Acetazolamide SPECT scans in the evaluation of symptomatic and asymptomatic patients with carotid occlusive disease

Acetazolamide (ACZ)-enhanced Single Photon Emission Computer Tomography (SP ECT) scans can assess both cerebral perfusion and vascular reactivity. Pati ents with poor reactivity lack perfusion reserve, and are at risk for strok e should perfusion diminish further. This study compared the preoperative A CZ-enhanced SPECT scans of 60 symptomatic to 40 asymptomatic patients with internal carotid artery stenosis (ICAS) in an effort to better define the c ause of their symptoms and effects of carotid endarterectomy (CEA) on cereb ral perfusion and reactivity in these two groups of patients. Symptomatic p atients had at least a 60% (x=84%) ICAS. Asymptomatic patients had at least an 80% (x=90%) ICAS. Preoperative ACZ SPECT scans were obtained usually on e week before CEA. All patients underwent CEA. Postoperative ACZ SPECT scan s were obtained in 78 of the patients, usually at the first postoperative ( similar to 30 days) visit. GRAPHICS Asymptomatic patients demonstrated poorer perfusion than symptomatic patien ts, which tends to support the premise that most strokes and carotid sympto ms are secondary to emboli rather than hypoperfusion. Interestingly, cerebr al reactivity was poor in both symptomatic and asymptomatic patients before CEA, suggesting inadequate collaterals and dependency on the ipsilateral c arotid. Carotid endarterectomy improved vasoreactivity in 84% of the patien ts. ACZ SPECT scans provided evidence of the return of cerebral perfusion a nd reactivity following endarterectomy.