Dynamic Magnetic Resonance Imaging Scans Research Articles

Two resected cases of benign adenomyoepithelioma

BackgroundAdenomyoepithelioma (AME) of the breast is an uncommon tumor characterized by the proliferation of ductal epithelial and myoepithelial cells with the heterogeneity. Although benign AME is relatively easy to differentiate from breast cancer by core needle biopsy (CNB) alone, a definitive diagnosis is often difficult. The imaging findings of AME are also variable, and there are particularly few reports about radiological features, including contrast-enhanced magnetic resonance imaging (MRI) and apparent diffusion coefficient (ADC) values in AME.Case presentationWe present two cases of benign AME. Case 1 is a 30-year-old woman with a history of asthma. The cystic tumor shows smooth borders, and the intracystic solid component is irregular in shape and high vascularity. The pathological findings of the tumor were benign on CNB. The MRI scan showed a decreased ADC value. Case 2 is a 60-year-old woman with only a history of arrhythmia. The tumor shows a lobulated mass with cystic space and coarse calcifications. The pathological findings of the tumor were found to be benign by CNB. Dynamic MRI scan showed a fast washout pattern with a decreased ADC value. Both patients underwent excisional biopsy to confirm the diagnosis, and the pathological diagnosis was benign AME in both cases.ConclusionsThe AME of the breast has little specific imaging information, so it can be difficult to diagnose based on pathological findings of biopsy specimen. In our case, the ADC values were exceptionally low, contrary to previous reports. It is essential to carefully diagnose AME, considering the discrepancies in imaging findings observed in this case.

Preliminary Development of an MRI Atlas for Application to Cleft Care: Findings and Future Recommendations.

To introduce a highly innovative imaging method to study the complex velopharyngeal (VP) system and introduce the potential future clinical applications of a VP atlas in cleft care. Four healthy adults participated in a 20-min dynamic magnetic resonance imaging scan that included a high-resolution T2-weighted turbo-spin-echo 3D structural scan and five custom dynamic speech imaging scans. Subjects repeated a variety of phrases when in the scanner as real-time audio was captured. Multisite institution and clinical setting. Four adult subjects with normal anatomy were recruited for this study. Establishment of 4-D atlas constructed from dynamic VP MRI data. Three-dimensional dynamic magnetic resonance imaging was successfully used to obtain high quality dynamic speech scans in an adult population. Scans were able to be re-sliced in various imaging planes. Subject-specific MR data were then reconstructed and time-aligned to create a velopharyngeal atlas representing the averaged physiological movements across the four subjects. The current preliminary study examined the feasibility of developing a VP atlas for potential clinical applications in cleft care. Our results indicate excellent potential for the development and use of a VP atlas for assessing VP physiology during speech.

Assessment of Regional Functional Effects of Surgical Treatment in Thoracic Insufficiency Syndrome via Dynamic Magnetic Resonance Imaging.

Quantitative regional assessment of thoracic function would enable clinicians to better understand the regional effects of therapy and the degree of deviation from normality in patients with thoracic insufficiency syndrome (TIS). The purpose of this study was to determine the regional functional effects of surgical treatment in TIS via quantitative dynamic magnetic resonance imaging (MRI) in comparison with healthy children. Volumetric parameters were derived via 129 dynamic MRI scans from 51 normal children (November 2017 to March 2019) and 39 patients with TIS (preoperatively and postoperatively, July 2009 to May 2018) for the left and right lungs, the left and right hemi-diaphragms, and the left and right hemi-chest walls during tidal breathing. Paired t testing was performed to compare the parameters from patients with TIS preoperatively and postoperatively. Mahalanobis distances between parameters of patients with TIS and age-matched normal children were assessed to evaluate the closeness of patient lung function to normality. Linear regression functions were utilized to estimate volume deviations of patients with TIS from normality, taking into account the growth of the subjects. The mean Mahalanobis distances for the right hemi-diaphragm tidal volume (RDtv) were -1.32 ± 1.04 preoperatively and -0.05 ± 1.11 postoperatively (p = 0.001). Similarly, the mean Mahalanobis distances for the right lung tidal volume (RLtv) were -1.12 ± 1.04 preoperatively and -0.10 ± 1.26 postoperatively (p = 0.01). The mean Mahalanobis distances for the ratio of bilateral hemi-diaphragm tidal volume to bilateral lung tidal volume (BDtv/BLtv) were -1.68 ± 1.21 preoperatively and -0.04 ± 1.10 postoperatively (p = 0.003). Mahalanobis distances decreased after treatment, suggesting reduced deviations from normality. Regression results showed that all volumes and tidal volumes significantly increased after treatment (p < 0.001), and the tidal volume increases were significantly greater than those expected from normal growth for RDtv, RLtv, BDtv, and BLtv (p < 0.05). Postoperative tidal volumes of bilateral lungs and bilateral hemi-diaphragms of patients with TIS came closer to those of normal children, indicating positive treatment effects from the surgical procedure. Quantitative dynamic MRI facilitates the assessment of regional effects of a surgical procedure to treat TIS. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

