Time Course of Vascular Reactivity Using Repeated Phase-Contrast MR Angiography in Patients With Carotid Artery Stenosis

Abstract

Background and Purpose-Cerebral vascular reactivity assessment is typically performed with 2 perfusion measurements before and after a vasodilatory challenge. The aim of this study was to assess the time course of the vasodilatory effect in the brain-feeding arteries after a challenge with acetazolamide in patients with a stenosis of the internal carotid artery (ICA). Methods-Twenty-one patients with a symptomatic ICA stenosis and 18 healthy control subjects underwent 2-dimensional phase-contrast MR angiography to repeatedly measure the blood flow (mL/min) in both ICAs at baseline and in 5-minute intervals for 30 minutes after intravenous administration of acetazolamide. Results-At baseline, the blood flow was significantly lower in the stenosed ICAs of patients (155Ϯ17 mL/min) than in the contralateral ICAs (237Ϯ21 mL/min, PϽ0.05) and the ICAs of healthy control subjects (249Ϯ15 mL/min, PϽ0.05) and remained lower throughout the time course. The maximum vasodilatory effect in the stenosed ICAs was observed after 15.3Ϯ0.9 minutes, which was significantly later than in the contralateral ICAs (within 12.9Ϯ0.

Morphometric evaluation of the delayed cerebral arteries response to acetazolamide test in patients with chronic carotid artery stenosis using computed tomography angiography

“…Interestingly, our results with respect to ACA and MCA reactivity are in opposition to most of the available studies, for example [10,13,20]. The maximum vasodilatory effect of acetazolamide is usually reached later in the stenosed ICAs than in the contralateral ICAs of patients and the ICAs of healthy control subjects [10,13].…”

“…The maximum vasodilatory effect of acetazolamide is usually reached later in the stenosed ICAs than in the contralateral ICAs of patients and the ICAs of healthy control subjects [10,13]. In the Hartkamp et al [10] study in the stenosed ICAs a stepwise decrease in blood flow was observed in the 20-to 25-min and the 25-to 30-min intervals which may indicate that the vasodilatory Alternatively, our population consisted of patients with chronic (over 5 years) CAS ≥ 90% on the ipsilateral side and, ≤ 50% on the contralateral side. The Hartkamp et al [10] population were much healthier with an unilateral symptomatic ICA stenosis > 50%.…”

“…In the Hartkamp et al [10] study in the stenosed ICAs a stepwise decrease in blood flow was observed in the 20-to 25-min and the 25-to 30-min intervals which may indicate that the vasodilatory Alternatively, our population consisted of patients with chronic (over 5 years) CAS ≥ 90% on the ipsilateral side and, ≤ 50% on the contralateral side. The Hartkamp et al [10] population were much healthier with an unilateral symptomatic ICA stenosis > 50%. Finally, we included only patients with fully developed CoW.…”

“…Cerebral perfusion of the brain tissue is measured before and after a vasodilatory challenge. The evidence accumulates that the response to the acetazolamide test is delayed on the ipsilateral side to stenosis [10,13]. Hartkamp et al [10] measured reactivity till 30 min after acetazolamide infusion while Murakami et al [13] completed the experiments after 20 min.…”

Blood Flow Distribution in Cerebral Arteries

“…7 An accurate blood flow measurement in specific arteries is important since it reflects blood distribution and possible compensatory mechanisms of the collateral flow, which are important for treatment decisions and for determining outcome of ischemic stroke. 8 There is also an increasing interest for determination of cerebral blood flow in different patient groups with vascular disease 9 such as cerebral ischemia 10 and carotid stenosis, 11 and also in patients with cognitive impairment 12 and migraine. 13 Further, global hypoperfusion has been proposed as an etiological factor in vascular theories related to mild cognitive impairment 14 and Alzheimer's disease.…”