MR排便造影在后盆腔障碍性疾病中的评估价值

后盆腔障碍疾病是以肛直肠解剖和功能异常为主的一类盆底功能障碍性疾病,伴有便秘、便失禁等临床症状。MR排便造影是一种动态MR成像方法,可对后盆腔结构形态和运动功能异常情况直观显示,能够鉴别后盆腔障碍性疾病的类型并认识其发病原因,如直肠膨出、肠疝、盆腔器官脱垂和直肠套叠、脱垂等,同时对便失禁早期的肛直肠形态学和功能学异常改变的诊断有重要提示价值。     

Anal sphincter defects in patients with fecal incontinence: endoanal versus external phased-array MR imaging

PURPOSE: To prospectively compare external phased-array magnetic resonance (MR) imaging with endoanal MR imaging in depicting external and internal anal sphincter defects in patients with fecal incontinence and to prospectively evaluate observer reproducibility in the detection of external and internal anal sphincter defects with both MR imaging techniques. MATERIALS AND METHODS: The medical ethics committees of both participating hospitals approved the study, and informed consent was obtained. Thirty patients (23 women, seven men; mean age, 58.7 years; range, 37-78 years) with fecal incontinence underwent MR imaging with both endoanal and external phased-array coils. MR images were evaluated by three radiologists with different levels of experience for external and internal anal sphincter defects. Measures of inter- and intraobserver agreement of both MR imaging techniques and of differences between both imaging techniques were calculated. RESULTS: Both MR imaging techniques did not significantly differ in the depiction of external (P > .99) and internal (P > .99) anal sphincter defects. The techniques corresponded in 25 (83%) of 30 patients for the depiction of external anal sphincter defects and in 28 (93%) of 30 patients for the depiction of internal anal sphincter defects. Interobserver agreement was moderate to good for endoanal MR imaging and poor to fair for external phased-array MR imaging. Intraobserver agreement ranged from fair to very good for both imaging techniques. CONCLUSION: External phased-array MR imaging is comparable to endoanal MR imaging in the depiction of clinically relevant anal sphincter defects. Because of the weak interobserver agreement, both MR imaging techniques can be recommended in the diagnostic work-up of fecal incontinence only if sufficient experience is available.     

Rectal cancer: MR imaging in local staging--is gadolinium-based contrast material helpful?

PURPOSE: To determine retrospectively whether addition of gadolinium-enhanced T1-weighted magnetic resonance (MR) sequence to T2-weighted turbo spin-echo (SE) MR imaging is valuable for preoperative assessment of T stage and circumferential resection margin in patients with primary rectal cancer. MATERIALS AND METHODS: Local institutional review board approved study and waived informed patient consent. Eighty-three patients with operable primary rectal cancer underwent preoperative MR imaging. Retrospectively, two observers independently scored T2-weighted turbo SE MR images and, in a second reading, T2-weighted images combined with gadolinium-enhanced T1-weighted turbo SE MR images for tumor penetration through rectal wall and tumor extension into mesorectal fascia. A confidence level scoring system was used, and receiver operating characteristic (ROC) curves were generated. Histologic findings were standard of reference. Difference in performance of T2-weighted and combined T2-weighted plus gadolinium-enhanced T1-weighted sequences was analyzed by comparing corresponding areas under ROC curves (A(z)) for each observer. Interobserver agreement was calculated by using linear weighted kappa statistics. RESULTS: Addition of contrast-enhanced T1-weighted to T2-weighted MR imaging did not significantly improve diagnostic accuracy for prediction of tumor penetration through rectal wall (A(z) of T2-weighted vs T2-weighted plus T1-weighted images for observer 1, 0.740 vs 0.764; observer 2, 0.856 vs 0.768) and tumor extension into mesorectal fascia (A(z) for observer 1, 0.962 vs 0.902; observer 2, 0.902 vs 0.911). Diagnostic performance (A(z)) of MR and interobserver agreement were high for prediction of tumor extension into mesorectal fascia (kappa = 0.61, 0.74) but only moderate for penetration through rectal wall (kappa = 0.47, 0.45). CONCLUSION: Gadolinium-enhanced MR sequences did not improve diagnostic accuracy for assessment of tumor penetration through rectal wall and tumor extension into mesorectal fascia.     

