Accuracy of Thin-Section Magnetic Resonance Imaging With a Pelvic Phased-Array Coil in the Local Staging of Rectal Cancer

Abstract

The goal of this study was to determine the accuracy of thin-section magnetic resonance imaging (MRI) using a pelvic phased-array coil for preoperative local staging of rectal carcinoma. Ninety-three patients with primary rectal cancer were prospectively evaluated by thin-section MRI using a pelvic phased-array coil for T and N staging. After radical surgery, MRI results were compared with the histological findings of the resected specimens, and accuracy, sensitivity, specificity, and positive and negative predictive values were assessed. According to pathological staging, 93 tumors were classified based on the TNM classification as follows:Four tumors were pT1, 26 tumors were pT2, 51 tumors were pT3, and 12 tumors were pT4. The MRI had an overall accuracy of 82.8% (77 of 93) for discriminating between early (ie, ≤pT2) and advanced (ie, pT3-pT4) tumors, with a sensitivity of 67% (20 of 30) for early tumors and a sensitivity of 90% (57 of 63) for advanced tumors. It yielded a diagnostic accuracy of 75% (70 of 93) in predicting T stage.Regarding lymph node metastases, the MRI prediction was correct in 58 of 93 patients, which yielded an overall accuracy of 62.4%. Despite some limitations, thin-section MRI with pelvic phased-array coil can be reliably used in the preoperative evaluation of rectal cancer patients for local tumor staging. It seems highly effective in predicting T stages and can provide useful information regarding lymph node metastases of rectal cancer.