Hemodynamic Failure Staging With Blood Oxygenation Level–Dependent Cerebrovascular Reactivity and Acetazolamide‐Challenged (15O‐)H2O‐Positron Emission Tomography Across Individual Cerebrovascular Territories

Abstract

<h3>Background</h3><p>Staging of hemodynamic failure (HF) in symptomatic patients with cerebrovascular steno‐occlusive disease is required to assess the risk of ischemic stroke. Since the gold standard positron emission tomography‐based perfusion reserve is unsuitable as a routine clinical imaging tool, blood oxygenation level–dependent cerebrovascular reactivity (BOLD‐CVR) with CO₂ is a promising surrogate imaging approach. We investigated the accuracy of standardized BOLD‐CVR to classify the extent of HF.</p><h3>Methods and Results</h3><p>Patients with symptomatic unilateral cerebrovascular steno‐occlusive disease, who underwent both an acetazolamide challenge (¹⁵O‐)H₂O‐positron emission tomography and BOLD‐CVR examination, were included. HF staging of vascular territories was assessed using qualitative inspection of the positron emission tomography perfusion reserve images. The optimum BOLD‐CVR cutoff points between HF stages 0–1–2 were determined by comparing the quantitative BOLD‐CVR data to the qualitative (¹⁵O‐)H₂O‐positron emission tomography classification using the 3‐dimensional accuracy index to the randomly assigned training and test data sets with the following determination of a single cutoff for clinical application. In the 2‐case scenario, classifying data points as HF 0 or 1–2 and HF 0–1 or 2, BOLD‐CVR showed an accuracy of >0.7 for all vascular territories for HF 1 and HF 2 cutoff points. In particular, the middle cerebral artery territory had an accuracy of 0.79 for HF 1 and 0.83 for HF 2, whereas the anterior cerebral artery had an accuracy of 0.78 for HF 1 and 0.82 for HF 2.</p><h3>Conclusions</h3><p>Standardized and clinically accessible BOLD‐CVR examinations harbor sufficient data to provide specific cerebrovascular reactivity cutoff points for HF staging across individual vascular territories in symptomatic patients with unilateral cerebrovascular steno‐occlusive disease.</p>