Benjamin M. Ellingson1,2, Mark G. Malkin1,3, Scott D. Rand1,2, Jennifer M. Connelly1,4, Pete S. LaViolette1,5, Devyani P. Bedekar1,2, Kathleen M. Schmainda1,2
1Translational Brain Tumor Program, Medical College of Wisconsin, Milwaukee, WI, United States; 2Dept. of Radiology, Medical College of Wisconsin, Milwaukee, WI, United States; 3Dept. of Neurology and Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States; 4Dept. of Neurology, Medical College of Wisconsin, Milwaukee, WI, United States; 5Dept. of Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States
Diffusion weighted imaging (DWI) measures of apparent diffusion coefficient (ADC) is believed to reflect the level of tumor cellularity in malignant gliomas. Functional diffusion maps (fDMs) were developed to examine voxel-wise changes in ADC, then stratify voxels as either increasing ADC (indicative of necrosis or "hypocellularity"), decreasing ADC (indicative of growing tumor or "hypercellularity"), or not changing within regions of contrast-enhancement or FLAIR signal abnormality. Because the particular threshold used for voxel classification dictates the sensitivity and specificity to changes in tumor cell density, we hypothesize that a graded fDM technique that stratifies voxels into varying degrees of change, applied to the whole brain, may be useful for visualizing invading and proliferating tumor with both high sensitivity and specificity. In the current study we examine graded fDMs in 120 patients and discuss how graded fDMs can be used to detect and monitor brain tumor growth and invasion beyond the traditional malignant boundary.