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FIG 7. A–D, T1-weighted (32/8/1) (A) and T2-weighted (2500/30/1) (B) images resampled to the resolution of the rCBV map (C) and corresponding spectra (D) of a patient with an oligoastrocytoma. Spectra with elevated Cho and decreased NAA coincide with the abnormality on the T2-weighted image. The abnormal regions on the conventional T1- and T2-weighted images were interpreted to be areas of possible tumor, post-treatment changes, and/or edema, whereas the rCBV map was elevated relative to normal white matter and the spectra showed a tumor pattern. Therefore, conventional MR imaging was not specific for the presence of tumor, whereas both the rCBV map and the proton spectra indicated tumor. Note also the difficulty of assessing increased microvascularity near the middle cerebral artery on the rCBV map. This case is typical for low-grade tumors and unusual for most treated higher-grade tumors, because there are regions of hyperintensity on the rCBV map in nonenhancing regions
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