A novel method for measuring bowel motility and velocity with dynamic magnetic resonance imaging in two and three dimensions.

Increasingly, dynamic magnetic resonance imaging (MRI) has potential as a noninvasive and accessible tool for diagnosing and monitoring gastrointestinal motility in healthy and diseased bowel. However, current MRI methods of measuring bowel motility have limitations: requiring bowel preparation or long acquisition times; providing mainly surrogate measures of motion; and estimating bowel-wall movement in just two dimensions. In this proof-of-concept study we apply a method that provides a quantitative measure of motion within the bowel, in both two and three dimensions, using existing, vendor-implemented MRI pulse sequences with minimal bowel preparation. This method uses a minimised cost function to fit linear vectors in the spatial and temporal domains. It is sensitised to the spatial scale of the bowel and aims to address issues relating to the low signal-to-noise in high-temporal resolution dynamic MRI scans, previously compensated for by performing thick-slice (10-mm) two-dimensional (2D) coronal scans. We applied both 2D and three-dimensional (3D) scanning protocols in two healthy volunteers. For 2D scanning, analysis yielded bi-modal velocity peaks, with a mean antegrade motion of 5.5 mm/s and an additional peak at ~9 mm/s corresponding to longitudinal peristalsis, as supported by intraoperative data from the literature. Furthermore, 3D scans indicated a mean forward motion of 4.7 mm/s, and degrees of antegrade and retrograde motion were also established. These measures show promise for the noninvasive assessment of bowel motility, and have the potential to be tuned to particular regions of interest and behaviours within the bowel.

A Dynamic Magnetic Resonance Imaging–Based Method to Examine In Vivo Levator Veli Palatini Muscle Function During Speech

Purpose The aim of this study was to develop a method able to quantify levator veli palatini (LVP) muscle shortening and contraction velocities using dynamic magnetic resonance imaging (MRI) throughout speech samples and relate these measurements to velopharyngeal portal dimensions. Method Six healthy adults (3 men and 3 women, M = 24.5 years) produced syllables representing 4 different manners of production during real-time dynamic MRI scans. We acquired an oblique-coronal slice of the velopharyngeal mechanism, which captured the length of the LVP, and manually segmented each frame. LVP shortening and muscle velocities were calculated from the acquired images. Results Using our method, we found that subjects demonstrated greater LVP shortening and higher maximum contraction velocities during fricative and plosive syllable production than during nasal or vowel syllable production. LVP shortening and maximum contraction velocity positively correlated with velopharyngeal port depth. Conclusions In vivo LVP function differs between manners of production, as expected, and an individual's velopharyngeal portal dimensions influence LVP function. These measures, contextualized with the force-length and force-velocity muscle relationships, provide new insight into LVP function. Future studies could use this method to investigate LVP function in healthy speakers and individuals with velopharyngeal dysfunction and how function relates to velopharyngeal anatomy.

A Hypothesis Generating the Mechanical Systems Underlying Posterior Vaginal Prolapse Based on Observed Displacements by Dynamic Magnetic Resonance Imaging.

