Preoperative Local Staging of Rectal Cancer With Magnetic Resonance Imaging With Pathologic Correlation in Kenyan Patients

Abstract

Background Rectal cancer (RC) is a leading cause of cancer related morbidity and mortality in the Kenyan population. Its incidence has increased from 12.3 to 12.9 per 100,000 people per year. Magnetic Resonance Imaging (MRI) is currently the most accurate imaging modality in the loco-regional staging of RC because of its superior soft tissue contrast and multiplanar capability and is used in planning surgical approach, assessing need for additional therapy pre and post- operatively and predicting overall prognosis. This study seeks to evaluate the diagnostic accuracy of MRI in loco-regional staging of RC. Broad objective To establish whether preoperative local MRI staging performed using recommended protocols corresponds with the pathological tumor (T) and nodal (N) stage in patients with rectal carcinoma between October 2020 and January 2021. Methodology A prospective, cross-sectional study was carried out among patients with RC presenting for MRI at Kenyatta National Hospital and Plaza Imaging Centre. MRI studies of 48 patients were reviewed and T and N stage, MRF and CRM involvement were assigned. Histopathologic assessment was then done postoperatively. The findings were keyed in Microsoft Excel and imported to IBM SPSS Statistics version 21 for analysis and 2x2 tables were constructed to determine the diagnostic accuracy of MRI as a preoperative loco-regional staging tool. Results The sensitivity, specificity, PPV, NPV and accuracy of MRI in the T staging of rectal tumors were 85.7%, 92.8%, 97.2%, 66.7% and 91.8%. The MRI sensitivity, specificity, NPV, PPV and accuracy in assessment of MRF involvement were 85.5%, 94.4%, 85.5%, 94.4% and 92%. As regards CRM evaluation, the sensitivity, specificity, PPV and NPV and accuracy were 83.3%, 92.3%, 90.9%, 85.7% and 88% respectively. The nodal sensitivity, specificity, PPV, NPV and accuracy were 85.7%, 92.8%, 97.2%, 66.7% and 91.8% Conclusion. MRI has high diagnostic accuracy in evaluation of depth of tumor spread, MRF and CRM assessment and evaluation of metastatic nodal involvement. It should therefore be used as the primary tool in the local staging of RC.