Upright 0.5T Open MR Defaecating Proctography: an investigation into the inter- and intra-observer variability of pelvic floor measures using seated proctography

Upright 0.5T Open MR Defaecating Proctography: an investigation into the inter- and intra-observer variability of pelvic floor measures using seated proctography | 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 Upright 0.5T Open MR Defaecating Proctography: an investigation into the inter- and intra-observer variability of pelvic floor measures using seated proctography Rashed Sobhan, Paul Glover, Penny Gowland, Rahul Munyal, Olivier Mougin, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6641364/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 Object : We tested the feasibility, data quality, and reliability of an upright magnetic resonance defaecating proctography (uMRDP) technique using an Open 0.5T ASG MRI scanner Materials and Methods: Eight healthy volunteers (2 males) performed seated defaecation on a purpose-built radio-frequency commode coil in an Open scanner. An optimised T2-weighted HASTE sequence captured dynamic changes during all three phases of the Kegel manoeuvre. Inter- and intra-rater variability was measured from the pelvic floor metrices extracted by two radiologists. Results: All relevant pelvic floor landmarks could be identified and metrices were extracted with acceptable inter- and intra-rater variability. Intra-rater variation was marginal, with relative absolute differences ranging from 5−21% and 3.2−44%. Inter-rater variability was reported using correlation and Bland-Altman plots. Correlation between raters was satisfactory, with r 2 > 0.93, and bias ranged from -1.8−0.65 mm. Moreover, the limit of agreement in the Bland-Altman plot was small, ranging from 5.8−20.4 mm, indicating satisfactory precision. Discussion: The proposed upright MRDP technique can be used as a feasible and reliable alternative to supine MRDP, without the necessity of gadolinium injection and bowel preparation. It can capture defaecation in regular seated posture and can provide information complementary to standard-of-care fluoroscopic proctography for clinicians. Nuclear Medicine & Medical Imaging Upright Proctography pelvic floor imaging open magnet repeatability reproducibility Figures Figure 1 Figure 2 Figure 3 Introduction Defaecation disorders such as intussusception, rectocele, enterocele and pelvic organ prolapse severely impact the quality of life of sufferers and incur a significant economic burden on health services [ 1 ]. Due to age and prior history of multiple instrumented or vaginal deliveries, nearly 50% of multiparous women aged more than 50 years suffers from some form of pelvic floor disorder[ 2 ]. In the UK, a survey by the Royal College of Obstetricians and Gynaecologists on two thousand women reported that over 60% of women have at least one symptom of poor pelvic floor health, with 69% not having spoken about their pelvic floor health to anyone in the NHS [ 3 ]. In the USA, nearly 25% of women receive a diagnosis of pelvic floor disorder, and approximately 200,000 women undergo surgery every year [ 4 ]. Patients typically present with complaints/symptoms of faecal incontinence, pain during defaecation, chronic constipation, abnormal urination, sphincter defects, or sexual dysfunction [ 5 ] [ 4 , 1 ]. Imaging of the rectum is an important component of the conventional clinical assessment of pelvic floor disorder and subsequent surgical planning. The two main techniques used routinely are fluoroscopic proctography or supine magnetic resonance imaging (MRI) defaecography. Fluoroscopic proctography involves collecting a series of X-rays during defaecation after administering barium contrast per-rectum (and often orally to outline the small bowel). As X-ray imaging is a planar imaging tool, fluoroscopic proctography cannot image all three pelvic floor compartments at one time, it only images the luminal aspect of the bowel wall [ 6 ]. Thus, it is less sensitive at detecting abnormalities in the anterior pelvic compartment e.g., the urinary bladder, caused by general pelvic floor weakness [ 5 ]. Moreover, it involves a significant level of ionising radiation exposure [ 5 , 7 ] for women of child-bearing age [ 1 ] with a mean effective dose of 4.9mSv [ 8 ]. Contrary to X-ray-based technique, MRI involves no ionising radiation and, therefore, has no potential detrimental effects to future health. Moreover, it allows superior temporal and spatial resolution as well as imaging in multiple planes [ 8 ] with superior contrast to enable better delineation of the pelvic floor anatomy. However, conventional supine MR-based defaecating proctography (sMRDP) involves patients attempting to push out a gel from their rectums whilst lying down; patients find it difficult and uncomfortable to carry out the voiding phase, which reveals the most clinically relevant information[ 1 ]. Also, due to this abnormal posture, the process fails to mimic the normal structural or functional changes of pelvic floor during defaecation [ 9 ], partially limiting the clinical/diagnostic value of sMRDP. For example, fluoroscopic proctography is more sensitive than MRDP in detecting rectal intussusception, a condition where the bowel wall folds in on itself during defaecation [ 9 ]. A study has shown that only 50% of patients were able to push out an artificial stool when lying down compared to 80% when sitting up [ 10 ]. Upright MRDP (uMRDP) with an open configuration magnet allows patients to defaecate in their regular seated posture. Thus, it mitigates the limitations of sMRDP and enables clinicians to visualise anorectal morphology and functional changes of the complete pelvic floor while patients are defaecating in their typical upright posture. Many previous studies have investigated the prospects of uMRDP and compared its utility to fluoroscopic proctography, but not without limitations related to patient comfort, image quality, and/or resolution for capturing dynamic details. For example, many used T 1 -weighted imaging to suppress water contrast, which results in poor imaging of bladder and bowel. They enhanced contrast by mixing gadolinium-based contrast agent (GBCA) with rectal paste (i.e., ultrasound gel, mashed potatoes, etc)[ 8 , 5 , 7 , 6 , 1 ], but gadolinium contrast carries the risks of allergic reaction and involves the additional cost and environmental impact of GBCA [ 11 ]. Many studies have also used urethral catheters or placed markers in vagina and/or rectum to optimise their data quality [ 8 , 12 – 15 , 1 ], but such methods are invasive, may be uncomfortable, and could increase the risk of infection. Moreover, the existing radio-frequency (RF) coils for typical uMRDP imaging might not give dedicated coverage to the pelvic floor areas, limiting image quality. Coils strapped around the pelvis might cause discomfort and intervene the natural manoeuvres during defaecation [ 8 ] [ 7 ]. Therefore, alternative imaging sequences and a comfortable RF coil structure with suitable coverage should improve the efficacy of the technique. In this study, we use a 0.5T ASG Open MR scanner with a purpose-built RF commode coil and optimised T2-w acquisition protocol to propose a safe and comfortable method of performing uMRDP in the sitting position. The commode system with integrated RF coils substitutes the strapping of coils around the pelvis and ensures comfort as well as uninterrupted pelvic floor movement during defaecation. The T2-w dynamic sequence aims to provide sufficient contrast without invasive GBCA injection into the vagina, urinary bladder or small bowel. Our aim is three-fold: firstly, to investigate the feasibility of the equipment and sequences for imaging seated defaecation in healthy volunteers; secondly, to assess the quality of the dynamic data for extracting the conventional anatomical and functional metrices used for clinical assessments; finally, to evaluate the inter-rater and intra-rater variability in pelvic floor metrices, as extracted by two expert Radiologists. Material and Method Participants and Experimental Set-up After approval from the local ethics committee (FMHS 215–0223), participants were recruited via advertisement and written consent was received before scanning. Eight healthy volunteers (2 males; median age 23 years, ranging from 21 − 44 years) with no history of pelvic floor abnormalities, bowel disorders, neurological or psychiatric conditions were scanned inside a 56 cm lateral gap vertical open 0.5T scanner (MROpen, Paramed, Genoa, Italy) at University of Nottingham, UK in between September 2023 to May 2024. The Open MRI scanner allows scanning in seated, supine, prone, and standing positions and can operate with a maximum gradient strength of 20 mT/m and a maximum slew rate of 33 mT/m/ms in all three axes. No prior bowel preparation was necessary for participants. Privacy was ensured with opaque screens around the scanner and clinical room door; necessary communication during scans was achieved using an intercom. To ensure patient comfort as well as to obtain optimal anatomical coverage, we built a dedicated RF coil with a commode moulded on it, instead of using strapped coils (Fig. 1 a). Figure 1 b provides a schematic diagram of the components of the commode coil. The two coils of the RF commode were arranged at 105°, but with a small bend in the vertical/back coil to null the coupling between coils. The horizontal coil shape was determined by the outline of the bedpan cutout moulding, and the vertical coil is oblong. The single-turn coils were made from 4 mm diameter copper wire, tuned, and matched to 50 ohms. The coils were passively switched off during transmit pulses using crossed diodes. The pre-amplifiers were low-noise Mini-Circuits PHA-13LN + devices. Image Acquisition For the first half of the scanning, before injecting any ultrasound (US) gel, participants were asked to sit on the commode coil in their regular defaecation posture, leaning on a hand-rail to increase stability and reduce movement artefacts. Static images were acquired using a sagittal fast spin-echo (FSE) sequence and an axial FSE single-slice sequence.. A slice passing through the midline in the sagittal plane was selected for dynamic imaging. Dynamic images were acquired every 1.5 seconds during different stages of defaecation. To optimise the dynamic acquisition protocol, several half-Fourier acquisition half-Fourier single-shot turbo spin echo (HASTE) sequences were run while participants were instructed by the Radiologist to rest, clench, and push (i.e., strain) their pelvic floor without performing any defaecation. Table 1 gives the parameters of the sequences compared. The Radiologist then selected the most appropriate dynamic sequence with suitable contrast and resolution to be used for the latter half of the scanning with rectum filling. Table 1 Imaging parameters for static and dynamic imaging. Sequence TR/TE (ms) FA (°) FOV (mm) Resolution Slice Thickness (mm) Comment SAG FSE T2 4865/ 104 90/180 471 × 350 1.40 × 1.40 4 Two excitations to increase SNR AX FSE T2 800/ 104 90/180 634 × 350 1.40 × 1.40 5.5 PCL used for planning the slice. HASTE-OPTIM-10mm 1500/ 150 90/160 471 × 350 2.50× 2.30 10 Higher slice thickness to explore more SNR (n = 2) HASTE-OPTIM-7mm 1500/ 150 90/160 471 × 350 2.50 x 2.30 7 Reduction of the slice thickness to increase resolution (n = 5) HASTE-OPTIM-5mm 1520/ 100 90 /160 471 × 350 2.40 x 1.30 5 Further reduction of slice thickness to increase resolution (n = 1) Note: Baseline FSEs and HASTE-OPTIM-10mm and HASTE-OPTIM-7mm were acquired for comparison for all subjects; ‘n’ in the comment column presents the number of subjects for whom the sequence was deemed optimal by the Radiologists. For one subject, neither 7 nor 10mm was optimal, but 5mm was satisfactory. Abbreviations: PCL, pubo-coccygeal line; FSE, fast spin echo; TR, repetition time; TE, echo time; FOV, field of view; FA, flip angle; SNR, signal-to-noise ratio; HASTE, half Fourier single-shot turbo spin echo; mm, millimetres; After the first half, participants were taken to a clinical room and approximately 150 ml US gel was injected into the rectum while participants lay in left-lateral position. Participants were then asked to sit back on the commode coil in complete privacy. After acquiring the structural scans, dynamic data were collected with the pre-selected optimised dynamic sequence while participants performed Kegel manoeuvres expelling the gel under the Radiologist's instructions (i.e., 'rest', 'clench', ‘push’). If all the US were not evacuated in one run, the next optimal dynamic sequence was run whilst the participant was again asked to perform the Kegel manoeuvre in synchrony to the Radiologist’s command. The overall scan time for each participant was under one hour. Image analysis For each stage of the Kegel manoeuvre − namely, rest, clench, and defaecation − two Radiologists (CC and RM) with 8 and 4 years of consultant experience, respectively, extracted the following pelvic floor metrices: Pubo-coccygeal line (PCL): the line drawn on the sagittal plane that extends from the inferior border of the pubic symphysis (PS) to the last visible coccygeal joint [ 1 ]. It defines the base of the pelvic floor [ 1 ] and acts as the reference line for pelvic floor disorder grading. The spatial locations of other organ-specific reference points at rest and different stages of manoeuvres are defined as the perpendicular distance from PCL. H-line (hiatal width): the line from the inferior border of PS to the posterior border of the pubo-rectalis muscle. This line acts as an index of widening of the pubo-rectal hiatus and used to measure the anteroposterior diameter of the pelvic hiatus [ 1 ] [ 4 ]. M-line (hiatal descent): the line perpendicular to the PCL from the posterior-most border of H-line. This line gives the index of pelvic floor descent. The distance between the PCL and the lowest recognizable part of the urinary bladder, posterior vaginal fornix, rectum, and small intestine. Anorectal angle (ARA): ARA is the angle at the intersection between line tangent to the posterior wall of the rectum and a line parallel to the axis of the anal canal and the anorectal junction. ARA represents the function of the pubo-rectal muscle. An increase in ARA collectively reflects an increase in the intra-abdominal pressure. Each Radiologist extracted the above metrices twice, separated by at least a one-month time interval. Before making these measurements, both raters reached a consensus on how they defined the two end-points of PCL from the dynamic data. As most metrices were calculated as perpendicular distances from PCL, subjective choice of PCL end-points can introduce significant inter-rater variability in those metrices. No pelvic floor disorder grading was performed as the cohort was healthy and our primary target was to assess data quality and consistency in measurements between multiple raters. Inter- and intra-rater variability analysis All statistical analysis was performed using MATLAB (R2023a, Natick, MA). Intra-rater variability was assessed by quantifying the relative absolute difference (RAD) between two measurements from the same Radiologist. The mean and interquartile range (IQR) of RADs were reported for each pelvic floor metric. Inter-rater agreement was reported using correlation and Bland-Altman plot for each metric [ 16 ]. From the correlation plots, the following parameters are reported: sum of squared error for the linear regression fit (SSE); r 2 : Pearson correlation r-value squared; linear fit equation with slope and intercept. From the Bland-Altman plot, bias and coefficient of variation were reported along with reproducibility coefficient estimate based on IQR (RPC np =1.45×IQR) as all metrices failed the Kolmogorov-Smirnov normality test (with ks > 0.05). ARA was interpreted separately as it is an angular metric, as opposed to the other length metrices. Results Quality of dynamic data Figure 2 shows three time points from three dynamic HASTE data corresponding to each stage of the Kegel manoeuvre. The sequence had sufficient temporal resolution to capture the changes in the H-line, M-line, ARA, and other metrices during each stage of defaecation. As can be seen with the different HASTE sequences with different slice thicknesses, the pelvic floor organs and specific landmarks can be identified. Regardless of slice thickness, the bladder, pubic symphysis, posterior vaginal fornix, vagina and cervix, rectum can be located, and their lowest part can be identified to make the measurements. For most of the participants (5 out of 8), the Radiologists preferred the HASTE sequence with 7mm slice thickness as the optimal compromise between signal-to-noise ratio and resolution. The supplementary document contains gifs showing dynamic MRI of defaecation for the three participants in Fig. 2 . Inter- and intra-rater variability Table 2 summarises intra- and inter-rater variability parameters and Fig. 3 gives the correlation and Bland-Altman plot for the metrices. Median of intra-rater variability parameter (RAD) ranged from 5 − 21% and 3.2 − 44% for two raters; the differences in distance measures are small in comparison to the relative size of the pelvic floor organs, which suggests good intra-rater repeatability using uMRDP acquisition. Table 2 Intra- and inter-rater variability parameters for the pelvic floor metrices. Measures H-line M-line Bladder Prolapse Rectum Prolapse ARA (°) SI distance PVF distance Intra-rater variability Median (IQR) of Rater 1 RAD (%) 8.9 (8.6) 18.2 (46.4) 7 (22) 8.9 (11.7) 5 (6.4) 20.9 (29.5) 16.6 (37.6) Median (IQR) of Rater 2 RAD (%) 7.8 (12.5) 44.3 (79.5) 3.2 (27.7) 14.6 (17.3) 13.1 (10.4) 28.9 (43.3) 15.3 (29) Inter-rater variability Pearson r 2 (slope of correlation line) 0.93 (1.01) 0.94 (0.93) 0.99 (1.04) 0.97 (1.03) 0.96 (1.09) 0.94 (1.04) 0.96 (1.06) Bias -1.8 0.50 0.65 -0.5 3 -0.65 -2.0 LOA 20.4 18.4 5.8 13 22 18.8 9.8 CV (%) 6 22 54 13 5.6 13 21 Abbreviations: RAD, relative absolute difference; IQR, interquartile range; ARA, anorectal angle; SI, small intestine; PVF, posterior vaginal fornix, IQR, interquartile range; LOA, limit of agreement (2×RPC np ); CV, coefficient of variation. All metrics are in millimetres except ARA which is in degrees. Notes: 'RPC np ' – reproducibility coefficient estimate based on interquartile range (non-parametric statistics) where RPC np = 1.45*IQR ~ RPC (if distribution of differences is normal); 'CV' - coefficient of variation (standard deviation of mean values in %); Pearson r 2 is the square of correlation coefficient, describing agreement between the raters. The correlation plots of the length-based metrices show a good linear correlation between the raters, with r 2 ranging from 0.93 to 0.99. The slopes of the linear fits range between 0.93–1.09. For ARA, the r 2 was 0.96 with a slope of linear fit as 1.1; this suggests good agreement between the raters. From the Bland-Altman plots of the metrices, it is evident that the mean of the differences for each metric is close to zero (ranging from − 0.5 to 0.65mm), suggesting marginal bias between the two raters. For all the metrices, the differences are scattered randomly around the mean with no visible trend, indicating consistent, non-systematic difference across measurements. The 95% confidence interval of the differences, i.e., the limit of agreement (2×RPC np ), is between 5.8 mm (Bladder Prolapse) to 20.4 mm (H-line), which suggests that raters have extracted metrices with satisfactory precision. Further, the