Tmax Mismatch Ratio to Identify Intracranial Atherosclerotic Stenosis-Related Large-Vessel Occlusion Before Endovascular Therapy

Predictors for recurrent ischemic stroke in patients with watershed infarct induced by intracranial artery stenosis

BACKGROUND AND PURPOSE

Symptomatic intracranial artery stenosis (sICAS) is strongly associated with an elevated risk of recurrent ischemic stroke, yet the underlying risk factors remain elusive. In this present study, we aimed to investigate the risk factors and predictive value of imaging features for recurrent ischemic stroke in patients with watershed infarction caused by ICAS.

METHODS

We prospectively collected clinical information and imaging data from patients with watershed infarction caused by ICAS. The primary outcome was recurrent ischemic cerebrovascular events in the same territory within 1 year. The original magnetic resonance images (MRI) were post-processed by the Fast-processing of ischemic stroke (F-Stroke) software to compute the perfusion parameters. The assessment of white matter hyperintensity (WMH) was performed in accordance with the Fazekas scale. Binary logistic regression analysis was performed to explore the association of imaging characteristics and recurrent ischemic stroke. Subsequently, we performed ROC curve analyses to determine their discriminatory capacity for ischemic stroke recurrence.

RESULTS

A total of 139 patients were successfully enrolled in the present study. The recurrence rate in the total population was 18.71 %. Compared with patients without recurrent ischemic stroke, those who experienced recurrence had a higher proportion of prior ischemic stroke history (25.66 % vs. 53.85 %) and severe WMH (30.77 % vs. 7.97 %), as well as higher baseline NIHSS scores and volume of Tmax > 4 s. Logistic regression analysis revealed that both the volume of Tmax > 4 s and severe WMH significantly influenced the risk of recurrent ischemic stroke occurrence. Furthermore, ROC curve analyses demonstrated that the discriminatory capacity of the volume of Tmax > 4 s (AUC = 0.64, 95 %CI = 0.51-0.77, P = 0.029) was marginally superior to WMH scores (AUC = 0.62, 95 %CI = 0.49-0.75, P = 0.066). Whereas, the combination of the volume of Tmax > 4 s and the WMH scores showed better discriminatory capacity (AUC = 0.73, 95 %CI = 0.61-0.85, P < 0.001).

CONCLUSION

MR-guiding cerebral hypoperfusion and severe WMH is susceptible to recurrence of ischemic stroke, thereby serving as valuable predictors for recurrence in patients with watershed infarction caused by ICAS.

Diagnostic value of the perfusion mismatch ratio in identifying intracranial atherosclerotic disease related occlusion

BACKGROUND

The ability to differentiate intracranial atherosclerotic disease (ICAD) related large vessel occlusion (LVO) from embolism is critical for stroke management. We hypothesized that the mismatch ratio derived from the automated computed tomography perfusion (CTP) could predict underlying ICAD.

METHODS

Patients with acute ischemic stroke (AIS) and LVO from prospective registry databases who underwent CTP were included in the derivation cohort (n=1100). The mismatch ratio, calculated as the ratio of the hypo-perfused volume to the infarct core volume by software, was defined. Receiver Operating Characteristic (ROC) analysis was performed to assess the predictive performance of the mismatch ratio for ICAD, and logistic regression analysis was used to identify independent predictors of LVO associated with underlying ICAD. External validation was conducted using cohorts from two other stroke centers (n=385).

RESULTS

In the derivation cohort, 390 patients were classified as ICAD and 720 as embolism. The ICAD group had a higher mismatch ratio (9.8 vs 3.6, P<0.001). The mismatch ratio outperformed age and National Institutes of Health Stroke Scale (NIHSS) score in predicting ICAD (area under the curve (AUC), 0.77 vs 0.36 vs 0.28, P<0.001). The ROC curve had a best cut-off of 7.1 for predicting ICAD, which was an independent predictor of ICAD-related occlusion (adjusted odds ratio (aOR) 5.43, 95% CI 3.68 to 8.03), with 68% sensitivity and 76% specificity. These results were validated in an external cohort (AUC=0.78; 95% CI, 0.73 to 0.83).

CONCLUSION

The perfusion mismatch ratio may be an optimal and simple predictor of anterior circulation ICAD- related LVO before endovascular treatment (EVT). When this ratio was ≥7.1, ICAD was five times more likely than embolism.

