Clinical implications of CT hyperdense artery sign in patients with acute middle cerebral artery occlusion in the era of modern mechanical thrombectomy

External validation of different predictive scores for symptomatic intracranial hemorrhage after intravenous thrombolysis in Asian stroke patients

OBJECTIVE

This study aimed to externally validate different predictive scores for symptomatic intracranial hemorrhage (SICH) after intravenous thrombolysis (IVT), with a particular focus on their predictive abilities in Asian stroke patients.

METHODS

We retrospectively enrolled stroke patients who received a standard dose of alteplase within 4.5 hours from symptom onset at the First Affiliated Hospital of Dalian Medical University from July 2010 to August 2023. SICH was defined as the hemorrhagic transformation detected on the head CT scan completed within 48 h post-IVT, accompanied by a clinical deterioration of at least a 4-point increase in NIHSS score. Predictive abilities of the HAT, MSS, SEDAN, SPAN-100, and GRASPS scores were tested. Discrimination and calibration were performed using the area under the receiver operating characteristic curve (ROC-AUC), DeLong test, and Hosmer-Lemeshow (H-L) goodness-of-fit test.

RESULTS

The study included 1007 stroke patients, of whom 31 (3.08 %) developed SICH. ROC-AUCs for predicting SICH were: 0.796 (95 %CI: 0.726-0.866) for the GRASPS score, 0.724 (95 %CI: 0.644-0.804) for the MSS score, 0.715 (95 %CI: 0.619-0.811) for the SEDAN score, 0.714 (95 %CI: 0.611-0.817) for the HAT score, and 0.605 (95 %CI: 0.491-0.720) for the SPAN-100 score (all P < 0.05). DeLong tests showed that the GRASPS score demonstrated significantly better discrimination than the MSS score (P = 0.010), the SEDAN score (P = 0.009), the HAT score (P = 0.049), and the SPAN-100 score (P = 0.000). H-L tests indicated good calibrations which were ranked HAT > SEDAN > MSS > SPAN-100 > GRASPS scores.

CONCLUSION

The GRASPS score showed reasonable predictive ability for SICH, indicating its potential utility for Asian stroke patients receiving IVT.

Outcomes of mechanical thrombectomy in M1 occlusion patients with or without hyperdense middle cerebral artery sign: A systematic review and meta-analysis

BACKGROUND

The comparison of mechanical thrombectomy (MT) outcomes between patients with the hyperdense middle cerebral artery sign (HMCAS) and non-HMCAS is important to evaluate the impact of this radiological finding on treatment efficacy. This meta-analysis aimed to assess the association between HMCAS and clinical outcomes in patients undergoing thrombectomy, comparing the outcomes over non-HMCAS.

METHODS

A systematic literature search was conducted in PubMed, Ovid Embase, Google Scholar, and Cochrane Library to identify studies on MT outcomes for M1 occlusions of HMCAS over non-HMCAS. Inclusion criteria encompassed modified Rankin Scale (mRS) score, mortality, symptomatic intracranial hemorrhage (sICH), and successful recanalization. Using R software version 4.1.2, we calculated pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CI).

RESULTS

The meta-analysis was performed for 5 studies with 724 patients. There was no association found between presence of HMCAS and achieving mRS 0-2 (OR = 0.65, 95% CI: 0.29-1.47; p = .544). Mortality analysis also showed no significant association with presence of HMCAS (OR = 0.78, 95% CI: 0.37-1.65; p = .520). No significant difference in sICH risk (OR = 1.54, 95% CI: 0.24-9.66; p = .646) was found between groups. Recanalization analysis showed a non-significant positive association (OR = 1.23, 95% CI: 0.67-2.28; p = .501). Heterogeneity was observed in all analyses.

CONCLUSION

Our findings showed that there is no statistically significant difference in mRS scores, mortality, sICH, and recanalization success rates between the HMCAS and non-HMCAS groups.

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.

Hyperdense sign as a predictor for successful recanalization and clinical outcome in acute ischemic stroke: A systematic review and meta-analysis

OBJECTIVE

To assess the prognostic values of hyperdense sign on pretreatment non-contrast head CT scan for successful recanalization (mTICI ≥2b) and 90-day good functional outcome (mRs 0-2) in patients with acute ischemic stroke undergoing mechanical thrombectomy (MT).

