72-year-old male status post stereotactic radiosurgery for an occipital metastasis. An irregular, peripherally enhancing lesion is present in the right occipital lobe measuring 33 x 23 x 23 mm. The lesion is somewhat T2 hypointense centrally with superimposed internal susceptibility consistent with hemosiderin staining. Confluent T2 hyperintense signal is evident in the adjacent white matter compatible with edema. Single and multivoxel spectroscopy with an intermediate TE of 144 was performed on the lesion and on contralateral normal tissue. A large voxel which encompassed the enhancing rim and nonenhancing core of the right occipital lesion demonstrated a prominent lipid-lactate peak, with relative slight increased choline with respect to the normal side, as well as moderately decreased NAA. A smaller voxel which encompassed predominantly the enhancing rim showed reduction of all major metabolites. Multi voxel spectroscopy performed of the right and left occipital regions showed no worrisome choline elevation at any point within or adjacent to the lesion. rCBV mapping showed low blood volume over a majority of the enhancing portions of the lesion.No additional enhancing lesions are seen. Mass effect from the lesion induced edema results in local sulcal effacement and partial effacement of the right ventricular atrium and the right temporal horn. No midline shift or brain herniation is detected. Numerous small non specific foci of T2 hyperintensity as seen scattered throughout the brain. Mild cerebellar atrophy is suspected.
Right occipital ring-enhancing lesion with spectroscopy and relative cerebral blood volume findings which favor radiation necrosis/injury over recurrent viable tissue.