Contrast- vs. non-contrast enhanced MR data sets for characterization of perianal fistulas

PURPOSE

To evaluate the diagnostic efficacy between pre- and post-contrast MRI sequences in perianal fistulas using intra-operative findings as the gold standard.

MATERIALS AND METHODS

Retrospective analysis of 50 patients with a history of perianal fistula and MRI performed between January 2006 and January 2018 was performed. The inclusion criteria were patients who underwent MRI prior to surgery and had a detailed surgical report available. Pre- and post-contrast MR data sets were evaluated by two radiologists at two-week-intervals, assessed fistula type, internal/external opening, presence of abscess/secondary tracts, and confidence scores. The area under the curve (AUC) was used for comparison the diagnostic ability. The sensitivity and specificity were compared using the McNemar's test.

RESULTS

The confidence scores in detecting perianal fistulas were significantly higher in the post-contrast MR data set (p < 0.003). The post-contrast MR data set had similar ability to classify perianal fistulas as combined T2-DWI and isolated T2 data sets in 49/50 cases. For internal/external opening, the post-contrast MR, combined T2-DWI, and isolated T2 data sets had 100% concordance with intra-operative reports. For perianal abscess, there was no significant difference in sensitivity or AUC value between the isolated T2 or combined T2-DWI data sets and post-contrast MR data set (p > 0.05). All MR data sets correctly identified secondary tracts in all 50 cases.

CONCLUSIONS

Although contrast-enhanced MR studies can improve a radiologist's confidence, non-contrast MR studies had similar diagnostic efficacy in identifying perianal fistulas and their complications. Therefore, a non-contrast study may suffice in selected patients such as those with renal impairment.

Can MR imaging be useful in differentiating low rectal cancer from anal cancer?

PURPOSE

To evaluate the role of pelvic MR imaging in differentiating between low rectal and anal cancers using the pathological results as the gold standard.

MATERIALS AND METHODS

In this study, retrospective analysis of 100 patients with a history of low rectal (n = 50) or anal (n = 50) cancers who underwent staging pelvic MR imaging before treatment was performed. The following parameters were analyzed: distance from the anal verge to the tumor, percentage of tumor above puborectalis muscle, tumor size, T2W signal intensity, sphincter/levator muscles invasion, organ invasion, and MRI diagnosis. Multivariable logistic regression was performed to determine factors associated with low rectal and anal cancers. Distances from the anal verge to the tumor were compared using receiver-operating characteristic (ROC) curves.

RESULTS

From the ROC curves, the cut-off value for the distance from the anal verge to the tumor in differentiating between low rectal and anal cancers was 2.1 cm and the area under the ROC curve was 0.90 (95% CI 0.84-0.97). Multivariate logistic regression revealed three significant factors in differentiating between low rectal and anal cancers, including T2 mixed hyper- and hyposignal intensity (OR 66.00, 95% CI 4.66-934.81), distance cut-off value (OR 34.72, 95% CI 5.73-210.27), and absence of sphincter invasion (OR 18.75, 95% CI 1.91-183.96), with sensitivity, specificity, PPV, and NPV of 98%, 88%, 89%, and 97%, respectively, and diagnostic accuracy increased from 79% (reader 1) and 82% (reader 2) to 93%.

CONCLUSION

MR imaging can be useful to differentiating between low rectal and anal cancers which benefits staging and treatment planning.

Diagnostic performance of dynamic MR defecography in assessment of dyssynergic defecation

PURPOSE

To assess diagnostic performance of MR defecographic findings in diagnosis of dyssynergic defecation (DD).

METHODS

This retrospective study included 46 patients with chronic constipation who met the Rome IV criteria for diagnosis of present or absent DD and underwent MRI between Jan 2015 and June 2020. Patients were divided into DD group (n = 24) and non-DD group (n = 22). Nine parameters were analyzed by two radiologists: anorectal angle (ARA) and M line at rest, defecation, and change between 2 phases; anal canal width; prominent puborectalis muscle; abnormal evacuation. Receiver operating characteristic (ROC) curves were plotted to extract the optimal cut-offs and area under the curve (AUC). Multivariate analysis was performed.