ObjectiveThe aim of this study was to analyze quantified displacements of the posterior vaginal wall (PVW) on dynamic magnetic resonance imaging (MRI), which may generate hypotheses for the detailed mechanisms that underlie the development of posterior vaginal prolapse.MethodsPelvic dynamic MRI scans were obtained for 12 women with normal vaginal structure (stage 0) and 62 women with 4 consecutive stages (1–4) of posterior vaginal prolapse. Structural locations (apex vagina, distal vagina, and mid–perineal body [PB]) and equidistant points along the PVW (points 4–6 were considered as midvagina) were identified, and PVW length, straight distance of PVW, levator ani parameters (levator hiatus length [LHL], levator hiatus width [LHW], levator plate angle, anorectal angle, and M line [ML]), urogenital hiatus, and prolapse diameter were measured at rest and maximal Valsalva, respectively. The displacement of these measurements was obtained.ResultsFrom stage 0 to 2, the variables LHL, LHW, levator plate angle, anorectal angle, and ML increased gradually, but midvagina, distal vagina, and mid-PB were the opposite. From stage 2 to 3, apex vagina, midvagina, distal vaginal, mid-PB, LHL, LHW, and ML raised rapidly and peaked at stage 3, then declined at stage 4. In addition, the correlation coefficients between each measurement from stage 2 to 3 were statistically higher than those from stage 0 to 2.ConclusionsQuantified displacements of the PVW and its supporting structure were shown on dynamic MRI, and the mechanical mechanisms were hypothesized regarding the interaction between pressure and the support force contributing to the deformation of the PVW and the supporting structures.

Safety of Dynamic Magnetic Resonance Imaging of the Cervical Spine in Children Performed without Neurosurgical Supervision

The need for neurosurgical supervision as well as the general safety and utility of dynamic magnetic resonance imaging (MRI) of the cervical spine in children remains controversial. We present the largest descriptive cohort study of cervical flexion-extension MRI scans in pediatric patients to help elucidate the safety and utility of this technique. We retrospectively reviewed all cervical spine MRI scans performed at Lucile Packard Children's Hospital at Stanford from 2009 to 2015. We identified 66 dynamic cervical MRI scans performed in 45 children and 2young adults for further study. General anesthesia was used in 43 scans. The neuroradiology team performed all scans with no direct supervision by the neurosurgery team. There were no adverse events. Dynamic MRI detected significant instability that was not clearly seen on dynamic radiographs (5patients) and cord compression not seen on static MRI (9 patients). One patient with asymptomatic instability found on flexion-extension radiographs had no cord compression with movement on MRI and was managed conservatively. Two neonates with significant congenital malformations of the cervical spine were cleared for operative positioning for cardiac procedures based on flexion-extension MRI. Dynamic MRI is a safe tool for evaluating the cervical spine and cervicomedullary junction in various pediatric populations and can be performed safely without direct neurosurgical supervision. We describe for the first time the use of flexion-extension MRI to clear neonates with severe congenital cervical spine abnormalities for complex operative positioning and further care in the intensive care unit.

Congenital agenesis of the internal jugular vein: an extremely rare anomaly.

Vascular anomalies of major venous vessels are rarely seen. Moreover, congenital absence of internal jugular vein is extremely uncommon. In our case, a female patient presented with primary unknown left cervical mass. Cervical ultrasonography demonstrated absence of right internal jugular vein. In addition, computed tomography and dynamic magnetic resonance imaging scans confirmed this diagnosis. Compensatory left internal jugular vein enlargement mimicked sort of cervical mass. Venous magnetic resonance imaging images revealed the absence of right internal jugular vein with compensatory left internal jugular vein dominance. In the literature, the agenesis of IJV was mentioned in a case with concomitant multiple problems. Here, an asymptomatic case is reported with an incident diagnosis. No interventions were planned upon the patient's request. It should be kept in mind that any kind of anomalies can be seen during venous access and neck surgery.

