases (P > .05). In conclusion, temporal MIP and AIP images from 4D CT can reduce noise and maintain measurement reliability in motion phantoms, achieving performance levels comparable to conventional CT images. Health sciences/Health care/Medical imaging/Tomography/Computed tomography Health sciences/Health care/Medical imaging/Three dimensional imaging Health sciences/Health care/Medical imaging/Whole body imaging Four-Dimensional Computed Tomography Tomography X-Ray Computed Image Processing Computer-Assisted Computed Tomography Angiography Whole Body Imaging Figures Figure 1 Figure 2 Figure 3 Introduction Computed tomography (CT) technology has evolved to provide four-dimensional (4D) imaging through high-speed scanning [1], adding the dimension of time to traditional three-dimensional (3D) imaging. This advancement enables the detailed visualization of temporal and spatial information for moving organs and hemodynamics. Four-dimensional CT is particularly valuable in assessing respiratory motion and determining treatment margins for radiotherapy planning [2, 3]. Additionally, 4D CT angiography is useful in evaluating cerebral flow dynamics [4, 5]. However, the limited coverage area of high-speed CT scans restricts the regions available for 4D imaging, which relies on acquiring continuous multiphase data over short periods [6, 7]. The introduction of 320-row area detector CTs has extended the 4D CT scan range to 160 mm [4], while third-generation dual-source CT scanners have further expanded this capability to whole-trunk 4D imaging using adaptive 4D-spiral CT [8-11]. Despite these technological advancements, the total radiation dose associated with multiphase imaging remains high. To mitigate this issue, reducing the radiation dose per phase is necessary, but this reduction often leads to increased noise and diminished image quality. To address these challenges, image processing techniques such as temporal maximum intensity projection (MIP) and temporal average intensity projection (AIP) have become essential. These techniques are instrumental in reducing noise and improving image quality while maintaining a lower radiation dose over extended acquisition times. The temporal MIP technique evaluates enhancement over time for each voxel in 3D volume data by selecting the time point with the maximum CT values [12]. This approach can derive high-quality CT angiography from CT perfusion data, enhance arterial contrast, and reduce the required dose of contrast media [8-10]. In contrast, the temporal AIP technique calculates the average CT values over time for each voxel in the 4D CT dataset [13-15]. Both techniques require precise motion correction through non-rigid registration and noise reduction, which can affect image quality and clinical measurements [16]. It is essential to comprehend the properties of each technique in order to establish the optimal 4D CT protocol and post-processing methods to achieve the target of examinations. To date, no specific phantom studies have investigated the quality of temporal MIP or AIP images. Therefore, this ex vivo study aimed to compare the image noise, spatial resolution, and measurements of temporal MIP and AIP images with those of conventional CT images using phantoms. Materials and methods Three ex vivo phantom studies were conducted to evaluate the performance of temporal MIP and AIP techniques. (1) CT values, image noise, and the noise power spectrum (NPS) were evaluated using a water phantom with a 20 cm diameter. (2) The task transfer function (TTF) was measured using a polyoxymethylene rod phantom with a diameter of 30 mm and 300 Hounsfield units (HU) at 120 kV in water. (3) Vessel diameter measurements in the motion phantoms on temporal MIP and AIP images were compared with those on conventional CT images acquired with a single spiral scan. For this, a cubic water phantom containing three vessel phantoms with diameters of 2 mm, 5 mm, and 10 mm (all with a radiodensity of 300 HU at 120 kV) was mounted on a respiratory motion platform (QUASAR; Modus QA Medical Devices, Ontario, Canada) (Figure 1). The vessel phantoms were positioned at a 45-degree oblique angle to the CT scan plane within the water phantom. During the 10-phase 4D CT scan, the motion phantom was moved horizontally along the CT table at a constant speed of 1 mm/s, resulting in a total displacement of 25 mm. Image acquisition and reconstruction All CT examinations were performed using a third-generation 192-detector, dual-source CT scanner (SOMATOM Force; Siemens Healthineers, Forchheim, Germany). The phantoms underwent a single-source spiral scan for one phase as a reference and 4D scans using adaptive 4D Spiral CT scan mode (Siemens Healthineers) for ten phases, with an equivalent total volume CT dose index of 10 mGy. Therefore, the volume CT dose index per phase in the 4D scan was set to 1 mGy. Detailed parameters for image acquisition and reconstruction are listed in Table 1. All CT images were reconstructed with a 1.0 mm slice thickness using a Bv40 kernel and iterative reconstruction (ADMIRE, Siemens Healthineers) with a strength level of 3. The reconstructed image datasets were then transferred to the workstation ( syngo .via, Siemens Healthineers), where temporal MIP and AIP images from the 4D CT datasets were generated using a software package (CT Dynamic Angio; Siemens Healthineers), which incorporates automatic motion correction with a non-rigid registration and noise reduction algorithm [8, 13]. Image analysis We compared the CT values and image noise of the temporal MIP and AIP images from phases two, four, six, eight, and ten of the 4D CT scans with those of a single spiral scan used as the reference. The CT values in Hounsfield units (HU) and standard deviations (SD) were averaged across five points, namely the center of the water phantom and four points in the upper, lower, left, and right directions [17]. The NPS was assessed to measure noise at each spatial frequency for the water phantom, using temporal MIP and AIP images generated by combining two, four, six, eight, and ten phases of 4D CT scans. The NPS was calculated using the radial frequency method [18, 19]. Iterative reconstruction can exhibit nonlinear signal characteristics that affect system resolution properties differently compared to standard filtered back projection [20]. Therefore, TTF was selected to analyze the spatial resolution of 4D CT for vessel assessment using iterative reconstruction instead of conventional modulation transfer function measurements. The in-plane resolution properties were measured