Differentiation betweenOligodendroglioma Genotypes Using Dynamic Susceptibility Contrast Perfusion-Weighted Imaging and ProtonMR Spectroscopy

BACKGROUND AND PURPOSE: Oligodendrogliomas with 1p/19q chromosome LOH are more sensitive to chemoradiation therapy than those with intact alleles. The usefulness of dynamic susceptibility contrast–PWI-guided 1H-MRS in differentiating these 2 genotypes was tested in this study. MATERIALS AND METHODS: Forty patients with oligodendrogliomas, 1p/19q LOH (n 23) and intact alleles (n 17), underwent MR imaging and 2D-1H-MRS. 1H-MRS VOI was overlaid on FLAIR images to encompass the hyperintense abnormality on the largest cross-section of the neoplasm and then overlaid on CBV maps to coregister CBV maps with 1H-MRS VOI. rCBVmax values were obtained by measuring the CBV from each of the selected 1H-MRS voxels in the neoplasm and were normalized with respect to contralateral white matter. Metabolite ratios with respect to ipsilateral Cr were computed from the voxel corresponding to the rCBVmax value. Logistic regression and receiver operating characteristic analyses were performed to ascertain the best model to discriminate the 2 genotypes of oligodendrogliomas. Qualitative evaluation of conventional MR imaging characteristics (patterns of tumor border, signal intensity, con-trast enhancement, and paramagnetic susceptibility effect) was also performed to distinguish the 2 groups of oligodendrogliomas. RESULTS: The incorporation of rCBVmax value and metabolite ratios (NAA/Cr, Cho/Cr, Glx/Cr, myo-inositol/Cr, and lipid lactate/Cr) into the multivariate logistic regression model provided the best discriminatory classification with sensitivity (82.6%), specificity (64.7%), and accuracy (72%) in distinguishing 2 oligodendroglioma genotypes. Oligodendrogliomaswith 1p/19q LOHwere alsomore associatedwit