METHODS

Literature search on PubMed, EMBASE, and Cochrane databases from inception up to 1 November 2023 was conducted. Twelve studies which reported hyperdense sign, recanalization and clinical outcomes were included in qualitative synthesis and meta-analysis.

RESULTS

Pooled analysis demonstrated a statistically significant association between successful recanalization and hyperdense sign-positive patients who underwent MT (odd ratios (OR) = 1.47, 95% confidence interval (CI) = 1.03-2.10, p = 0.04). No statistically significant association was demonstrated between presence of hyperdense sign and good functional outcome (OR = 1.04, 95% CI: 0.72-1.49, p = 0.85) or symptomatic intracranial hemorrhage sICH (OR: 1.80, 95% CI 0.72-4.47, p = 0.21).

CONCLUSIONS

This meta-analysis demonstrated that pre-intervention hyperdense sign on CT imaging might be useful in prediction of successful recanalization after MT.

What is a Challenging Clot? : A DELPHI Consensus Statement from the CLOTS 7.0 Summit

BACKGROUND

Predicting a challenging clot when performing mechanical thrombectomy in acute stroke can be difficult. One reason for this difficulty is a lack of agreement on how to precisely define these clots. We explored the opinions of stroke thrombectomy and clot research experts regarding challenging clots, defined as difficult to recanalize clots by endovascular approaches, and clot/patient features that may be indicative of such clots.

METHODS

A modified DELPHI technique was used before and during the CLOTS 7.0 Summit, which included experts in thrombectomy and clot research from different specialties. The first round included open-ended questions and the second and final rounds each consisted of 30 closed-ended questions, 29 on various clinical and clot features, and 1 on number of passes before switching techniques. Consensus was defined as agreement ≥ 50%. Features with consensus and rated ≥ 3 out of 4 on the certainty scale were included in the definition of a challenging clot.

RESULTS

Three DELPHI rounds were performed. Panelists achieved consensus on 16/30 questions, of which 8 were rated 3 or 4 on the certainty scale, namely white-colored clots (mean certainty score 3.1), calcified clots under histology (3.7) and imaging (3.7), stiff clots (3.0), sticky/adherent clots (3.1), hard clots (3.1), difficult to pass clots (3.1) and clots that are resistant to pulling (3.0). Most panelists considered switching endovascular treatment (EVT) techniques after 2-3 unsuccessful attempts.

CONCLUSION

This DELPHI consensus identified 8 distinct features of a challenging clot. The varying degree of certainty amongst the panelists emphasizes the need for more pragmatic studies to enable accurate a priori identification of such occlusions prior to EVT.

Key CT markers for predicting haemorrhagic transformation after ischaemic stroke: a prospective cohort study in China

OBJECTIVES

Limited studies have systematically addressed the CT markers of predicting haemorrhagic transformation (HT). We aimed to (1) investigate the predictive ability of the imaging factors on multimodal CT for HT and (2) identify the key CT markers that can accurately predict HT while maintaining easy and rapid assessment in the early stage of stroke.

DESIGN AND SETTING

This was a prospective cohort study conducted in a tertiary hospital in Southwest China.

PARTICIPANTS

Patients with ischaemic stroke admitted within 24 hours after onset were included.

OUTCOME MEASURES

The primary outcome was measured as the overall HT. The secondary outcomes were the presence of parenchymal haematoma, symptomatic HT and spontaneous HT.

RESULTS

A total of 763 patients were included. The early hypodensity >1/3 of the middle cerebral artery (MCA) territory, Alberta Stroke Programme Early CT Score≤7, midline shift, hyperdense middle cerebral artery sign (HMCAS), poor collateral circulation, infarct core and penumbra was independently associated with the increased risk of HT (all p < 0.05). The sensitivity of midline shift for predicting HT was only 3.5%, whereas its specificity was 99.8%. The combination of the early hypodensity >1/3 of the MCA territory, midline shift and HMCAS showed a good predictive performance for HT (area under the curve 0.80, 95% CI 0.75 to 0.84).