in terms of the TTF using a radial edge technique on rod inserts within a water phantom [21]. The target CT value was set at 300 HU to simulate the arterial phase of the vessel. Phantom vessel diameters of 2, 5, and 10 mm were measured five times using the full width at half maximum (FWHM) method with a workstation (Ziostation2; Ziosoft, Tokyo, Japan). Measurements were performed on temporal MIP and AIP images generated by summing the 2, 4, 6, 8, and 10 phases of 4D CT scans, as well as the reference images acquired using single spiral CT scans. Statistical analysis Continuous variables are expressed as mean ± standard deviation. All measured values were analyzed using one-way analysis of variance (ANOVA) to determine differences between the parameters. Post hoc Tukey’s tests were conducted among the groups if the overall ANOVA indicated statistical significance. A p-value of less than 0.01 was considered statistically significant. Results The CT values of the temporal AIP images were comparable to those of the reference CT images acquired with single spiral scans, regardless of the number of summed phases. However, the CT values of the temporal MIP images were significantly higher than those of the reference CT images (P < .01), and these values progressively increased with the number of summed phases (Table 2). Furthermore, the image noise in temporal AIP images with six or more phases was equal to or lower than that of the reference image, which was 9.0 ± 0.6 HU. In contrast, temporal MIP images showed high noise levels regardless of the number of summed phases (Table 3). The NPS curves for both temporal MIP and AIP images gradually decreased as the number of summed phases increased (Figure S1). Figure 2 illustrates the spatial frequency at which the TTF is reduced to 50% (f50) and 10% (f10) as a function of the number of summed phases. The TTF of temporal AIP images was comparable to that of the reference CT images obtained from single spiral scans. However, the TTF of the temporal MIP images decreased gradually with an increase in the number of summed phases. Table 4 shows the diameters of the vessel phantoms (2, 5, and 10 mm) measured using conventional CT and temporal MIP and AIP images. No significant differences in vessel diameter measurements were observed among the three groups or across the different numbers of summed phases (P > .05). Additionally, temporal MIP and AIP images, generated from multiphase 4D CT scans of the motion phantom, showed no blurring or morphological changes when compared to conventional CT images (Figure 3). Discussion In this study, both temporal MIP and AIP techniques demonstrated a reduction in noise as more phases were summed. The image noise in temporal AIP images with more than six phases was equal to or lower than that of conventional CT images, with a comparable spatial resolution. In contrast, temporal MIP images exhibited significantly higher CT values and substantially more severe image noise compared to conventional CT images. Despite these variations, no significant differences were observed in the diameter measurements of temporal MIP and AIP images when compared to conventional CT images, even when summing multiphase 4D CT images of the motion phantom. Temporal AIP images generated using six phases (60%) of the 4D CT image data exhibited noise levels comparable to those of conventional CT images. This result is noteworthy because each phase of the 4D CT images, when taken at a low radiation dose, typically results in higher noise levels. We attribute this outcome to the denoising algorithm applied and the cumulative denoising effect of additive averaging of the images. Furthermore, the AIP images showed consistent CT values, making AIP a viable option in clinical settings where preserving CT values and achieving low-noise images are essential. Temporal AIP have been reported to improve myocardial delayed enhancement and extracellular volume CT images through the reduction of image noise with minimal effect on CT values [13-15]. In contrast, the CT values in temporal MIP images gradually increased with the number of summing phases, as temporal MIP captures the maximum CT values over time for each voxel. This study showed significantly higher CT values in temporal MIP images than those of conventional CT images. Therefore, temporal MIP images are not suitable for evaluating CT values in clinical practice. However, the unique characteristics of temporal MIP make it particularly useful for vascular assessment. Temporal MIP can enhance intravascular CT values to clinically appropriate levels, even with 4D CT images obtained with reduced contrast media doses. Temporal MIP images have already been reported to generate high-quality CT angiography [8-10], increase arterial contrast enhancement, and reduce both contrast media dose and image noise. When temporal MIP and AIP summing techniques were applied to multiphase 4D images using a motion phantom, no changes in the vessel diameters were observed. Temporal MIP images had an insignificant effect on vessel phantom measurements and did not significantly deteriorate spatial resolution, as assessed using TTF. These minimal changes in spatial resolution are considered acceptable in clinical practice, especially within in the trunk region where motion is present. However, it is important to note that physiological variability in organs includes not only movement but also morphological changes. Temporal AIP and MIP images can effectively measure smaller lung masses targeted in radiotherapy [16], but their application may be limited in cases involving significant deformations or distortions, or images with motion artifacts owing to large movements during imaging. Consequently, temporal MIP and AIP images obtained from 4D CT scans are more suitable for regions with less physiological variability, such as the brain and aorta [8-10, 12]. In clinical practice, substantial knowledge of the advantages and disadvantages of each technique can maximize the potential of 4D CT scanning to achieve the target of the examinations. This study had several limitations. First, complex movements and morphological changes in the phantoms were not evaluated. Complex physiological movements such as respiratory and peristaltic motions can cause significant morphological changes over longer acquisition times across multiple phases. These changes may lead to a deterioration in image quality and measurement accuracy in temporal MIP and AIP images. Second, this study did not consider the effect of contrast bolus flow on image quality. For