PT  - JOURNAL ARTICLE
AU  - Y.-L. Wang
AU  - J. Yao
AU  - A. Chakhoyan
AU  - C. Raymond
AU  - N. Salamon
AU  - L.M. Liau
AU  - P.L. Nghiemphu
AU  - A. Lai
AU  - W.B. Pope
AU  - N. Nguyen
AU  - M. Ji
AU  - T.F. Cloughesy
AU  - B.M. Ellingson
TI  - Association between Tumor Acidity and Hypervascularity in Human Gliomas Using pH-Weighted Amine Chemical Exchange Saturation Transfer Echo-Planar Imaging and Dynamic Susceptibility Contrast Perfusion MRI at 3T
AID  - 10.3174/ajnr.A6063
DP  - 2019 May 16
TA  - American Journal of Neuroradiology
4099  - http://www.ajnr.org/content/early/2019/05/16/ajnr.A6063.short
4100  - http://www.ajnr.org/content/early/2019/05/16/ajnr.A6063.full
AB  - BACKGROUND AND PURPOSE: Acidification of the tumor microenvironment from abnormal metabolism along with angiogenesis to meet metabolic demands are both hallmarks of malignant brain tumors; however, the interdependency of tumor acidity and vascularity has not been explored. Therefore, our aim was to investigate the association between pH-sensitive amine chemical exchange saturation transfer echoplanar imaging (CEST-EPI) and relative cerebral blood volume (CBV) measurements obtained from dynamic susceptibility contrast (DSC) perfusion MRI in patients with gliomas.MATERIALS AND METHODS: In this retrospective study, 90 patients with histologically confirmed gliomas were scanned between 2015 and 2018 (median age, 50.3 years; male/female ratio = 59:31). pH-weighting was obtained using chemical exchange saturation transfer echo-planar imaging estimation of the magnetization transfer ratio asymmetry at 3 ppm, and CBV was estimated using DSC-MR imaging. The voxelwise correlation and patient-wise median value correlation between the magnetization transfer ratio asymmetry at 3 ppm and CBV within T2-hyperintense lesions and contrast-enhancing lesions were evaluated using the Pearson correlation analysis.RESULTS: General colocalization of elevated perfusion and high acidity was observed in tumors, with local intratumor heterogeneity. For patient-wise analysis, median CBV and magnetization transfer ratio asymmetry at 3 ppm within T2-hyperintense lesions were significantly correlated (R = 0.3180, P = .002), but not in areas of contrast enhancement (P = .52). The positive correlation in T2-hyperintense lesions remained within high-grade gliomas (R = 0.4128, P = .001) and in isocitrate dehydrogenase wild-type gliomas (R = 0.4300, P = .002), but not in World Health Organization II or in isocitrate dehydrogenase mutant tumors. Both magnetization transfer ratio asymmetry at 3 ppm and the voxelwise correlation between magnetization transfer ratio asymmetry and CBV were higher in high-grade gliomas compared with low-grade gliomas in T2-hyperintense tumors (magnetization transfer ratio asymmetry, P = .02; Pearson correlation, P = .01). The same trend held when comparing isocitrate dehydrogenase wild-type gliomas and isocitrate dehydrogenase mutant gliomas (magnetization transfer ratio asymmetry, P = .04; Pearson correlation, P = .01).CONCLUSIONS: A positive linear correlation between CBV and acidity in areas of T2-hyperintense, nonenhancing tumor, but not enhancing tumor, was observed across patients. Local heterogeneity was observed within individual tumors.CEST-EPIchemical exchange saturation transfer echo-planar imagingIDHisocitrate dehydrogenaseIDHMUTIDH mutantIDHWTIDH wild-typeLGGlow-grade gliomaHGGhigh-grade gliomaMTRasymmagnetization transfer ratio asymmetrySAGEspin and gradient-echoWHOWorld Health OrganizationMGMTO-6-methylguanine-DNA methyltransferase