title: Paradoxical reduction of cerebral blood flow after acetazolamide loading: a hemodynamic and metabolic study with (15)O PET.
abstract: Paradoxical reduction of cerebral blood flow (CBF) after administration of the vasodilator acetazolamide is the most severe stage of cerebrovascular reactivity failure and is often associated with an increased oxygen extraction fraction (OEF). In this study, we aimed to reveal the mechanism underlying this phenomenon by focusing on the ratio of CBF to cerebral blood volume (CBV) as a marker of regional cerebral perfusion pressure (CPP). In 37 patients with unilateral internal carotid or middle cerebral arterial (MCA) steno-occlusive disease and 8 normal controls, the baseline CBF (CBF(b)), CBV, OEF, cerebral oxygen metabolic rate (CMRO2), and CBF after acetazolamide loading in the anterior and posterior MCA territories were measured by (15)O positron emission tomography. Paradoxical CBF reduction was found in 28 of 74 regions (18 of 37 patients) in the ipsilateral hemisphere. High CBF(b) (> 47.6 mL/100 mL/min, n = 7) was associated with normal CBF(b)/CBV, increased CBV, decreased OEF, and normal CMRO2. Low CBF(b) (< 31.8 mL/100 mL/min, n = 9) was associated with decreased CBF(b)/CBV, increased CBV, increased OEF, and decreased CMRO2. These findings demonstrated that paradoxical CBF reduction is not always associated with reduction of CPP, but partly includes high-CBF(b) regions with normal CPP, which has not been described in previous studies.
authors.affiliation: Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Suita, Japan, twatabe@mi.med.osaka-u.ac.jp.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Watabe
authors.forename: Eku
authors.initials: E
authors.lastname: Shimosegawa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kato
authors.forename: Kayako
authors.initials: K
authors.lastname: Isohashi
authors.forename: Mana
authors.initials: M
authors.lastname: Ishibashi
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Tatsumi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kitagawa
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Fujinaka
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yoshimine
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
mesh_terms: D000086:Acetazolamide / Q000009:adverse effects*; D000368:Aged; D001810:Blood Volume / Q000187:drug effects; D002540:Cerebral Cortex / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010104:Oxygen Radioisotopes; D049268:Positron-Emission Tomography; D012039:Regional Blood Flow / Q000187:drug effects; D014665:Vasodilator Agents / Q000009:adverse effects*
chemical_list: D010104:Oxygen Radioisotopes; D014665:Vasodilator Agents; D000086:Acetazolamide
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