Benjamin M. Ellingson1,2, Devyani P. Bedekar1,2, Mark G. Malkin1,3, Scott D. Rand1,2, Alastair Hoyt4, Jennifer Connelly3, 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
A new technique was developed that combines voxel-by-voxel changes in apparent diffusion coefficient (functional diffusion maps) and relative cerebral blood volume (functional perfusion maps) to examine regions of hypercellularity and hypervascularity, respectively. Results showed spatially separated clusters of hypercellularity and hypervascularity with an average separation of around 2-cm. Trends in affected volumes revealed two distinct temporal patterns after treatment with bevacizumab: vascular-independent and vascular-coupled tumor growth, which likely represent two distinct populations of tumor cells: infiltrative cells that thrive in ischemic/hypoxic conditions (such as "stem-like" cells) and cells that proliferate largely in the presence of high blood volume, respectively.