Changes in blood flow and oxygen metabolism during visual stimulation in carotid artery disease: effect of baseline perfusion and oxygen metabolism.
OBJECTIVE
Severe atherosclerotic disease of the carotid arteries may affect perfusion in the posterior circulation according to the degree of collateral supply. The purpose of this study was to determine whether the responses of regional cerebral blood flow (rCBF) and regional cerebral metabolic rate of oxygen (rCMRO2) during neural stimulation are affected by the baseline perfusion or oxygen metabolism.


METHODS
We used PET to measure rCBF, rCMRO2, and regional oxygen extraction fraction (rOEF) in 13 patients with carotid artery steno-occlusive lesions at baseline and during visual stimulation. We examined whether the changes in CBF, CMRO2, and OEF during visual stimulation were correlated with the baseline values of these parameters in the visual cortex.


RESULTS
With visual stimulation, rCBF increased in all patients, whereas rCMRO2 showed variable changes. The baseline rCMRO2 value showed a positive relationship with the degree of rCBF increase and a negative relationship to the degree of rCMRO2 increase. rCMRO2 decreased in patients with relatively high baseline rCMRO2 values, resulting in dissociation of the rCMRO2 response from the rCBF response. The rCBF increase was large in the region with an increased baseline rOEF value. These variable changes in rCBF and rCMRO2 resulted in a significant correlation between the values of rCBF and rCMRO2 during visual stimulation in contrast to the lack of such a correlation at baseline.


CONCLUSIONS
In patients with cerebrovascular disease, neural stimulation may induce variable changes in rCBF and rCMRO2 according to the baseline perfusion and oxygen metabolism.
Yamauchi
Hiroshi
H
Research Institute, Shiga Medical Center, Moriyama, Japan. yamauchi@shigamed.moriyama.shiga.jp
Okazawa
Hidehiko
H
Kishibe
Yoshihiko
Y
Sugimoto
Kanji
K
Takahashi
Masaaki
M
D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D010775:Photic Stimulation; D012016:Reference Values; D014055:Tomography, Emission-Computed; D014793:Visual Cortex / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000503:physiopathology*
D010100:Oxygen