Rectal tumours — MR imaging with endorectal and/or phased-array coils, and histopathological staging on giant sections

OBJECTIVE: To investigate the accuracy of MR imaging in the preoperative staging of patients with clinically resectable rectal tumours. MATERIAL AND METHODS: Forty-eight consecutive patients with rectal tumours were examined, 29 with a pelvic phased-array coil and 19 with a multi-coil arrangement including a pelvic phased-array coil and an endorectal coil. MR images and histopathological specimens and sections were reviewed independently and tumours were staged according to the TNM classification. RESULTS: A more complete visualisation of the various layers of the rectal wall was achieved on the endorectal MR images than on the pelvic phased-array images. The sensitivity of MR in correctly staging T3 tumours compared with histopathology was 81% with a specificity of 82%. Penetration of the rectal wall was predicted with a sensitivity of 82% and a specificity of 87%. Sensitivity and specificity in predicting lymph node metastases was 83% and 74% respectively. CONCLUSION: MR imaging with both pelvic phased-array and endorectal coils allowed the preoperative staging of rectal tumours with a high degree of accuracy.