FINDINGS: A focal lesion measuring about 3 x 3 cm with surrounding marked vasogenic edema is seen in the right frontal lobe. Mild mass effect is seen over the frontal horn of the right lateral ventricle. The lesion has irregular lobulated outlines with vividly enhancing walls and a central cystic non-enhancing matrix. On DWI, the lesion shows central diffusion restriction and on long TR MRS, the lesion displays high lipid/lactate peaks with reduced choline/creatine and NAA peaks. No other intra or extra-axial lesion is noted.
CONCLUSION: The above described MRI and MRS features are slightly more in favor of brain abscess; however, considering the current clinical context; prime differential diagnosis would be necrotic brain metastasis.