External anal sphincter defects in patients with fecal incontinence: comparison of endoanal MR imaging and endoanal US

PURPOSE: To prospectively compare in a multicenter study the agreement between endoanal magnetic resonance (MR) imaging and endoanal ultrasonography (US) in depicting external anal sphincter (EAS) defects in patients with fecal incontinence. MATERIALS AND METHODS: The study was approved by the medical ethics committee of all participating centers. A total of 237 consenting patients (214 women, 23 men; mean age, 58.6 years +/- 13 [standard deviation]) with fecal incontinence were examined from 13 different hospitals by using endoanal MR imaging and endoanal US. Patients with an anterior EAS defect depicted on endoanal MR images and/or endoanal US scans underwent anal sphincter repair. Surgical findings were used as the reference standard in the determination of anterior EAS defects. The Cohen kappa statistic and McNemar test were used to calculate agreement and differences between diagnostic techniques. RESULTS: Agreement between endoanal MR imaging and endoanal US was fair for the depiction of sphincter defects (kappa = 0.24 [95% confidence interval: 0.12, 0.36]). At surgery, EAS defects were found in 31 (86%) of 36 patients. There was no significant difference between MR imaging and US in the depiction of sphincter defects (P = .23). Sensitivity and positive predictive value were 81% and 89%, respectively, for endoanal MR imaging and 90% and 85%, respectively, for endoanal US. CONCLUSION: In the selection of patients for anal sphincter repair, both endoanal MR imaging and endoanal US are sensitive tools for preoperative assessment, and both techniques can be used to depict surgically repairable anterior EAS defects.     

Integrated study of fecal incontinence with defecography, anal ultrasonography, perineography, and manometry

INTRODUCTION: Imaging methods such as defecography, anal US and perineography, combined with manometry, now permit to identify a growing number of causes of anorectal and pelvic floor deficiency. Fecal incontinence patients can thus be approached correctly relative to both diagnosis and treatment. We investigated the role of these techniques in the work-up of fecal incontinence. MATERIAL AND METHODS: Thirty-eight subjects suffering from fecal incontinence were examined. Defecography was carried out with a special commode and videorecorded on a VHS cassette. Anal US was performed with a 7-MHz rotating probe (type 1846) with 3-cm focus length. Perineography was carried out in 15 female patients. RESULTS: The anorectal angle (ARA) at rest was increased (mean: 106 degrees; normal range: 90-100 degrees) in 34 cases; involuntary barium leakage was seen in 8 patients, especially on coughing. On squeezing, ARA was normal in 10 cases (mean: 72 degrees; normal range: 60-90 degrees); in 5 cases of puborectal hypotonia there was no angular excursion between rest and squeezing (mean: 105 degrees). During evacuation, the average ARA value was 166 degrees in 21 cases and ARA stretched to verticalization in 8 cases (mean: 179 degrees). Morphofunctional anorectal changes appeared as rectal mucosal prolapse (12 cases), rectocele (10 cases), perineal descent syndrome (8 cases) and external rectal prolapse (3 cases). Anal US identified 15 interruptions in sphincterial rings: 12 patterns were hypoechoic, 2 mixed and 1 hyperechoic. Atrophic thinning of internal anal sphincter was seen in 5 idiopathic incontinence patients. Perineography demonstrated cystocele in 5 cases and cystourethrocele in 1 case. Manometry showed sphincterial hypotonia at rest in 15 cases, lower values of anorectal pressure on squeezing in 8 and smaller air volumes inhibiting external sphincterial tone in 19 cases. CONCLUSIONS: Defecographic studies with evaluation of ARA and its changes are an important tool with high diagnostic yield. When combined with other techniques, they provide differential criteria for sphincterial and puborectal causes and permits to identify associated pelvic floor dysfunctions. We believe that defecography, anal US (and perineography in complex disorders) are necessary techniques for the correct clinical approach to fecal incontinence patients, whose role and diagnostic yield are a valid support to manometry.     

