Computed tomographic evaluation of subdural and epidural metastases.

Head computed tomography scans of eight patients with calvarial metastases revealed extension of the tumors into the epidural and subdural spaces; Epidural and subdural extensions enhanced after contrast medium administration and were either crescentic or biconcave. In six patients, these tumors produced sufficient mass effect to displace intraparenchymal structures. The subdural and epidural tumor extensions appeared similar to subdural and epidural hematomas, but could be diagnosed correctly because the former enhanced uniformly and were associated with destructive calvarial changes.