coefficient of variation values was generally low, except for bladder prolapse. The Bland-Altman plot for ARA shows a small bias of 3°, suggesting good agreement between the two raters. As with the other metrices, the differences are also randomly scattered around the mean with no visible trend. The 95% confidence interval was 22°, which suggests satisfactory precision. Finally, the coefficient of variation is 0.056 which provides further evidence of moderate precision. Discussion This preliminary study investigates the feasibility of an upright MRDP setup and explores the quality of the data acquired using a purpose-built RF coil and optimised T2-w protocol to extract pelvic floor metrices. Moreover, the inter- and intra-rater variability in the pelvic floor metrices are investigated to report whether Radiologists can reliably extract the conventional and complementary metrices from healthy pelvic floors using the proposed uMRDP method. This study is performed on healthy volunteers to test and optimise the safety, participant management procedures, set-up, protocol, and equipment so that in future extensions, a pelvic floor disorder patient cohort can be included. The dynamic data is of satisfactory quality in extracting relevant pelvic floor organs, landmarks, and spatial locations of organ-specific reference points. The agreement between raters was satisfactory for all pelvic floor metrices; also, the intra-rater variation was marginal (in the order of millimetres) to suggest satisfactory repeatability and reproducibility of the proposed uMRDP protocol. The purpose-built RF coil ensured expected participant comfort; participant could take their typical seated posture during defaecation. Unlike studies where participants could experience additional discomfort of being strapped around pelvis [ 7 ] while defaecating, this RF coil could capture the natural physiological changes during defaecation. Further, the comfortable sitting arrangement and complete privacy provided patients with a setup that was more similar to standard fluoroscopic proctography, follow the Radiologists commands and perform the Kegel manoeuvres without any stress or discomfort. The T2-w sequence gave an acceptable balance between the spatial and temporal resolution and signal-to-noise ratio while allowing sufficient soft-tissue-contrast to help Radiologists delineate landmarks like the rectum wall, coccygeal joints, organ borders, and specific reference points. The volume and texture of rectum-injected US gel mimicked those of faecal matter and provided sufficient contrast to visualise faecal movement. This allowed us to avoid using T1-w sequences and contrast-enhancement with either intravenous injection of GBCA [ 5 ] or filling [ 1 ] [ 15 ] [ 5 ] [ 7 ] [ 8 ] of bladder, vagina, or/and rectum with synthetic stool containing GBCA. Also, unlike previous studies, this method needed no bowel preparation or invasive catheterisation procedure to distend the urinary bladder or vagina with GBCA [ 1 ] [ 15 ]. Both raters extracted the metrices with sufficient repeatability and reproducibility. Defining the end-points of PCL was an essential initial step as most of the metrices depend on the perpendicular distance from PCL, and inconsistent definition causes higher variability. As a feasibility study, this work has some limitations. First, the small sample size might limit the power of the statistical analysis. Secondly, only healthy volunteers were chosen; the parameters of the optimal T 2 -w sequence might need some modification for pelvic floor disorder patient cohort. For example, a different slice thickness might be suitable for specific pelvic floor disorders. This study aimed at establishing the methodology for such patient studies; it defines a robust protocol with good quality data that can be used on pelvic floor disorder cohort to compare fluoroscopic proctography and uMRDP in terms of patient experience, acceptance, image quality, and diagnostic accuracy. Extension of the study to the pelvic floor disorder cohort will be more informative in a clinical context. Thirdly, the necessity of a prior consensus limits the immediate scalability of the study, although this should be addressable with a clearly defined published consensus to keep the inter-rater variability within acceptable range. Fourth, no study to our knowledge suggests an acceptable range of inter- and intra-rater variability for MRDP. Thus, we cannot suggest whether the variability is acceptable or not. However, as the bias is near zero, the limit of agreement is small, and the correlation between raters is sufficiently linear, we can suggest that the proposed uMRDP could be repeatable and reproducible across centres. For pelvic floor disorder diagnosis and treatment planning, uMRDP with an associated commode coil and optimal sequence selection gives information complementary to standard-of-care fluoroscopic proctography, including all compartments of the pelvic floor. For example, complete pelvic coverage and high soft-tissue contrast will allow radiologists to understand the degree of intussusception and/or rectal prolapse. Surgeons could be more certain as to whether any enterocele or sigmoidocele is co-existing with a rectocele (thus instigating or suggesting a transabdominal approach). Conclusion This preliminary feasibility study demonstrates that upright MRDP using a commode coil, and no contrast agent can provide a feasible alternative to supine MRDP. This approach allows more complete or near complete defaecation without the necessity to defaecate while lying supine. With the inclusion of purpose-built RF coil and optimised T2-w sequence, the proposed uMRDP provides good quality dynamic data while ensuring utmost comfort avoiding invasive procedures such as urinary bladder or vaginal catheterisation and GBCA administration into body. The variability analysis suggests that the quality of uMRDP dynamic data is good enough for Radiologists to identify the associated pelvic floor landmarks and extract metrices with acceptable inter- and intra-rater variability. For centres with access to upright scanners, this technique could provide complementary information to fluoroscopic proctography for the clinicians. Our next step will be to conduct an extended acceptability study with pelvic floor disorder patients and compare uMRDP and fluoroscopic proctography in terms of patient experience, acceptance as well as data quality. Abbreviations ARA anorectal angle CV coefficient of variation FA flip angle FOV field of view FSE fast spin echo GBCA Gadolinium-based contrast agent HASTE half Fourier single-shot turbo spin echo IQR interquartile range LOA limit of agreement MRDP magnetic resonance defaecating proctography MRI magnetic resonance imaging PCL pubo-coccygeal line PS pubic symphysis PVF posterior vaginal fornix RAD relative absolute difference RF radio-frequency RPC reproducibility coefficient SD standard deviation SI small intestine SNR signal-to-noise ratio SSE sum of squared error TE echo time TR repetition time uMRDP upright magnetic resonance defaecating proctography US ultrasound. Declarations Authors’ Contribution Sobhan: acquisition of Data, data curation, analysis and interpretation of data, drafting of manuscript, project administration. Glover: study conception and design, RF coil design and manufacturing, methodology, critical revision. Gowland: study conception and design, funding acquisition, supervision, validation, critical revision. Munyal: analysis and interpretation of data, supervision, validation, critical revision. Mougin: methodology, acquisition of data, supervision, critical revision Clarke: study conception and design, funding acquisition, analysis and interpretation of data, methodology, resources, supervision, validation, critical revision. Data availability statement Data sets generated during the current study are available from the corresponding author on reasonable request. Acknowledgements We acknowledge "EPSRC grant: Realising the potential of open MRI for dynamic studies of human anatomy and function (EP/V025856/1)" and “Nottingham University Hospital NHS Trust: Open Magnet T2 Weighted Defaecating Proctography for Evaluation of Defaecatory disorders - a feasibility study (47/185334/CPKILV)” for funding this study. 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Eur Radiol 7(8):1309–1317 Fielding JR, Griffiths DJ, Versi E, Mulkern RV, Lee ML, Jolesz FA (1998) MR imaging of pelvic floor continence mechanisms in the supine and sitting positions. AJR Am J Roentgenol 171(6):1607–1610 Popović ZB, Thomas JD (2017) Assessing observer variability: a user’s guide. Cardiovasc Diagnosis Therapy 7(3):317–324 Additional Declarations The authors declare potential competing interests as follows: There is no conflict of interest in this work. Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. 