Our the Often-neglected Vertebral Artery

tative marker of cerebral perfusion, since its variation is so small. In accordance with other technical approaches,8 we hypothesize that a delay of TPI forecasts hypoperfused and potentially still salvageable tissue, whereas regions without detectable perfusion kinetic forecasts ischemia, ie, the core of the infarction. As a cut-off for a significant TPI delay we determined the double of the maximum variation in the healthy cohort, ie, 4 seconds. These considerations were supported by preliminary cases of acute stroke patients examined by the same protocol,9 in one of which we could demonstrate a region without a perfusion kinetic (where eventually infarction occurred) and a region with a delayed perfusion kinetic, where eventually tissue stayed viable after clinically successful thrombolytic therapy (Figure). Thus, we propose that for future ultrasonic perfusion imaging protocols using the bolus-kinetic, the bilateral approach should be applied with settings optimized for a quantitative evaluation of the kinetic parameters in order to differentiate “penumbra” and core of infarction.