Collaterals influence oxygen metabolism on admission MRI in acute ischemic stroke

IntroductionThis study aimed to correlate cerebral collateral status and MRI-derived oxygen metabolism at admission in acute ischemic stroke (AIS) patients treated with mechanical thrombectomy. MethodsThe HIBISCUS-STROKE cohort (CoHort of Patients to Identify Biological an Imaging markerS of CardiovascUlar Outcomes in Stroke; NCT: 03149705), a single-center observational study, enrolled AIS patients for thrombectomy following MRI triage due to anterior circulation large vessel occlusion treated with mechanical thrombectomy. Dynamic-Susceptibility Contrast perfusion (DSC perfusion), Diffusion-Weighted Imaging (DWI) and penumbral volume (Tmax [&ge;] 6 secs) were post-processed to generate oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) maps within DWI and penumbral anomalies, compared to contralateral areas. Collateral status, assessed via pretreatment digital subtraction angiography, was categorized as poor (0-2) or good (3-4) based on ASITN/SIR collateral grading system score from Higashida. ResultsBetween October 2016 and October 2022, 321 participants were enrolled in the cohort. Of these, 184 (57.3%) were excluded due to missing admission DSC perfusion MRI in 61 patients and artifacts precluding collateral status evaluation on DSA. A total of 137 patients were included (mean age 71 years; 56.2% male). The median National Institutes of Health Stroke Scale (NIHSS) score was 15 (interquartile range [IQR]: 8.0-18.0), and the median time from symptom onset to admission was 96.0 minutes ([IQR]: 78.0-137.0). Patients with good collaterals (78) exhibited a smaller baseline infarct core (median 9.83 mL; (P<0.0001) less impairment cerebral blood flow (CBF) within the DWI lesion (median -65.89%; (P<0.0001), and less severe decrease CMRO2 within the ischemic penumbra (median -17.29%; (P=0.03). Good collaterals were independently associated with a smaller baseline infarct core volume and less decrease in CMRO2 within the ischemic penumbra (respectively OR = 0.94; 95% CI: [0.92; 0.96]; (P<0.0001), and (OR = 1.30; 95% CI: [1.06; 1.82]; P=0.001). ConclusionGood collaterals are associated with a smaller infarct core and better CMRO2 within the ischemic penumbra.