Introduction With continued expansion in indications for endovascular thrombectomy (EVT), understanding the pathophysiology of reperfusion injury and hemorrhagic transformation (HT) becomes increasingly important. Pre-EVT infarct topography may have implications for treatment decisions acutely (such as stenting), and with post EVT care (such as antithrombotics and blood pressure goals). We sought to quantify region-specific volumes of infarcted tissue on MRI before EVT, understand their importance for reperfusion injury and HT, and identify associations with clinical and imaging characteristics.

Methods Patients were identified from a prospectively maintained database. Each patient’s diffusion weighted sequence underwent manual infarct delineation and was registered to a standard space for overlay with cortical, subcortical, and white matter atlases. HT was defined as ECASS PH1 or PH2. Variables with p<0.10 in univariate analyses were included in multivariable models.

Results 165 participants [median age 69 (IQR 56-79), 56% women] were identified. Intravenous alteplase was administered to 52%; 70% achieved TICI 2b-3 reperfusion. HT occurred in 8%. The distribution of pre-EVT infarcts was 48% (38-60%) white matter, 23% (6-47%) cortex, and 15% (4-28%) basal ganglia. Pre-EVT infarct volumes [median (IQR)] were 22 cc (12-43 cc) for total, 11 cc (6-19 cc) for white matter, 5 cc (1-19 cc) for cortex, and 3 cc (1-6 cc) for basal ganglia infarct. Paramagnetic sequences showed 3% had petechial hemorrhage and 40% had susceptibility vessel sign. Basal ganglia infarct volume was independently associated with HT (OR=1.342, 95%CI=1.002,1.797) in a model accounting for white matter infarct volume, cortex infarct volume, smoking, and puncture-to-recanalization time. Basal ganglia infarct volume was linked to susceptibility vessel sign (Beta=0.233, p=0.006) and NIHSS (Beta=0.220, p=0.012), when controlling for total infarct volume.

Conclusions Greater basal ganglia infarct volume was associated with a higher risk of HT when accounting for infarct volumes in other regions. Susceptibility vessel sign was associated with basal ganglia infarct volume, which may be related to acute middle cerebral artery perforator occlusion.

Disclosures R. Regenhardt: 1; C; National Institutes of Health, Society of Vascular and Interventional Neurology, Heitman Stroke Foundation. 6; C; DSMB for Rapid Medical. A. Bonkhoff: None. M. Schirmer: None. A. Das: None. A. Dmytriw: None. J. Vranic: None. R. Gupta: None. J. Hirsch: None. J. Rabinov: None. C. Stapleton: None. T. Leslie-Mazwi: None. A. Patel: 2; C; Penumbra, Microvention, Medtronic. N. Rost: None.