A non-invasive, patient-specific method for estimating detrusor bladder pressure

The purpose of this study was to investigate the use of a combination of uroflowmetry, magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) simulations for estimating detrusor bladder pressure. Single-plane dynamic MRI scans of four human subjects with LUTS were first digitised. Thereafter, CFD simulations were carried out based on 3D models of the prostatic channels and urethras. Pressure-flow nomograms for each human subject were generated and the maximum pressures were then determined from the respective maximum flow rate obtained from standard uroflowmetry. The simulated maximum pressure was compared with actual values obtained using urodynamics pressure-flow studies (PFS). Detrusor bladder pressure estimation based on a combination of uroflowmetry, MRI and CFD technique is found to be a feasible non-invasive method for supplementing the current bladder outlet obstruction (BOO) diagnosis. This approach can be used to provide both qualitative and quantitative information to both physicians and the patients on the estimated detrusor pressure during maximum void and its indication before any more invasive treatments.

Simultaneous measurement of tissue oxygen level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) effects in abdominal tissue oxygenation level studies.

To assess oxygenation in abdominal organs with magnetic resonance imaging (MRI), a novel approach is presented to simultaneously measure both T1 - and T2*-maps serially during a single dynamic MRI scan in response to an oxygen challenge. The proposed acquisition scheme consists of a multishot multiecho gradient echo planar imaging sequence (ms-GEPI) interleaved with a multishot inversion recovery echo planar imaging (ms-IR-EPI) sequence. Respiratory motion compensation was accomplished with standard belt triggering and by acquiring all image data at the same phase of expiration. This respiratory-triggered, free-breathing, interleaved tissue oxygenation level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) acquisition technique was validated on phantoms and seven healthy volunteers in response to an oxygen challenge. Measurements of relaxation times both in vitro and in vivo were in good agreement with those obtained using conventional pulse sequences and reported in the literature. The interleaved sequence was able to measure oxygen-induced relaxation time changes in human abdominal organs. The free-breathing respiratory-triggered interleaved T1 and T2* sequence successfully provided relaxation time maps of abdominal organs in a dynamic scan without the need for image registration. The simultaneous monitoring of tissue and blood oxygenation improves time efficiency and should enhance studies comparing dynamic T1 and T2* data within the abdomen.

Predicting three‐dimensional patellofemoral kinematics from static imaging‐based alignment measures

Patellofemoral pain syndrome causes significant discomfort and disability among much of the general population. Despite recent breakthroughs in dynamic three-dimensional imaging technologies to assess pathological patellofemoral motion, such tools remain costly for clinical diagnostics applications. Thus, this study investigated whether three-dimensional patellofemoral kinematics could be predicted from routine two-dimensional static measures of patellofemoral joint alignment quantified from magnetic resonance imaging (MRI) data acquired in full knee extension. Twenty-six volunteers clinically diagnosed with patellofemoral pain (19 F/7 M, 25.9 ± 11.1 years) and 26 control subjects (19 F/7 M, 25.3 ± 7.7 years) were included in this IRB-approved study. Static three-dimensional sagittal T1-weighted gradient recall echo and dynamic MRI scans were acquired. For the dynamic image acquisition, subjects cyclically flexed and extended their knee (at 30 cycles/min) while a full cine-phase contrast MRI set (24 time frames of anatomic images and x-, y-, and z-velocity images) was acquired. From these data, static measures of patellofemoral alignment and three-dimensional patellofemoral kinematics were derived. Single and multiple regressions between static and kinematic variables were evaluated. Although shown reliable, the static MRI measures could only partially predict patellofemoral kinematics, with r(2) -values ranging from 16% to 77%. This makes it imperitave that the current precise, accurate, 3D, dynamic imaging techniques be translated into clinical tools.

