Purpose Robust pial arterial collaterals (PAC) preserve blood flow to critically hypoperfused brain tissue in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). CT angiography (CTA) based methods of pial collateral assessment do not provide tissue level perfusion information, and prior studies have shown that PAC assessment on CT perfusion imaging strongly predicts outcome in AIS-LVO patients treated by thrombectomy. Patients with favorable pial collaterals and brain tissue perfusion also likely have robust cortical venous drainage relative to patients with more impaired cerebral perfusion. We determined the venous microperfusion profile (VMP) in AIS-LVO patients. We hypothesized that robust PAC on CT perfusion predict robust cortical venous contrast opacification on pre-treatment CTA and that a favorable VMP is associated with good clinical outcomes in AIS-LVO patients.
Materials and Methods We performed a multicenter retrospective cohort study of consecutive AIS-LVO patients who underwent thrombectomy. Included patients had interpretable pre-thrombectomy CT angiography (CTA) and CT perfusion (CTP) studies and clinical outcome data. Patient details were obtained from prospectively maintained stroke databases and the electronic medical record. Pre-thrombectomy CTA and CTP studies were reviewed and scored for tissue-level collaterals using the Hypoperfusion Intensity Ratio (HIR). HIR was defined as the volume ratio of brain tissue with [Tmax>10 sec/ Tmax>6 sec] such that a lower HIR correlates with favorable collaterals. HIR was automatically calculated by RAPID (iSchemaView). VMP was determined by opacification of the vein of Labbé, sphenoparietal sinus, and superficial middle cerebral vein on CTA as: 0, not visible; 1, moderate opacification; and 2, full. Primary outcome measure was VMP. Secondary outcome measure was ordinal modified Rankin Scale (mRS). Ordinal linear regression models were performed to predict the effect of HIR on VMP, as well as the effect of VMP on mRS.
Results 186 patients met inclusion criteria. HIR was dichotomized into lower (≤0.4, good collaterals) and higher (≥0.5, poor collaterals) ratios. Mann-Whitney-U test indicated that subjects with higher HIR (median COVES = 1) had lower VMP than patients with lower HIR (median COVES = 3) (p<0.001). In an ordinal logistic regression model, we tested the effects of VMP on mRS at 90 days after discharge while controlling for HIR (nondichotomized), age, and TICI score. High (favorable) VMP predicted lower (favorable) mRS (OR=0.544, [95% CI 0.4- 0.7]; p=0.032), which indicates that patients with robust VMP had better neurological outcomes 90 days after discharge.
Conclusion A robust cerebral venous microperfusion profile reflects greater tissue microperfusion, good arterial collateralization status and is associated with improved clinical outcome in patients with AIS.
Disclosures T. Faizy: None. R. Kabiri: None. M. Leipzig: None. S. Christensen: None. G. Broocks: None. F. Flottmann: None. M. Lansberg: None. G. Albers: None. J. Fiehler: None. M. Wintermark: None. J. Heit: None.
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