BACKGROUND AND PURPOSE: Hemodynamic compromise in symptomatic patients with occlusive vascular disease (OVD) identified by cerebrovascular reserve (CVR) and oxygen extraction fraction (OEF) is an independent predictor of high stroke risk. However, up to 60% of patients compromised by CVR have normal OEF indicating a high rate of discordance. CVR is measured with an acetazolamide challenge, and OEF reactivity (OEFR) to acetazolamide, ie, a hemodynamic challenge, may reveal hemodynamic compromise and less discordance with measurements of CVR. METHODS: Nine symptomatic patients with OVD were studied by positron emission tomography before and 15 minutes after 15 mg/kg intravenous acetazolamide in the middle cerebral artery territories of each hemisphere. RESULTS: A close correlation between hemispheric CVR and OEFR was observed. Two hemispheres from two different patients showed an increase in OEF to acetazolamide challenge despite a normal baseline OEF. The two hemispheres showing an increase in OEF in response to acetazolamide were also associated with the lowest CVR and severest white matter hyperintensities. CONCLUSIONS: These observations suggest that positive OEFR may distinguish hemispheres in hemodynamic compromise despite normal OEF and show less discordance with CVR. However, these preliminary observations require confirmation in a larger study.
BACKGROUND AND PURPOSE: Hemodynamic compromise in symptomatic patients with occlusive vascular disease (OVD) identified by cerebrovascular reserve (CVR) and oxygen extraction fraction (OEF) is an independent predictor of high stroke risk. However, up to 60% of patients compromised by CVR have normal OEF indicating a high rate of discordance. CVR is measured with an acetazolamide challenge, and OEF reactivity (OEFR) to acetazolamide, ie, a hemodynamic challenge, may reveal hemodynamic compromise and less discordance with measurements of CVR. METHODS: Nine symptomatic patients with OVD were studied by positron emission tomography before and 15 minutes after 15 mg/kg intravenous acetazolamide in the middle cerebral artery territories of each hemisphere. RESULTS: A close correlation between hemispheric CVR and OEFR was observed. Two hemispheres from two different patients showed an increase in OEF to acetazolamide challenge despite a normal baseline OEF. The two hemispheres showing an increase in OEF in response to acetazolamide were also associated with the lowest CVR and severest white matter hyperintensities. CONCLUSIONS: These observations suggest that positive OEFR may distinguish hemispheres in hemodynamic compromise despite normal OEF and show less discordance with CVR. However, these preliminary observations require confirmation in a larger study.
Authors: Ken Uchino; Ridwan Lin; Syed F Zaidi; Hiroto Kuwabara; Donald Sashin; Nicholas Bircher; Yue-Fang Chang; Maxim D Hammer; Vivek Reddy; Tudor G Jovin; Nirav Vora; Mouhammad Jumaa; Lori Massaro; Julia Billigen; Fernando Boada; Howard Yonas; Edwin M Nemoto Journal: Transl Stroke Res Date: 2010-09-01 Impact factor: 6.829
Authors: Renata F Leoni; Kelley C Mazzetto-Betti; Afonso C Silva; Antonio C Dos Santos; Draulio B de Araujo; João P Leite; Octavio M Pontes-Neto Journal: Radiol Res Pract Date: 2012-06-20