CONCLUSIONS

Seven imaging factors on multimodal CT were independently associated with HT. The high specificity of midline shift suggests the need to consider it as an imaging indicator when assessing the risk of HT. The early hypodensity >1/3 of the MCA territory, midline shift and HMCAS was identified as the key CT markers for the early prediction of HT. The coexistence of the three key factors might be a valuable index for identifying individuals at high bleeding risk and guiding further treatments.

The risk and outcome of malignant brain edema in post-mechanical thrombectomy: acute ischemic stroke by anterior circulation occlusion

BACKGROUND AND PURPOSE

Malignant brain edema (MBE) occurring after mechanical thrombectomy (MT) in acute ischemic stroke (AIS) could lead to severe disability and mortality. We aimed to investigate the incidence, predictors, and clinical outcomes of MBE in patients with AIS after MT.

METHODS

The clinical and imaging data of 155 patients with AIS of anterior circulation after MT were studied. Standard non-contrast CT was used to evaluate baseline imaging characteristics at admission. Clinical outcomes were measured using the 90-day modified Rankin Scale (mRS) score. Based on the follow-up CT scans performed within 72 h after MT, the patients were classified into MBE and non-MBE group. MBE was defined as a midline shift of ≥ 5 mm with signs of local brain swelling. Univariate and multivariate regression analyses were used to analyze the relationship between MBE and clinical outcomes and identify the predictors that correlate with MBE.

RESULTS

MBE was observed in 19.4% of the patients who underwent MT and was associated with a lower rate of favorable 90-day clinical outcomes. Significant differences were observed in both MBE and non-MBE groups: baseline Alberta Stroke Program Early CT (ASPECT) score, hyperdense middle cerebral artery sign (HMCAS), baseline signs of early infarct, angiographic favorable collaterals, number of retrieval attempts, and revascularization rate. Multivariate analysis indicated that low baseline ASPECT score, absent HMCAS, angiographic poor collaterals, more retrieval attempt count, and poor revascularization independently influenced the occurrence of MBE in AIS patients with anterior circulation after MT.

CONCLUSION

MBE was associated with a lower rate of favorable 90-day clinical outcomes. Low baseline ASPECT score, absent HMCAS, angiographic poor collaterals, more retrieval attempt count and poor revascularization were independently associated with MBE after MT.

Reocclusion after successful endovascular treatment in acute ischemic stroke: systematic review and meta-analysis

BACKGROUND

Endovascular treatment (EVT) is the standard of care for selected patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO).

OBJECTIVE

To systematically review the available data on: (1) incidence, predictors, and outcomes of patients with reocclusion after successful EVT for AIS and, (2) the characteristics, complications, and outcomes of patients with reocclusion treated with repeated EVT (rEVT) within 30 days of the first procedure.

METHODS

PubMed was searched (between January 2012 and April 2021) to identify studies reporting reocclusion following successful EVT (Thrombolysis in Cerebral Infarction ≥2b) in patients with AIS due to LVO. Pooled incidence of reocclusion per 100 patients with successful recanalization following EVT was calculated using a random-effects model with Freeman-Tukey double arcsine transformation. Extracted incidences of reocclusion according to etiology and use of intravenous thrombolysis were pooled using random-effects meta-analytic models.

RESULTS

A total of 840 studies was identified and seven studies qualified for the quantitative analysis, which described 91 same-vessel reocclusions occurring within the first 7 days after treatment among 2067 patients (4.9%; 95% CI 3% to 7%, I2=70.2%). Large vessel atherosclerosis was associated with an increased risk of reocclusion (OR=3.44, 95% CI 1.12 to 10.61, I2=50%). We identified 90 patients treated with rEVT for recurrent LVO, described in five studies. The rates of procedural complications, mortality, and unfavorable functional outcome at 3 months were 18.0%, 18.9%, and 60.3%, respectively.

CONCLUSION

In cohorts of patients with AIS due to LVO, 5% of patients experienced reocclusion within 7 days after successful EVT. Repeated EVT can be a safe and effective treatment for selected patients with reocclusion.

