Diagnosis and Treatment of Acute Ischemic Stroke Guided by Stroke MRI

Kang, Dong Wha

Abstract

Multimodal stroke MRI including diffusion- and perfusion-weighted imaging has provided new insights into the diagnosis, mechanism and treatment of acute ischemic stroke. The concept of transient ischemic attack has been changed. New criteria of acute ischemic cerebrovascular syndrome based on MRI findings have been proposed. Various ischemic lesion patterns on diffusion-weighted imaging have a diagnostic value of stroke mechanism. Natural history studies have shown that acute ischemic stroke is a highly dynamic process. Silent recurrent ischemic lesions on MRI were frequent in the early post-stroke period and associated with subsequent clinical events. MRI markers of early blood-brain-barrier disruption predicted subsequent reperfusion, hemorrhagic transformation and poor clinical outcomes. Prospective studies showed that MRI can replace CT in the diagnosis of acute intracerebral hemorrhage, and MRI screening prior to thrombolytic therapy may be safe and feasible. Phase II clinical trials using MRI criteria showed that thrombolysis beyond 3 hours in patients with perfusion-diffusion mismatch may be safe and effective. MRI provides a tissue clock replacing the currently used time clock when deciding whether to initiate thrombolytic therapy. MRI is an established application in acute evaluation of stroke patients and will be a tool for selection criteria and surrogate endpoints in future clinical trials.