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.