Radiological predictors of final infarct volume in patients with proximal vascular occlusion

INTRODUCTION

Various clinical and radiologic variables impact the neurologic prognosis of patients with ischemic cerebrovascular accidents. About 30% of ischemic cerebrovascular accidents are caused by proximal obstruction of the anterior circulation; in these cases, systemic thrombolysis is of limited usefulness. CT angiography is indicated in candidates for endovascular treatment. Various radiologic factors, including the grade of leptomeningeal collateral circulation, as well as the length, density, and extension of the thrombus, have been identified as predictors of neurologic prognosis after anterior ischemic cerebrovascular accidents due to proximal vascular obstruction. Final infarct volume correlations with mortality and long-term functional outcome in these patients. This study aimed to determine the best predictors of final infarct volume on CT angiography in patients with ischemic cerebral accidents due to proximal occlusion.

MATERIALS AND METHODS

This retrospective observational study included adults with ischemic cerebrovascular accidents due to obstruction of the anterior circulation diagnosed by CT angiography in the period comprising June 2009 through December 2019. We measured the length and density of the thrombus in unenhanced CT images, and we used the clot burden score to record the grade of leptomeningeal collateral circulation and the extension of the thrombus. Then we measured the final infarct volume on follow-up CT and analyzed the correlations among these radiologic factors in the infarct volume.

RESULTS

We included 54 patients [mean age, 82 y; 41 (75%) women] with ischemic cerebrovascular accidents due to proximal occlusion. About 60% of the cerebrovascular accidents affected the right cerebral hemisphere, and the most commonly affected vessel was the M1 segment of the medial cerebral artery (40.7%). Final infarct volume correlated with the grade of leptomeningeal collateral circulation (p=0.03) and with the clot burden score (p=0.01). Neither the length nor the density of the thrombus correlated with final infarct volume.

CONCLUSION

The final infarct volume can be estimated on the initial CT angiogram. Nevertheless, we found no useful predictive factors in unenhanced CT images. The best independent radiologic predictors of the final infarct volume are the grade of collateral circulation and the clot burden score, especially in patients who did not undergo mechanical thrombectomy, because mechanical thrombectomy improves outcomes. These factors are important for decision making in the management of patients with ischemic cerebrovascular accidents due to proximal occlusion.

Preprocedural determination of an occlusion pathomechanism in endovascular treatment of acute stroke: a machine learning-based decision

OBJECTIVE

To evaluate whether an occlusion pathomechanism can be accurately determined by common preprocedural findings through a machine learning-based prediction model (ML-PM).

METHODS

A total of 476 patients with acute stroke who underwent endovascular treatment were retrospectively included to derive an ML-PM. For external validation, 152 patients from another tertiary stroke center were additionally included. An ML algorithm was trained to classify an occlusion pathomechanism into embolic or intracranial atherosclerosis. Various common preprocedural findings were entered into the model. Model performance was evaluated based on accuracy and area under the receiver operating characteristic curve (AUC). For practical utility, a decision flowchart was devised from an ML-PM with a few key preprocedural findings. Accuracy of the decision flowchart was validated internally and externally.

RESULTS

An ML-PM could determine an occlusion pathomechanism with an accuracy of 96.9% (AUC=0.95). In the model, CT angiography-determined occlusion type, atrial fibrillation, hyperdense artery sign, and occlusion location were top-ranked contributors. With these four findings only, an ML-PM had an accuracy of 93.8% (AUC=0.92). With a decision flowchart, an occlusion pathomechanism could be determined with an accuracy of 91.2% for the study cohort and 94.7% for the external validation cohort. The decision flowchart was more accurate than single preprocedural findings for determining an occlusion pathomechanism.

CONCLUSIONS

An ML-PM could accurately determine an occlusion pathomechanism with common preprocedural findings. A decision flowchart consisting of the four most influential findings was clinically applicable and superior to single common preprocedural findings for determining an occlusion pathomechanism.

Imaging diagnosis of intracranial atherosclerosis stenosis-related large vessel occlusion before and during endovascular therapy

It is becoming increasingly important to identify the type of stroke, especially the mechanism of occlusion, before and during its treatment. In the case of intracranial atherosclerotic stenosis-related large vessel occlusion, it is necessary to develop a treatment strategy that includes not only mechanical thrombectomy but also adjunctive therapies such as primary or rescue therapy (percutaneous angioplasty, intracranial/carotid stenting, local fibrinolysis) and perioperative antithrombotic therapy. However, in clinical practice we often encounter cases where it is difficult to identify the occlusive mechanism before endovascular treatment because of insufficient information in the minimal circumstances of the hyperacute phase of stroke. Here we focus on the imaging diagnosis before and during treatment of intracranial atherosclerotic stenosis-related large vessel occlusion with in situ thrombotic occlusion as the mechanism of thrombotic occlusion, based on previous reports. We describe the diagnosis of intracranial atherosclerotic stenosis-related large vessel occlusion from the perspectives of "thrombus imaging," "perfusion," and "occlusion margin."

