Imaging-based selection of patients for acute stroke treatment

Historically, brain imaging in acute stroke has sought to exclude brain hemorrhage in order to allow therapy aiming at recanalization of the occluded intracranial artery. The National Institute of Neurological Disorders and Stroke study, published in 1995, found a clinical benefit of IV thrombolysis in acute stroke after exclusion of brain hemorrhage based on noncontrast CT (NCCT).¹ More than 20 years later, the decision at most centers whether to give thrombolysis within the first 4.5 hours remains based on NCCT; often, the bolus of recombinant tissue plasminogen activator (rt-PA) is administered in the CT scanner suite even before vascular and perfusion imaging is performed to avoid any delay. While acknowledging that time is brain, the experienced stroke neurologist often feels that a more precise selection of patients, at the time of the decision for acute revascularization therapy, would be clinically beneficial. The publication of trials demonstrating higher rates of functional independence at 3 months in 2 studies (SWIFT PRIME² and EXTEND-IA³) that required the demonstration of substantial ischemic penumbra for inclusion (60% and 71%, respectively) compared to those that did not (MR CLEAN, 33%⁴; REVASCAT, 44%⁵; and ESCAPE, 53%⁶) underscores the dilemma. Better selection can improve patient outcome and avoid futile and costly endovascular treatments.