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(Stroke. 2006;37:534.)
© 2006 American Heart Association, Inc.

Research Reports

Relationship Between Cerebral Circulatory Reserve and Oxygen Extraction Fraction in Patients With Major Cerebral Artery Occlusive Disease

A Positron Emission Tomography Study

Kenichiro Yata, MD; Akifumi Suzuki, MD, PhD; Jun Hatazawa, MD, PhD; Eku Shimosegawa, MD, PhD; Ken Nagata, MD, PhD; Mika Sato, MD, PhD Junta Moroi, MD, PhD

From the Departments of Strokology (K.Y., A.S., K.N., M.S., J.M.) and Radiology (J.H., E.S.), Research Institute for Brain and Blood Vessels, Akita, Japan.

Correspondence to Akifumi Suzuki, MD, Department of Strokology, Research Institute for Brain and Blood Vessels, Akita, 6-10 Senshu-kubota-machi, Akita 010-0874, Japan. E-mail akifumi{at}akita-noken.go.jp

Background and Purpose— The present study examined the relationship between circulatory and metabolic reserve in patients with hemodynamic impairment.

Methods— Positron emission tomography was used to investigate 40 patients with major cerebral artery occlusive disease. The ratio of cerebral blood volume to cerebral blood flow (CBV/CBF) and vasoreactivity in response to hypercapnia (%CBF_hypercapnia) and acetazolamide (ACZ) stress (%CBF_ACZ) were measured to evaluate circulatory reserve. Oxygen extraction fraction (OEF) was measured to evaluate metabolic reserve. To detect relationships between circulation reserve and OEF, cerebral hemispheres were grouped into 5 or 6 stepwise groups based on reduction of circulation reserve.

Results— OEF was significantly elevated in hemispheres with CBV/CBF 0.11 minutes and in hemispheres with %CBF_hypercapnia <0%. OEF was significantly increased according to %CBF_ACZ in hemispheres with %CBF_ACZ <15% and plateaued at levels below –15%.

Conclusions— Metabolic reserve consumption began at CBV/CBF 0.11 minutes, CBF_hypercapnia <0%, and CBF_ACZ <15%.

Key Words: ischemia • tomography, emission computed