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; e xact localization of abnormalities may be very difficult. These limita tions may be overcome by SPECT. Seventeen patients with clinical featu res of basal skull involvement were assessed by CT, SPECT, and planar scintigraphy. Subsequent clinical diagnoses were malignancy in 15 pati ents, vasculitis in 1 patient, and osteomyelitis in 1 patient. Compute d tomography with IV contrast was performed through the skull base at 5 mm intervals. Planar scintigraphy with Tc-99m MDP was followed by SP ECT. Bony involvement compatible with the clinical findings was demons trated by CT scans in 6 patients, by planar scintigraphy in 7 patients , and by SPECT in 9 patients. The abnormalities that were identified b y CT were all identified by SPECT. This study suggests that, in imagin g the skull base, SPECT is more sensitive and provides better anatomic al localization than planar imaging and appears useful in patients wit h a negative CT study.