Dynamic perviousness is a novel imaging biomarker, with clot density measurements at multiple timepoints to allow longer contrast to thrombus interaction. We investigated the correlations between dynamic perviousness and clot composition in the setting of acute ischemic stroke. Thirty-nine patients with large vessel occlusion (LVO) undergoing mechanical thrombectomy (MT) were analyzed. Patients received a three-phase CT imaging pre-thrombectomy and histopathological analysis of retrieved clots. Clot densities for every phase and change in densities between phases were calculated, leading to four patterns of dynamic perviousness: no contrast uptake, early contrast uptake with and without washout and late uptake. Clots were categorized into three groups based on dominant histologic composition: red blood cell (RBC)-rich, fibrin/platelet-rich and mixed. Clot composition was correlated with dynamic perviousness using the Kruskal–Wallis test and Pearson’s correlation analysis. The dynamic perviousness categories showed a significant difference between fibrin-rich clots when compared to RBC-rich plus mixed groups. The uptake without washout category had significantly fewer fibrin clots compared to the uptake with washout (p = 0.036), and nearly significantly fewer fibrin clots when compared to the no uptake category (p = 0.057). Contrast uptake with different patterns of contrast washout showed significant differences of the likelihood for fibrin-rich clots.

Background: The predictive value of thrombus perviousness in acute ischemic stroke (AIS), as measured by computed tomography (CT), has been intensively studied with conflicting results. In this study, we investigate the predictive potential of the novel concept of dynamic perviousness using three-dimensional (3D) volumetric evaluation of occlusive thrombi. Methods: The full thrombus volume in 65 patients with a hyperdense artery sign on non-contrast CT (NCCT), who underwent mechanical thrombectomy (MT), was segmented. Perviousness maps were computed voxel-wise for the entire thrombus volume as thrombus attenuation increase (TAI) between NCCT and CT angiography (CTA) as well as between CTA and late venous phase CT (CTV). Perviousness was analyzed for its association with NIHSS at admission, Thrombolysis In Cerebral Infarction (TICI) score, and number of MT passes. Results: The mean late-uptake TAI of thrombi with NIHSS scores greater than 21 at admission was approximately 100% higher than for lower scored NIHSS (p between 0.05 and 0.005). Concerning revascularization results, thrombi requiring less than four MT passes had ca. 80% higher group mean late-uptake TAI than clots requiring four or more passes (p = 0.03), and thrombi with TICI score III had ca. 95% higher group mean late-uptake TAI than thrombi with TICI II (p = 0.03). Standard perviousness showed no significant correlation with MT results. Conclusion: Standard thrombus perviousness of 3D clot volume is not associated with revascularization results in AIS. In contrast, dynamic perviousness assessed with a voxel-wise characterization of 3D thrombi volume may be a better predictor of MT outcomes than standard perviousness.

Background: The predictive value of thrombus standard perviousness (SP) in acute ischemic stroke (AIS) for the technical success rates of mechanical thrombectomy (MT) or functional outcomes is not yet conclusive. We investigated the relationship between dynamic perviousness (DP) and revascularization results using time-dependent enhancement curve types determined with computed tomography (CT). Methods: A retrospective analysis of 137 AIS patients was performed. DP was calculated as the thrombus attenuation increase (TAI) using three time points and categorized into four groups: (1) no enhancement (CNE); (2) late enhancement (CLE); (3) early enhancement with washout (CW); (4) early enhancement without washout (CNW). Associations with the technical success rate and functional outcomes were assessed. Results: Late enhancement (CLE) had approximately two times higher odds for successful MT as compared to clots with other enhancement dynamics. The odds ratios (logistic regression model with CNW as the reference) for the TICI III scores were 4.04 (p = 0.067), 1.82 (p = 0.3), and 1.69 (p = 0.4) for CLE, CW, and CNE, respectively. The NIHSS scores at discharge and mRS scores at three months showed regression coefficients (linear regression model with CNW as reference) of −3.05 (p = 0.10), −1.17 (p = 0.51), and −1.24 (p = 0.47); and −1.30 (p = 0.097), −0.85 (p = 0.25), and −0.15 (p = 0.83) for CLE, CW, and CNE, respectively. Conclusions: Thrombi with late enhancement patterns showed a higher revascularization rate and better outcomes as compared to clots with early uptake or no washout.

