Fig. 3

Axial post-contrast T1WI demonstrating a right occipital melanoma metastasis (a, dotted circle), which was treated with 20 Gy single-fraction SRS. The metastasis responded to SRS (arrow), but subtle linear enhancement developed in the adjacent right cerebellar hemisphere (b, arrowhead) four years later. Despite the linear appearance raising the possibility of leptomeningeal disease, this enhancement convincingly involved the cerebellar parenchyma rather than the folia. Geographic correlation of the area of enhancement with the high radiation dose region is illustrated by the 20 Gy, 15 Gy and 10 Gy isodose lines (in decreasing grayscale brightness) from the SRS plan (c). Ongoing stability of the cerebellar enhancement confirmed RN