Role of MR imaging in evaluation of neoplastic lesions of the skull base

Twenty-five patients with known neoplasms and clinical evidence of involvement of the skull base were evaluated by CT (General Electric 9800) and MR imaging (General Electric Signa, 1.5 T). The studies were evaluated independently for evidence and extent of the disease. Fourteen lesions were considered to be extensive and these were equally well demonstrated by both MR imaging and CT. MR imaging offered superior visualization of the relationship of the tumor mass to the vascular structures. In six patients, the CT scan was considered to show the extent of bone disease better than the MR image did. In five equivocal cases, all located with the sphenoid bone, MR images showed abnormal signal arising from the clivus. This was evident on T1-weighted images as decreased intensity of the clivus on the sagittal view indicating replacement of bone marrow. The authors' experience indicates that the majority of the lesions of the skull base are equally well evaluated by both modalities. However, MR imaging is superior in assessment of the lesions arising from the sphenoid bone