Impact of clinical and radiological factors on CT-Perfusion timing in acute ischemic stroke

Abstract

Background and purpose: To assess the impact of radiological and clinical variables on brain CT-perfusion (CTP) curves in patients with acute ischemic stroke.

Materials and methods: IRB-approved retrospective observational cohort study, need for informed consent was waived. We included 295 patients who underwent CTP for acute ischemic stroke in our Institution (Jan2020-Mar2024). Two radiologist evaluated arterial input function (AIF) and reference vessel (RefV) curves to assess bolus arrival delay and time to equilibrium; discrepancies were resolved by consensus. Additionally, they evaluated the unenhanced brain CTs acquired before CTP for the presence of microangiopathy (van Swieten scale) and intracranial arterial wall calcifications (yes/no). CT-Angiography was evaluated for the site of occlusion. Age, sex, arterial blood pressure, heart rate, presence of arrhythmias, and NIHSS were retrieved from an institutional database. A univariate analysis was performed to establish significant variables; variables with a P value <0.1 in the univariate analysis were subsequently included in a multivariate logistic regression model to adjust for potential confounding factors.

Results: Logistic regression identified cardiac arrhythmias and increasing age as independent predictors of non-diagnostic perfusion CT exams (p < 0.001). Other factors, including arterial calcifications, white-matter lesions, NIHSS score, and large vessel occlusion, were not significantly associated with non-diagnostic outcomes. Logistic regression analysis revealed that the arterial time-to-peak value was significantly associated with the presence of cardiac arrhythmias (p<0.0001), with higher time-to-peak values observed among patients with arrhythmias (24.0s; IQR 20.2 -27.1s) compared to those without (18.6s; IQR 15.5 -21.7s). Similarly, the venous time-to-peak was found to be longer in patients with cardiac arrhythmias (median 30.2s; IQR 26.4 -32.0s) compared to those without (25.6s; IQR 22.5 -28.7s), p<0.0001.

Conclusions: Our study showed that patients with cardiac arrhythmias need longer CTP acquisition times to avoid perfusion curve truncation and potentially non-diagnostic results. The knowledge of the impact of clinical variables on CTP may help better tailor the acquisition delays to improve diagnostic quality and avoid unnecessary radiation doses.

Abbreviations: AIS = acute ischemic stroke; AIF = arterial input function; RefV = reference vessel curve; LVO = Large Vessel Occlusion; IQR = interquartile range.