FIG 7. Surgically induced enhancement: problematic case. Preoperative MR (left) (674/20/2) shows a ring-enhancing lesion. Intraoperative T1-weighted images (middle images, 5 and 20 minutes postcontrast) (532/15/3) show enhancement at the resection margin with some time dependence. A confident differential diagnosis of this enhancement (tumor or not?) could not be made, and the surgery was terminated. Early postoperative MR image (right) (674/20/2) shows possible residual tumor (arrowhead)