Validation of functional diffusion maps (fDMs) as a biomarker for human glioma cellularity |
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Authors: | Benjamin M Ellingson PhD Mark G Malkin MD FRCPC Scott D Rand MD PhD Jennifer M Connelly MD Carolyn Quinsey BS Pete S LaViolette MS Devyani P Bedekar MS Kathleen M Schmainda PhD |
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Institution: | 1. Translational Brain Tumor Program, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;2. Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;3. Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;4. Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;5. Department of Biophysics, Medical College of Wisconsin, USA |
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Abstract: | Purpose: To present comprehensive examinations of the assumptions made in functional diffusion map (fDM) analyses and provide a biological basis for fDM classification. Materials and Methods: Sixty‐nine patients with gliomas were enrolled in this study. To determine the sensitivity of apparent diffusion coefficients (ADCs) to cellularity, cell density from stereotactic biopsy specimens was correlated with preoperative ADC maps. For definition of ADC thresholds used for fDMs, the 95% confidence intervals (CI) for changes in voxel‐wise ADC measurements in normal appearing tissue was analyzed. The sensitivity and specificity to progressing disease was examined using both radiographic and neurological criteria. Results: Results support the hypothesis that ADC is inversely proportional to cell density with a sensitivity of 1.01 × 10?7 mm2/s]/nuclei/mm2]. The 95% CI for white matter = 0.25 × 10?3 mm2/s, gray matter = 0.31 × 10?3 mm2/s, a mixture of white and gray matter = 0.40 × 10?3 mm2/s, and a mixture of white matter, gray matter, and cerebrospinal fluid = 0.75 × 10?3 mm2/s. Application of these measurements as ADC thresholds produce varying levels of sensitivity and specificity to disease progression, which were all significantly better than chance. Conclusion: This study suggests fDMs are valid biomarkers for brain tumor cellularity. J. Magn. Reson. Imaging 2010;31:538–548. ©2010 Wiley‐Liss, Inc. |
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Keywords: | diffusion MRI brain tumor glioma functional diffusion maps fDM |
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