A Comparative Study of Magnetic Resonance Imaging and Colonoscopy in Evaluation of Colorectal Diseases

Introduction: Colorectal disease, especially carcinoma, is an important cause of morbidity and mortality in modern era. With rising incidence of colorectal diseases and due to limitations of conventional flexible fiber-optic colonoscopy (gold standard tool), imaging plays a significant role in evaluation of these patients. Recent technical advancements coupled with noninvasive and radiation-free nature has made magnetic resonance imaging (MRI) an acceptable screening tool in colorectal diseases. Hence, we planned this study to evaluate role of MRI in colorectal diseases in our tertiary care, medical college, hospital. Materials and Methods: Forty-four patients with signs and symptoms of colorectal disease were evaluated by 1.5 Testa MRI followed by conventional, flexible, fiber-optic colonoscopy on the same day after obtaining approval from the institutional ethics committee and after obtaining written informed consent using strict criteria. Bowel preparation was done using polyethylene glycol. Data from MRI and colonoscopy were recorded in predesigned pro forma and compared with the final diagnosis. Appropriate statistical methods and tools were used to evaluate the results. Results: Majority of the patients in the study were in the age group of 21–40 years with male predominance. Altered bowel habit followed by bleeding per rectum was the most common presentations. Both MRI and colonoscopy overdiagnosed the lesions as malignant with higher errors by MRI. MRI was very effective in the detection of growth, strictures, diverticulosis, mucosal thickening/edema, and extracolonic manifestation but failed in detecting small polyps and ulcers. MRI had high sensitivity and negative predictive value (NPV) of 100% with an accuracy of more than 70%. Conclusions: Although conventional colonoscopy is considered as a gold standard tool in the diagnosis of colorectal diseases, it has several limitations including its invasive nature and low yield as a screening tool. Hence, MRI with its noninvasive and radiation-free nature along with its high sensitivity and NPV for malignant lesions should be considered over colonoscopy as well as computed tomography in evaluation of colorectal diseases.