Intra-domain task-adaptive transfer learning to determine acute ischemic stroke onset time

•A novel intra-domain task-adaptive transfer learning approach for medical imaging datasets is described.•2D and 3D deep learning models were evaluated to classify acute ischemic stroke onset time.•The proposed models surpass state-of-the-art performance and apply to a broad population of patients.•Results support the value of imaging in determining the use of thrombolytic therapy in unwitnessed stroke.