Defecation 2: Internal anorectal resistance is a critical factor in defecatory disorders

The aim of this study was to test our hypothesis that the reason why imaging is of little assistance in diagnosing "constipation" causes may be related to the high sensitivity of internal anorectal flow resistance in defecation to small changes in geometry. We applied a mathematical model to describe the effects on flow mechanics of observed changes in the shape of the rectum and anus during defecation. Three groups of patients were studied with video proctograms. Group 1 comprised 4 patients with normal defecation studied with video proctography or magnetic resonance imaging (MRI). Group 2 comprised 8 patients with fecal incontinence, studied by video X-ray electromyography. Group 3 comprised 8 patients with constipation evaluated by video MRI. Three muscle vectors open the anorectal angle prior to defecation, causing the anorectal luminal diameter to increase to approximately twice its resting size. These vectors are forwards (anterior wall), backwards and downwards (posterior wall). Resistance to passage of a fecal bolus through the anorectum is determined by viscous friction against the anorectal wall and by the energy required to deform the bolus as it flows. The observed changes in anorectal geometry serve to reduce both the viscous friction in the anus and the deformation of the bolus, which reduces the force required to facilitate its passage through the anus. For example, if the effective diameter of the anus is doubled during defecation, the frictional resistance is reduced by a factor of 8. The sensitivity of flow resistance to geometry explains why MRI or computed tomography (CT) scans taken during defecation are not often helpful in diagnosing causation. Small changes in geometry can have a disproportionate affect on flow resistance. Combining accurate directional measurements during dynamic MRI or CT scans taken during defecation with observations of bolus deformation, and if possible, simultaneous anorectal manometry, may provide clinically helpful insights on patients with anorectal evacuation disorders.

Do repetitive Valsalva maneuvers change maximum prolapse on dynamic MRI?

This study seeks to quantify differences in anterior vaginal wall prolapse during sequential Valsalva attempts on dynamic magnetic resonance imaging (MRI). Subjects were taken from an on-going case-control study evaluating anterior vaginal wall prolapse. Women with a prolapse whose leading edge extended >or=1 cm beyond the hymenal ring were included (n = 40). All subjects performed three maximal Valsalva efforts while mid-sagittal dynamic MRI scans were obtained. Bladder descent between the first, second, and third maximal Valsalva efforts were compared. Forty percent of women had a greater than 2-cm increase in prolapse size from their first to third Valsalva attempt. Ninety-five percent of women extended their prolapse further with a third Valsalva. As is true during clinical examination, several attempts may be required to have maximal anterior compartment prolapse present during dynamic MRI of the pelvic floor.

The clinical usefulness of preoperative dynamic MRI to select decompression levels for cervical spondylotic myelopathy

The study subjects included 54 patients with cervical spondylotic myelopathy who underwent a selective laminoplasty. The patients were divided into three groups according to the number of decompressed levels: two levels, three levels and four or five levels. The number of cord compressions at every intervertebral level was determined in the flexion, neutral, and extension position using a dynamic magnetic resonance imaging (MRI) scan in consideration of both static and dynamic compressions. For each group, the clinical outcomes were evaluated. Moreover, the patients were divided into two groups according to their age. Then, the appearance ratios of cord compression between the neutral and extension position were compared at each intervertebral level. The clinical outcomes were satisfactory. There were no statistical differences among the three groups, except for the age and operation time. The position of the neck influenced the number of cord compressions. The appearance ratios of cord compression, which were especially prominent at C2/3, C3/4 and C4/5, showed high scores in the aged. The preoperative dynamic MRI scan was clinically useful. In the aged, attention should be given to C2/3, C3/4 and C4/5.

Patient allocation based on preoperative assessment of pancreatic fibrosis to secure pancreatic anastomosis performed by trainee surgeons: a prospective study

