Clinical significance of cerebrovascular reserve in acetazolamide challenge -comparison with acetazolamide challenge H2O-PET and Gas-PET.
OBJECTIVE
The response of cerebral blood flow (CBF) to acetazolamide (ACZ) challenge is frequently determined in clinical settings to evaluate cerebrovascular reserve (CVR). A reduced CVR can indicate patients with occlusive cerebrovascular disease and compromised hemodynamics who may be at increased risk of cerebral ischemia. However, how precisely ACZ reflects cerebral hemodynamic impairment remains obscure. The present study aims to clarify the pathological significance of CVR in patients with occluded carotid arteries.


METHODS
We recruited seventeen patients with occlusive lesions in the internal carotid artery (ICA) or middle cerebral artery (MCA). We assessed these patients in terms of resting cerebral blood flow (CBF) and the CVR response to ACZ challenge using H20 positron emission tomography (PET). In addition, we evaluated hemodynamic parameters including oxygen extraction fraction (OEF) using Gas-PET.


RESULTS
We identified a significant negative correlation between the CVR and OEF or the cerebral blood volume (CBV)/CBF ratio, as a potential index of cerebral perfusion pressure. Although the CVR values were reduced in all regions with elevated OEF (Stage II), these values were highly variable regardless of the CBV/CBF ratios. The cut-off value of CVR alone could not detect Stage II, but when combined with resting CBF, misery perfusion accompanied by increased OEF was detected with high sensitivity (6/7) and specificity (61/62).


CONCLUSIONS
CVR could be applied as an index reflecting both autoregulatory capacity and OEF. The present study also supported the notion that SPECT with ACZ challenge can be clinically applied to detect misery perfusion.
Imaizumi
Masao
M
Division of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, Japan. imaizumi@tracer.med.osaka-u.ac.jp
Kitagawa
Kazuo
K
Oku
Naohiko
N
Hashikawa
Kazuo
K
Takasawa
Masashi
M
Yoshikawa
Takuya
T
Osaki
Yasuhiro
Y
Matsushita
Kouji
K
Matsumoto
Masayasu
M
Hori
Masatsugu
M
Hatazawa
Jun
J
D000086:Acetazolamide; D000328:Adult; D000368:Aged; D002257:Carbonic Anhydrase Inhibitors; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010291:Paresis / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D011859:Radiography; D012044:Regression Analysis; D014867:Water
D002257:Carbonic Anhydrase Inhibitors; D014867:Water; D000086:Acetazolamide