A team from the University Hospital of Maastricht, the Netherlands assessed the accuracy of magnetic resonance imaging (MRI) with a phased-array coil for predicting the preoperative tumor stage of rectal cancers. They also predicted the distance of the tumour from the circumferential resection margin in a total mesorectal excision.
Their findings have been reported in the current issue of the Lancet.
MRI was used to preoperatively assess 76 patients with primary rectal cancer.
Two observers independently scored the tumour stage and the measured distance to the mesorectal fascia. These observations were compared with the final histological findings.
The MRI tumour stage agreed with the histological stage in 83% of patients for observer 1, and in 67% of patients for observer 2. In 12 patients with an obvious T4 tumour, a margin of 0 mm was correctly predicted. Of 29 patients for whom the pathologist reported a distance of at least 10 mm, and without specifying the actual distance, a distance of at least 10 mm was predicted in 28 by observer 1 and 27 by observer 2.
The circumferential resection margin can be predicted with high accuracy and consistency using MRI.
For the remaining 35 patients, a histological distance of at least 1.0 mm was predicted with high confidence when the measured distance on MRI is at least 5.0 mm.
Dr. Beets-Tan commented on behalf of the group, "MRI with a phased-array coil showed moderate accuracy and reproducibility for predicting the tumour stage of rectal cancers."
"The clinically more important circumferential resection margin can, however, be predicted with high accuracy and consistency, allowing preoperative identification of patients at risk of recurrence who will benefit from preoperative radiotherapy, more extensive surgery, or both," it was concluded.