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Vasoreactive effect of acetazolamide as a function of time with sequential PET 15O-water measurement
K Hayashida1, Y Tanaka, Y Hirose
1Department of Radiology, National Cardiovascular Centre, Osaka University, Japan.
Insights
Accurate assessment of cerebrovascular disease risk requires measuring cerebral blood flow (CBF) 10 minutes after acetazolamide administration. This timing optimizes the evaluation of vascular reserve in patients with internal carotid or middle cerebral artery occlusions.
Area of Science:
- Neurology
- Vascular Medicine
- Medical Imaging
Background:
- Accurate assessment of vascular flow reserve is critical for managing patients with cerebrovascular disease.
- Cerebrovascular disease poses significant risks, necessitating precise evaluation methods.
Purpose of the Study:
- To determine the optimal timing for measuring cerebral blood flow (CBF) after acetazolamide administration to assess vasoreactivity.
- To evaluate the difference in vasoreactive response between occluded and non-occluded cerebral arterial territories.
Main Methods:
- Positron emission tomography (PET) was used to measure CBF in seven patients with unilateral arterial occlusions.
- Cerebral blood flow was measured at rest and at 10, 20, and 30 minutes after administering 1 mg of acetazolamide.
- Regions of interest were analyzed in both occluded and non-occluded hemispheres, covering cortical and deep territories.
Main Results:
- A significant difference in mean CBF was observed between non-occluded and occluded sites in the cortical middle cerebral arterial territory (Area I).
- The most pronounced difference (25.1%) occurred 10 minutes post-acetazolamide administration.
- Deep territories (Area II) showed less pronounced differences between occluded and non-occluded sites.
Conclusions:
- Measuring CBF 10 minutes after acetazolamide provides the most accurate assessment of vascular reserve in patients with cerebrovascular disease.
- This specific time point effectively highlights differences in vasoreactivity between affected and unaffected brain regions.
Abstract:
The accurate assessment of vascular flow reserve is crucial for the evaluation of risk among patients with cerebrovascular disease. In six patients with unilateral occlusion of the internal carotid artery and one patient with unilateral occlusion of the middle cerebral artery (mean +/- S.D. age = 68 +/- 3 years), we measured cerebral blood flow (CBF) after the administration of 940 MBq 15O-water using a remotely controlled power injector. Studies were performed at rest, after 10 min, and then 10, 20 and 30 min after the administration of 1 mg acetazolamide to evaluate the vasoreactive effect, as reflected by an increase in CBF. Sixteen regions of interest (ROIs) were drawn over the CBF images. These ROIs were as follows in each hemisphere: Area I, four areas in the cortical middle cerebral arterial territory (superior frontal, frontal, temporal and parietal areas); Area II, four areas of the deep middle cerebral and vertebral arterial territory (occipital area, basal ganglia, thalamus and cerebellum). Taking normalized resting CBF to be 100%, the mean CBF measured 10, 20 and 30 min post-injection using sequential positron emission tomography was as follows: Area I, 141.4 +/- 16.3, 127.7 +/- 15.3 and 128.2 +/- 17.4% for non-occluded sites and 116.3 +/- 22.8, 112.7 +/- 16.4 and 114.9 +/- 17.1% for occluded sites; Area II, 143.4 +/- 14.5, 126.2 +/- 10.4 and 125.0 +/- 12.9% for non-occluded sites and 141.9 +/- 28.9, 126.0 +/- 20.5 and 124.1 +/- 17.1% for occluded sites. A significant difference in mean CBF was noted between the non-occluded and occluded sites in Area I, the most marked difference of 25.1% being observed 10 min after the administration of the acetazolamide. We conclude that for an accurate assessment of vascular reserve in patients with cerebrovascular disease, CBF should be measured 10 min post-administration of the acetazolamide.