S100B and Stroke: In the present study, we collected blood samples 24 h after IVT from patients at 16 centers in northeast China to (a) test the serum S100β levels in patients 24 h after IVT; (b) explore the relationship between serum S100β levels and hemorrhagic transformation (HT); and (c) explore the association between serum S100β levels and final infarct volume, National Institutes of Health Stroke Scale (NIHSS), and modified Rankin Scale (mRS) at 90 days in these patients.