A fragile or non-fibrotic pancreas increases the risk of postoperative pancreatic fistula (POPF) after pancreatic head resection, whereas pancreatic fibrosis decreases the risk. The degree of pancreatic fibrosis can be estimated using the time-signal intensity curve (TIC) of the pancreas, obtained with dynamic magnetic resonance imaging (MRI). We have investigated whether trainee surgeons can perform pancreatic anastomosis safely, without the occurrence of POPF, when patients are selected carefully based on a preoperative assessment of pancreatic fibrosis. Seventy-two consecutive patients who underwent pancreatic head resection were enrolled in this prospective trial. Dynamic contrast-enhanced MRI of the pancreas was performed preoperatively in all patients who, based on their pancreatic TIC profile, were then allocated to one of two groups: Group A comprised patients with type I pancreatic TIC, signifying a normal pancreas without fibrosis (n = 46); Group B comprised patients with type II or III pancreatic TIC, signifying a fibrotic pancreas (n = 26). An end-to-side duct-to-mucosa pancreaticojejunostomy was performed in all patients, with all patients in Group A operated on by two experienced surgeons, and all patients in Group B operated on by one of eight trainee surgeons at various stages of training. There was no operative mortality. POPF developed in 19 patients: 12 patients with grade A POPF and seven with grade B. All except one of the POPF occurred in Group A patients. The POPF in the one patient from Group B was grade A (p < 0.001). A trainee surgeon can perform a secure pancreatic anastomosis without the occurrence of POPF in patients with a pancreas displaying a fibrotic pancreatic TIC on dynamic MRI scans.

An in vivo magnetic resonance imaging technique for measurement of rat lumbar vertebral body blood perfusion

The technical feasibility of dynamic contrast-enhanced magnetic resonance imaging (MRI) measurement of rat vertebral blood perfusion using a 1.5 T clinical scanner and a small surface coil was investigated in this study. Nine male 7-month-old Wistar-Kyoto rats were used. Computed tomographic assessment of lumbar vertebral bone mineral density (BMD) and MRI assessment of lumbar vertebral blood perfusion were performed twice with 8 weeks' interval. A 4.7 cm surface coil was used for receiving radiofrequency signal. Gadolinium-DOTA (0.3 mmol/kg) was injected through the tail vein of the rat as a quick bolus and dynamic MRI scan was carried out on the central sagittal plane of the lumbar spine for 8 min with a temporal resolution of 0.6 s. Blood perfusion parameters of wash-in rate, maximum enhancement and wash-out rate were derived from the dynamic MR images. No vertebral body size and vertebral BMD difference was detected between the two time points (P=0.222 and 0.123, respectively). Wash-in rate was 0.105 (+/-0.016)% and 0.111 (+/-0.018)%, maximum enhancement 126.5 (+/-10.6)% and 129.2 (+/-13.4)%, and wash-out rate 0.788 (+/-0.182)% and 0.792 (+/-0.182)% for the two time points. With these parameters, no difference was found between the two time points with a P value of 0.575, 0.889 and 0.754, respectively. We conclude that dynamic contrast-enhanced MRI measurement of rat vertebral blood perfusion using a 1.5 T clinical scanner and a small surface coil is feasible and reliable. This technique offers a non-invasive means to probe vertebral blood perfusion changes associated with rat disease models.

Bone oedema predicts erosive progression on wrist MRI in early RA--a 2-yr observational MRI and NC scintigraphy study

