Fig 1. Axial FLAIR image, T2-weighted FSE MR image, axial contrast-enhanced T1-weighted SE MR image, and axial CBV map in a 38-year-old woman with primary CNS lymphoma. There is T2 hyperintensity involving the left temporoparietal lobe. There is minimal mass effect; the lesion exhibits patchy heterogeneous enhancement on the postgadolinium images. The CBV map demonstrates a moderately increased blood volume in the lesion compared with the normal contralateral side (rCBV, 1.66, which is higher than the cutoff point of 1.5). A, B, The abnormal signal intensity of the lesion extended over 8 FLAIR sections (5-mm section thickness, no gap; with 5 sections showing the bulk of the lesion). Images shown of the Cho, Cr, NAA, and lactate metabolites were reconstructed from the MRSI section exhibiting the largest metabolic abnormalities (MRSI, section 2). Axial T1-weighted SE localizer image with proton MR spectra of the lesion (voxel 2) and the corresponding control spectrum (voxel 1) are shown. Compared with the contralateral side, the metabolite images and spectra of the lesion show elevated Cho and Cr, and decreased NAA signals, with an NAA/Cho ratio of 0.58 (below the cutoff point of 0.61). Slight contamination of spectra with lipid signals, most likely because of the patient’s head motion, was noted in this examination.