Functional and technical outcomes in acute ischemic stroke patients with hyperdense middle cerebral artery sign treated with endovascular thrombectomy

Background and objective

The hyperdense middle cerebral artery sign (HMCAS) is observed in a proportion of patients with acute ischemic stroke (AIS). This sign reflects the presence of an intravascular thrombus rich in red blood cells. Several studies have demonstrated that HMCAS increases the risk of poor outcomes in AIS patients treated with IV thrombolysis or no reperfusion therapy; however, whether HMCAS predicts a poor outcome in patients treated with endovascular thrombectomy (EVT) is less clear. We aimed to evaluate the functional outcome by the modified Rankin scale (mRS) at 90 days and technical challenges in patients with HMCAS undergoing EVT.

Methods

We studied 143 consecutive AIS patients with middle cerebral artery M1 segment or internal carotid artery + M1 occlusions who underwent EVT.

Results

There were 73 patients (51%) with HMCAS. Patients with HMCAS had a higher frequency of cardioembolic stroke (p = 0.038); otherwise, no other baseline difference was observed. No differences in functional outcomes (mRS) at 90  days (p = 0.698), unfavorable outcomes (mRS > 2) (p = 0.929), frequency of symptomatic intracranial hemorrhage (p = 0.924), and mortality (mRS-6) (p = 0.736) were observed between patients with and without HMCAS. In patients with HMCAS, EVT procedures were 9  min longer, requiring a higher number of passes (p = 0.073); however, optimal recanalization scores (modified thrombolysis in cerebral infarction: 2b-3) were equally achieved by both groups.

Conclusion

Patients with HMCAS treated with EVT do not have a worse outcome at 3  months compared with no-HMCAS patients. Patients with HMCAS required a greater number of thrombus passes and longer procedure times.

Dual-energy CT in assessment of thrombus perviousness and its application in predicting outcomes after intravenous thrombolysis in acute ischemic stroke

PURPOSE

To evaluate the feasibility of using iodine overlay maps reconstructed from dual-energy CT (DECT) to assess thrombus perviousness and investigate its value in predicting outcomes after intravenous thrombolysis in patients with acute ischemic stroke.

METHOD

86 patients with proximal intracranial occlusions of the anterior circulation who underwent intravenous thrombolysis were included in this study. Thrombus iodine concentrations (IC_thrombus) and normalized iodine concentrations (NIC_thrombus) were compared to conventional perviousness parameters (thrombus attenuation increase, TAI; void fraction, ε and CTA-index). The associations between perviousness parameters and outcomes were analyzed by Spearman's correlation and regression analysis.

RESULTS

IC_thrombus and NIC_thrombus were significantly correlated with conventional perviousness parameters (P < 0.001). The median IC_thrombus was 6.81 (interquartile range [IQR], 4.76-8.73) mg/ml in the favorable functional outcome group, which was higher than 3.52 (IQR, 2.08-6.86) mg/ml in the unfavorable outcome group (P = 0.001). The median NIC_thrombus was 0.095 (IQR, 0.068-0.116) and 0.054 (IQR, 0.031-0.083) in the favorable and unfavorable outcome groups, respectively (P < 0.001). NIC_thrombus predicted favorable outcome with a higher area under the curve (AUC) of 0.755 than any conventional perviousness parameter (P < 0.05). In the multivariable regression model, IC_thrombus was independently associated with favorable outcome (odds ratio [OR] = 1.472, 95 % CI: 1.154-1.877, P = 0.002) and successful recanalization (OR = 1.356, 95 % CI: 1.093-1.681, P = 0.006). IC_thrombus was negatively correlated with the final infarct volume (FIV) (r = -0.262, P = 0.020). Results for NIC_thrombus were similar.

