Diagnostic accuracy of contrast enhanced MRI in staging of rectal carcinoma by taking histopathology as gold standard

Abstract

OBJECTIVES: To determine the diagnostic accuracy of contrast enhanced MRI in staging of rectal carcinoma by taking histopathological findings as gold standard. STUDY DESIGN: Cross-sectional validation study. SETTING: Department of Radiology, Combined Military Hospital, Rawalpindi from 15-03-2022 to 14-09-2022. METHODOLOGY: A total of 100 patients were included with suspected CA rectum of either gender aged 20 to 50 years. Patients with claustrophobia, cardiac pacemakers/ metal implants, allergic to contrast agent or not willing to participate in study were excluded. Magnetic resonance imaging was performed on a 1.5 T MR system (Siemens) centered on pelvis which was covered with body-matrix coil. Findings of MRI were evaluated by the researcher which were supervised by a consultant radiologist. Staging was done according to the TNM classification system. Histopathological reports were evaluated at histopathology department of hospital. RESULTS: Diagnostic accuracy of contrast enhanced MRI in T2 staging of rectal carcinoma showed sensitivity 87.5%, specificity 83.7%, PPV 31.8%, NPV 98.7%, diagnostic accuracy 84%. T3 staging demonstrate sensitivity,Specificity, PPV,NPV and diagnostic accuracy of 73.2%, 77.2%, 80.3%, 69.3% and 75% respectively. T4 staging showed sensitivity 75%, specificity 100%, PPV 100%, NPV 87.6%, diagnostic accuracy 91%. Diagnostic accuracy of MRI in nodes showed sensitivity 85.9%, specificity 72.7%, PPV 91.8%, NPV 59.2%, diagnostic accuracy 83%. Diagnostic accuracy of MRI in CRM revealed sensitivity 72.8%, specificity 89.4%, PPV 96.7%, NPV 43.5%, diagnostic accuracy 76%. CONCLUSION: In conclusion, contrast enhanced MRI is a non-invasive technique with high degree of sensitivity and accuracy in the diagnosis of staging of rectal carcinoma.
Key words: Rectal carcinoma, diagnostic accuracy, contrast enhanced MRI, histopathology.