[Staging of rectal cancer by means of MRI. Experiences with the first twenty-five patients].

INTRODUCTION: The Danish Surgical Society recommends preoperative radiation for patients with T4 tumours of the rectum. However, the clinical examination with regard to fixation, especially for tumours in the upper part of the rectum, is encumbered by much uncertainty. MR imaging is a new modality in the staging procedure of the patient with rectal cancer. Our experience with the first 25 patients is presented. METHODS: After clinical examination, an MRI of the rectum was done and in the case of a T4 tumour preoperative radiotherapy was established. Preoperative MRI staging was correlated with the histopathology of the resection specimen. RESULTS: In cases of tumours in the lower third of the rectum, we found total agreement between the clinical examination and the MRI findings. In the middle third it was impossible to assess clinical fixation in two out of seven patients and in the upper third it was impossible in eight out of ten. With respect to possible involvement of lymph nodes, the MRI revealed a true positive diagnostic frequency of 0.78, a true negative diagnostic frequency of 0.92, a true positive nosographic frequency of 0.88 and a true negative nosographic frequency of 0.85. The corresponding values for tumour invasion were 0.94, 0.75, 0.94 and 0.75. DISCUSSION: Our results seem to indicate that preoperative MRI--especially in patients with tumours in the upper two-thirds of the rectum--is suitable for predicting fixation. MRI also seems to be suitable in the complete staging of the patient with a tumour of the rectum.