Impact of Clinical and Radiologic Factors on CTP Timing in Acute Ischemic Stroke

CT perfusion is widely used to assess infarct core and penumbra in acute stroke, but scan durations vary and may be affected by patient-specific delays in contrast arrival. Our purpose was assess the impact of radiologic and clinical variables on brain CTP curves in patients with acute ischemic stroke.

We included 295 patients who underwent CTP for acute ischemic stroke in our institution (January 2020 to March 2024). Two radiologists evaluated arterial input function and reference vessel 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). CTA 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 < .1 in the univariate analysis were subsequently included in a multivariate logistic regression model to adjust for potential confounding factors.

Logistic regression identified cardiac arrhythmias and increasing age as independent predictors of nondiagnostic perfusion CT examinations (P < .001). Other factors, including arterial calcifications, white matter lesions, NIHSS score, and large vessel occlusion, were not significantly associated with nondiagnostic outcomes. Logistic regression analysis revealed that the arterial time-to-peak value was significantly associated with the presence of cardiac arrhythmias (P < .0001), with higher time-to-peak values observed among patients with arrhythmias (24.0 seconds; interquartile range [IQR]: 20.2-27.1 seconds) compared with those without (18.6 seconds; IQR: 15.5-21.7 seconds). Similarly, the venous time-to-peak was found to be longer in patients with cardiac arrhythmias (median 30.2 seconds; IQR: 26.4-32.0 seconds) compared with those without (25.6 seconds; IQR: 22.5-28.7 seconds), P < .0001.

Our study showed that patients with cardiac arrhythmias need longer CTP acquisition times to avoid perfusion curve truncation and potentially nondiagnostic 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.