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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-6641364","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":454961820,"identity":"47917995-1d5b-4ac1-9ede-062cbbf8415d","order_by":0,"name":"Rashed Sobhan","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0003-4972-2744","institution":"Sir Peter Mansfield Imaging Centre, University of Nottingham","correspondingAuthor":true,"prefix":"","firstName":"Rashed","middleName":"","lastName":"Sobhan","suffix":""},{"id":454961821,"identity":"e8c2da2a-ca9d-4150-aaa9-85ba59345f29","order_by":1,"name":"Paul Glover","email":"","orcid":"","institution":"Sir Peter Mansfield Imaging Centre, University of Nottingham","correspondingAuthor":false,"prefix":"","firstName":"Paul","middleName":"","lastName":"Glover","suffix":""},{"id":454961822,"identity":"09f42d06-aca0-4194-9924-b7b30e3dedec","order_by":2,"name":"Penny Gowland","email":"","orcid":"https://orcid.org/0000-0002-4900-4817","institution":"Sir Peter Mansfield Imaging Centre, University of Nottingham","correspondingAuthor":false,"prefix":"","firstName":"Penny","middleName":"","lastName":"Gowland","suffix":""},{"id":454961823,"identity":"f84ea70c-a980-4629-9517-a9e52ad49589","order_by":3,"name":"Rahul Munyal","email":"","orcid":"","institution":"Nottingham University Hospitals NHS Trust","correspondingAuthor":false,"prefix":"","firstName":"Rahul","middleName":"","lastName":"Munyal","suffix":""},{"id":454961824,"identity":"78527e8e-1681-480f-b730-e478a2b97afe","order_by":4,"name":"Olivier Mougin","email":"","orcid":"","institution":"Sir Peter Mansfield Imaging Centre, University of Nottingham","correspondingAuthor":false,"prefix":"","firstName":"Olivier","middleName":"","lastName":"Mougin","suffix":""},{"id":454961825,"identity":"df0f424d-d921-4f6f-bffd-eed5db1956b5","order_by":5,"name":"Chistopher Clarke","email":"","orcid":"","institution":"Nottingham University Hospitals NHS Trust","correspondingAuthor":false,"prefix":"","firstName":"Chistopher","middleName":"","lastName":"Clarke","suffix":""}],"badges":[],"createdAt":"2025-05-11 19:58:51","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":true,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":true,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-6641364/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6641364/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":82702331,"identity":"c296ca4c-40fa-478a-a62f-3feab19f6ea6","added_by":"auto","created_at":"2025-05-14 09:45:29","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":504654,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Experimental setup for upright MR defaecating proctography. The purpose-built RF commode coil is circled in red; (b) the schematic diagram showing the components of the RF commode coil.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6641364/v1/af0d719da8776e293c62c74b.png"},{"id":82701223,"identity":"0b5ec964-f65c-4181-bef8-dd2b80ced0ba","added_by":"auto","created_at":"2025-05-14 09:37:29","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1057319,"visible":true,"origin":"","legend":"\u003cp\u003ePelvic floor metrices extracted at (a) rest, (b) clench, and (c) push stages of defaecation. Colours: the base of pelvic floor−pubococcygeal line (PCL)−in yellow; the descent of levator plate (M-line) in bright green; the length of the hiatus (H-line) in dark blue; distance from PCL for the lowest recognisable parts of: rectum, green; bladder, brown; posterior vaginal fornix, magenta; small intestine, light blue.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6641364/v1/0924d6b5a607f068a6ee0588.png"},{"id":82702332,"identity":"6bec2372-5945-4183-94c2-43087a8ac471","added_by":"auto","created_at":"2025-05-14 09:45:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":250727,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation and Bland-Altman plots showing the inter-rater agreement in pelvic floor measures. Correlation plot: ‘SSE’ - sum of squared error for the linear regression fit; 'r\u003csup\u003e2\u003c/sup\u003e' - Pearson r-value squared; 'eq' – linear fit equation with slope and intercept; Bland-Altman plot: 'RPC\u003csub\u003enp\u003c/sub\u003e' – reproducibility coefficient (RPC) estimate based on interquartile range (for non-parametric statistics); 'ks' - Kolmogorov-Smirnov test (ks \u0026lt;0.05 rejects the null hypothesis that the distribution is normal); 'CV' - coefficient of variation (SD of mean values in %).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6641364/v1/50976be6d7fb4f4474219ea4.png"},{"id":82703220,"identity":"6bc028a9-c0e8-4cf6-99c9-d19433cf65e2","added_by":"auto","created_at":"2025-05-14 09:53:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2387257,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6641364/v1/abdeb4a4-f7be-4a26-a697-d51f94e6b079.pdf"}],"financialInterests":"The authors declare potential competing interests as follows: There is no conflict of interest in this work. ","formattedTitle":"\u003cp\u003e\u003cstrong\u003eUpright 0.5T Open MR Defaecating Proctography: an investigation into the inter- and intra-observer variability of pelvic floor measures using seated proctography\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDefaecation disorders such as intussusception, rectocele, enterocele and pelvic organ prolapse severely impact the quality of life of sufferers and incur a significant economic burden on health services [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Due to age and prior history of multiple instrumented or vaginal deliveries, nearly 50% of multiparous women aged more than 50 years suffers from some form of pelvic floor disorder[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In the UK, a survey by the Royal College of Obstetricians and Gynaecologists on two thousand women reported that over 60% of women have at least one symptom of poor pelvic floor health, with 69% not having spoken about their pelvic floor health to anyone in the NHS [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. In the USA, nearly 25% of women receive a diagnosis of pelvic floor disorder, and approximately 200,000 women undergo surgery every year [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Patients typically present with complaints/symptoms of faecal incontinence, pain during defaecation, chronic constipation, abnormal urination, sphincter defects, or sexual dysfunction [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eImaging of the rectum is an important component of the conventional clinical assessment of pelvic floor disorder and subsequent surgical planning. The two main techniques used routinely are fluoroscopic proctography or supine magnetic resonance imaging (MRI) defaecography. Fluoroscopic proctography involves collecting a series of X-rays during defaecation after administering barium contrast per-rectum (and often orally to outline the small bowel). As X-ray imaging is a planar imaging tool, fluoroscopic proctography cannot image all three pelvic floor compartments at one time, it only images the luminal aspect of the bowel wall [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Thus, it is less sensitive at detecting abnormalities in the anterior pelvic compartment e.g., the urinary bladder, caused by general pelvic floor weakness [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Moreover, it involves a significant level of ionising radiation exposure [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] for women of child-bearing age [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] with a mean effective dose of 4.9mSv [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eContrary to X-ray-based technique, MRI involves no ionising radiation and, therefore, has no potential detrimental effects to future health. Moreover, it allows superior temporal and spatial resolution as well as imaging in multiple planes [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] with superior contrast to enable better delineation of the pelvic floor anatomy. However, conventional supine MR-based defaecating proctography (sMRDP) involves patients attempting to push out a gel from their rectums whilst lying down; patients find it difficult and uncomfortable to carry out the voiding phase, which reveals the most clinically relevant information[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Also, due to this abnormal posture, the process fails to mimic the normal structural or functional changes of pelvic floor during defaecation [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], partially limiting the clinical/diagnostic value of sMRDP. For example, fluoroscopic proctography is more sensitive than MRDP in detecting rectal intussusception, a condition where the bowel wall folds in on itself during defaecation [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. A study has shown that only 50% of patients were able to push out an artificial stool when lying down compared to 80% when sitting up [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eUpright MRDP (uMRDP) with an open configuration magnet allows patients to defaecate in their regular seated posture. Thus, it mitigates the limitations of sMRDP and enables clinicians to visualise anorectal morphology and functional changes of the complete pelvic floor while patients are defaecating in their typical upright posture.\u003c/p\u003e \u003cp\u003eMany previous studies have investigated the prospects of uMRDP and compared its utility to fluoroscopic proctography, but not without limitations related to patient comfort, image quality, and/or resolution for capturing dynamic details. For example, many used T\u003csub\u003e1\u003c/sub\u003e-weighted imaging to suppress water contrast, which results in poor imaging of bladder and bowel. They enhanced contrast by mixing gadolinium-based contrast agent (GBCA) with rectal paste (i.e., ultrasound gel, mashed potatoes, etc)[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], but gadolinium contrast carries the risks of allergic reaction and involves the additional cost and environmental impact of GBCA [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Many studies have also used urethral catheters or placed markers in vagina and/or rectum to optimise their data quality [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], but such methods are invasive, may be uncomfortable, and could increase the risk of infection. Moreover, the existing radio-frequency (RF) coils for typical uMRDP imaging might not give dedicated coverage to the pelvic floor areas, limiting image quality. Coils strapped around the pelvis might cause discomfort and intervene the natural manoeuvres during defaecation [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Therefore, alternative imaging sequences and a comfortable RF coil structure with suitable coverage should improve the efficacy of the technique.