Digital videoradiography applied to the study of the recto-anal region during defecography

The authors have employed a real-time fluoroscopic computerized equipment during defecography. Digitalized images were acquired at a rate of three frames/s and then processed and became immediately available. Digital defecography was employed in 67 patients with various anorectal diseases--i.e., rectocele, descending perineum, rectal prolapse, non-relaxing puborectalis syndrome and fecal incontinence. We found time-interval difference (TID) technique especially useful for it allowed different functional phases of defecation to be depicted on a single subtracted image and an evaluation of the movements of anorectal region. The high contrast resolution of the computerized equipment demonstrated even minimal contrast medium leaks in fecal incontinence. The examination is easy and rapid to perform with a low radiation dose to the patients.     

Opaque enema and radiography of defecation in the pre- and postoperative morpho-functional evaluation of rectal neoplasms

From November 1989 to April 1990, 16 patients with rectal cancer were examined preoperatively by means of double contrast barium enema and defecography. Double contrast barium enema was used to identify the cancer: based on the distance of cancer from anal rima, the patients were divided into 3 groups: 1) less than 6 cm; 2) 6-11 cm; 3) more than 11 cm. In all patients defecography was performed at the end of barium enema to evaluate rectal wall mobility. Thus, the morphological information yielded by barium enema could be integrated with the dynamic data from defecography. The evaluation was thus possible of both longitudinal and, indirectly, transverse tumor spread. All the patients underwent surgery and radiological findings were compared with surgical ones. In those patients in whom defecography had shown rigidity of the rectal walls, extraparietal tumor spread was observed during surgical resection. Seven patients underwent anterior resection, and were subsequently examined by the same combination of barium enema and defecography. The combined use of the two methods was useful to evaluate the anastomosis and to show possible dynamic changes after surgery.     

Evacuation proctography in normal volunteers

Constipated patients evaluated by evacuation proctography may be subjected to vigorous medical therapy or surgery, even colectomy, based on radiographic findings that have been called "abnormal" in the literature. Criteria for normal defecography are not uniformly established, nor has correlation of structural or functional findings with symptoms been clearly documented. We prospectively studied 21 asymptomatic volunteers to assess the frequency of findings in a control population, and to establish a quantitative measure of normal rectal emptying. Standard defecography technique demonstrated rectocele, intussusception, pelvic descent, or puborectalis spasm in 14/21 volunteers (67%). The range of rectal emptying was 12.5% to 100%, with four subjects (19%) evacuating less than or equal to 40% of the barium paste. There was no correlation between severity of radiographic findings and degree of evacuation. Defecography results in patients being considered for symptomatic intervention should be interpreted cautiously, given the wide range of normal variation in a control population.     

Experience of 4 years with open MR defecography: pictorial review of anorectal anatomy and disease.

Functional disorders of the pelvic floor are a common clinical problem. Diagnosis and treatment of these disorders, which frequently manifest with nonspecific symptoms such as constipation or incontinence, remain difficult. Fluoroscopic x-ray defecography has been shown to aid in detection of functional and morphologic abnormalities of the anorectal region. With the advent of open-configuration magnetic resonance (MR) imaging systems, MR defecography with the patient in a vertical position became possible. MR defecography permits analysis of the anorectal angle, the opening of the anal canal, the function of the puborectal muscle, and the descent of the pelvic floor during defecation. Good demonstration of the rectal wall permits visualization of intussusceptions and rectoceles. Excellent demonstration of the perirectal soft tissues allows assessment of spastic pelvic floor syndrome and descending perineum syndrome and visualization of enteroceles. MR defecography with an open-configuration magnet allows accurate assessment of anorectal morphology and function in relation to surrounding structures without exposing the patient to harmful ionizing radiation.     

