Role of magnetic resonance imaging in colorectal diseases

Abstract

Introduction: Modern society is experiencing a noticeable increase in the prevalence of colorectal disease due to a variety of causes, including changes in lifestyle and dietary habits as well as increased use of a variety of chemicals in the form of preservatives flavouring agents and stabilisers. Colorectal diseases are a cause of significant morbidity, hence, often gaining attention early in the disease. Although colonoscopy is a standard, the preferred tool for diagnosis and at times for management is often uncomfortable for the patient besides being incomplete in a significant percentage of patients. Hence, magnetic resonance imaging (MRI) has gained importance in recent years for the evaluation of colorectal diseases not only due to its non-invasive nature but also due to lack of radiation, a boon over computed tomography, which is considered a standard imaging tool. Hence, we planned this pilot study to evaluate the role of MRI in our tertiary care, medical college and hospital. Materials and Methods: Twenty patients with signs and symptoms of colorectal disease were evaluated by 1.5T MRI followed by conventional, flexible, fibreoptic colonoscopy on the same day after obtaining approval from the Institutional Ethics Committee and after obtaining written informed consent using strict criteria. Appropriate statistical methods and tools were used to evaluate the results from the data of MRI and colonoscopy that was recorded in predesigned pro forma and compared with the final tissue diagnosis. Results: Both the median and mean age of patients in our study were 40–45 years with male predominance (M:F = 4:1). Altered bowel habits followed by bleeding per rectum were the most common presentations seen in more than 90% of patients. Both MRI and colonoscopy misdiagnosed the lesions as malignant with higher errors by MRI. MRI had high sensitivity and negative predictive value in diagnosing a malignant lesion with moderate accuracy approaching 70%. In contrast, colonoscopy was superior in specificity and positive predictive value with higher accuracy of 80%. Conclusion: Although conventional colonoscopy is the standard tool for the diagnosis of colorectal diseases, several shortcomings of colonoscopy, including its invasive nature, several contraindications and risk of complications coupled with low yield limits, are used as a screening tool. However, non-invasive and radiation-free MRI with its high sensitivity and negative predictive value for malignant lesions make it preferable as a screening tool in the evaluation of colorectal diseases.