Long-term prognostic value of [15O]H2O PET imaging in patients suspected for cerebral hemodynamic insufficiency

Objectives: Quantitative regional cerebral perfusion (rCBF) measurements using [15O]H2O PET with arterial cannulation and acetazolamide (ACZ) challenge have been reserved to identify high-risk patients that are can-didates for by-pass operation. We aimed to assess the prognostic value of various parameters in quantitative [15O]H2O PET measurements in patients not subsequently undergoing surgery.Methods: We identified 32 eligible patients who underwent [15O]H2O brain PET imaging for suspicion of he-modynamic insufficiency between 2009 and 2020. Cerebrovascular events were defined as new ischemic lesions on MRI, stroke, transient ischemic attack, vascular dementia. Follow-up period was 91 months (range: 26-146). rCBF before (rCBFbase) and after (rCBFacz) ACZ challenge and the relative increase (CVR), were examined in the anterior (ACA), middle (MCA), and posterior (PCA) cerebral artery territories of the affected hemisphere, and the most recent MRI scans were scored for infarcts and white matter lesions.Results: Receiver operating characteristic (ROC) curve analysis showed higher prognostic accuracy for rCBFac-z(AUC:0.82) compared to CVR (AUC:0.72) and rCBFbase (AUC:0.77). ROC AUC, optimal thresholds (and corre-sponding sensitivity/specificity/accuracy) for rCBFacz after ACZ in individual territories were 0.79 and 37.8 mL 100g-1 min-1 (0.81/0.63/0.72) for the ACA, 0.84 and 32 mL 100g-1 min-1 (0.81/0.75/0.78) for the MCA, and 0.70 and 43.9 ml/(mL 100g-1 min-1 (0.81/0.43/0,62) for the PCA. Kaplan Meier survival curve showed longer event-free survival in patients with rCBFacz below cut-off (p=0.007). In multivariate analysis rCBFacz remained a significant predictor when correcting for age.Conclusion: Quantitative rCBF measurements after ACZ challenge with [15O]H2O PET provided high prognostic value for future cerebrovascular events.