RESULTS

Seven findings showed statistically significant difference between DD and non-DD groups. M line at defecation had highest odds ratio, followed by ARA change, ARA at defecation, M line change, prominent puborectalis muscle, abnormal evacuation and anal canal width, respectively. ARA change and prominent puborectalis muscle had highest specificity (95.5% and 100%, respectively). The optimal cut-offs of ARA at defecation, ARA change, M line at defecation, M line change and anal canal width were 122°, 1.5°, 3.25 cm, 1.9 cm and 8.5 mm, respectively. Multivariate logistic regression revealed two significant findings in differentiating between DD and non-DD, including M line at defecation (OR 23.31, 95% CI 3.10-175.32) and ARA at defecation (OR 13.63, 95% CI 1.94-95.53) with sensitivity, specificity, PPV, NPV and AUC of 79.2%, 95.5%, 95%, 80.8% and 0.87(95% CI 0.78-0.97), respectively.

CONCLUSION

MR defecography has high diagnostic performance in diagnosis of DD. Although M line and ARA at defecation are two significant findings on multivariate analysis, ARA change less than 1.5 degrees and prominent puborectalis muscle have good specificity in DD diagnosis.

MR defecography: comparison of HMO system measurement between supine and lateral decubitus patient position

BACKGROUND

Pelvic floor dysfunction (PVD), a prevalent clinical issue impacting quality of life, can be effectively assessed using magnetic resonance defecography (MRD) with the patient either supine or in the lateral decubitus position.

PURPOSE

To compare the measurement value and grading in dynamic MRD within the closed-magnet system of PFD patients performed in supine versus lateral decubitus position using the H line, M line, and organ prolapse (HMO) classification system.

MATERIAL AND METHODS

During 2017-2019, 100 patients with PFD underwent MRD during defecation in both supine and lateral decubitus positions. MR images were measured and graded by two blinded radiologists. The mean value of each HMO parameter and grading severity were compared between supine and lateral positions. Image quality (IQ) between two positions was also evaluated. Paired t-test and Wilcoxon ranked test were performed for significant difference. P < 0.05 was considered statistically significant.

RESULTS

For HMO measurement, M-line, levator plate angle (LPA), urethral hypermobility (UH), uterine prolapse, and peritoneocele had significantly higher mean values when measured in the lateral decubitus position than in the supine position. For grading, M-line, uterine prolapse, and peritoneocele also had more grading severity in the lateral decubitus than supine position with statistical significance (P = 0.002, 0.004, and 0.001, respectively). Only anterior rectocele had a mean value and grading severity in the supine more than the lateral position (P = 0.003 and P = 0.005). IQ in the supine was better than in the lateral decubitus position (P < 0.001).

CONCLUSION

MRD in lateral decubitus showed a more severe degree of PFD in most parameters based on the HMO grading system irrespective of inferior imaging quality.

Gastrointestinal: Direct Visualization of Biliary Tuberculosis

BACKGROUND

Biliary tuberculosis is a rare type of hepatobiliary tuberculosis. Clinical presentation, imaging, or cholangiogram are difficult to distinguish from other common causes of cholangiopathy or malignancy. Direct visualization of bile duct via cholangioscopy and targeted biopsy was introduced as one of effective investigations for tissue acquisition and diagnosis.

CASE REPORT

We present a case of biliary tuberculosis presented with pruritus, progressive painless jaundice and significant weight loss. Laboratory findings showed an obstructive jaundice. MRI showed multifocal bile duct stricture and intrahepatic duct stone. Single operator cholangioscopy revealed ductal stricture with papillary projection at common hepatic duct and pigmented stone. Targeted biopsy was performed, which showed non-necrotizing granulomatous inflammation and detection of Mycobacterium tuberculosis complex DNA.

CONCLUSION

Direct visualization via cholangioscopy can aid and increase diagnostic yield of biliary tuberculosis.