Radiologic investigation of external rectal prolapse. Assessment in 48 patients with defecography, seven of them also with dynamic CT of the pelvis

PURPOSE: To report our personal experience in 48 patients with external rectal prolapse examined with defecography, evaluating radiological signs and the indications for surgical treatment. We also report the results of 7 patients with severe prolapse submitted to dynamic CT of pelvis. MATERIAL AND METHODS: The findings relative to 48 patients suffering from external prolapse, 27 women and 21 men, (mean age 58 years), were retrospectively reviewed. In our study protocol the patient is made to sit on a defecographic commode with the pelvis in lateral projection and radiographic images are acquired at rest, on contraction and on evacuation. Dynamic CT of pelvis with axial and coronal scans of the pelvic floor was carried out in 7 patients with severe prolapses. Twenty-six of 48 patients underwent rectopexy. RESULTS: The main symptoms were anorectal and perineal weight sensation (93%), perineal disturbance in the sitting position (91%) and anorectal pain extended to sacral area (83%). Manometry, which was performed in 36 cases, showed a rectoanal inhibitory reflex evokable at high volumes of air, especially in incontinent subjects. Defecography demonstrated external rectal prolapse in all cases; rectal intussusception in 32, mucosal prolapse in 30, abnormal widening of the anorectal angle in 24 (16 of them were incontinent), rectocele in 22 and perineal descent syndrome in 16 cases. DISCUSSION AND CONCLUSIONS: External rectal prolapse is sometimes a dynamic progression of a rectal intussusception. In anorectal intussusceptions, the invaginatum involves the anal canal, thus causing the external prolapse. Defecography clearly shows the continuation of invagination out of the anus, with the formation of prolapse. Dynamic CT proved accurate in detecting the rectum morphology, but added no further information to defecography, except for the diastasis of anosphincterial muscles. Therefore, we conclude that defecography is the method of choice, though complementary to other instrumental techniques such as manometry, electromyography and endoscopy, in the diagnostic workup of these patients. Moreover, it can recognize other alterations, such as incontinence and rectocele, which can be submitted to surgical correction with rectopexy.     

Prospective assessment of interobserver agreement for defecography in fecal incontinence

OBJECTIVE: The primary aim of our study was to determine the interobserver agreement of defecography in diagnosing enterocele, anterior rectocele, intussusception, and anismus in fecal-incontinent patients. The subsidiary aim was to evaluate the influence of level of experience on interpreting defecography. SUBJECTS AND METHODS: Defecography was performed in 105 consecutive fecal-incontinent patients. Observers were classified by level of experience and their findings were compared with the findings of an expert radiologist. The quality of the expert radiologist's findings was evaluated by an intraobserver agreement procedure. RESULTS: Intraobserver agreement was good to very good except for anismus: incomplete evacuation after 30 sec (kappa, 0.55) and puborectalis impression (kappa, 0.54). Interobserver agreement for enterocele and rectocele was good (kappa, 0.66 for both) and for intussusception, fair (kappa, 0.29). Interobserver agreement for anismus: incomplete evacuation after 30 sec was moderate (kappa, 0.47), and for anismus: puborectalis impression was fair (kappa, 0.24). Agreement in grading of enterocele and rectocele was good (kappa, 0.64 and 0.72, respectively) and for intussusception, fair (kappa, 0.39). Agreement separated by experience level was very good for rectocele (kappa, 0.83) and grading of rectoceles (kappa, 0.83) and moderate for intussusception (kappa, 0.44) at the most experienced level. For enterocele and grading, experience level did not influence the reproducibility. CONCLUSION: Reproducibility for enterocele, anterior rectocele, and severity grading is good, but for intussusception is fair to moderate. For anismus, the diagnosis of incomplete evacuation after 30 sec is more reproducible than puborectalis impression. The level of experience seems to play a role in diagnosing anterior rectocele and its grading and in diagnosing intussusception.     

