Female, 52 years old, with speech changes and and abnormality noted on prior imaging. Evaluate for changes in lesion status. An ill-defined region of T2 hyperintensity is redemonstrated involving the medial superior left temporal lobe, left periatrial white matter and left lateral thalamus. The extent of this abnormality is stable or at most very slightly increased when compared to prior examinations. However, there remains no evidence of significant mass effect. Ill-defined enhancement is again seen in this region, but the enhancement is stable to slightly reduced when compared to the prior study. Single voxel spectroscopy of this region shows markedly diminished NAA. The choline peak, however, has increased from that seen on the prior exam, and is now slightly higher than that observed in the contralateral normal hemisphere. A small doublet peak is evident at 1.15 ppm which may be artifactual, though propylene glycol, a common pharmaceutical and food additive, produces just such a peak in this location of the spectrum.A subcentimeter focus of enhancement and minimal diffusion restriction in the left centrum semiovale is unchanged. Likewise, a similarly sized T2 hyperintense non-enhancing lesion in the right parietal white matter is unchanged. Streaky perivenular enhancement in the right parietal lobe is still present though less distinct than on the prior exam.
Overall, there has been little if any significant change in the appearance of scattered lesions as demonstrated on the conventional MRI sequences. MR spectroscopy of the dominant left temporal/periatrial lesion does, however, shows an interval increase in the choline peak, which is a marker for cell membrane turnover. Such a finding can be seen in gliosis or post-inflammatory repair, but also in neoplastic processes.As before, the differential diagnosis would include granulomatous disease, lupus, vasculitis, a post-inflammatory autoimmune phenomenon, and atypical demyelinating disease. Atypical neoplastic processes, such as intravascular (angiocentric) lymphoma, can also present with similar findings. While the overall stability of the lesion is somewhat reassuring, the MR spectroscopic evidence for increased membrane turnover warrants at least one additional follow up exam, perhaps at 6 months. 