instance, in the case of the aorta, MIP demonstrates the most contrast-enhanced CT values when a time series is captured before, during, and after the arrival of the contrast bolus. In contrast, AIP averages the CT values in the aorta, resulting in lower CT values than those observed with MIP. These effects on image quality should be addressed in future studies. In conclusion, temporal MIP and AIP 4D CT images reduce noise and maintain the reliability of measurements using a motion phantom, achieving results comparable to those of conventional CT images. Declarations Data availability statement The data that support the findings of this study are available from the corresponding author upon reasonable request. Acknowledgements The authors thank Dr. Toshihide Itoh for the scientific advice and Editage (www.editage.jp) for English language editing. Author contributions H.H.: original draft, funding acquisition. T.S., T.N., N.N., S.T.: conceptualization, investigation, formal analysis, review, editing. K.S., T.F.: review and editing. Additional information Funding: This work was supported by JSPS KAKENHI Grant Number 18K15634. Competing interests: The authors declare no competing interests. References Rietzel, E., Pan, T., & Chen, G. T. Four-dimensional computed tomography: image formation and clinical protocol. Medical physics, 32(4), 874–889 (2005). Pan, T., Lee, T. Y., Rietzel, E., & Chen, G. T. 4D-CT imaging of a volume influenced by respiratory motion on multi-slice CT. Medical physics, 31(2), 333–340 (2004). Wu, G., Lian, J., & Shen, D. Improving image-guided radiation therapy of lung cancer by reconstructing 4D-CT from a single free-breathing 3D-CT on the treatment day. 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CT values measurements (in Hounsfield units) Convention al CT Number of summing phases Temporal MIP Temporal AIP -1.1 ± 0.6 2 2.3 ± 0.5 -0.2 ± 0.5 4 10.0 ± 0.8 -0.4 ± 0.4 6 13.8 ± 1.0 -0.5 ± 0.4 8 16.2 ± 1.1 -0.5 ± 0.5 10 18.5 ± 1.1 -0.5 ± 0.4 Data are presented as means ± standard deviations. * Statistically significant difference compared with conventional CT with a single spiral scan (10 mGy) (P < .01). AIP - Average Intensity Projection; CT - Computed Tomography; MIP - Maximum Intensity Projection Table 3. Image noise measurements (in Hounsfield units) Conventional CT Number of summing phases Temporal MIP Temporal AIP 9.0 ± 0.6 2 16.5 ± 1.2 * 16.3 ± 1.2 * 4 13.2 ± 1.1 * 11.6 ± 1.0 * 6 11.9 ± 0.8 * 9.3 ± 0.7 8 11.0 ± 0.7 * 8.1 ± 0.5 * 10 10.8 ± 0.6 * 7.4 ± 0.4 * Data are presented as means ± standard deviations. * Significant difference compared with conventional CT with a single spiral scan (10 mGy) (P < .01). AIP - Average Intensity Projection; CT - Computed Tomography; MIP - Maximum Intensity Projection Table 4. Measurements of vessel phantom diameter by Full width at half maximum (FWHM) Vessel phantom diameter Conventional CT The number of summing phases Temporal MIP Temporal AIP 10 mm 14.4 ± 0.3 2 14.3 ± 0.3 14.4 ± 0.3 4 14.3 ± 0.3 14.4 ± 0.3 6 14.4 ± 0.2 14.2 ± 0.2 8 14.5 ± 0.2 14.3 ± 0.2 10 14.5 ± 0.2 14.3 ± 0.2 5 mm 5.9 ± 0.2 2 6.1 ± 0.1 6.0 ± 0.1 4 6.1 ± 0.2 6.1 ± 0.2 6 6.0 ± 0.1 6.0 ± 0.1 8 6.0 ± 0.1 6.0 ± 0.1 10 6.0 ± 0.1 6.0 ± 0.1 2 mm 2.2 ± 0.3 2 2.1 ± 0.2 2.1 ± 0.2 4 2.1 ± 0.2 2.1 ± 0.2 6 2.1 ± 0.2 2.1 ± 0.2 8 2.2 ± 0.2 2.2 ± 0.2 10 2.2 ± 0.2 2.2 ± 0.2 Data are presented as means ± standard deviations (mm). AIP - Average Intensity Projection; CT - Computed Tomography; MIP - Maximum Intensity Projection Additional Declarations No competing interests reported. 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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-5148491","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":364520620,"identity":"061c2646-42da-4aeb-97bf-46c8bfb2f030","order_by":0,"name":"Hiroki Horinouchi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIiWNgGAWjYBACA2YgwdjAwMDGAGZIyIHoAw9I0WIM1pKATwsDVAsDlJEIZuPTYs7O+/AB4w6bfD7p5mMSP3dYpM8PO/wQaIudnG4Ddi2WzezGBoxn0izbZI6lSfaekcjdeDvNAKgl2djsAA6HHWZjk2BsO2zAJpFjJs3YBtQyOwGk5UDiNmK1pBvOTv9AmpYEeekcgrYwGyS2pQG1pCVb9rZJGG6Qzik4kGCAxy/njzE++NhmYyA/I/ngjZ9tdfLys9M3f/hQYSeHSwsYJKAYAlZpgEc5BpBvIEX1KBgFo2AUjAQAANLwV0hhopxMAAAAAElFTkSuQmCC","orcid":"","institution":"National Cerebral and Cardiovascular Center","correspondingAuthor":true,"prefix":"","firstName":"Hiroki","middleName":"","lastName":"Horinouchi","suffix":""},{"id":364520621,"identity":"5748f01f-74ed-43dc-bcb4-0f9200e13d09","order_by":1,"name":"Toshinori Sekitani","email":"","orcid":"","institution":"Osaka College of High Technology","correspondingAuthor":false,"prefix":"","firstName":"Toshinori","middleName":"","lastName":"Sekitani","suffix":""},{"id":364520622,"identity":"72c218a3-d964-48b4-8942-be1bc2b380e2","order_by":2,"name":"Tatsuya Nishii","email":"","orcid":"","institution":"National Cerebral and Cardiovascular Center","correspondingAuthor":false,"prefix":"","firstName":"Tatsuya","middleName":"","lastName":"Nishii","suffix":""},{"id":364520623,"identity":"223fbaaf-a015-4c9b-9fea-0b247d972054","order_by":3,"name":"Noriyuki Negi","email":"","orcid":"","institution":"Kobe University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Noriyuki","middleName":"","lastName":"Negi","suffix":""},{"id":364520624,"identity":"87eda0d4-c41a-4f48-b03a-f5b072f86a2f","order_by":4,"name":"Keitaro Sofue","email":"","orcid":"","institution":"Kobe University Graduate School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Keitaro","middleName":"","lastName":"Sofue","suffix":""},{"id":364520625,"identity":"50c1f468-ae13-4a6f-8322-b886511beba2","order_by":5,"name":"Tetsuya Fukuda","email":"","orcid":"","institution":"National Cerebral and Cardiovascular Center","correspondingAuthor":false,"prefix":"","firstName":"Tetsuya","middleName":"","lastName":"Fukuda","suffix":""},{"id":364520626,"identity":"f903b4b0-3ba5-480b-90f6-4244b11c4f8d","order_by":6,"name":"Satoru Takahashi","email":"","orcid":"","institution":"Takatsuki General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Satoru","middleName":"","lastName":"Takahashi","suffix":""}],"badges":[],"createdAt":"2024-09-25 03:23:05","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5148491/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5148491/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":67199861,"identity":"58cddefa-d0bd-45c5-8c8d-ed16ad6accf8","added_by":"auto","created_at":"2024-10-22 09:48:50","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":200719,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMotion platform and vessel phantoms with 2 mm, 5 mm, and 10 mm diameters.