Defecography and treatment of essential anal pain

INTRODUCTION: Proctalgia is a chronic anal pain in the absence of any organic conditions of the anorectum and excluding such morphofunctional disorders as rectal prolapse, intussusception and solitary rectal ulcer, which are easily shown with defecography but not with other imaging techniques. Proctalgia patients undergo a long workup and many instrumental and radiologic examinations and are finally referred to the proctologist with a condition which is difficult to diagnose and treat. We investigated the defecographic findings and anorectal abnormalities of essential proctalgia, as well as the correlation between radiologic findings, clinical symptoms and efficacy of biofeedback treatment. MATERIALS AND METHODS: We retrospectively examined 31 patients (21 women and 10 men; age range: 25-67 years, mean: 46) with defecography, clinico-proctologic investigations integrated with anoscopy and sigmoidoscopy, anorectal manometry and psychological tests. The women were submitted to gynecologic examination: 8 patients had a history of anorectal and pelvic surgery. We did not perform anal electromyography because it may cause painful sphincterial spasms. All patients underwent 30-minute weekly sessions of biofeedback till regression of symptoms. RESULTS: Anal pain was described as anorectal in 18 cases, anoperineal in 7, anosphincterial in 5 and rectovaginal in 1 case. It radiated to the sacrum in 42% of cases, thighs in 23%, gluteus muscles in 19%, and was related to evacuation in 39% of cases. Pain lasted some hours (58%) to a few minutes (42%). Manometric data showed sphincterial hypertonia in 14 patients. Eleven patients suffered from anxiety and were on drug treatment. Defecography demonstrated rectocele in 15 cases, puborectalis muscle syndrome in 14, external sphincter spasm in 12, perineal descent in 8, rectal muscosal prolapse in 4, intussusception in 3 and fecal incontinence in 2 cases. After 10 weeks of biofeedback training, all patients reported improvement of symptoms, which was confirmed at manometry as reduced sphincterial pressure. CONCLUSIONS: The etiology of essential proctalgia is unknown, but functional disorders of the pelvic floor and sphincterial muscles, as well as altered perineal stasis and pudendal conditions, all play an important role. These data are confirmed in our study where puborectalis syndrome, external sphincterial spasm and perineal descent are involved in over 70% of cases. Defecography is a useful tool because it permits to diagnose abnormal anorectal morphology and to diagnose sphincterial and puborectalis muscle dysfunctions which are missed with other instrumental and imaging techniques.     

Diffusion-weighted MR imaging sequence in the detection of postoperative recurrent cholesteatoma

PURPOSE: To prospectively evaluate a fast spin-echo (SE) diffusion-weighted sequence for magnetic resonance (MR) imaging of recurrent cholesteatoma in patients who have undergone middle ear surgery. MATERIALS AND METHODS: The study was approved by the institutional review board, and informed consent was obtained from all patients. Twenty-four patients (10 female and 14 male patients; mean age, 44 years) who had undergone resection of cholesteatoma were referred for MR imaging. MR imaging was performed with a 1.5-T unit by using unenhanced diffusion-weighted fast SE imaging at b factors of 0 and 800 sec/mm(2), unenhanced T2-weighted fast SE imaging, unenhanced T1-weighted SE imaging, and delayed contrast material-enhanced T1-weighted imaging. Two radiologists evaluated the diffusion-weighted fast SE images for the presence of a high-signal-intensity cholesteatoma. Results from MR imaging were compared with reports from second- or third-look surgery. Interobserver agreement was assessed with the kappa statistic. RESULTS: A recurrent cholesteatoma was correctly identified in 13 of 14 patients with diffusion-weighted fast SE images obtained with a b factor of 800 sec/mm(2), for a positive predictive value of 93%. In patients without recurrent cholesteatoma, all diffusion-weighted fast SE MR images obtained with a b factor of 800 sec/mm(2) were correctly interpreted as showing no high signal intensity. Thus, the negative predictive value was 100%. Sensitivity and specificity were 100% (13 of 13 patients) and 91% (10 of 11 patients), respectively. Interobserver agreement was excellent (kappa = 0.92). The smallest recurrent cholesteatoma was 5 mm in diameter, and this was correctly detected with the diffusion-weighted fast SE sequence. CONCLUSION: Diffusion-weighted fast SE imaging enables the depiction of recurrent cholesteatoma in patients who have undergone middle ear surgery.     

