MRI features of signet ring rectal cancer.

PURPOSE: Signet Ring Rectal Cancer (SRRC) of rectum is rare high-grade subtype with poor prognosis and characteristic histopathology. We evaluated its imaging appearance and correlated its outcomes. MATERIALS AND METHODS: We conducted a retrospective review of the rectal MRIs of 97 patients with rectal SRRC, evaluating tumor morphology, T2 signal, length, location, pattern of tumor growth, nodal status and location, EMVI (extramural vascular invasion), site of metastases, and response to chemotherapy. The tumor signal on T2W images was categorized into intermediate, T2 hyperintense, and fluid/mucin bright. Imaging findings were correlated with risk of metastatic/ recurrent disease, disease-free survival, and overall survival. RESULTS: The median age of patients of SRRC in our study was 35 years and more frequently found in male patients. The common imaging features of SRRC were T2-hyperintense signal (63%), infiltrative growth pattern (76%), positive MR CRM (Circumferential Resection Margin on MRI) (84%), presence of EMVI (51%), and advanced T and N stage (97% and 84%, respectively). Peritoneum and nodes were the most common sites of metastases. Raised serum CEA (Carcino-embryonic Antigen) levels, positive MR CRM status, extramesorectal adenopathy, and advanced N stage had statistically significant predictive value for recurrence or metastases. Elevated serum CEA levels (p = 0.019) and intermediate T2 signal (p = 0.012) demonstrated significant independent association with poor overall survival, while advanced N stage (p = 0.033) demonstrated significant independent association with worse disease-free survival in multivariate analysis. CONCLUSION: SRRC affected young patients and demonstrated T2-hyperintense signal and subepithelial spread in an infiltrative pattern. Elevated CEA levels and T2-intermediate signal intensity are independent predictors for worse overall survival and advanced nodal stage is independent prognostic factor of poor disease-free survival. MRI rectum can pinpoint the pathology given the distinct MRI morphology and age of presentation.

Role of MRCP in Differentiation of Benign and Malignant Causes of Biliary Obstruction.

BACKGROUND: Differentiation of the benign and malignant etiology of biliary obstruction is difficult. We studied the diagnostic accuracy of MRCP (Magnetic Resonance Cholangio-pancreatography) in differentiating between benign and malignant causes of biliary obstruction. AIM: To evaluate the role of Magnetic Resonance Cholangio-Pancreatography in differentiating benign from malignant causes of biliary obstruction using surgical, ERCP or histopathological findings as gold standard. MATERIALS AND METHODS: Seventy five patients with clinical and laboratory finding suggestive of biliary obstruction underwent MRI/MRCP. The final diagnosis was based on either surgical findings, histopathology of resected specimen or ERCP findings. Diagnostic effectivity of MRCP was calculated which included sensitivity, specificity and accuracy. Statistical analysis was done by using chi-square test and p value was calculated. RESULTS: Out of 75 cases, there were 54 benign and 21 malignant cases. Mean age of patients with malignant obstruction was more than benign with slight male preponderance. The diagnostic accuracy of MRCP in differentiating benign from malignant biliary obstructive diseases in correlation with surgical, ERCP and histopathological outcome was 93.3%, sensitivity 85.7%, specificity 96.3%. It was found that irregular, asymmetric and long segment narrowing was more common in malignant stricture. CONCLUSIONS: MRCP is the investigation of choice for suspected choledocholithiasis, choledochal cyst and primary sclerosing cholangitis. A benign stricture can be differentiated from a malignant one if it shows regular, symmetric and short segment narrowing. Irregular, asymmetric and long segment narrowing was more commonly found in malignant stricture.