\u003c/p\u003e \u003cp\u003eIn this study, we use a 0.5T ASG Open MR scanner with a purpose-built RF commode coil and optimised T2-w acquisition protocol to propose a safe and comfortable method of performing uMRDP in the sitting position. The commode system with integrated RF coils substitutes the strapping of coils around the pelvis and ensures comfort as well as uninterrupted pelvic floor movement during defaecation. The T2-w dynamic sequence aims to provide sufficient contrast without invasive GBCA injection into the vagina, urinary bladder or small bowel. Our aim is three-fold: firstly, to investigate the feasibility of the equipment and sequences for imaging seated defaecation in healthy volunteers; secondly, to assess the quality of the dynamic data for extracting the conventional anatomical and functional metrices used for clinical assessments; finally, to evaluate the inter-rater and intra-rater variability in pelvic floor metrices, as extracted by two expert Radiologists.\u003c/p\u003e"},{"header":"Material and Method","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants and Experimental Set-up\u003c/h2\u003e \u003cp\u003e After approval from the local ethics committee (FMHS 215\u0026ndash;0223), participants were recruited via advertisement and written consent was received before scanning. Eight healthy volunteers (2 males; median age 23 years, ranging from 21\u0026thinsp;\u0026minus;\u0026thinsp;44 years) with no history of pelvic floor abnormalities, bowel disorders, neurological or psychiatric conditions were scanned inside a 56 cm lateral gap vertical open 0.5T scanner (MROpen, Paramed, Genoa, Italy) at University of Nottingham, UK in between September 2023 to May 2024. The Open MRI scanner allows scanning in seated, supine, prone, and standing positions and can operate with a maximum gradient strength of 20 mT/m and a maximum slew rate of 33 mT/m/ms in all three axes.\u003c/p\u003e \u003cp\u003e No prior bowel preparation was necessary for participants. Privacy was ensured with opaque screens around the scanner and clinical room door; necessary communication during scans was achieved using an intercom. To ensure patient comfort as well as to obtain optimal anatomical coverage, we built a dedicated RF coil with a commode moulded on it, instead of using strapped coils (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb provides a schematic diagram of the components of the commode coil. The two coils of the RF commode were arranged at 105\u0026deg;, but with a small bend in the vertical/back coil to null the coupling between coils. The horizontal coil shape was determined by the outline of the bedpan cutout moulding, and the vertical coil is oblong. The single-turn coils were made from 4 mm diameter copper wire, tuned, and matched to 50 ohms. The coils were passively switched off during transmit pulses using crossed diodes. The pre-amplifiers were low-noise Mini-Circuits PHA-13LN\u0026thinsp;+\u0026thinsp;devices.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eImage Acquisition\u003c/h3\u003e\n\u003cp\u003eFor the first half of the scanning, before injecting any ultrasound (US) gel, participants were asked to sit on the commode coil in their regular defaecation posture, leaning on a hand-rail to increase stability and reduce movement artefacts. Static images were acquired using a sagittal fast spin-echo (FSE) sequence and an axial FSE single-slice sequence.. A slice passing through the midline in the sagittal plane was selected for dynamic imaging. Dynamic images were acquired every 1.5 seconds during different stages of defaecation. To optimise the dynamic acquisition protocol, several half-Fourier acquisition half-Fourier single-shot turbo spin echo (HASTE) sequences were run while participants were instructed by the Radiologist to rest, clench, and push (i.e., strain) their pelvic floor without performing any defaecation. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e gives the parameters of the sequences compared. The Radiologist then selected the most appropriate dynamic sequence with suitable contrast and resolution to be used for the latter half of the scanning with rectum filling.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\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\u003eImaging parameters for static and dynamic imaging.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSequence\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTR/TE (ms)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFA (\u0026deg;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFOV\u003c/p\u003e \u003cp\u003e(mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eResolution\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSlice Thickness (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eComment\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSAG FSE T2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4865/ 104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90/180\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e471 \u0026times; 350\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.40 \u0026times; 1.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eTwo excitations to increase SNR\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAX FSE T2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e800/ 104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90/180\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e634 \u0026times; 350\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.40 \u0026times; 1.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003ePCL used for planning the slice.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHASTE-OPTIM-10mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1500/ 150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90/160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e471 \u0026times; 350\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.50\u0026times; 2.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eHigher slice thickness to explore more SNR (n\u0026thinsp;=\u0026thinsp;2)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHASTE-OPTIM-7mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1500/ 150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90/160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e471 \u0026times; 350\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.50 x 2.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eReduction of the slice thickness to increase resolution (n\u0026thinsp;=\u0026thinsp;5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHASTE-OPTIM-5mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1520/ 100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e/160\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e471 \u0026times; 350\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.40 x 1.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFurther reduction of slice thickness to increase resolution (n\u0026thinsp;=\u0026thinsp;1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eNote: Baseline FSEs and HASTE-OPTIM-10mm and HASTE-OPTIM-7mm were acquired for comparison for all subjects; \u0026lsquo;n\u0026rsquo; in the comment column presents the number of subjects for whom the sequence was deemed optimal by the Radiologists. For one subject, neither 7 nor 10mm was optimal, but 5mm was satisfactory.\u003c/p\u003e \u003cp\u003eAbbreviations: PCL, pubo-coccygeal line; FSE, fast spin echo; TR, repetition time; TE, echo time; FOV, field of view; FA, flip angle; SNR, signal-to-noise ratio; HASTE, half Fourier single-shot turbo spin echo; mm, millimetres;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAfter the first half, participants were taken to a clinical room and approximately 150 ml US gel was injected into the rectum while participants lay in left-lateral position. Participants were then asked to sit back on the commode coil in complete privacy. After acquiring the structural scans, dynamic data were collected with the pre-selected optimised dynamic sequence while participants performed Kegel manoeuvres expelling the gel under the Radiologist's instructions (i.e., 'rest', 'clench', \u0026lsquo;push\u0026rsquo;). If all the US were not evacuated in one run, the next optimal dynamic sequence was run whilst the participant was again asked to perform the Kegel manoeuvre in synchrony to the Radiologist\u0026rsquo;s command. The overall scan time for each participant was under one hour.\u003c/p\u003e\n\u003ch3\u003eImage analysis\u003c/h3\u003e\n\u003cp\u003eFor each stage of the Kegel manoeuvre\u0026thinsp;\u0026minus;\u0026thinsp;namely, rest, clench, and defaecation\u0026thinsp;\u0026minus;\u0026thinsp;two Radiologists (CC and RM) with 8 and 4 years of consultant experience, respectively, extracted the following pelvic floor metrices:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003ePubo-coccygeal line (PCL): the line drawn on the sagittal plane that extends from the inferior border of the pubic symphysis (PS) to the last visible coccygeal joint [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. It defines the base of the pelvic floor [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] and acts as the reference line for pelvic floor disorder grading. The spatial locations of other organ-specific reference points at rest and different stages of manoeuvres are defined as the perpendicular distance from PCL.