Internal carotid artery stenosis: accuracy of subjective visual impression for evaluation with digital subtraction angiography and contrast-enhanced MR angiography

PURPOSE: To prospectively determine, for both digital subtraction angiography (DSA) and contrast material-enhanced magnetic resonance (MR) angiography, the accuracy of subjective visual impression (SVI) in the evaluation of internal carotid artery (ICA) stenosis, with objective caliper measurements serving as the reference standard. MATERIALS AND METHODS: Local ethics committee approval and written informed patient consent were obtained. A total of 142 symptomatic patients (41 women, 101 men; mean age, 70 years; age range, 44-89 years) suspected of having ICA stenosis on the basis of Doppler ultrasonographic findings underwent both DSA and contrast-enhanced MR angiography. With each modality, three independent neuroradiologists who were blinded to other test results first visually estimated and subsequently objectively measured stenoses. Diagnostic accuracy and percentage misclassification for correct categorization of 70%-99% stenosis were calculated for SVI, with objective measurements serving as the reference standard. Interobserver variability was determined with kappa statistics. RESULTS: After exclusion of arteries that were unsuitable for measurement, 180 vessels remained for analysis with DSA and 159 vessels remained for analysis with contrast-enhanced MR angiography. With respect to 70%-99% stenosis, SVI was associated with average misclassification of 8.9% for DSA (8.9%, 7.8%, and 10.0% for readers A, B, and C, respectively) and of 11.7% for contrast-enhanced MR angiography (11.3%, 8.8%, and 15.1% for readers A, B, and C, respectively). Negative predictive values were excellent (92.3%-100%). Interobserver variability was higher for SVI (DSA, kappa = 0.62-0.71; contrast-enhanced MR angiography, kappa = 0.57-0.69) than for objective measurements (DSA, kappa = 0.75-0.80; contrast-enhanced MR angiography, kappa = 0.66-0.72). CONCLUSION: SVI alone is not recommended for evaluation of ICA stenosis with both DSA and contrast-enhanced MR angiography. SVI may be acceptable as an initial screening tool to exclude the presence of 70%-99% stenosis, but caliper measurements are warranted to confirm the presence of such stenosis.     

Association between extrinsic and intrinsic carpal ligament injuries at MR arthrography and carpal instability at radiography: initial observations

