MR Imaging and Single-Photon Emission CT Findings after Gene Therapy for Human Glioblastoma

Flare enhancement and tumor relapse after complete resection. MR images obtained on day 1 and weeks 2, 9, and 41 postoperatively show development of a strong flare after resection of all enhancing tissue within the temporal lobe. There is initial regression of flare, but eventually there is recurrence of local tumor (enhanced T1-weighted axial MR images, patient 18).fig 4. Flare enhancement and tumor relapse after incomplete resection. MR images on day 1 and weeks 2, 4, and 33 after surgery show development of a strong flare after incomplete tumor resection with two remnants within the temporal lobe. The flare enhancement regresses at first, but eventually the tumor recurs from the remnants (enhanced T1-weighted axial MR images, patient 20).fig 5. Benign postsurgical enhancement. MR images from day 1 and weeks 2, 4, and 17 after tumor resection show development of thin, linear, benign enhancement and local tumor recurrence within the temporooccipital region (enhanced T1-weighted axial images, patient 19)

Volume curves of enhancing tissue during the postoperative course of four patients with flare. There is an early and quick increase in enhancement volume, a high peak at 4 weeks, and slow but continuous decrease during the following months. In patients without tumor recurrence, flare enhancement disappears within 1 year (patients 1 [triangles] and 22 [squares]). In case of tumor recurrence, the regression of flare enhancement is overcome by increasing tumor enhancement (patients 18 [diamonds] and 20 [circles]). The “Screen” point at the bar reflects the preoperative volume of enhancing tumor. For presentation, data for the postoperative images on day 1 or 2 are fixed to week 0, and note the nonlinear time axis.fig 7. Volume curves of benign postsurgical enhancement and residual tumor in two patients with benign postsurgical enhancement and two patients with residual tumor. For benign postsurgical enhancement, there is a delayed and slow increase in enhancement volume, stabilization at a plateau (instead of reaching a peak), and no significant regression. In the later course, the curve is moving upward because of recurrent tumor enhancement (lower two curves; patients 2 [squares] and 19 [diamonds]). Patients with residual tumor without flare or benign postsurgical enhancement show a continuous increase in enhancement volume because of tumor progression (upper two curves; patients 6 [triangles] and 7 [circles]). The “Screen” point at the bar reflects the preoperative enhancing tumor volume. For presentation, data for the postoperative images on day 1 or 2 are fixed to week 0, and note the nonlinear time axis