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eH-line (hiatal width): the line from the inferior border of PS to the posterior border of the pubo-rectalis muscle. This line acts as an index of widening of the pubo-rectal hiatus and used to measure the anteroposterior diameter of the pelvic hiatus [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eM-line (hiatal descent): the line perpendicular to the PCL from the posterior-most border of H-line. This line gives the index of pelvic floor descent.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe distance between the PCL and the lowest recognizable part of the urinary bladder, posterior vaginal fornix, rectum, and small intestine.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eAnorectal angle (ARA): ARA is the angle at the intersection between line tangent to the posterior wall of the rectum and a line parallel to the axis of the anal canal and the anorectal junction. ARA represents the function of the pubo-rectal muscle. An increase in ARA collectively reflects an increase in the intra-abdominal pressure.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cp\u003eEach Radiologist extracted the above metrices twice, separated by at least a one-month time interval. Before making these measurements, both raters reached a consensus on how they defined the two end-points of PCL from the dynamic data. As most metrices were calculated as perpendicular distances from PCL, subjective choice of PCL end-points can introduce significant inter-rater variability in those metrices. No pelvic floor disorder grading was performed as the cohort was healthy and our primary target was to assess data quality and consistency in measurements between multiple raters.\u003c/p\u003e\n\u003ch3\u003eInter- and intra-rater variability analysis\u003c/h3\u003e\n\u003cp\u003eAll statistical analysis was performed using MATLAB (R2023a, Natick, MA). Intra-rater variability was assessed by quantifying the relative absolute difference (RAD) between two measurements from the same Radiologist. The mean and interquartile range (IQR) of RADs were reported for each pelvic floor metric. Inter-rater agreement was reported using correlation and Bland-Altman plot for each metric [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. From the correlation plots, the following parameters are reported: sum of squared error for the linear regression fit (SSE); r\u003csup\u003e2\u003c/sup\u003e: Pearson correlation r-value squared; linear fit equation with slope and intercept. From the Bland-Altman plot, bias and coefficient of variation were reported along with reproducibility coefficient estimate based on IQR (RPC\u003csub\u003enp\u003c/sub\u003e=1.45\u0026times;IQR) as all metrices failed the Kolmogorov-Smirnov normality test (with ks\u0026thinsp;\u0026gt;\u0026thinsp;0.05). ARA was interpreted separately as it is an angular metric, as opposed to the other length metrices.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eQuality of dynamic data\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows three time points from three dynamic HASTE data corresponding to each stage of the Kegel manoeuvre. The sequence had sufficient temporal resolution to capture the changes in the H-line, M-line, ARA, and other metrices during each stage of defaecation. As can be seen with the different HASTE sequences with different slice thicknesses, the pelvic floor organs and specific landmarks can be identified. Regardless of slice thickness, the bladder, pubic symphysis, posterior vaginal fornix, vagina and cervix, rectum can be located, and their lowest part can be identified to make the measurements. For most of the participants (5 out of 8), the Radiologists preferred the HASTE sequence with 7mm slice thickness as the optimal compromise between signal-to-noise ratio and resolution. The supplementary document contains gifs showing dynamic MRI of defaecation for the three participants in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eInter- and intra-rater variability\u003c/h3\u003e\n\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e summarises intra- and inter-rater variability parameters and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e gives the correlation and Bland-Altman plot for the metrices. Median of intra-rater variability parameter (RAD) ranged from 5\u0026thinsp;\u0026minus;\u0026thinsp;21% and 3.2\u0026thinsp;\u0026minus;\u0026thinsp;44% for two raters; the differences in distance measures are small in comparison to the relative size of the pelvic floor organs, which suggests good intra-rater repeatability using uMRDP acquisition.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\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\u003eIntra- and inter-rater variability parameters for the pelvic floor metrices.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMeasures\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eH-line\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM-line\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBladder Prolapse\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRectum\u003c/p\u003e \u003cp\u003eProlapse\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eARA\u003c/p\u003e \u003cp\u003e(\u0026deg;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSI\u003c/p\u003e \u003cp\u003edistance\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003ePVF\u003c/p\u003e \u003cp\u003edistance\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"8\" nameend=\"c8\" namest=\"c1\"\u003e \u003cp\u003eIntra-rater variability\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian (IQR) of Rater 1 RAD (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.9\u003c/p\u003e \u003cp\u003e(8.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.2\u003c/p\u003e \u003cp\u003e(46.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7\u003c/p\u003e \u003cp\u003e(22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.9\u003c/p\u003e \u003cp\u003e(11.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003cp\u003e(6.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e20.9\u003c/p\u003e \u003cp\u003e(29.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e16.6\u003c/p\u003e \u003cp\u003e(37.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian (IQR) of Rater 2 RAD (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.8\u003c/p\u003e \u003cp\u003e(12.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44.3\u003c/p\u003e \u003cp\u003e(79.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.2\u003c/p\u003e \u003cp\u003e(27.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14.6\u003c/p\u003e \u003cp\u003e(17.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e13.1\u003c/p\u003e \u003cp\u003e(10.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e28.9\u003c/p\u003e \u003cp\u003e(43.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e15.3\u003c/p\u003e \u003cp\u003e(29)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"8\" nameend=\"c8\" namest=\"c1\"\u003e \u003cp\u003eInter-rater variability\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePearson r\u003c/b\u003e\u003csup\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sup\u003e \u003cb\u003e(slope of correlation line)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.93\u003c/p\u003e \u003cp\u003e(1.01)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003cp\u003e(0.93)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003cp\u003e(1.04)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.97\u003c/p\u003e \u003cp\u003e(1.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.96\u003c/p\u003e \u003cp\u003e(1.09)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003cp\u003e(1.04)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.96\u003c/p\u003e \u003cp\u003e(1.06)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBias\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-2.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLOA\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e18.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCV (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"8\" nameend=\"c8\" namest=\"c1\"\u003e \u003cp\u003eAbbreviations: RAD, relative absolute difference; IQR, interquartile range; ARA, anorectal angle; SI, small intestine; PVF, posterior vaginal fornix, IQR, interquartile range; LOA, limit of agreement (2\u0026times;RPC\u003csub\u003enp\u003c/sub\u003e); CV, coefficient of variation. All metrics are in millimetres except ARA which is in degrees.\u003c/p\u003e \u003cp\u003eNotes: 'RPC\u003csub\u003enp\u003c/sub\u003e' \u0026ndash; reproducibility coefficient estimate based on interquartile range (non-parametric statistics) where RPC\u003csub\u003enp\u003c/sub\u003e = 1.45*IQR\u0026thinsp;~\u0026thinsp;RPC (if distribution of differences is normal); 'CV' - coefficient of variation (standard deviation of mean values in %); Pearson r\u003csup\u003e2\u003c/sup\u003e is the square of correlation coefficient, describing agreement between the raters.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe correlation plots of the length-based metrices show a good linear correlation between the raters, with r\u003csup\u003e2\u003c/sup\u003e ranging from 0.93 to 0.99. The slopes of the linear fits range between 0.93\u0026ndash;1.09. For ARA, the r\u003csup\u003e2\u003c/sup\u003e was 0.96 with a slope of linear fit as 1.1; this suggests good agreement between the raters.\u003c/p\u003e \u003cp\u003eFrom the Bland-Altman plots of the metrices, it is evident that the mean of the differences for each metric is close to zero (ranging from \u0026minus;\u0026thinsp;0.5 to 0.65mm), suggesting marginal bias between the two raters. For all the metrices, the differences are scattered randomly around the mean with no visible trend, indicating consistent, non-systematic difference across measurements. The 95% confidence interval of the differences, i.e., the limit of agreement (2\u0026times;RPC\u003csub\u003enp\u003c/sub\u003e), is between 5.8 mm (Bladder Prolapse) to 20.4 mm (H-line), which suggests that raters have extracted metrices with satisfactory precision. Further, the coefficient of variation values was generally low, except for bladder prolapse.