Fig 3. A, Axial fluid-attenuated inversion recovery MR image (TR/TE/TI = 9000/109/2500) demonstrates a large region of increased T2-weighted signal intensity in the left frontal and temporal lobes, primarily in the white matter and extending into the corpus callosum. The lesion is exerting mass effect with compression of the left lateral ventricle and left to right subfalcine herniation. There was no significant enhancement of the lesion on postcontrast images.

B, Voxel localization for proton MR spectroscopy of the mass.

C, ¹H-MR spectroscopy of the abnormality shows mild choline elevation, presence of lipid, and marked elevation of lactate. There is very significant elevation of the ß,-Glx peaks (arrow). This large solitary nonenhancing mass lesion is another example of the varied imaging appearance of tumefactive multiple sclerosis. NAA indicates N-acetylaspartate; Cho, choline; Cr, creatine; Lac, lactate; Lip, lipid.

D, Voxel localization for proton MR spectroscopy of contralateral control.

E, Normal proton MR spectrum of contralateral control.