Brain metastases. This patient has widespread metastatic disease from breast cancer. These images are from a contrast-enhanced CT and show multiple small metastases in both cerebral hemispheres. You’ll notice that all of these lesions are quite peripheral in location – this is the typical appearance of brain metastases, as they tend to develop at the junction between grey and white matter (where there is a rich blood supply). The majority of brain metastases are found in the cerebral hemispheres, with a small proportion (10-15%) occurring in the cerebellum. Brainstem metastases are relatively rare. The most common sources of brain metastases in adults are breast, lung and renal cell cancers, as well as melanoma.