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe water phantom was mounted on a motion platform that moved horizontally on a computed tomography (CT) table at 1 mm/s. Vessel phantoms with diameters of 2, 5, and 10 mm with a radiodensity of 300 HU were placed in the water phantom at 45° oblique to the CT scan plane.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5148491/v1/0ec10b4c53bfeb0f93057a36.png"},{"id":67199857,"identity":"6d6a9503-86da-42ab-86bf-fd153a02e85a","added_by":"auto","created_at":"2024-10-22 09:48:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":54785,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe task transfer function (TTF) of f50 and f10.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe f50 (a) and f10 (b) from the TTF curve of temporal average intensity projection (AIP) images were similar to those of the reference conventional CT images, while those of the temporal (maximum intensity projection (MIP) images decreased gradually with more summed phases.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5148491/v1/08d4a955c37bb0b1aeddfb93.png"},{"id":67201243,"identity":"c9492443-705f-4335-8eb7-ed7b422a9507","added_by":"auto","created_at":"2024-10-22 09:56:51","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":75174,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThree-dimensional maximum intensity projection images of vessel phantoms with diameters of 2 mm, 5 mm, and 10 mm with temporal MIP, temporal AIP, and conventional CT.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAIP - Average Intensity Projection; CT - Computed Tomography; MIP - Maximum Intensity Projection\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5148491/v1/f24a863f1404f6faacb2b4ac.png"},{"id":75426567,"identity":"fb852fc4-a7bf-44ad-a08d-cd486dce5829","added_by":"auto","created_at":"2025-02-04 12:17:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1174928,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5148491/v1/753a67bb-3d36-49be-b024-7958a97b75c5.pdf"},{"id":67199858,"identity":"fd85ac4c-a9b2-4acb-8169-b596efc2eff3","added_by":"auto","created_at":"2024-10-22 09:48:50","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":129230,"visible":true,"origin":"","legend":"","description":"","filename":"SRSupplementalfile4D.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5148491/v1/3a14f21a4e1dc5568075ca33.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of Image Quality of Temporal Maximum Intensity Projection and Average Intensity Projection of Adaptive 4D Spiral CT Scans: A Phantom Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eComputed tomography (CT) technology has evolved to provide four-dimensional (4D) imaging\u0026nbsp;through high-speed scanning [1], adding the dimension of time to traditional three-dimensional (3D) imaging. This advancement enables\u0026nbsp;the detailed visualization of temporal and spatial information for moving organs and hemodynamics.\u0026nbsp;Four-dimensional\u0026nbsp;CT is particularly valuable in assessing respiratory motion and determining treatment margins for radiotherapy planning [2, 3]. Additionally, 4D\u0026nbsp;CT angiography\u0026nbsp;is useful in evaluating cerebral flow dynamics [4, 5]. However, the limited coverage area of high-speed CT scans restricts\u0026nbsp;the regions available for 4D imaging, which relies on acquiring\u0026nbsp;continuous multiphase data over short periods [6, 7]. The introduction of 320-row area detector CTs has extended the 4D CT scan range to 160 mm [4], while third-generation dual-source CT scanners have further expanded this capability to whole-trunk 4D imaging using adaptive 4D-spiral CT [8-11]. Despite these technological advancements, the total radiation dose associated with multiphase imaging remains high. To mitigate this issue, reducing the radiation dose per phase is necessary, but this reduction often leads to\u0026nbsp;increased noise and diminished image quality. To address these challenges, image processing techniques such as temporal maximum intensity projection (MIP) and temporal average intensity projection (AIP) have become essential. These techniques are instrumental in reducing noise and improving image quality\u0026nbsp;while\u0026nbsp;maintaining a lower radiation dose over extended acquisition times.\u003c/p\u003e\n\u003cp\u003eThe temporal MIP technique evaluates\u0026nbsp;enhancement over time for each voxel in 3D volume data\u0026nbsp;by selecting the time point with\u0026nbsp;the\u0026nbsp;maximum CT values [12]. This approach can derive high-quality CT angiography from CT perfusion data, enhance arterial contrast, and reduce\u0026nbsp;the required dose of contrast media [8-10]. In contrast, the temporal AIP technique calculates the average CT values over time for each voxel in the 4D CT dataset [13-15]. Both techniques require precise motion correction through non-rigid registration and noise reduction, which can affect image quality and clinical measurements [16]. It is essential to comprehend the properties of each technique in order to establish the optimal 4D CT protocol and post-processing methods to achieve the target of examinations.\u003c/p\u003e\n\u003cp\u003eTo date, no specific phantom studies have investigated the quality of temporal MIP or AIP images. Therefore, this ex vivo study aimed to compare the image noise, spatial resolution, and measurements of temporal MIP and AIP images with\u0026nbsp;those of conventional CT images using phantoms.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003eThree ex vivo phantom studies were conducted to evaluate the performance of temporal MIP and AIP techniques. (1) CT values, image noise, and the noise power spectrum (NPS) were evaluated using a water phantom with a 20 cm diameter. (2) The task transfer function (TTF) was measured using a polyoxymethylene rod phantom with a diameter of 30 mm and 300 Hounsfield units (HU) at 120 kV in water. (3) Vessel diameter measurements in the motion phantoms on temporal MIP and AIP images were compared with those on conventional CT images acquired with a single spiral scan. For this, a cubic water phantom containing three vessel phantoms with diameters of 2 mm, 5 mm, and 10 mm (all with a radiodensity of 300 HU at 120 kV) was mounted on a respiratory motion platform (QUASAR; Modus QA Medical Devices, Ontario, Canada) (Figure 1). The vessel phantoms were positioned at a 45-degree oblique angle to the CT scan plane within the water phantom. During the 10-phase 4D CT scan, the motion phantom was moved horizontally along the CT table at a constant speed of 1 mm/s, resulting in a total displacement of 25 mm.