Influence of Onset to Imaging Time on Radiological Thrombus Characteristics in Acute Ischemic Stroke

Abstract

Introduction: Radiological thrombus characteristics are associated with patient outcomes and treatment success after acute ischemic stroke. These characteristics could be expected to undergo time-dependent changes due to factors influencing thrombus architecture like blood stasis, clot contraction, and natural thrombolysis. We investigated whether stroke onset-to-imaging time was associated with thrombus length, perviousness, and density in the MR CLEAN Registry population. Methods: We included 245 patients with M1-segment occlusions and thin-slice baseline CT imaging from the MR CLEAN Registry, a nation-wide multicenter registry of patients who underwent endovascular treatment for acute ischemic stroke within 6.5 h of onset in the Netherlands. We used multivariable linear regression to investigate the effect of stroke onset-to-imaging time (per 5 min) on thrombus length (in mm), perviousness and density (both in Hounsfield Units). In the first model, we adjusted for age, sex, intravenous thrombolysis, antiplatelet use, and history of atrial fibrillation. In a second model, we additionally adjusted for observed vs. non-observed stroke onset, CT-angiography collateral score, direct presentation at a thrombectomy-capable center vs. transfer, and stroke etiology. We performed exploratory subgroup analyses for intravenous thrombolysis administration, observed vs. non-observed stroke onset, direct presentation vs. transfer, and stroke etiology. Results: Median stroke onset-to-imaging time was 83 (interquartile range 53-141) min. Onset to imaging time was not associated with thrombus length nor perviousness (β 0.002; 95% CI -0.004 to 0.007 and β -0.002; 95% CI -0.015 to 0.011 per 5 min, respectively) and was weakly associated with thrombus density in the fully adjusted model (adjusted β 0.100; 95% CI 0.005-0.196 HU per 5 min). The subgroup analyses showed no heterogeneity of these findings in any of the subgroups, except for a significantly positive relation between onset-to-imaging time and thrombus density in patients transferred from a primary stroke center (adjusted β 0.18; 95% CI 0.022-0.35). Conclusion: In our population of acute ischemic stroke patients, we found no clear association between onset-to-imaging time and radiological thrombus characteristics. This suggests that elapsed time from stroke onset plays a limited role in the interpretation of radiological thrombus characteristics and their effect on treatment results, at least in the early time window.

Keywords: acute ischemic stroke; computed tomography; endovascular treatment; ischemic stroke; radiological thrombus characteristics; thrombus density; thrombus length; thrombus perviousness.

Figure 1

Scatter and box plots of image characteristics. (A) Time from symptom onset to imaging distribution, (B) thrombus length histogram, (C) thrombus perviousness histogram, (D) thrombus density histogram, (E) onset to imaging time vs. thrombus length, (F) onset to imaging time vs. perviousness, (G) onset to imaging time vs. non-contrast CT density. HU, Hounsfield Units; mm, millimeter.