Abstract WP65: Relationships Between Brain Perfusion and Early Recanalization After Intravenous Thrombolysis for Acute Stroke With Large Vessel Occlusion

Introduction: In large vessel occlusion (LVO) stroke, it is unclear whether severity of ischemia is involved in early post-intravenous thrombolysis (IVT) recanalization over and above thrombus site and length. Here we assessed the relationships between perfusion parameters and early recanalization following IVT administration in LVO patients. Methods: From a multicentre registry, 218 thrombolysed LVO patients referred for thrombectomy since May 2015 with both i) pre-IVT MRI, including diffusion-weighted imaging (DWI), T2* imaging, MR-angiography and dynamic susceptibility-contrast perfusion-weighted imaging (PWI); and ii) recanalization evaluated on first angiographic run or non-invasive imaging ≤3hrs from IVT start, were identified. Infarct core volume on DWI, PWI-DWI mismatch volume and Hypoperfusion Intensity Ratio (HIR; defined as the proportion of Tmax>6s volume with Tmax>10sec), a validated index of hypoperfusion severity, were determined using commercially available software. Results: Early recanalization occurred in 34 (16%) patients, and was independently associated with lower HIR ( P =0.006), shorter thrombus on T2* imaging ( P <0.001) and more distal occlusion ( P= 0.006). DWI lesion volume and PWI-DWI mismatch volume both had significant univariable association with recanalization but were not retained in the multivariable model. In addition, there was a significant interaction between thrombus length and HIR such that the effect of lower HIR on recanalization was stronger for smaller thrombi. Conclusion: This study disclosed a novel, independent association between milder hypoperfusion severity, as assessed by the HIR, and early post-IVT recanalization. Perfusion imaging may help to identify LVO patients most likely to benefit from IVT before thrombectomy.