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImage acquisition and reconstruction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll CT examinations were performed using a third-generation 192-detector, dual-source CT scanner (SOMATOM Force; Siemens Healthineers, Forchheim, Germany). The phantoms underwent a single-source spiral scan for one phase as a reference\u0026nbsp;and 4D scans\u0026nbsp;using adaptive 4D Spiral CT scan mode (Siemens Healthineers) for ten phases, with an equivalent total volume CT dose index of 10 mGy. Therefore, the volume CT dose index per phase in the 4D scan was set to 1 mGy. Detailed parameters for image acquisition and reconstruction are listed in Table 1.\u003c/p\u003e\n\u003cp\u003eAll CT images were reconstructed with a 1.0 mm slice thickness using a Bv40 kernel and iterative reconstruction (ADMIRE, Siemens Healthineers)\u0026nbsp;with a strength level of 3.\u0026nbsp;The reconstructed image datasets were then transferred to the workstation (\u003cem\u003esyngo\u003c/em\u003e.via, Siemens Healthineers), where temporal MIP and AIP images from\u0026nbsp;the 4D CT\u0026nbsp;datasets were generated using a software package (CT Dynamic Angio; Siemens Healthineers), which incorporates automatic motion correction with\u0026nbsp;a\u0026nbsp;non-rigid registration and noise reduction algorithm [8, 13].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImage analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe compared the CT values and image noise of\u0026nbsp;the temporal MIP and AIP images from\u0026nbsp;phases two, four, six, eight, and ten of\u0026nbsp;the 4D CT scans with those of a single spiral scan used as the reference. The CT values in Hounsfield units (HU) and\u0026nbsp;standard deviations (SD) were averaged across five points, namely the center of the water phantom and four points in the upper, lower, left, and right directions [17].\u0026nbsp;The NPS was assessed to measure noise at each spatial frequency for the water phantom, using temporal\u0026nbsp;MIP and AIP images generated by combining two, four, six, eight, and ten phases of 4D CT scans.\u0026nbsp;The NPS was calculated using the radial frequency method [18, 19].\u003c/p\u003e\n\u003cp\u003eIterative reconstruction can exhibit nonlinear signal characteristics that affect\u0026nbsp;system resolution properties differently compared to standard filtered back projection [20]. Therefore,\u0026nbsp;TTF was selected to analyze the spatial resolution of 4D CT for vessel assessment using iterative reconstruction instead of conventional modulation transfer function measurements. The in-plane resolution properties were measured in terms of the TTF using a radial edge technique on rod inserts within a water phantom [21]. The target CT value was set at 300 HU to simulate the arterial phase of the vessel.\u003c/p\u003e\n\u003cp\u003ePhantom vessel diameters of 2, 5, and 10 mm were measured five times using the full width at half maximum (FWHM) method with a workstation (Ziostation2; Ziosoft, Tokyo, Japan). Measurements were performed on temporal MIP and AIP images generated by summing the 2, 4, 6, 8, and 10 phases of 4D CT scans, as well as the reference images acquired using single spiral CT scans.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eContinuous variables are expressed as mean \u0026plusmn; standard deviation. All measured values were analyzed using one-way analysis of variance (ANOVA) to determine differences between the parameters. Post hoc Tukey\u0026rsquo;s tests were conducted among the groups if the overall ANOVA indicated statistical significance. A p-value of less\u0026nbsp;than 0.01 was considered statistically significant.\u003cstrong\u003e\u003cbr\u003e\u003c/strong\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe CT values of\u0026nbsp;the temporal AIP images were comparable to those of the reference CT images acquired with single spiral scans, regardless of the number of summed phases. However, the CT values of the temporal MIP images were significantly higher than those of the reference\u0026nbsp;CT images (P \u0026lt; .01), and these values progressively increased with the number of summed phases (Table 2). Furthermore, the image noise in temporal AIP images with six or more phases was equal to or lower than that of the reference\u0026nbsp;image, which was 9.0 ± 0.6 HU.\u0026nbsp;In contrast,\u0026nbsp;temporal MIP images showed high noise levels regardless of the number of summed phases (Table 3). The NPS curves for both temporal MIP and AIP images gradually decreased as the number of summed phases\u0026nbsp;increased (Figure\u0026nbsp;S1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFigure 2 illustrates the spatial frequency at which the TTF\u0026nbsp;is reduced to 50% (f50) and 10% (f10) as a function of the number of summed phases.\u0026nbsp;The TTF of\u0026nbsp;temporal AIP images was comparable to that of the reference CT images obtained from single\u0026nbsp;spiral scans. However, the TTF of\u0026nbsp;the temporal\u0026nbsp;MIP images decreased gradually with an increase in the number of summed phases. Table 4 shows the diameters of\u0026nbsp;the vessel phantoms (2, 5, and 10 mm) measured using conventional CT and temporal MIP and AIP images. No significant differences in\u0026nbsp;vessel diameter measurements were observed among the three groups or across the different numbers of summed phases (P \u0026gt; .05). Additionally, temporal MIP and AIP images, generated from\u0026nbsp;multiphase 4D CT scans of the motion phantom, showed no blurring or morphological changes when compared to conventional CT images (Figure 3).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this study, both\u0026nbsp;temporal MIP and AIP techniques demonstrated a reduction in\u0026nbsp;noise\u0026nbsp;as more phases were summed. The image noise in temporal AIP images with more than six phases was equal to or lower than\u0026nbsp;that of conventional CT images, with a comparable spatial resolution. In contrast,\u0026nbsp;temporal MIP images exhibited significantly higher CT values\u0026nbsp;and substantially more severe image noise compared to conventional CT images. Despite these variations, no significant differences were observed in\u0026nbsp;the diameter measurements\u0026nbsp;of temporal MIP and AIP images\u0026nbsp;when\u0026nbsp;compared to conventional CT images, even when summing multiphase 4D CT images of the motion phantom.