Multi-detector Row Computed Tomography (MDCT) versus Endorectal Coil Magnetic Resonance Imaging (ECMRI) in Staging of Carcinoma Rectum

BACKGROUND: Rectal cancer is one of the most common tumors in industrialized countries and one of the most common malignant tumors of the gastrointestinal tract. OBJECTIVE: To compare the diagnostic accuracy of MDCT and ECMRI in preoperative staging of rectal cancers and correlation with intraoperative and histo-pathologic staging of resected specimen with respect to depth of tumor invasion (T-staging), lymph node metastasis (N- staging), and extra rectal spread (M-staging). METHODS: The study was a prospective one and consisted of 68 patients with biopsy proved rectal carcinoma. Patients were randomly selected for either of these two staging modalities (i.e., MDCT or ECMRI) using a random number table. MDCT and ECMRI findings were compared with intraoperative and histopathologic (reference standard) findings. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of each diagnostic modality were assessed. RESULTS: The diagnostic accuracies of MDCT and ECMRI for T1/T2 lesions were 75% and 87.5%, respectively, the difference being significant. For T3 lesions, the diagnostic accuracies of MDCT and ECMRI were 85.2% and 100%, respectively. The diagnostic accuracy of both for T4 lesions was found to be 100%. Both ECMRI and MDCT were found to be almost equally accurate and specific in detecting perirectal lymph node involvement. CONCLUSION: Endorectal coil MRI is superior to MDCT in local (T) staging of tumor and has overall more diagnostic accuracy, sensitivity and specificity than MDCT. ECMRI has a less tendency to under-stage the disease. However, both ECMRI and MDCT are almost equally accurate and specific in detecting perirectal lymph node involvement. JMS 2012;15(1):32-38.