Changes in Cerebral Vascular Reserve Capacity after Carotid Artery Stenting: A 6-Month Follow-up Study

BACKGROUND: Assessment of cerebral vascular reserve capacity prior to carotid artery stenting is used for predicting hyperperfusion syndrome. However, the changes in vascular reserve capacity after carotid stenting are not fully understood. In this study we investigated the effects of carotid artery stenting on the restoration of vascular reserve capacity using (99m)TC-hexamethylpropylene amine oxime (HMPAO) single-photon-emission computed tomography (SPECT). METHODS: The study population comprised 29 patients who underwent carotid artery stenting. Patients were divided into groups according to occlusion of the contralateral internal carotid artery (unilateral group vs bilateral group) and according to the presence or absence of symptoms related to carotid stenosis (symptomatic group vs asymptomatic group). Pre- and postacetazolamide-activated (99m)TC-HMPAO SPECT were performed prior to stent insertion and at 1 and 6 months postoperatively. Vascular reserve capacity was assessed based on pre-, and 1- and 6-month postacetazolamide gamma count ratio (Post0, Post1, and Post6, respectively) and cerebrovascular reactivity (CVR0, CRV1, and CRV6, respectively). RESULTS: The postacetazolamide gamma count ratio and cerebrovascular reactivity tended to improve at 1 month after stenting, but tended to deteriorate at 6 months after stenting in the unilateral group compared with the bilateral group [Post0-Post1=0.045+/-0.078 (mean+/-SD), p=0.014; Post0-Post6=0.025+/-0.063, p=0.042; Post1-Post6=-0.020+/-0.047, p=0.102; CVR0-CVR1=0.043+/-0.071, p=0.008, CVR0-CVR6=0.019+/-0.063, p=0.097; CVR1-CVR6=-0.024+/-0.047, p=0.008] and in the symptomatic group compared with the asymptomatic group (Post0-Post1=0.058+/-0.106, p=0.038; Post0-Post6=0.048+/-0.103, p=0.061; Post1-Post6=-0.010+/-0.048, p=0.700; CVR0-CVR1=0.037+/-0.083, p=0.074; CVR0-CVR6=0.014+/-0.073, p=0.344; CVR1-CVR6=-0.023+/-0.054, p=0.055). CONCLUSIONS: The observed increases in postacetazolamide gamma count ratio and cerebrovascular reactivity at 1 month followed by decreases at 6 months may reflect the restoration of vascular reserve capacity. Carotid artery stenting can improve vascular reserve capacity, especially in patients with unilateral stenosis and with symptomatic stenosis.

Comparison between Acetazolamide and Dipyridamole Activated SPECT for Cerebral Vascular Reserve Capacity Measurement

Object of this study was to make comparison between acetazolamide and dipyridamole activated SPECT for measurement of cerebral vascular reserve capacity. This study was also carried out to evaluate response in acetazolamide and dipyridamole activated SPECT in relation to clinical parameters, such as Glasgow Coma Scale, Hunt & Hess grade, Fisher grade and Glasgow Outcome Scale. It is concluded from study that. Acetazolamide and dipyridamole activated SPECT study proved to be valuable for cerebral vascular reserve capacity. Dipyridamole activated SPECT study was somewhat equivocal because of systemic vascular dilatation effect, but this problem could be resolved by Gamma Count Ratio. Although there were minimal transient side effect of dipyridamole such as dizziness, no complication.

A Study on the Usefulness of Acetazolamide Activated 99mTc-HMPAO SPECT in Subarachnoid Hemorrhage

Cerebral vascular reserve capacity was evaluated by acetazolamide activated 99m Tc-HMPAO brain SPECT in 17 patients with subarachnoid hemorrhage. Abnormal reactivity of the vascular reserve capacity correlated very well with the prognosis of these patients. This study would also help to make decision of the surgical timing for the ruptured aneurysm. In patients with normal response to acetazolamide activated vascular reactivity, vasodilatory drug such as calcium channel blocker is recommaned for the treatment of vasospasm. This study should be done as early as possible during the period of vasospasm to aid in the diagnosis, and in treating the vasospasm. Although this study has a minimal transient side effect of acetazolamide such as dizziness there was no major complication.