Improved detection of cerebral hypoperfusion with internal carotid balloon test occlusion and 99mTc-HMPAO cerebral perfusion SPECT imaging.

A new method that employs a cerebral perfusion imaging agent, 99mTc-HMPAO, is described for identifying those patients who clinically pass an internal carotid artery balloon test occlusion but who then may develop a cerebral infarction after permanent occlusion. Test balloon occlusion of the internal carotid artery was performed in 17 patients, and 99mTc-HMPAO was injected intravenously while the balloon was inflated. The balloon was deflated and removed approximately 15-20 min later, and single-photon emission CT (SPECT) imaging of the brain was performed. In patients with an area of focal hypoperfusion, the 99mTc-HMPAO study was repeated the next day to determine if the hypoperfusion was due to the temporary balloon occlusion or to a preexisting abnormality. All 17 patients had normal neurologic examinations at the time of the balloon test occlusion. Fifteen had symmetric perfusion on the 99mTc-HMPAO SPECT scans. Five of these had permanent internal carotid artery occlusion, and four did not develop a neurologic deficit. One patient developed an ipsilateral watershed infarction after internal carotid artery occlusion during significant intraoperative hypotension. Two patients had ipsilateral regions of hypoperfusion with the test occlusion. Both these patients had repeat nonocclusion 99mTc-HMPAO SPECT studies that were normal. One patient is being followed. The second patient had ipsilateral EEG changes associated with temporary intraoperative occlusion of the internal carotid artery during aneurysm surgery. Although the numbers are relatively small, this study suggests that this protocol may be able to predict a good outcome after permanent carotid artery occlusion as well as to identify patients who are at greater risk for developing cerebral infarction after permanent occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)