History of brain biopsy with unknown pathology. Evaluate for regrowth or change. There is evidence of prior left frontal approach biopsy. The previously demonstrated rim enhancing lesion within the left basal ganglia is now smaller in size. There remains increased T2 signal along its periphery with some decreased T2 signal internally. There is a partial rim of intrinsic T1 hyperintensity inferiorly. On post-contrast imaging, the enhancement remains heterogeneous, but more solid appearing, likely due to collapse and apposition of the enhancing walls. On perfusion imaging, there is decreased relative cerebral blood volume corresponding to the lesion. Single voxel spectroscopy at multiple TE's over the core of the lesion demonstrate a very large lipid resonance. There is no evidence of detectable lactate, amino acids, choline, creatine or NAA. A voxel placed over the tissue immediately adjacent to the lesion demonstrates no abnormal infiltrative or neoplastic process.There is a new 6 mm focus of diffusion restriction in the right mesial temporal lobe. Elsewhere, no restricted diffusion is seen. A few scattered foci of white matter signal abnormality are noted, at least some of which were present on the prior exam. No new areas of significant edema or mass effect. No extra-axial fluid collection is identified. The left lateral ventricle has reexpanded with otherwise unremarkable ventricular caliber.
Interval decrease in size of the lesion in the left basal ganglia with some change in the pattern of enhancement likely related to lesion collapse. Both perfusion and MR spectroscopy are compatible with necrotic tissue. No evidence of any infiltrative or neoplastic process is seen within or adjacent to the lesion. Given these findings and the presence of a new focus of restricted diffusion suggesting ischemia in the right temporal lobe, the original lesion in the left basal ganglia is also favored to represent a late subacute stroke. At least one additional follow-up exam is suggested to ensure expected evolution.