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American Journal of Neuroradiology
DOI 10.3174/ajnr.A1844
BRAIN
Candidate Biomarkers of Extravascular Extracellular Space: A Direct Comparison of Apparent Diffusion Coefficient and Dynamic Contrast-Enhanced MR Imaging–Derived Measurement of the Volume of the Extravascular Extracellular Space in Glioblastoma Multiforme
From the Imaging Science and Biomedical Engineering Department (S.J.M., C.J.R., S.C., S.Z., G.J.M.P., A.J.), School of Cancer and Imaging Sciences, University of Manchester, Withington, Manchester, United Kingdom; Department of Neuroradiology (S.J.M., C.S., A.J.), Hope Hospital, Salford, United Kingdom; and Biomedical Imaging Institute (S.J.M., C.J.R., S.C., S.Z., G.J.M.P., A.J.), University of Manchester, Manchester, United Kingdom.
Please address correspondence to Samantha Mills, M.D., Wolfson Molecular Imaging Centre, Imaging Sciences and Biomedical Engineering, University of Manchester, 27 Palatine Rd, Withington, Manchester, M20 3LJ, United Kingdom; e-mail: samantha.mills{at}manchester.ac.uk
BACKGROUND AND PURPOSE: ADC measurements have been shown to have an inverse relationship with tumor cell density. DCE-MR imaging modeling techniques can produce a measurement of the ve, which would also be expected to have an inverse relationship with cell density. The objective of this study was to test the hypothesis that areas of increased cellularity, and therefore low ADC, would be expected to have a small EES (low ve).
MATERIALS AND METHODS: Nineteen patients with GBM were recruited. All imaging was performed before surgery on a 3T MR imaging scanner. Imaging included diffusion tensor imaging, T1-weighted DCE-MR imaging, and anatomic sequences. Tumor VOIs were defined on the anatomic images and modified to contain only enhancing voxels. Parametric maps of ADC and ve were generated. Statistical analysis of ADC and ve was performed on both a voxel-by-voxel basis and comparison of median values.
RESULTS: No correlation was demonstrated between ADC and ve in either a voxel-by-voxel analysis or comparison of median values (P = .124).
CONCLUSIONS: This study failed to demonstrate a correlation between ADC and ve. This is important because it suggests that though the mechanisms underlying these parameters are theoretically similar, they actually reflect different aspects of tumor microenvironment. Consequently ADC and ve should be considered to provide independent information about the properties of the EES.
Abbreviations: VOI, volume of interest