Use of Imaging to Select Patients for Late Window Endovascular Therapy

Gregory W. Albers, MD


Stroke. 2018;49(9):2256-2260. 

In This Article

Estimating the Ischemic Penumbra With CTP

Positron emission tomography scan and Xenon CBF studies, as well as clinical trials, have demonstrated that in acute stroke patients, the Tmax >6 seconds perfusion parameter can estimate tissue that is likely to be critically hypoperfused (CBF <20 mL/100 g per minute) and is at high risk for progressing to infarction if reperfusion is not obtained.[8–10] The mismatch between the Tmax >6 seconds volume and the ischemic core volume was used to estimate the volume of salvageable tissue in DEFUSE 3.

It is important to be aware that the Tmax maps are sensitive to delayed contrast arrival, and in some circumstances, delayed arrival does not imply critical hypoperfusion. For example, in a patient with a chronic carotid occlusion, Tmax delays may be present despite normal CBF, cerebral blood volume (CBV), and mean transit times.