Background: Computed tomography (CT) could be a suitable method for acute exclusion of left atrial appendage thrombus (LAAT) prior to cardioversion of atrial fibrillation (AF) and atrial flutter (AFL) at the emergency department. Our aim was to present our experiences with this modality in recent years. Methods: This registry-based observational study was performed at the Department of Emergency Medicine at the Medical University of Vienna, Austria. We studied all consecutive patients with AF and AFL who underwent CT between January 2012 and January 2023 to rule out LAAT before cardioversion to sinus rhythm was attempted. Follow-ups were conducted by telephone and electronic medical records. The main variables of interest were the rate of LAAT and ischemic stroke at follow-up. Results: A total of 234 patients (143 [61%] men; median age 68 years [IQR 57–76], median CHA₂DS₂-VASc 2 [IQR 1–4]) were analyzed. Follow-up was completed in 216 (92%) patients after a median of 506 (IQR 159–1391) days. LAAT was detected in eight patients (3%). A total of 163 patients (72%) in whom LAAT was excluded by CT were eventually successfully cardioverted to sinus rhythm. No adverse events occurred during their ED stay. All patients received anticoagulation according to the CHA₂DS₂-VASc risk stratification, and no patient had suffered an ischemic stroke at follow-up, resulting in an incidence risk of ischemic strokes of 0% (95% CI 0.0–1.2%). Conclusion: LAAT was rare in patients admitted to the ED with AF and AFL who underwent cardiac CT prior to attempted cardioversion. At follow-up, no patient had suffered an ischemic stroke. Prospective studies need to show whether this strategy is suitable for the acute treatment of symptomatic AF in the emergency setting.

Background: Acute ischemic stroke (AIS) is one of the leading causes of death in the industrialized world and causes a heavy personal and economic burden. Thrombus perviousness, measured with pre-interventional computed tomography (CT), is a relatively new imaging biomarker with the potential to estimate clinical outcome in AIS and optimize therapy. However, reported findings on the relationship between thrombus perviousness and clinical parameters in AIS are conflicting. In this study, we investigated the characteristics of the time-resolved contrast agent uptake in thrombi and the predictive potential for clinical outcomes. Methods: We analyzed 55 AIS patients who underwent pre-interventional CT perfusion and recanalization with mechanical thrombectomy. A thrombus with a visible hyperdense artery sign was segmented in 2D. Thrombus standard perviousness was measured as the mean thrombus attenuation increase (TAI) between CT angiography (CTA) and NCCT. For dynamic perviousness, the time-resolved contrast agent uptake curve (CAU) was derived from a 30-phase CT perfusion (CTP) measurement. The rise time (t_rise) and the TAI increase rate per second (∆d), as well as the time window for the 10th (tW₁₀), 20th (tW₂₀), and 30th (tW₃₀) percentiles of the CAU peak, were calculated. The standard and dynamic perviousness (t_rise, ∆d, tW₁₀, tW₂₀, and tW₃₀₎ were analyzed for their associations with clinical outcomes (3-month mRS) with the Wilcoxon signed rank test. Results: Dynamic perviousness was associated with the clinical outcome. The group mean t_rise and ∆d for thrombi with good clinical outcomes (mRS ≤ 2) were approximately 20% lower (p = 0.04) and 36% higher (p = 0.02) than those for thrombi with poor outcomes (mRS > 2). The time windows for the 10, 20, and 30% maximum contrast agent concentrations in the thrombus were approximately 40% (p = 0.004), 18% (p = 0.02) and 33% (p = 0.004) lower in thrombi with good outcomes than in thrombi with poor outcomes, respectively. Standard perviousness showed no association with clinical outcome. Conclusion: Dynamic perviousness from perfusion imaging retrieves the CAU characteristics of thrombi with greater resolution detail than standard perviousness. Thrombi with relatively fast contrast agent uptake dynamics are more prone to good clinical outcomes than thrombi with slow uptake dynamics.