COMPARISON OF CEREBRAL PERFUSION RESERVE AND COLLATERAL CIRCULATION IN PATIENTS WITH INTERNAL CAROTID-ARTERY DISEASE

The cerebral hemodynamics in patients with carotid disease is influenc ed by a network of extra-and intracranial collaterals,The purpose of t his study was to compare the findings of regional cerebral perfusion r eserve (rCPR) with angiographically proven collateral circulation. In 41 patients (28 men, 13 women, age 63 +/- 10 years) with angiographica lly proven carotid stenoses or occlusions (30 stenoses, 11 occlusions) 24 Tc-99m-HMPAO-SPECT and 25 dynamic Xe-CT investigations were conduc ted, both before and after acetazolamide stimulation. rCPR was quantif ied as the ratio (1) of the absolute rCBF values obtained by Xe-CT a n d (2) of the count density measured by HMPAO-SPECT of the acetazolamid e administration. A rCPR of less than 95 % in a vascular territory was classified as compromised rCPR. A recent CT examination was available in all cases. According to the angiographic findings the patients cou ld be classified into (1) group A (n = 9) with residual carotid perfus ion,(2) Group B (n = 8) with collateralization via the circle of Willi s, and (3) group C (n = 24) with leptomeningeal or ophthalmic artery c ollateral circulation. The rCPR values were significantly different in groups 8 and C with both methods, Xe-CT (P = 0.0035)and HMPAO-SPECT(P = 0.0014). rCPR was decreased in 13/14 group C patients invest igated with Xe-CT and in 11/14 examined with HMPAO-SPECT. All patients in gr oup B showed normal rCPR according to Xe-CT and HMPAO-SPECT. In group A, six of seven revealed decreased rCPR an Xe-CT,while rCPR values wer e normal in all four group A-patients examined with HMPAO-SPECT. The c erebral hemodynamics depend on a collateralization network and not onl y on the degree of internal carotid artery (ICA) stenosis. A decreased CPR in a vascular territory ipsilateral to an ICA stenosis or occlusi on correlates strongly with the angiographic finding of leptomeningeal or ophthalmic artery collateral circulation.