Neuroradiologic applications of central nervous system SPECT

Single photon emission computed tomography (SPECT) of the central nervous system (CNS) has many potentially useful interventional neuroradiologic applications. CNS SPECT allows easy and safe evaluation of the collateral circulation during internal carotid balloon test occlusion. The cerebrovascular distribution of intracarotid amobarbital sodium, which is used in the Wada test, can be accurately determined with simultaneous injection of a radiopharmaceutical. Easy and safe evaluation of the extent and distribution of vasospasm associated with subarachnoid hemorrhage or cerebral angiography is also possible with CNS SPECT. Images obtained after administration of acetazolamide can be compared with baseline images to evaluate cerebrovascular reserve before carotid endarterectomy. Seizure foci can be identified if peripheral intravenous injection is performed during an ictus. Thallium-201 imaging can be used to direct stereotactic brain biopsy to check for tumor recurrence. Radiologists need to familiarize themselves and their clinical colleagues with the many uses of this imaging technique.