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTemporal AIP images generated using six phases (60%) of the 4D CT image data\u0026nbsp;exhibited noise levels comparable to those of conventional CT images. This result is noteworthy because each phase of\u0026nbsp;the 4D CT images, when taken at a low radiation dose, typically results in higher noise levels. We attribute this outcome to the denoising algorithm applied and the cumulative denoising effect of additive averaging of the images. Furthermore, the AIP images showed consistent CT values, making AIP a viable option in clinical settings where preserving CT values and achieving low-noise images are essential. Temporal AIP have been reported to improve myocardial delayed enhancement and extracellular volume CT images through the reduction of image noise with minimal effect on CT values [13-15].\u003c/p\u003e\n\u003cp\u003eIn contrast, the CT values in\u0026nbsp;temporal MIP images gradually increased\u0026nbsp;with the number of summing phases, as temporal MIP captures the maximum CT values over time for each voxel. This study showed significantly higher CT values in temporal MIP images than those of conventional CT images. Therefore, temporal MIP images are not suitable for evaluating CT values in clinical practice. However, the unique characteristics of temporal MIP make it particularly useful for vascular assessment. Temporal MIP can enhance intravascular CT values to clinically appropriate levels, even with 4D CT images obtained with reduced contrast media doses. Temporal MIP images have already been reported to generate high-quality CT angiography [8-10], increase arterial contrast enhancement, and reduce both contrast media dose and image noise.\u003c/p\u003e\n\u003cp\u003eWhen temporal MIP and AIP summing techniques\u0026nbsp;were applied to multiphase 4D images using a motion phantom, no changes in\u0026nbsp;the vessel diameters were\u0026nbsp;observed. Temporal MIP images had an insignificant effect on vessel phantom measurements and did not significantly deteriorate spatial resolution, as assessed using TTF. These minimal changes in spatial resolution are considered acceptable in clinical practice, especially within in the trunk region where motion is present. However, it is important to note that physiological variability in organs includes not only movement but also morphological changes. Temporal AIP and MIP images can effectively measure smaller lung masses targeted in radiotherapy [16], but their application may be limited in cases involving significant deformations or distortions, or images with motion artifacts\u0026nbsp;owing to large movements during imaging. Consequently,\u0026nbsp;temporal MIP and AIP images obtained from 4D CT scans are more suitable for regions with less physiological variability, such as the brain and aorta\u0026nbsp;[8-10, 12]. In clinical practice,\u0026nbsp;substantial knowledge of the advantages and disadvantages of each technique can maximize the potential of 4D CT scanning to achieve the target of the examinations.\u003c/p\u003e\n\u003cp\u003eThis study had several limitations. First, complex movements and morphological changes in the phantoms\u0026nbsp;were not evaluated. Complex physiological movements\u0026nbsp;such as respiratory and peristaltic motions can cause significant morphological changes over longer acquisition times across multiple phases. These changes may lead to a deterioration in image quality and measurement accuracy in temporal MIP and AIP images. Second, this study did not consider the effect of contrast bolus flow on image quality. For instance, in the case of the aorta, MIP demonstrates the most contrast-enhanced CT values when a time series is captured before, during, and after the arrival of the contrast bolus. In contrast, AIP averages the CT values in the aorta, resulting in lower CT values than those observed with MIP. These effects on\u0026nbsp;image quality\u0026nbsp;should be addressed in future studies.\u003c/p\u003e\n\u003cp\u003eIn conclusion, temporal MIP and AIP 4D CT images reduce noise and maintain the reliability of measurements using\u0026nbsp;a\u0026nbsp;motion phantom, achieving results comparable to those of conventional CT images.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank Dr. Toshihide Itoh for the scientific advice and Editage (www.editage.jp) for English language editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eH.H.: original draft, funding acquisition. T.S., T.N., N.N., S.T.: conceptualization, investigation, formal analysis, review, editing. K.S., T.F.: review and editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eThis work was supported by JSPS KAKENHI Grant Number 18K15634.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eRietzel, E., Pan, T., \u0026amp; Chen, G. T. Four-dimensional computed tomography: image formation and clinical protocol. Medical physics, 32(4), 874\u0026ndash;889 (2005).\u003c/li\u003e\n \u003cli\u003ePan, T., Lee, T. Y., Rietzel, E., \u0026amp; Chen, G. T. 4D-CT imaging of a volume influenced by respiratory motion on multi-slice CT. 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Quick evaluation of lower leg ischemia in patients with peripheral arterial disease by time maximum intensity projection CT angiography: a pilot study. BMC medical imaging, 21(1), 7 (2021).\u003c/li\u003e\n \u003cli\u003eHaubenreisser, H., et al. From 3D to 4D: Integration of temporal information into CT angiography studies. European journal of radiology, 84(12), 2421\u0026ndash;2424 (2015).\u003c/li\u003e\n \u003cli\u003eSmit, E. J., et al. Timing-invariant reconstruction for deriving high-quality CT angiographic data from cerebral CT perfusion data. Radiology, 263(1), 216\u0026ndash;225 (2012).\u003c/li\u003e\n \u003cli\u003eNishii, T., et al. Deep Learning-based Post Hoc CT Denoising for Myocardial Delayed Enhancement. Radiology, 305(1), 82\u0026ndash;91 (2022).\u003c/li\u003e\n \u003cli\u003eScully, P. R., et al. Identifying Cardiac Amyloid in Aortic Stenosis: ECV Quantification by CT in TAVR Patients. JACC. Cardiovascular imaging, 13(10), 2177\u0026ndash;2189 (2020).\u003c/li\u003e\n \u003cli\u003eKurobe, Y., et al. Myocardial delayed enhancement with dual-source CT: advantages of targeted spatial frequency filtration and image averaging over half-scan reconstruction. Journal of cardiovascular computed tomography, 8(4), 289\u0026ndash;298 (2014).\u003c/li\u003e\n \u003cli\u003eBorm, K. J., Oechsner, M., Wiegandt, M., Hofmeister, A., Combs, S. E., \u0026amp; Duma, M. N. Moving targets in 4D-CTs versus MIP and AIP: comparison of patients data to phantom data. BMC cancer, 18(1), 760 (2018).