Intravoxel distribution of DWI decay rates reveals C6 glioma invasion in rat brain

The hypothesis was tested that the intravoxel distribution of water diffusion rates, as measured with a stretched‐exponential model of diffusion‐weighted imaging (DWI), is a marker of brain tumor invasion. Eight rats underwent intracerebral inoculation of C6 glioma cells. In three rats, cells were l...

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Bibliographic Details
Published in:Magnetic resonance in medicine 2004-11, Vol.52 (5), p.994-1004
Main Authors: Bennett, Kevin M., Hyde, James S., Rand, Scott D., Bennett, Raoqiong, Krouwer, Hendrikus G. J., Rebro, Kelly J., Schmainda, Kathleen M.
Format: Article
Language:English
Subjects:
Animals
Body Water - metabolism
Brain Neoplasms - pathology
diffusion
Diffusion Magnetic Resonance Imaging - methods
glioma
Glioma - pathology
Image Processing, Computer-Assisted
invasion
magnetic resonance imaging
Male
Microscopy, Fluorescence
Models, Statistical
Neoplasm Invasiveness
Rats
Rats, Sprague-Dawley
stretched exponential
Tumor Cells, Cultured
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Summary:The hypothesis was tested that the intravoxel distribution of water diffusion rates, as measured with a stretched‐exponential model of diffusion‐weighted imaging (DWI), is a marker of brain tumor invasion. Eight rats underwent intracerebral inoculation of C6 glioma cells. In three rats, cells were labeled with a fluorescent dye for microscopy. One rat was inoculated with a saline solution, and five more rats were imaged without inoculation as controls. Five healthy uninoculated rats were also imaged. DWI was performed 14–15 days after inoculation, with diffusion‐weighting factor b = 500 to 6500 sec/mm2, and the resulting signal attenuation was fitted with the stretched‐exponential model. The heterogeneity index values were significantly lower (P < 0.05) in the peritumor ROI than in normal gray matter and significantly higher than in normal white matter. The distributed diffusion coefficient values were significantly lower than in normal white matter or normal gray matter. Fluorescence microscopy confirmed the presence of tumors in the peritumor region that could be histologically distinguished from the main tumor mass. There was no change in proton density or T2‐weighted images in the peritumor region, making vasogenic edema unlikely as a source of contrast. It is therefore thought that the heterogeneity parameter α is a marker of brain tumor invasion. Magn Reson Med 52:994–1004, 2004. © 2004 Wiley‐Liss, Inc.
ISSN:0740-3194
1522-2594
DOI:10.1002/mrm.20286