\u003c/p\u003e \u003cp\u003eThe Bland-Altman plot for ARA shows a small bias of 3\u0026deg;, suggesting good agreement between the two raters. As with the other metrices, the differences are also randomly scattered around the mean with no visible trend. The 95% confidence interval was 22\u0026deg;, which suggests satisfactory precision. Finally, the coefficient of variation is 0.056 which provides further evidence of moderate precision.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis preliminary study investigates the feasibility of an upright MRDP setup and explores the quality of the data acquired using a purpose-built RF coil and optimised T2-w protocol to extract pelvic floor metrices. Moreover, the inter- and intra-rater variability in the pelvic floor metrices are investigated to report whether Radiologists can reliably extract the conventional and complementary metrices from healthy pelvic floors using the proposed uMRDP method. This study is performed on healthy volunteers to test and optimise the safety, participant management procedures, set-up, protocol, and equipment so that in future extensions, a pelvic floor disorder patient cohort can be included. The dynamic data is of satisfactory quality in extracting relevant pelvic floor organs, landmarks, and spatial locations of organ-specific reference points. The agreement between raters was satisfactory for all pelvic floor metrices; also, the intra-rater variation was marginal (in the order of millimetres) to suggest satisfactory repeatability and reproducibility of the proposed uMRDP protocol.\u003c/p\u003e \u003cp\u003eThe purpose-built RF coil ensured expected participant comfort; participant could take their typical seated posture during defaecation. Unlike studies where participants could experience additional discomfort of being strapped around pelvis [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] while defaecating, this RF coil could capture the natural physiological changes during defaecation. Further, the comfortable sitting arrangement and complete privacy provided patients with a setup that was more similar to standard fluoroscopic proctography, follow the Radiologists commands and perform the Kegel manoeuvres without any stress or discomfort.\u003c/p\u003e \u003cp\u003eThe T2-w sequence gave an acceptable balance between the spatial and temporal resolution and signal-to-noise ratio while allowing sufficient soft-tissue-contrast to help Radiologists delineate landmarks like the rectum wall, coccygeal joints, organ borders, and specific reference points. The volume and texture of rectum-injected US gel mimicked those of faecal matter and provided sufficient contrast to visualise faecal movement. This allowed us to avoid using T1-w sequences and contrast-enhancement with either intravenous injection of GBCA [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] or filling [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] of bladder, vagina, or/and rectum with synthetic stool containing GBCA. Also, unlike previous studies, this method needed no bowel preparation or invasive catheterisation procedure to distend the urinary bladder or vagina with GBCA [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBoth raters extracted the metrices with sufficient repeatability and reproducibility. Defining the end-points of PCL was an essential initial step as most of the metrices depend on the perpendicular distance from PCL, and inconsistent definition causes higher variability.\u003c/p\u003e \u003cp\u003eAs a feasibility study, this work has some limitations. First, the small sample size might limit the power of the statistical analysis. Secondly, only healthy volunteers were chosen; the parameters of the optimal T\u003csub\u003e2\u003c/sub\u003e-w sequence might need some modification for pelvic floor disorder patient cohort. For example, a different slice thickness might be suitable for specific pelvic floor disorders. This study aimed at establishing the methodology for such patient studies; it defines a robust protocol with good quality data that can be used on pelvic floor disorder cohort to compare fluoroscopic proctography and uMRDP in terms of patient experience, acceptance, image quality, and diagnostic accuracy. Extension of the study to the pelvic floor disorder cohort will be more informative in a clinical context. Thirdly, the necessity of a prior consensus limits the immediate scalability of the study, although this should be addressable with a clearly defined published consensus to keep the inter-rater variability within acceptable range. Fourth, no study to our knowledge suggests an acceptable range of inter- and intra-rater variability for MRDP. Thus, we cannot suggest whether the variability is acceptable or not. However, as the bias is near zero, the limit of agreement is small, and the correlation between raters is sufficiently linear, we can suggest that the proposed uMRDP could be repeatable and reproducible across centres.\u003c/p\u003e \u003cp\u003eFor pelvic floor disorder diagnosis and treatment planning, uMRDP with an associated commode coil and optimal sequence selection gives information complementary to standard-of-care fluoroscopic proctography, including all compartments of the pelvic floor. For example, complete pelvic coverage and high soft-tissue contrast will allow radiologists to understand the degree of intussusception and/or rectal prolapse. Surgeons could be more certain as to whether any enterocele or sigmoidocele is co-existing with a rectocele (thus instigating or suggesting a transabdominal approach).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis preliminary feasibility study demonstrates that upright MRDP using a commode coil, and no contrast agent can provide a feasible alternative to supine MRDP. This approach allows more complete or near complete defaecation without the necessity to defaecate while lying supine. With the inclusion of purpose-built RF coil and optimised T2-w sequence, the proposed uMRDP provides good quality dynamic data while ensuring utmost comfort avoiding invasive procedures such as urinary bladder or vaginal catheterisation and GBCA administration into body. The variability analysis suggests that the quality of uMRDP dynamic data is good enough for Radiologists to identify the associated pelvic floor landmarks and extract metrices with acceptable inter- and intra-rater variability. For centres with access to upright scanners, this technique could provide complementary information to fluoroscopic proctography for the clinicians. Our next step will be to conduct an extended acceptability study with pelvic floor disorder patients and compare uMRDP and fluoroscopic proctography in terms of patient experience, acceptance as well as data quality.\u003c/p\u003e "},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eARA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eanorectal angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ecoefficient of variation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eflip angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFOV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003efield of view\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFSE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003efast spin echo\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eGBCA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e\u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eGadolinium-based contrast agent\u003c/div\u003e \u003cdiv class=\"Description\"\u003e\u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eHASTE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ehalf Fourier single-shot turbo spin echo\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIQR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003einterquartile range\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLOA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003elimit of agreement\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMRDP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003emagnetic resonance defaecating proctography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMRI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003emagnetic resonance imaging\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePCL\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003epubo-coccygeal line\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003epubic symphysis\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePVF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eposterior vaginal fornix\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRAD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003erelative absolute difference\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eradio-frequency\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRPC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ereproducibility coefficient\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003estandard deviation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003esmall intestine\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSNR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003esignal-to-noise ratio\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSSE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003esum of squared error\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eecho time\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003erepetition time\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003euMRDP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eupright magnetic resonance defaecating proctography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eUS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eultrasound.