To investigate if disease assessment by contrast-enhanced dynamic and static magnetic resonance imaging (MRI) and quantitative nanocolloid (NC) scintigraphy gives useful additional information in early rheumatoid arthritis (RA). Twenty-seven patients with early RA (disease duration < or =12 months) were followed up for 1 yr and 24 of them for 2 yrs with contrast-enhanced MRI and NC scintigraphy of the wrist joint. Synovial inflammation was assessed by measuring time-dependent enhancement rates (E-rate) from dynamic MRI scans and technetium(99m)-labelled nanocolloid ((99m)Tc-NC) uptake from scintigraphy scans. Synovial membrane hypertrophy, bone oedema and erosions were semiquantitatively scored according to the Outcome Measures in Rheumatology Clinical Trials RA-MRI scoring system from static MR images. Response to the treatment was evaluated based on whether or not > or = 50% improvement was achieved in the tender and swollen joint scores and the Health Assessment Questionnaire score, with normal C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) levels. Progression of the erosion score on wrist MRI was evaluated as the outcome. The baseline MRI bone oedema score (rho= 0.67), MRI synovitis score (rho= 0.57), ESR (rho= 0.56), CRP (rho= 0.48), E-rate (rho= 0.47) and (99m)Tc-NC uptake (rho= 0.45) were related with the change in the MRI erosion score from baseline to 2 yrs (rho= Spearman's correlation). In the multivariate logistic regression model, the bone marrow oedema score was the only baseline variable that predicted erosive progression at 2 yrs' follow-up (OR 4.2, 95% CI 1.3-13.8). The median (interquartile range) change in the erosion score from baseline to 2 yrs was 0 (0, 0) and 4 (2, 5) in the patients with (n= 9) and without (n= 15) a persistent clinical response over the 2 yrs, respectively (P= 0.001). The non-responders who presented with erosive progression from 1 yr to 2 yrs had higher MRI synovitis scores, bone oedema scores, E-rate and (99m)Tc-NC uptake at 1-yr follow-up than the non-responders without progressive bone damage. The degree of local synovial inflammation at baseline, evaluated by dynamic and static MRI and quantitative NC scintigraphy, is closely related to the progression of wrist joint erosions during the first 2 yrs of the disease. Furthermore, at follow-up, if no persistent clinical response is achieved, these imaging methods may help to predict future erosiveness and help in clinical therapeutic decision making.

Magnetic Resonance Imaging of Normal Levator Ani Anatomy and Function

In Brief OBJECTIVE To evaluate the anatomy and function of the levator ani in normal women by dynamic magnetic resonance imaging. METHODS Twelve asymptomatic, nulliparous, premenopausal women with no previous pelvic surgery underwent a dynamic magnetic resonance imaging scan of their pelvis. The origin, orientation, thickness, and function of the two components of the levator ani were studied. RESULTS The ileococcygeus is a thin muscle with an upward convexity. It slopes forward and medially. It is of variable thickness (mean thickness 2.9 mm, standard deviation 0.8 mm). There are apparent gaps in the muscle diaphragm and at its site of origin from the obturator fascia. The puborectalis is a thicker muscle. It is shaped like a belt encasing the pelvic organs. It is taller posteriorly than anteriorly. It is not attached to the bladder neck, but the midurethra and lower urethra lie in close proximity to it. The puborectalis moves dorsoventrally, whereas the ileococcygeus moves craniocaudally. CONCLUSION The levator ani is not a single muscle but has two functional components that vary in thickness, origin, and function. The ileococcygeus has a mainly supportive function, whereas the puborectalis has a sphincteric function. Gaps in the diaphragmatic portion of the ileococcygeus are a normal finding. Individual components of the levator ani may be prone to different types of childbirth trauma and should therefore be assessed separately when planning rehabilitation. Anatomy and function of levator ani is studied in normal nulliparous women using dynamic magnetic resonance imaging.

Magnetic resonance imaging of normal levator ani anatomy and function.

To evaluate the anatomy and function of the levator ani in normal women by dynamic magnetic resonance imaging. Twelve asymptomatic, nulliparous, premenopausal women with no previous pelvic surgery underwent a dynamic magnetic resonance imaging scan of their pelvis. The origin, orientation, thickness, and function of the two components of the levator ani were studied. The ileococcygeus is a thin muscle with an upward convexity. It slopes forward and medially. It is of variable thickness (mean thickness 2.9 mm, standard deviation 0.8 mm). There are apparent gaps in the muscle diaphragm and at its site of origin from the obturator fascia. The puborectalis is a thicker muscle. It is shaped like a belt encasing the pelvic organs. It is taller posteriorly than anteriorly. It is not attached to the bladder neck, but the midurethra and lower urethra lie in close proximity to it. The puborectalis moves dorsoventrally, whereas the ileococcygeus moves craniocaudally. The levator ani is not a single muscle but has two functional components that vary in thickness, origin, and function. The ileococcygeus has a mainly supportive function, whereas the puborectalis has a sphincteric function. Gaps in the diaphragmatic portion of the ileococcygeus are a normal finding. Individual components of the levator ani may be prone to different types of childbirth trauma and should therefore be assessed separately when planning rehabilitation.