\u003c/li\u003e\n \u003cli\u003eAmerican Association of Physicists in Medicine. AAPM Report No.39 : Specification and Acceptance Testing of Computed Tomography Scanners. AAPM : New York, https://doi.org/10.37206/38 (1993).\u003c/li\u003e\n \u003cli\u003eRiederer, S. J., Pelc, N. J., \u0026amp; Chesler, D. A. The noise power spectrum in computed X-ray tomography. Physics in medicine and biology, 23(3), 446\u0026ndash;454 (1978).\u003c/li\u003e\n \u003cli\u003eBoedeker, K. L., Cooper, V. N., \u0026amp; McNitt-Gray, M. F. Application of the noise power spectrum in modern diagnostic MDCT: part I. Measurement of noise power spectra and noise equivalent quanta. Physics in medicine and biology, 52(14), 4027\u0026ndash;4046 (2007).\u003c/li\u003e\n \u003cli\u003eRichard, S., Husarik, D. B., Yadava, G., Murphy, S. N., \u0026amp; Samei, E. Towards task-based assessment of CT performance: system and object MTF across different reconstruction algorithms. Medical physics, 39(7), 4115\u0026ndash;4122 (2012).\u003c/li\u003e\n \u003cli\u003eChen, B., Christianson, O., Wilson, J. M., \u0026amp; Samei, E. Assessment of volumetric noise and resolution performance for linear and nonlinear CT reconstruction methods. Medical physics, 41(7), 071909 (2014).\u003cstrong\u003e\u003cbr\u003e\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1. Acquisition and reconstruction parameters\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eScan protocol\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 193px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSingle spiral scan\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAdaptive 4D spiral scan\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eTube voltage (kV)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 394px;\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eScan times (phases)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 193px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eRadiation dose per phase (mGy)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 193px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eCTDIvol (mGy)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 193px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eKernel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 394px;\"\u003e\n \u003cp\u003eBv40\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eSlice thickness (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 394px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eCollimation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 394px;\"\u003e\n \u003cp\u003e0.6 \u0026times; 192\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eADMIRE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 394px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCTDIvol \u0026ndash; Volume CT dose index\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. CT values measurements (in Hounsfield units)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eConvention\u003c/strong\u003e\u003cstrong\u003eal\u0026nbsp;CT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNumber of summing phases\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTemporal MIP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTemporal AIP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" style=\"width: 158px;\"\u003e\n \u003cp\u003e-1.1 \u003cstrong\u003e\u0026plusmn;\u0026nbsp;\u003c/strong\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e2.3 \u0026plusmn; 0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e-0.2 \u0026plusmn; 0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e10.0 \u0026plusmn; 0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e-0.4 \u0026plusmn; 0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e13.8 \u0026plusmn; 1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e-0.5 \u0026plusmn; 0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e16.2 \u0026plusmn; 1.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 158px;\"\u003e\n \u003cp\u003e-0.5 \u0026plusmn; 0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e18.5 \u0026plusmn; 1.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e-0.5 \u0026plusmn; 0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eData are presented as means \u0026plusmn; standard deviations.\u003c/p\u003e\n\u003cp\u003e* Statistically significant difference compared with conventional CT with a single spiral scan (10 mGy) (P \u0026lt; .01).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAIP - Average Intensity Projection; CT - Computed Tomography; MIP - Maximum Intensity Projection\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. Image noise measurements (in Hounsfield units)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"667\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eConventional CT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNumber of summing phases\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTemporal MIP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTemporal AIP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" style=\"width: 167px;\"\u003e\n \u003cp\u003e9.0 \u003cstrong\u003e\u0026plusmn;\u0026nbsp;\u003c/strong\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e16.5 \u0026plusmn; 1.2 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e16.3 \u0026plusmn; 1.2 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e13.2 \u0026plusmn; 1.1 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e11.6 \u0026plusmn; 1.0 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e11.9 \u0026plusmn; 0.8 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e9.3 \u0026plusmn; 0.7 \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e11.0 \u0026plusmn; 0.7 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e8.1 \u0026plusmn; 0.5 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e10.8 \u0026plusmn; 0.6 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 167px;\"\u003e\n \u003cp\u003e7.4 \u0026plusmn; 0.4 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eData are presented as means \u0026plusmn; standard deviations.\u003c/p\u003e\n\u003cp\u003e* Significant difference compared with conventional CT with\u0026nbsp;a single spiral scan (10 mGy)\u0026nbsp;(P \u0026lt; .01).