Arterial Input Function Dispersal on Acute Brain CT Perfusion Scan in Patients With Acute Stroke and an Intracardiac Thrombus

Hyperacute cardiac CT has shown greater yield for intracardiac thrombus identification compared with transthoracic echocardiography. However, routine use comes with higher cost and additional contrast and radiation exposure. Pretest identification of patients with low probability of thrombus would enable rationalization of its use. Arterial input function (AIF) curves are generated automatically as part of brain perfusion CT. Time from scan onset to the end of AIF (AIF dispersal) is correlated with left ventricular ejection fraction. We hypothesized that there would be an association between AIF dispersal and (1) presence of intracardiac thrombus and (2) 3-month outcome after ischemic stroke/TIA. This is a retrospective analysis of prospectively collected patients with a final diagnosis of ischemic stroke or TIA presenting at 3 comprehensive stroke centers between September 2019 and August 2023. A total of 1,136 patients were included, and the median age was 74 years (interquartile range, IQR [62-81]). The median baseline National Institutes of Health Stroke Scale score was 6 (IQR [3-14]). Intracardiac thrombus was present in 59 patients (5.2%) on hyperacute cardiac CT. The median AIF dispersal was 27 (IQR [22-33]) seconds. Longer AIF dispersal duration was associated with presence of intracardiac thrombus, with an odds ratio (OR) of 1.09 (95% CI 1.05-1.13). AIF dispersal ≥33 seconds was the optimal cutoff point for presence of intracardiac thrombus with a positive association, with OR 6.66 (3.26-13.59). AIF dispersal as a continuous variable was associated with increased risk of poor outcome (modified Rankin Scale scores 5-6) 3 months after stroke in multivariate analysis (OR 1.03 [95% CI 1.00-1.05]). AIF dispersal ≥33 seconds was also associated with worse outcome after stroke in univariate analysis. Prolonged AIF dispersal identifies patients with stroke more likely to have (1) an intracardiac thrombus at the time of presentation and (2) poor outcome 3 months after stroke. These novel findings have significant clinical implications.