Quantification of Infarct Core Volume in Patients with Acute Ischemic Stroke Using Cerebral Metabolic Rate of Oxygen in CT Perfusion

BACKGROUND AND PURPOSE: The cerebral metabolic rate of oxygen (CMRO₂) is considered a robust marker of the infarct core in ¹⁵O-tracer–based PET. We aimed to delineate the infarct core in patients with acute ischemic stroke by using commonly used relative CBF (rCBF) < 30% and oxygen metabolism parameter of CMRO₂ on CT perfusion in comparison with pretreatment DWI-derived infarct core volume.

MATERIALS AND METHODS: Patients with acute ischemic stroke who met the inclusion criteria were recruited. The CMRO₂ and CBF maps in CT perfusion were automatically generated by using postprocessing software. The infarct core volume was quantified with relative cerebral metabolic rate of oxygen (rCMRO₂) <20% –30% and rCBF <30%. The optimal threshold was defined as those that demonstrated the smallest mean absolute error, lowest mean infarct core volume difference, narrowest 95% limit of agreement, and largest intraclass correlation coefficient (ICC) against the DWI.

RESULTS: This study included 76 patients (mean age ± standard deviation, 69.97 ± 12.15 years, 43 men). The optimal thresholds of rCMRO₂ <26% resulted in the lowest mean infarct core volume difference, narrowest 95% limit of agreement, and largest ICC among different thresholds. Bland-Altman analysis demonstrated a volumetric bias of 1.96 mL between DWI and rCMRO₂ <26%, whereas in cases of DWI and rCBF <30%, the bias was notably larger at 14.10 mL. The highest correlation was observed for rCMRO₂ <26% (ICC = 0.936), whereas rCBF <30% showed a slightly lower ICC of 0.934.

CONCLUSIONS: CT perfusion–derived CMRO₂ is a promising parameter for estimating the infarct core volume in patients with acute ischemic stroke.