Use of Imaging to Select Patients for Late Window Endovascular Therapy

Gregory W. Albers, MD


Stroke. 2018;49(9):2256-2260. 

In This Article

Technical Issues With CTP

To be confident about the accuracy of CTP volumes, it is important to have a technically adequate scan. CTP analysis programs typically require identification of the flow in a normal vessel that has early arrival of the contrast bolus (known as the arterial input function) and the flow through a venous sinus where the bolus departs the brain (known as the venous outflow function). The scan needs to be long enough in duration to capture the full arterial input waveform, as well as the venous output. In general, a scan time of 55 to 60 seconds is required to account for delayed and dispersed bolus arrival in patients with reduced cardiac output.[11]

Patient movement is the most common cause of CTP artifacts. Artifacts can be minimized by making sure that the patient is tightly secured in the scanner and is relatively calm at the time that perfusion imaging begins. An adequate contrast bolus, with a large bore IV, is also required.