After the MRI, what is the favoured diagnosis?
MRI features are of a cerebral malignant neoplasm, with metastasis favoured over GBM. Note that the lesion tends to spare the cortex and the increased T2/FLAIR surrounding the lesion is basically vasogenic oedema, with no features to suggest tumour infiltration.
Complex mass in the posterior aspect of the left temporal lobe is predominantly cystic with an intensely enhancing eccentric solid nodular component, which shows restricted diffusion and an elevated cerebral blood volume (CBV). No calcification was seen on the previous CT brain. The fluid component of the tumour is homogeneous and partially suppressed on FLAIR, with a thin enhancing capsule. Spectroscopy traces at the margins of the lesion do not show a choline peak or reduced NAA. Vasogenic oedema surrounds the lesion and the mass effect also compresses the left cerebral peduncle and left lateral ventricle, resulting in a 6.6 mm rightward midline shift. Scattered foci of high T2/FLAIR signal abnormalities through the infra- and supratentorial white matter are nonspecific, most likely representing chronic small vessel ischaemia, larger in number than expected for the patient's age group. Old pontine lacunar infarct left of midline.