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eAuthors\u0026rsquo; Contribution\u003c/h2\u003e \u003cp\u003eSobhan: acquisition of Data, data curation, analysis and interpretation of data, drafting of manuscript, project administration.\u003c/p\u003e \u003cp\u003eGlover: study conception and design, RF coil design and manufacturing, methodology, critical revision.\u003c/p\u003e \u003cp\u003eGowland: study conception and design, funding acquisition, supervision, validation, critical revision.\u003c/p\u003e \u003cp\u003eMunyal: analysis and interpretation of data, supervision, validation, critical revision.\u003c/p\u003e \u003cp\u003eMougin: methodology, acquisition of data, supervision, critical revision\u003c/p\u003e \u003cp\u003eClarke: study conception and design, funding acquisition, analysis and interpretation of data, methodology, resources, supervision, validation, critical revision.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eData availability statement\u003c/h2\u003e \u003cp\u003eData sets generated during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e \u003c/div\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eWe acknowledge \"EPSRC grant: Realising the potential of open MRI for dynamic studies of human anatomy and function (EP/V025856/1)\" and \u0026ldquo;Nottingham University Hospital NHS Trust: Open Magnet T2 Weighted Defaecating Proctography for Evaluation of Defaecatory disorders - a feasibility study (47/185334/CPKILV)\u0026rdquo; for funding this study. Big thanks to our colleague Arthur Harrison who has actively helped to find research participants.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFiaschetti V, Pastorelli D, Squillaci E, Funel V, Rascioni M, Meschini A, Salimbeni C, Sileri P, Franceschilli L, Simonetti G (2013) Static and dynamic evaluation of pelvic floor disorders with an open low-field tilting magnet. Clin Radiol 68(6):e293\u0026ndash;300\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaccioni F, Alt CD (2018) MRI of the Pelvic Floor and MR Defecography. In: Hodler J, Kubik-Huch RA, von Schulthess GK (eds) Diseases of the Abdomen and Pelvis 2018\u0026ndash;2021: Diagnostic Imaging - IDKD Book. Springer International Publishing, Cham, pp 13\u0026ndash;20. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/978-3-319-75019-4_2\u003c/span\u003e\u003cspan address=\"10.1007/978-3-319-75019-4_2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRoyal College of Obstetricians \u0026amp; Gynaecologists (2022) RCOG Position Statement: Pelvic floor health. RCOG. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.rcog.org.uk/about-us/campaigning-and-opinions/position-statements/pelvic-floor-health-position-statement/\u003c/span\u003e\u003cspan address=\"https://www.rcog.org.uk/about-us/campaigning-and-opinions/position-statements/pelvic-floor-health-position-statement/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Accessed 02 April 2025 2025\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRevels JW, Mansoori B, Fadl S, Wang SS, Olson MC, Moran SK, Terrazas MF, Fletcher JG, Perry WRG, Chernyak V, Mileto A (2023) MR Defecating Proctography with Emphasis on Posterior Compartment Disorders. Radiographics 43(1):e220119\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLamb GM, de Jode MG, Gould SW, Spouse E, Birnie K, Darzi A, Gedroyc WM (2000) Upright dynamic MR defaecating proctography in an open configuration MR system. Br J Radiol 73(866):152\u0026ndash;155\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDvorkin LS, Hetzer F, Scott SM, Williams NS, Gedroyc W, Lunniss PJ (2004) Open-magnet MR defaecography compared with evacuation proctography in the diagnosis and management of patients with rectal intussusception. Colorectal Dis 6(1):45\u0026ndash;53\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchoenenberger AW, Debatin JF, Guldenschuh I, Hany TF, Steiner P, Krestin GP (1998) Dynamic MR defecography with a superconducting, open-configuration MR system. Radiology 206(3):641\u0026ndash;646\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRoos JE, Weishaupt D, Wildermuth S, Willmann JK, Marincek B, Hilfiker PR (2002) Experience of 4 years with open MR defecography: pictorial review of anorectal anatomy and disease. Radiographics 22(4):817\u0026ndash;832\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGrossi U, Di Tanna GL, Heinrich H, Taylor SA, Knowles CH, Scott SM (2018) Systematic review with meta-analysis: defecography should be a first-line diagnostic modality in patients with refractory constipation. Aliment Pharmacol Ther 48(11\u0026ndash;12):1186\u0026ndash;1201\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRao SSC, Kavlock R, Rao S (2006) Influence of Body Position and Stool Characteristics on Defecation in Humans. Official J Am Coll Gastroenterol | ACG 101(12):2790\u0026ndash;2796\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParillo M, Mallio CA, Van der Molen AJ, Rovira \u0026Agrave;, Ramalho J, Ramalho M, Gianolio E, Karst U, Radbruch A, Stroomberg G, Clement O, Dekkers IA, Nederveen AJ, Quattrocchi CC (2023) Skin Toxicity After Exposure to Gadolinium-Based Contrast Agents in Normal Renal Function, Using Clinical Approved Doses: Current Status of Preclinical and Clinical Studies. Invest Radiol 58(8):530\u0026ndash;538\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang A, Mostwin JL, Rosenshein NB, Zerhouni EA (1991) Pelvic floor descent in women: dynamic evaluation with fast MR imaging and cinematic display. Radiology 179(1):25\u0026ndash;33\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHealy JC, Halligan S, Reznek RH, Watson S, Bartram CI, Kamm MA, Phillips RK, Armstrong P (1997) Magnetic resonance imaging of the pelvic floor in patients with obstructed defaecation. Br J Surg 84(11):1555\u0026ndash;1558\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLienemann A, Anthuber C, Baron A, Kohz P, Reiser M (1997) Dynamic MR colpocystorectography assessing pelvic-floor descent. Eur Radiol 7(8):1309\u0026ndash;1317\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFielding JR, Griffiths DJ, Versi E, Mulkern RV, Lee ML, Jolesz FA (1998) MR imaging of pelvic floor continence mechanisms in the supine and sitting positions. AJR Am J Roentgenol 171(6):1607\u0026ndash;1610\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePopović ZB, Thomas JD (2017) Assessing observer variability: a user\u0026rsquo;s guide. Cardiovasc Diagnosis Therapy 7(3):317\u0026ndash;324\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"University of Nottingham","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":"Upright Proctography, pelvic floor imaging, open magnet, repeatability, reproducibility","lastPublishedDoi":"10.21203/rs.3.rs-6641364/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6641364/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObject\u003c/strong\u003e: We tested the feasibility, data quality, and reliability of an upright magnetic resonance defaecating proctography (uMRDP) technique using an Open 0.5T ASG MRI scanner\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterials and Methods: \u003c/strong\u003eEight healthy volunteers (2 males) performed seated defaecation on a purpose-built radio-frequency commode coil in an Open scanner. An optimised T2-weighted HASTE sequence captured dynamic changes during all three phases of the Kegel manoeuvre. Inter- and intra-rater variability was measured from the pelvic floor metrices extracted by two radiologists.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eAll relevant pelvic floor landmarks could be identified and metrices were extracted with acceptable inter- and intra-rater variability. Intra-rater variation was marginal, with relative absolute differences ranging from 5−21% and 3.2−44%. Inter-rater variability was reported using correlation and Bland-Altman plots. Correlation between raters was satisfactory, with r\u003csup\u003e2\u003c/sup\u003e \u0026gt; 0.93, and bias ranged from -1.8−0.65 mm. Moreover, the limit of agreement in the Bland-Altman plot was small, ranging from 5.8−20.4 mm, indicating satisfactory precision.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiscussion: \u003c/strong\u003eThe proposed upright MRDP technique can be used as a feasible and reliable alternative to supine MRDP, without the necessity of gadolinium injection and bowel preparation. It can capture defaecation in regular seated posture and can provide information complementary to standard-of-care fluoroscopic proctography for clinicians.\u003c/p\u003e","manuscriptTitle":"Upright 0.5T Open MR Defaecating Proctography: an investigation into the inter- and intra-observer variability of pelvic floor measures using seated proctography","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-14 09:37:25","doi":"10.21203/rs.3.rs-6641364/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":"4a2714ec-7b59-4a5e-aea7-9d34da8d1368","owner":[],"postedDate":"May 14th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":48366035,"name":"Nuclear Medicine \u0026 Medical Imaging"}],"tags":[],"updatedAt":"2025-05-14T09:37:25+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-14 09:37:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6641364","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6641364","identity":"rs-6641364","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}