Acute Ischemic Stroke: Significance of Multimodal Pre-operative Prediction of Intracranial Atherosclerosis-Related Large Vessel Occlusion

When large-vessel occlusion (LVO) occurs in acute ischemic stroke, accurate differentiation of intracranial atherosclerosis-related occlusion (ICAD-O) from embolism-related occlusion (EMB-O) is critical for guiding treatment decisions. This review focuses on the preoperative prediction of ICAD-O and emphasizes the practical clinical and imaging factors. ICAD-O is often associated with younger age, male sex, and vascular risk factors, such as hypertension and diabetes, and the absence of atrial fibrillation is a key characteristic of its differentiation. Imaging findings, including truncal-type occlusion and non-culprit stenosis, further aid in the identification of ICAD-O. Predictive scales integrating clinical and imaging data, such as the ISAT, REMIT, ABC2D, and ATHE scores, provide structured approaches for distinguishing ICAD-O from EMB-O. By reviewing these predictive tools and findings, this review aims to enhance the accuracy and efficiency of the preoperative diagnosis, supporting better-informed clinical decision-making for stroke patients with LVO.

CTP-defined collaterals is a better predictor of intracranial atherosclerotic stenosis-related large-vessel occlusion than multiphase CTA-defined collaterals

The optimal neuroimaging modalities for differentiating intracranial atherosclerotic stenosis-related large vessel occlusion (ICAS-LVO) from embolism related LVO remain uncertain. This study aimed to address this question by directly comparing collateral circulation using either baseline CT perfusion (CTP) or multiphase CT angiogram (mCTA) to define collaterals. We retrospectively analyzed consecutive patients with acute large vessel occlusion from October 2021 to December 2023. All patients underwent CTP before endovascular therapy, and mCTA was reconstructed from CTP data. In-situ ICAS-LVO was confirmed by a neuro-interventional radiologist. Favorable collateral circulation was defined as a collateral index <0.4 on CTP or a collateral score ≥3 on mCTA. Of 377 patients, 72 (19%) had ICAS-LVO. Patients with only a collateral score ≥3 did not show significantly higher odds of ICAS-LVO (P = 0.681). In contrast, those with a collateral index <0.4 but not favorable mCTA collateral had higher odds of ICAS-LVO (OR2.69, 95%CI [1.07-7.01], P = 0.037). Subgroup analysis showed that a collateral grading scale ≥3 may not predict ICAS-LVO within 6 hours, whereas CTP's predictive performance remained consistently strong in both early and late windows. CTP defined favorable collaterals of collateral index <0.4 demonstrate greater predictive value for ICAS-LVO compared to mCTA, especially within an early time window.

Intensive blood pressure lowering in acute stroke with intracranial stenosis post-thrombectomy: A secondary analysis of the OPTIMAL-BP trial

BACKGROUND

Intensive blood pressure (BP) management within 24 h after successful reperfusion following endovascular thrombectomy (EVT) is associated with worse functional outcomes than conventional BP management in Asian randomized controlled trials. Given the high prevalence of intracranial atherosclerotic stenosis (ICAS) in Asia, ICAS may influence these outcomes.

AIMS

We aimed to assess whether ICAS affects the outcomes of intensive BP management after successful EVT.

METHODS

We conducted a secondary analysis of the Outcome in Patients Treated With Intra-Arterial Thrombectomy-Optimal Blood Pressure Control trial, which enrolled participants from June 2020 to November 2022. Patients with anterior circulation large vessel occlusion (LVO) were stratified into ICAS-related and embolic LVO groups. Clinical outcomes for intensive (target systolic BP < 140 mm Hg) and conventional BP management (target systolic BP = 140-180 mm Hg) were analyzed in each group. The primary outcome was a favorable outcome, defined as a modified Rankin Scale score of 0 to 2 at 3 months. Safety outcomes included symptomatic intracerebral hemorrhage within 36 h and stroke-related death within 3 months.

RESULTS

Among 192 patients, 59 were in the ICAS-related LVO group, and 133 were in the embolic LVO group. In the ICAS-related LVO group, the rate of achieving a favorable outcome at 3 months was 37.5% with intensive BP management and 55.6% with conventional management (adjusted odds ratio (OR) = 0.49 (95% confidence interval (CI) = 0.14 to 1.75); P = 0.27). In the embolic LVO group, these rates were 29.9% and 42.4%, respectively (adjusted OR = 0.64 (95% CI = 0.28 to 1.45); P = 0.29). No significant interaction was found (P for interaction = 0.68). In addition, the ICAS-related LVO group receiving intensive BP management had lower rates of successful reperfusion at 24 h compared to conventional management (67.7% vs. 91.7%; P = 0.03), while no significant difference was found in the embolic LVO group. A significant interaction effect on successful reperfusion at 24 h was observed between ICAS-related and embolic LVO groups (P for interaction = 0.04). No significant differences in safety outcomes were observed between intensive BP management and conventional management within both ICAS-related LVO and embolic LVO groups.

