Vascular reserve in chronic cerebral ischemia measured by the acetazolamide challenge test: comparison with positron emission tomography.
OBJECTIVE
To determine the value of the acetazolamide challenge test with stable xenon-enhanced CT (Xe CT) for making therapeutic decisions in patients with chronic cerebrovascular disease.


METHODS
We compared the Xe CT-measured acetazolamide response with various measures obtained by positron emission tomography. We performed both a positron emission tomographic scan and a Xe CT study in 11 patients with chronic cerebral ischemic diseases within a 1-week interval. An increase of cerebral blood flow after injection of acetazolamide was expressed as delta AT. Regional cerebral blood flow, cerebral oxygen metabolism, oxygen extraction fraction, and cerebral blood volume were measured with oxygen-15-labeled gases by positron emission tomography.


RESULTS
In low-cerebral blood flow regions, decreased delta AT was accompanied by a significant elevation of oxygen extraction fraction and cerebral blood volume, compared with oxygen extraction fraction and cerebral blood volume in regions of normal delta AT. Plotting of regional data indicated that delta was significantly dependent on oxygen extraction fraction and cerebral blood volume. The area of decreased vascular reserve determined by the Xe CT image corresponded to the area of "misery perfusion" determined by positron emission tomography.


CONCLUSIONS
The acetazolamide challenge test with Xe CT may offer an alternative to positron-emission tomography in detecting lesions with elevated oxygen extraction fraction and cerebral blood volume (misery perfusion) that result from chronic hemodynamic stress.
Nariai
T
T
Department of Neurosurgery, Tokyo Medical and Dental University, Japan.
Suzuki
R
R
Hirakawa
K
K
Maehara
T
T
Ishii
K
K
Senda
M
M
D000086:Acetazolamide; D000293:Adolescent; D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply*; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002540:Cerebral Cortex / Q000098:blood supply; D002544:Cerebral Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology; D002648:Child; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009072:Moyamoya Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D012039:Regional Blood Flow / Q000502:physiology; D014055:Tomography, Emission-Computed; D014980:Xenon Radioisotopes
D014980:Xenon Radioisotopes; D000086:Acetazolamide