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

Postcontrast T1-weighted images, T2-weighted FLAIR images, CBV, and pH-weighted MR images of a 68-year-old male patient (A) with a recurrent IDH^WT, MGMT-unmethylated anaplastic (WHO III) oligodendroglioma and a 68-year-old male patient (C) with a recurrent IDH^WT, MGMT-unmethylated glioblastoma. Note the high vascularity and acidity within the areas of contrast enhancement and high acidity extending into the areas of T2 hyperintensity. B and D, The bivariate histogram of pH-weighted MTR_asym and CBV of all voxels within the T2-hyperintense lesion and contrast-enhancing lesion of the corresponding patient. The lesion ROIs are outlined in red (contrast-enhancing lesion) and blue (T2-hyperintense lesion) in the MR images. In the patient in C, the white arrow indicates a nonenhancing part of the lesion, which demonstrates low CBV with elevated acidity, while the black arrow indicates an enhancing lesion with both high CBV and high MTR_asym contrast.