Incidence of Unreliable Automated Computed Tomography Perfusion Maps

Despite the increasing national adoption of automated computed tomography perfusion (CTP) to select thrombectomy patients 6 hours after last known well, reliability issues have been anecdotally reported. Unreliable diagnostic tests add time and confusion to a process that requires efficiency. Our study aims to critically assess an automated CTP program in a contemporary cohort of patients presenting with large vessel occlusion (LVO) in the extended time window by evaluating the rate of unreliable automated CTP maps and whether this influences clinical outcomes.

A retrospective review of consecutive thrombectomy candidates undergoing CTP imaging in the extended time window was performed. All automated CTP maps using RAPID software (iSchemaView, Menlo Park, CA) were assessed for reliability. Clinical outcomes were compared between patients with and without reliable RAPID reports.

Ninety-nine consecutive thrombectomy candidates underwent automated CTP imaging from February 2017 to December 2018. Of these, 78 (79%) had LVO determined by CT angiographyand were included in the study population. Automated CTP maps were unreliable in 13% of cases as a result of motion artifact (n = 3) and contrast bolus flow issues (n = 7). Heart failure was more frequent in patients with unreliable studies. Clinical outcomes did not significantly differ between patients with and without unreliable studies.

Thirteen percent of CTP maps generated by automated software were unreliable, with an increased frequency among patients with heart failure. Given the rate of unreliable automated CTP maps, further studies are warranted to not only establish the true necessity of currently available CTP software, but also more reliable methods to select patients for thrombectomy presenting in the extended time window.