\u003c/p\u003e\n\u003cp\u003eAIP - Average Intensity Projection; CT - Computed Tomography; MIP - Maximum Intensity Projection\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4. Measurements of vessel phantom diameter by Full width at half maximum (FWHM)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVessel phantom diameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eConventional CT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eThe number of summing phases\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTemporal MIP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 0px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTemporal AIP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" style=\"width: 126px;\"\u003e\n \u003cp\u003e10 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" style=\"width: 126px;\"\u003e\n \u003cp\u003e14.4 \u0026plusmn; 0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.3 \u0026plusmn; 0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.4 \u0026plusmn; 0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.3 \u0026plusmn; 0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.4 \u0026plusmn; 0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.4 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.2 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.5 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.3 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.5 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e14.3 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" style=\"width: 126px;\"\u003e\n \u003cp\u003e5 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" style=\"width: 126px;\"\u003e\n \u003cp\u003e5.9 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.1 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.0 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.1 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.1 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.0 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.0 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.0 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.0 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.0 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6.0 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" style=\"width: 126px;\"\u003e\n \u003cp\u003e2 mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" style=\"width: 126px;\"\u003e\n \u003cp\u003e2.2 \u0026plusmn; 0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.1 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.1 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.1 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.1 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.1 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.1 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.2 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.2 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.2 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2.2 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eData are presented as means \u0026plusmn; standard deviations (mm). AIP - Average Intensity Projection; CT - Computed Tomography; MIP - Maximum Intensity Projection\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Four-Dimensional Computed Tomography, Tomography, X-Ray Computed, Image Processing, Computer-Assisted, Computed Tomography Angiography, Whole Body Imaging","lastPublishedDoi":"10.21203/rs.3.rs-5148491/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5148491/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAdaptive four-dimensional (4D) spiral computed tomography (CT) scans facilitate the acquisition of volume perfusion data for organs or long-range vessels but optimizing image quality and reducing noise while minimizing radiation doses remains challenging. Thus, image-processing techniques such as temporal maximum intensity projection (MIP) and average intensity projection (AIP) are crucial in this context. This ex vivo study aimed to compare image noise, spatial resolution, and vessel diameter measurements between temporal MIP and AIP images with those of conventional CT images using phantoms.\u003cstrong\u003e \u003c/strong\u003eThree phantoms were scanned with equivalent radiation doses using single helical and adaptive 10-phase 4D spiral scans using a third-generation dual-source CT scanner. Temporal MIP and AIP images of 4D CT scans were generated by summing varying numbers of phases, incorporating automatic motion correction with non-rigid registration and a noise reduction algorithm. The CT values and image noise of the temporal MIP and AIP images were compared to conventional CT images. The task transfer function (TTF) was calculated using static phantoms. Vessel diameters of the phantoms for each image dataset were evaluated using motion phantoms. Temporal AIP images showed comparable CT values with those of the reference image, whereas the CT values of the temporal MIP images were significantly higher than those of the reference images (P \u0026lt; .01). The image noise of temporal AIP images with six or more phases was equal to or lower than that of the reference images. In contrast, temporal MIP images exhibited consistently high noise levels regardless of the number of summed phases. The TTF of temporal AIP images was comparable to that of the reference CT images. However, the TTF of temporal MIP images gradually decreased as the number of summed phases increased. No significant differences were observed in vessel diameter measurements among the three groups or with varying numbers of summed phases (P \u0026gt; .05). In conclusion, temporal MIP and AIP images from 4D CT can reduce noise and maintain measurement reliability in motion phantoms, achieving performance levels comparable to conventional CT images.\u003c/p\u003e","manuscriptTitle":"Evaluation of Image Quality of Temporal Maximum Intensity Projection and Average Intensity Projection of Adaptive 4D Spiral CT Scans: A Phantom Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-22 09:48:45","doi":"10.21203/rs.3.rs-5148491/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"4edefbb3-1703-4446-a108-39e79ea9a656","owner":[],"postedDate":"October 22nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":38782517,"name":"Health sciences/Health care/Medical imaging/Tomography/Computed tomography"},{"id":38782518,"name":"Health sciences/Health care/Medical imaging/Three dimensional imaging"},{"id":38782519,"name":"Health sciences/Health care/Medical imaging/Whole body imaging"}],"tags":[],"updatedAt":"2025-02-04T12:09:00+00:00","versionOfRecord":[],"versionCreatedAt":"2024-10-22 09:48:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5148491","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5148491","identity":"rs-5148491","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}