FIG 4. Surgically induced immediate intraparenchymal enhancement. Intraoperative T1-weighted images (upper row [from left to right], unenhanced and 5 and 20 minutes postcontrast) (532/15/3) show a solid-appearing, intraparenchymal contrast enhancement that shows almost no time dependence. Early (day 1 after surgery) postoperative T1-weighted images (lower row: left, unenhanced; right, postcontrast) show a intraparenchymal hyperintensity but no contrast enhancement (674/20/2). This type of enhancement probably represents (transient) blood-brain barrier disruption. The hyperintensity on the unenhanced T1-weighted images of the postoperative examination is possibly caused by contrast agent administered intraoperatively, which is "captured" in the tissue after the blood-brain barrier disruption resolves. It is, however, too early to represent methemoglobin.