Abstract
BACKGROUND AND PURPOSE: CVR is a measure of cerebral hemodynamic impairment. A recently validated technique quantifies CVR by using a precise CO2 vasodilatory stimulus and BOLD MR imaging. Our aim was to determine whether preoperative CO2 BOLD CVR predicts the hemodynamic effect of ECIC bypass surgery in patients with intracranial steno-occlusive disease.
MATERIALS AND METHODS: Twenty-five patients undergoing ECIC bypass surgery for treatment of intracranial stenosis or occlusion were recruited. CVR was measured preoperatively and postoperatively and expressed as %ΔBOLD MR signal intensity per mm Hg ΔPetCO2. Using normative data from healthy subjects, we stratified patients on the basis of preoperative CVR into 3 groups: normal CVR, reduced CVR, and negative (paradoxical) CVR. Wilcoxon 2-sample tests (2-sided, α = 0.05) were used to determine whether the 3 groups differed with respect to change in CVR following bypass surgery.
RESULTS: The group with normal preoperative CVR demonstrated no significant change in CVR following bypass surgery (mean, 0.22% ± 0.05% to 0.22% ± 0.01%; P = .881). The group with reduced preoperative CVR demonstrated a significant improvement following bypass surgery (mean, 0.08% ± 0.05% to 0.21 ± 0.08%; P < .001), and the group with paradoxical preoperative CVR demonstrated the greatest improvement (mean change, −0.04% ± 0.03% to 0.27% ± 0.03%; P = .028).
CONCLUSIONS: Preoperative measurement of CVR by using CO2 BOLD MR imaging predicts the hemodynamic effect of ECIC bypass in patients with intracranial steno-occlusive disease. The technique is potentially useful for selecting patients for surgical revascularization.
Abbreviations
- ACA
- anterior cerebral artery
- AFNI
- Analysis of Functional NeuroImages
- BOLD
- blood oxygen level−dependent
- CBF
- cerebral blood flow
- CO2
- carbon dioxide
- CTA
- CT angiography
- CVR
- cerebrovascular reactivity
- DSA
- digital subtraction angiography
- ECIC bypass
- extracranial-intracranial bypass
- FiCO2
- inspiratory partial pressure of CO2
- FLAIR
- fluid-attenuated inversion recovery
- L
- left
- MCA
- middle cerebral artery
- MRA
- MR angiography
- OEF
- oxygen extraction fraction
- PaCO2
- arterial partial pressure of carbon dioxide
- PET
- positron-emission tomography
- PetCO2
- end-tidal partial pressure of carbon dioxide
- PetO2
- end-tidal partial pressure of oxygen
- R
- right
- STA
- superficial temporal artery
- TCD
- transcranial Doppler
- TIA
- transient ischemic attack
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