CONCLUSIONS

ICAS did not significantly affect outcomes of intensive BP management within 24 h after successful EVT. After successful reperfusion by EVT, intensive BP management should be avoided regardless of ICAS presence.

DATA ACCESS STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Multiphase CTA Collateral Score to Identify Intracranial Atherosclerotic Stenosis-Related Large Vessel Occlusion

OBJECTIVE

Identification of acute ischemic stroke with large vessel occlusion (AIS-LVO) etiology is crucial for effective revascularization therapy. As collaterals are pivotal in maintaining cerebral perfusion in intracranial atherosclerotic stenosis (ICAS), we investigated whether multiphase CT angiography (mCTA) collateral score can be a diagnosis marker of ICAS-related LVO.

METHODS

We reviewed clinical and imaging data from 92 patients who presented with AIS-LVO and underwent mCTA (57 ICAS-related LVO and 35 embolic LVO). Logistic regression was used to identify ICAS-related LVO. The diagnostic accuracy of the mCTA collateral score for identifying ICAS-related LVO was determined using receiver operating characteristic (ROC) analysis.

RESULTS

Compared with patients with embolic LVO, those with ICAS-related LVO had a high median mCTA collateral score (4 vs. 3; P<0.0001). The multinomial logistic regression analysis revealed a significant increase in the mCTA collateral score (OR: 3.717, 95% CI: 2.009-6.876, P<0.0001) in patients with ICAS-related LVO. ROC analysis revealed that the optimal cutoff point of the mCTA collateral score to diagnosis the ICAS-related LVO was 3.5, the area under the curve (AUC) was 0.817 (95% CI: 0.736-0.899; P<0.0001), sensitivity was 80.7%, and specificity was 74.3%. Further analysis revealed that patients with a 4 to 5 mCTA collateral score exhibited a significantly higher median modified Rankin Scale (mRS) at discharge compared with those with a 0 to 3 score (P=0.0464).

CONCLUSIONS

The mCTA collateral score may be associated with ICAS-related LVO and could be beneficial in identifying the etiology of AIS-LVO.

Clinical and perfusion imaging characteristics of acute large vessel occlusion in intracranial atherosclerosis

OBJECTIVES

This study aimed to compare clinical and perfusion imaging profiles in acute ischemic stroke with large vessel occlusion (AIS-LVO) between patients with intracranial atherosclerotic disease (ICAD) and non-ICAD who underwent endovascular treatment (EVT).

METHODS

Data from AIS-LVO patients over the anterior circulation undergoing EVT across two stroke centers were retrospectively analyzed. Clinical profiles and perfusion parameters from automated processing of perfusion imaging were compared between ICAD and non-ICAD groups. Ischemic core was defined as relative cerebral blood flow < 30 % on CT perfusion or apparent diffusion coefficient ≤ 620 × 10-6 mm2/s on MR diffusion weighted imaging.

RESULTS

A total of 111 patients were included (46 ICAD, 65 non-ICAD). The ICAD group exhibited a higher male proportion (60.9 % vs. 35.4 %), more M1 segment occlusions (78.3 % vs. 56.9 %), lower atrial fibrillation rates (17.4 % vs. 63.1 %), and lower baseline NIH Stroke Scale (NIHSS) scores (median [IQR]: 13 [8.75-18] vs. 15 [10-21]) at presentation compared to non-ICAD (all p < 0.05). However, there was no difference in NIHSS scores at discharge or in good functional outcomes (modified Rankin Scale 0-2) at 3 months between the two groups. ICAD patients also had smaller median ischemic core volumes (0 [IQR 0-9.7] vs. 4.4 [0-21.6] ml, p = 0.038), smaller median Tmax >6s tissue volulmes (89.3 [IQR 51.1-147.1] vs. 124.4 [80.5-178.6] ml, p = 0.017) and lower median HIR (hypoperfusion intensity ratio defined as Tmax >10s divided by Tmax >6s; 0.28 [IQR 0.09-0.42] vs. 0.44 [0.24-0.60], p = 0.003). Higher baseline NIHSS scores correlated with larger Tmax >6s lesion volumes as well as higher HIR value in non-ICAD patients, but not in ICAD patients.

CONCLUSIONS

In anterior circulation of AIS-LVO, ICAD patients exhibited distinct clinical presentations and perfusion imaging characteristics when compared to non-ICAD patients. Perfusion imaging profiles may serve as indicators for identifying ICAD patients before EVT.

