Time Course of Vascular Reactivity Using Repeated Phase-Contrast MR Angiography in Patients With Carotid Artery Stenosis
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 (155±17 mL/min) than in the contralateral ICAs (237±21 mL/min, P<0.05) and the ICAs of healthy control subjects (249±15 mL/min, P<0.05) and remained lower throughout the time course. The maximum vasodilatory effect in the stenosed ICAs was observed after 15.3±0.9 minutes, which was significantly later than in the contralateral ICAs (within 12.9±0.7 minutes, P<0.05) and healthy ICAs (within 12.8±0.8 minutes, P<0.05).
Conclusions—The onset of the maximum vasodilatory effect after administration of acetazolamide is delayed in patients with a symptomatic ICA stenosis.
- Received August 28, 2011.
- Accepted September 15, 2011.
- © 2011 American Heart Association, Inc.