PURPOSE: To retrospectively compare the presence or absence of carpal instability on radiographs with the findings of magnetic resonance (MR) arthrographic evaluation of intrinsic and extrinsic ligament tears in patients with chronic wrist pain. MATERIALS AND METHODS: The institutional review board approved this study and did not require informed consent. Signs of carpal instability were assessed on static and dynamic radiographs of the wrist obtained in 72 patients (24 female, 48 male; mean age, 36 years; age range, 14-59 years) with posttraumatic wrist pain. MR arthrography was subsequently performed. Two musculoskeletal radiologists independently analyzed the radiographs and MR images. Each intrinsic and extrinsic ligament was individually evaluated for the presence of a ligament tear. The extent of the tear also was recorded. Interobserver agreement regarding MR arthrographic findings was tested by calculating kappa statistics. Statistical comparison between radiography and MR arthrography was performed by using the Fisher exact test. RESULTS: Twenty-five triangular fibrocartilage complex, 18 (five partial, 13 complete) scapholunate ligament, and 25 (10 partial, 15 complete) lunotriquetral ligament tears were visualized. Twenty-two (all complete) extrinsic ligament tears were detected: two radial collateral ligament, 10 radioscaphocapitate ligament, and 10 radiolunotriquetral ligament tears. Interobserver agreement regarding intrinsic and extrinsic ligament tear detection at MR arthrography was excellent (kappa = 0.80). Nineteen patients had evidence of carpal instability on radiographs. Fourteen (52%) of 27 patients with at least one complete intrinsic lesion had no sign of carpal instability. On the other hand, the association of scapholunate ligament and/or lunotriquetral ligament and extrinsic ligament tears was significantly correlated (P < .001) with carpal instability at radiography. CONCLUSION: The presence or absence of carpal instability on radiographs depends on the association between intrinsic and extrinsic ligament tears-even partial ones-rather than on the presence of intrinsic ligament tears alone, even when the tears are complete.     

Preoperative evaluation of living renal donors: comparison of CT angiography and MR angiography

PURPOSE: To compare computed tomographic (CT) angiography and magnetic resonance (MR) angiography for preoperative evaluation of living renal donors. MATERIALS AND METHODS: Thirty-five living renal donors underwent preoperative contrast material-enhanced CT angiography and gadolinium-enhanced MR angiography. Each study was interpreted by two independent radiologists blinded to all other studies and to interpretations provided by other reviewers. Eighteen kidneys had surgical correlation. RESULTS: CT demonstrated 33 supernumerary arteries in 19 patients, bilateral solitary arteries in 16 patients, and 18 proximal arterial branches in 16 patients. MR demonstrated 26 supernumerary arteries in 15 patients, bilateral solitary renal arteries in 20 patients, and 21 proximal arterial branches in 16 patients. Interobserver agreements for MR (kappa = 0. 74) and CT (kappa = 0.73) were similar to the agreement between MR and CT (kappa = 0.74). Among the kidneys chosen for nephrectomy, one small accessory artery and one proximal arterial branch were missed with CT and MR. Two of the accessory arteries suggested at CT were not found at nephrectomy. By averaging data for both modalities, supernumerary arteries were present in 49% of kidney donors and were bilateral in approximately 17%. Proximal arterial branches were present in 46% of kidney donors. CONCLUSION: Preoperative CT and MR angiography of the renal arteries in renal donors demonstrate substantial agreement. Interobserver disagreement in the interpretation of CT and MR angiograms is related to 1-2-mm-diameter vessels.     

Primary sclerosing cholangitis: evaluation with MR cholangiography-a case-control study

PURPOSE: To determine the accuracy of magnetic resonance (MR) cholangiography for detection of primary sclerosing cholangitis (PSC) and localization of PSC in the biliary tract. MATERIALS AND METHODS: In a prospective case-control study involving 102 patients, the MR cholangiograms obtained in 34 patients with PSC established with endoscopic retrograde cholangiopancreatography (ERCP) were compared with the MR cholangiograms obtained in 68 age-matched control patients with hepatobiliary diseases other than PSC. Two abdominal radiologists conducted an independent, blinded random review of the MR cholangiograms to assess for the presence or absence of PSC and determine the location of PSC in the biliary tract, and then compared the findings with those at ERCP. RESULTS: MR cholangiography was found to be accurate in detecting PSC and in defining the extent of disease. In the detection of PSC, the sensitivities were 88% and 85%; specificities, 97% and 92%; positive predictive values, 94% and 85%; and negative predictive values, 94% and 93% for readers 1 and 2, respectively. Interobserver agreement was excellent (kappa = 0.79). In the localization of extrahepatic PSC, the sensitivities were 83% and 89%; and specificities, 83% and 83% for readers 1 and 2, respectively. Interobserver agreement was good (kappa = 0.62). In the localization of intrahepatic PSC, the sensitivity was 87% for both readers; interobserver agreement was good (kappa = 0.71). CONCLUSION: MR cholangiography enables accurate detection and localization of PSC.     