Patchy profile sign in RAPID software: a specific marker for intracranial atherosclerotic stenosis in acute ischemic stroke

Purpose

Identifying the etiology of acute ischemic stroke (AIS) before endovascular treatment (EVT) is important but challenging. In CT perfusion imaging processed by perfusion software, we observed a phenomenon called patchy profile sign (PPS), that is, the hypoperfusion morphology in RAPID software is a discontinuous sheet pattern. This phenomenon is predominantly observed in patients diagnosed with intracranial atherosclerotic stenosis (ICAS). The study intends to assess whether the PPS can be used to differentiate ICAS from intracranial embolism.

Method

Patients with AIS due to M1 segment occlusion of the MCA who underwent mechanical thrombectomy were retrospectively enrolled. The receiver operating characteristic (ROC) curve analysis was performed to assess the value of PPS in predicting ICAS. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the PPS for prediction of ICAS were calculated.

Results

A total of 51 patients were included in the study. The PPS was observed in 10 of 19 (52.6%) patients with ICAS, and in 2 of 32 (6.3%) patients with intracranial embolism (p < 0.001). Interobserver agreement for identifying PPS was excellent (κ = 0.944). The sensitivity, specificity, PPV, NPV, and accuracy of the PPS for predicting ICAS were 52.6, 93.8, 83.3, 76.9, and 78.4%, respectively.

Conclusion

The PPS on RAPID software is an imaging marker with high specificity for ICAS. Larger sample sizes are imperative to validate the findings.

Clinico-radiological features of intracranial atherosclerosis-related large vessel occlusion prior to endovascular treatment

The identification of large vessel occlusion with underlying intracranial atherosclerotic disease (ICAS-LVO) before endovascular treatment (EVT) continues to be a challenge. We aimed to analyze baseline clinical-radiological features associated with ICAS-LVO that could lead to a prompt identification. We performed a retrospective cross-sectional study of consecutive patients with stroke treated with EVT from January 2020 to April 2022. We included anterior LVO involving intracranial internal carotid artery and middle cerebral artery. We analyzed baseline clinical and radiological variables associated with ICAS-LVO and evaluated the diagnostic value of a multivariate logistic regression model to identify ICAS-LVO before EVT. ICAS-LVO was defined as presence of angiographic residual stenosis or a trend to re-occlusion during EVT procedure. A total of 338 patients were included in the study. Of them, 28 patients (8.3%) presented with ICAS-LVO. After adjusting for confounders, absence of atrial fibrillation (OR 9.33, 95% CI 1.11-78.42; p = 0.040), lower hypoperfusion intensity ratio (HIR [Tmax > 10 s/Tmax > 6 s ratio], (OR 0.69, 95% CI 0.50-0.95; p = 0.025), symptomatic intracranial artery calcification (IAC, OR .15, 95% CI 1.64-26.42, p = 0.006), a more proximal occlusion (ICA, MCA-M1: OR 4.00, 95% CI 1.23-13.03; p = 0.021), and smoking (OR 2.91, 95% CI 1.08-7.90; p = 0.035) were associated with ICAS-LVO. The clinico-radiological model showed an overall well capability to identify ICAS-LVO (AUC = 0.88, 95% CI 0.83-0.94; p < 0.001). In conclusion, a combination of clinical and radiological features available before EVT can help to identify an ICAS-LVO. This approach could be useful to perform a rapid assessment of underlying etiology and suggest specific pathophysiology-based measures. Prospective studies are needed to validate these findings in other populations.

Emergent Large Vessel Occlusion due to Intracranial Stenosis: Identification, Management, Challenges, and Future Directions

This comprehensive literature review focuses on acute stroke related to intracranial atherosclerotic stenosis (ICAS), with an emphasis on ICAS-large vessel occlusion. ICAS is the leading cause of stroke globally, with high recurrence risk, especially in Asian, Black, and Hispanic populations. Various risk factors, including hypertension, diabetes, hyperlipidemia, smoking, and advanced age lead to ICAS, which in turn results in stroke through different mechanisms. Recurrent stroke risk in patients with ICAS with hemodynamic failure is particularly high, even with aggressive medical management. Developments in advanced imaging have improved our understanding of ICAS and ability to identify high-risk patients who could benefit from intervention. Herein, we focus on current management strategies for ICAS-large vessel occlusion discussed, including the use of perfusion imaging, endovascular therapy, and stenting. In addition, we focus on strategies that aim at identifying subjects at higher risk for early recurrent risk who could benefit from early endovascular intervention The review underscores the need for further research to optimize ICAS-large vessel occlusion treatment strategies, a traditionally understudied topic.