BEFAST FAST acute ischemic stroke alteplase artificial intelligence cardiovascular disease collateral status computed tomography scan decision-making diabetes mellitus diagnosis early neurological deterioration early neurological improvement exercise therapy gait high-density lipoprotein cholesterol hybrid assistive limb (HAL) imaging biomarkers intravenous thrombolysis ischaemic stroke ischemic stroke late arrival low-density lipoprotein cholesterol mechanical thrombectomy medical therapy neurosurgery outcome perfusion imaging peripheral artery disease physical therapy