Evaluation of the skull base by SPECT. A comparison with planar scintigraphy and computed tomography.

Computed tomography is currently the standard diagnostic tool for the evaluation of the skull base. The complex anatomy of this area is the primary reason why planar bone scintigraphy is often unsatisfactory; exact localization of abnormalities may be very difficult. These limitations may be overcome by SPECT. Seventeen patients with clinical features of basal skull involvement were assessed by CT, SPECT, and planar scintigraphy. Subsequent clinical diagnoses were malignancy in 15 patients, vasculitis in 1 patient, and osteomyelitis in 1 patient. Computed tomography with IV contrast was performed through the skull base at 5 mm intervals. Planar scintigraphy with Tc-99m MDP was followed by SPECT. Bony involvement compatible with the clinical findings was demonstrated by CT scans in 6 patients, by planar scintigraphy in 7 patients, and by SPECT in 9 patients. The abnormalities that were identified by CT were all identified by SPECT. This study suggests that, in imaging the skull base, SPECT is more sensitive and provides better anatomical localization than planar imaging and appears useful in patients with a negative CT study.