FIGURE 3. Axial intraoperative 3D-SPGR images after administration of MAGNEVIST® loaded into the navigational computer workstation running the 3D-Slicer. The arrow points at the central necrosis zone (3A), peripheral enhancing zone (3B) and surrounding edema zone (3C). Due to the high MRI sensitivity, especially after contrast administration, the distinction between the three aforementioned zones is easily made based on the images. This is not the case with visual inspection of the operative site. By means of visual inspection alone, differentiating between active growth zone and edema is extremely difficult and at times, impossible. The role of the intraoperative navigation system is to help establish the correspondence between the images and the actual operational field. TR 28.8, TE 12.8, FOV 22, slice thickness 2.5, matrix 256x128, NEX 1, flip angle 30°.

FIGURE 4. Postoperative axial T1-weighted spin echo images after closing the dura, demonstrating the extent of resection.