Benjamin M. Ellingson1,2, Mark G. Malkin1,3, Scott D. Rand1,2, Alastair Hoyt4, Jennifer Connelly3, Devyani P. Bedekar1,2, Shekar N. Kurpad1,4, Kathleen M. Schmainda1,2
1Translational Brain Tumor Program, Medical College of Wisconsin, Milwaukee, WI, USA; 2Department of Radiology, Medical College of Wisconsin, Milwaukee, WI, USA; 3Department of Neurology, Medical College of Wisconsin, Milwaukee, WI, USA; 4Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA
Functional diffusion maps (fDMs) examine voxel-by-voxel changes in diffusivity over time, which allows for visualization and quantification of local changes in tumor cellularity. We have expanded the traditional fDM approach from contrast-enhanced regions exclusively to include regions of FLAIR abnormality. We then compared cellularity metrics extracted from fDMs applied to the FLAIR abnormal regions between progressive, stable, or responsive patients treated with either standard therapies (chemotherapy & radiation therapy) or anti-angiogenic therapy combined with chemotherapy (bevacizumab & irinotecan). Results support the hypothesis that recurrence after treatment with bevacizumab results in growth of an infiltrative (i.e. non-enhancing) tumor type.