Clinical imaging factors of excellent outcome after thrombolysis in large-vessel stroke: a THRACE subgroup analysis

Imaging features of cardioembolic stroke on 4-dimensional computed tomography angiography

Background

Identifying cardioembolic stroke is important for the decision-making of endovascular treatment and anticoagulation therapy. We aimed to explore the features of cardioembolic stroke on 4-dimensional (4D) computed tomography angiography (4D-CTA) and assess whether these features can assist in classifying stroke etiology.

Methods

In this retrospective study, we analyzed the images of 294 patients with acute ischemic stroke (AIS) from July 2020 to February 2022 at the First Affiliated Hospital of Chongqing Medical University, which had been consecutively collected. The data of 110 patients with occlusion of the M1/M2 segment of the middle cerebral artery (MCA) with/without intracranial internal carotid artery (ICA) occlusion were analyzed to calculate the clot burden score (CBS) and collateral score (CS), and the data of 88 patients with a clear origin and distal part were analyzed to measure clot length. Maximum intensity projection (MIP) and time MIP (tMIP) post-processing were used to assess the clot features. The Mann-Whitney U test was used to compare the clot characteristics between the 2 groups. Binary logistic regression was performed to assess the association between the image characteristics and cardioembolic stroke. Moreover, the receiver operating characteristic (ROC) curve was used to test the diagnostic efficacy of MIP/tMIP clot features in classifying cardioembolic stroke.

Results

Age, high-risk factors for cerebrovascular disease, high/medium-risk sources of cardioembolic stroke, clot length, CBS, and CS were significantly different between the cardioembolic stroke group and non-cardioembolic stroke group (P<0.05). In the cardioembolic stroke group, the median MIP and tMIP clot length was 12 mm [interquartile range (IQR), 8.3-17.4 mm] and 9.3 mm (IQR, 6.8-14.3 mm), respectively. In the non-cardioembolic stroke group, the median MIP and tMIP clot length was 6.5 mm (IQR, 4.7-11.5 mm) and 5.8 mm (IQR, 3.9-10.6 mm), respectively. Binary logistic regression showed that cardioembolic stroke was significantly associated with MIP-clot length [odds ratio (OR), 1.15; 95% confidence interval (CI): 1.02-1.29; P<0.05], tMIP-clot length (OR, 1.18; 95% CI: 1.02-1.36; P<0.05), and tMIP-CBS (OR, 3.96; 95% CI: 1.08-14.58; P<0.05). The area under the ROC curve (AUC) values of MIP clot length for identifying cardioembolic stroke were 0.75 (95% CI: 0.65-0.84, P<0.05), with a cut-off value of >7.4 mm [sensitivity: 84.62% (95% CI: 69.50-94.10%); specificity: 59.18% (95% CI: 44.20-73.00%)]. The AUC value of tMIP clot length was 0.72 (95% CI: 0.61-0.81, P<0.05), with a cut-off value of >5.4 mm [sensitivity: 92.31% (95% CI: 79.10-98.40%); specificity: 48.98% (95% CI: 34.40-63.70%)].

Conclusions

Clot length and CBS were overestimated on MIP images. Among the clot characteristics, clot length could identify cardioembolic stroke.

Advances in Acute Ischemic Stroke Treatment: Current Status and Future Directions

The management of acute ischemic stroke has undergone a paradigm shift in the past decade. This has been spearheaded by the emergence of endovascular thrombectomy, along with advances in medical therapy, imaging, and other facets of stroke care. Herein, we present an updated review of the various stroke trials that have impacted and continue to transform stroke management. It is critical for the radiologist to stay abreast of the ongoing developments to provide meaningful input and remain a useful part of the stroke team.