Normal anorectum: dynamic MR imaging anatomy

In this study, the anatomy of the anorectum in relation to the surrounding structures and the anorectal angle were analyzed with magnetic resonance (MR) imaging at rest, during perineal contraction, and during straining in 10 asymptomatic subjects. The intra- and inter-observer and intra- and interpatient variations in the measurements of the anorectal angle, position of the anorectal junction, and position of the plica of Kohlrausch in the rectum were established at rest, during perineal contraction, and during straining. The values for the anorectal angle and position of the anorectal junction obtained with MR imaging were compared with standard radiography defecography findings. It was shown that MR imaging has the potential for measuring these parameters in a more precise and more patient-friendly way than defecography. Unlike dynamic defecography, MR imaging is able to depict the mobility of the posterior rectal wall. A descent of over 20 mm from rest to straining should be considered pathologic. This finding might play a role in patient selection for operation.     

High-resolution magnetic resonance imaging of the anal sphincter using a dedicated endoanal receiver coil

The use of a surface coil in MR imaging improves signal-to-noise ratio of adjacent tissues of interest. We therefore devised an endoanal receiver coil for imaging the anal sphincter. The probe is solid and re-usable: it comprises a saddle geometry receiver with integral tuning, matching and decoupling. It is placed in the anal canal and immobilised externally. Both in vitro and in vivo normal anatomy is identified. The mucosa is high signal intensity, the submucosa low signal intensity, the internal sphincter uniformly high signal intensity and the external sphincter low signal intensity on T1- and T2-weighted images. In females, the transverse perineal muscle bridges the inferior part of the external sphincter anteriorly. In perianal sepsis, collections and the site of the endoanal opening are identified. In early-onset fecal incontinence following obstetric trauma/surgery, focal sphincter defects are demonstrated; in late-onset fecal incontinence external sphincter atrophy is seen. In fecally incontinent patients with scleroderma, forward deviation of the anterior sphincter musculature with descent of rectal air and feces into the anal canal is noted. The extent of sphincter invasion is assessed in low rectal tumours. In children with congenital anorectal anomalies, abnormalities of the muscle components are defined using smaller-diameter coils. Such information is invaluable in the assessment and surgical planning of patients with a variety of anorectal pathologies. Received: 17 March 1998; Revision received: 19 May 1998; Accepted: 27 May 1998     

直肠前突手术前后的动态X线和MR排粪造影

目的:评价动态X线和磁共振排粪造影在直肠前突自动痔疮套扎术(RPH)治疗前后的应用价值.方法:中重度直肠前突患者16例纳入研究,年龄25～68岁,平均51岁,均为经产妇;全部完成RPH术前和术后的动态X线和MRI排粪造影检查.在两种检查图像上分别分析直肠前突的程度和并发症,并进行对比分析.结果:X线排粪造影显示术前重度直肠前突10例(58％)和中度直肠前突6例(42％),术后仅见中度直肠前突2例;直肠前壁黏膜脱垂、直肠内套叠和痔疮的显示术后(3例次)明显少于术前(33例次)(x2=14.933,P＜0.001).MR排粪造影显示术前重度直肠前突7例(43％)和中度直肠前突9例(57％),术后仅显示中度直肠前突1例;结直肠并发症显示(13例次)明显少于X线排粪造影(42例次)(x2=15.291,P＜0.001),但显示了更多的结直肠外合并症.结论:X线和MRI排粪造影评价直肠前突各有优缺点,综合评价更完整,并对RPH治疗后评估有良好应用价值.