Davis C. Woodworth1, 2, Timothy F. Cloughesy3, Robert J. Harris1, 2, Whitney B. Pope1, Albert Lai3, Phioanh (Leia) Nghiemphu3, Benjamin M. Ellingson1, 2
1Dept. of Radiological Sciences, UCLA, Los Angeles, CA, United States; 2Biomedical Physics, UCLA, Los Angeles, CA, United States; 3Neurology, UCLA, Los Angeles, CA, United States
Bevacizumab, a VEGF inhibitor, is a common second line treatment for glioblastoma after recurrence; however, bevacizumab results in reduction in contrast enhancement, which makes it difficult to assess true tumor burden and response to therapy. In the current study we explore the use of post-bevacizumab delta-T1 maps, where pre-contrast T1w images are subtracted from post-contrast T1w images, in 101 patients with recurrent glioblastoma. Results suggest delta-T1 maps reliably detect subtle contrast enhancement not apparent on normal post-contrast T1w images. Further, patients with a volume of delta-T1 hyperintense tumor greater than 15cc have a significantly shorter progression-free and overall survival.