Predictive value of ischemia location on multimodal CT in thrombectomy-treated patients

OBJECTIVE

Alberta Stroke Program Early CT Score (ASPECTS) applied to CT-perfusion (CTP) and CT-angiography-source-images (CTA-SI) may improve outcome prediction in large vessel occlusion (LVO) stroke if compared to non-contrast CT (NCCT) alone. Besides, ischemia location may have enhanced capabilities, compared to ischemia volume alone, in predicting stroke outcomes. We aim to evaluate the association between ischemia location as measured by ASPECTS regions in NCCT, CTP maps and CTA-SI and 3 months outcome in patients with LVO treated with mechanical thrombectomy (MT).

MATERIAL AND METHODS

Consecutive patients with anterior circulation stroke treated with MT were recorded in a prospectively maintained database at a single center. Modified Rankin scale (mRS) at 3 months >2 was considered a poor outcome. Association of patients' characteristics, NCCT, CTP, and CTA-SI parameters with outcome was evaluated using single-variable analysis and binary logistic regression multivariate analysis for each imaging technique.

RESULTS

177 patients were included. 115 (65%) patients reached a favorable outcome. The involvement of lenticular, caudate, M1, or M2 in all imaging techniques, insula in NCCT and CTA-SI and M5 in CBV maps and CTA-SI was related to functional outcome in bivariate analysis. However, in the multivariate analysis, none ischemia location was independently related to outcome, no matter the imaging technique studied. This finding remained unchanged when restricted to patients with good recanalization and when analyzing subpopulations according to hemisphere involvement or territories association.

CONCLUSIONS

Our study suggests ischemia location shouldn't be used solely for decision-making in LVO stroke patients. Its predictive value may be taken in consideration together with other clinical and radiological variables.

Factors That Influence Susceptibility Vessel Sign in Patients With Acute Stroke Referred for Mechanical Thrombectomy

Background and Purpose

The presence of a Susceptibility Vessel Sign (SVS) in the acute phase of proximal occlusion ischemic stroke indicates the presence of deoxyhemoglobin in the thrombus. Thrombi composition changes over time. The aim of this study was to investigate whether the absence of SVS is associated with a shorter symptom onset to imaging time.

Methods

We retrospectively analyzed all patients referred for mechanical thrombectomy at Besançon University Hospital between 1 January 2015 and 31 December 2020 for whom readable T2^*-weighted imaging was available. We compared patient characteristics according to the presence or absence of an SVS. We also studied the subgroup for whom the exact symptom onset time was known. We performed a univariate statistical analysis, then a multivariate analysis on the variables that were statistically significant in the univariate analysis.

Results

Of the 389 patients included, 309 (79.4%) were SVS+. We found no significant relationship between SVS– and the time between symptom onset and imaging in the whole cohort. In the multivariate analysis, SVS– was associated with anticoagulant treatment (p < 0.01), and SVS+ with age (p = 0.023) and carotid terminus occlusion (p = 0.042). In the known symptom onset subgroup, SVS– was significantly associated with a shorter symptom onset -imaging time (p < 0.001), and this was confirmed in the multivariate analysis (p = 0.011; OR 0.911; 95% CI [0.844; 0.972]).

Conclusion

In the acute phase of proximal occlusion ischemic stroke, absence of SVS was associated with a shorter symptom onset–imaging time for patients with a known symptom onset time.

Multimodality Characterization of the Clot in Acute Stroke

Aim: Current treatment of occluded cerebral vessels can be done by a variety of endovascular techniques. Sometimes, the clot responds in varying degrees to the treatment chosen. The Ex vivo characterization of the clot occluding the arteries in acute ischemic stroke can help in understanding the underlying imaging features obtained from pre-treatment brain scans. For this reason, we explored the potential of microCT when combined with electron microscopy for clot characterization. Results were compared to the clinical CT findings.

Methods: 16 patients (9 males, 8 females, age range 54–93 years) who were referred to our institution for acute stroke underwent dual-source CT.

Results: Clinical CT clots were seen as either iso or hyperdense. This was corroborated with micro-CT, and electron microscopy can show the detailed composition.

Conclusion: MicroCT values can be used as an indicator for red blood cells-rich composition of clots. Meaningful information regarding the clot composition and modalities of embedding along the stent retrievers can be obtained through a combination of microCT and electron microscopy.