CONCLUSIONS

DECT is of great value in assessing thrombus perviousness. NIC_thrombus is a meaningful predictor of stroke prognosis and recanalization after intravenous thrombolysis in acute ischemic stroke.

Proximal hyperdense middle cerebral artery sign is associated with increased risk of asymptomatic hemorrhagic transformation after endovascular thrombectomy: a multicenter retrospective study

OBJECTIVE

To investigate whether hyperdense middle cerebral artery sign (HMCAS) on pretreatment no-contrast CT (NCCT) is associated with hemorrhagic transformation (HT) after endovascular thrombectomy (EVT).

METHODS

Patients with acute middle cerebral artery (MCA) occlusion who received EVT in three comprehensive hospitals were retrospectively evaluated. They were divided into four groups based on the presence or absence of HMCAS and corresponding CTA findings, among whom differences were compared. Univariate and multivariate logistic regression analyses were performed to investigate the association between HMCAS and HT and its subtypes.

RESULTS

318 patients were included, among whom 149 (46.9%) had HMCAS. Patients in the proximal positive HMCAS group had higher National Institute of Health Stroke Scale scores and lower Alberta Stroke Program Early CT Scores (ASPECTS) than those in the proximal negative HMCAS group. The rate of HT was higher in the proximal positive HMCAS group than that in the proximal negative HMCAS group. In multivariate logistic regression analysis, the proximal HMCAS were independently associated with HT (adjusted OR = 2.073, 95% CI 1.211-3.551, p = 0.008) and aHT (adjusted OR = 2.271, 95% CI 1.294-3.986, p = 0.004), but not with sHT. Patients who developed HT, including aHT and sHT, had a lower rate of good outcome.

CONCLUSION

Proximal HMCAS on initial NCCT was independently associated with aHT in patients who received EVT for acute MCA occlusion. Both aHT and sHT had a detrimental effect on clinical outcome.

Hyperdense middle cerebral artery sign predicts favorable outcome in patients undergoing mechanical thrombectomy

Non-contrast computer tomography detects the presence of hyperdense middle cerebral artery sign (HMCAS). Studies on the prognostic value of HMCAS among patients undergoing mechanical thrombectomy (MT) are conflicting. A retrospective analysis of consecutive patients with acute ischemic stroke due to middle cerebral artery occlusion, presenting with or without HMCAS, who underwent MT, was performed. We enrolled 191 patients (HMCAS +, n = 140; HMCAS -, n = 51). Prevalence of successful recanalization was significantly higher in patients with HMCAS than in those without HMCAS (92.1% versus 74.5%, p = 0.001). Patients with HMCAS had a better clinical outcome than those HMCAS - (54.3% versus 37.3%, p = 0.037, for three-month favorable outcome; 62.9% versus 39.3%, p = 0.004, for major neurological improvement at discharge; 8.6% versus 19.6%, p = 0.035, for in-hospital mortality; 14.3% versus 27.5%, p = 0.035, for intracranial hemorrhage; 2.9% versus 17.6%, p = 0.001, for symptomatic intracranial hemorrhage). Multivariate analyses confirmed that HMCAS represents an independent predictor of three-month favorable outcome (OR 2.48, 95% CI 1.10-5.58, p = 0.028), major neurological improvement at discharge (OR 2.40, 95% CI 1.09-5.20, p = 0.030), in-hospital mortality (OR 0.29, 95% CI 0.010-0.81, p = 0.018), presence of ICH (OR 0.49, 95% CI 0.25-0.97, p = 0.042) and presence of SICH (OR 0.16, 95% CI 0.04-0.63, p = 0.009). HMCAS presence predicts favorable outcome in patients undergoing MT. This result may indicate that hyperdense clots are more likely to respond to MT than isodense ones. This effect is mediated by reduction in hemorrhagic transformation.

Risk factors of hemorrhagic transformation in acute ischaemic stroke: A systematic review and meta-analysis

Background

Hemorrhagic transformation (HT) following reperfusion therapies for acute ischaemic stroke often predicts a poor prognosis. This systematic review and meta-analysis aims to identify risk factors for HT, and how these vary with hyperacute treatment [intravenous thrombolysis (IVT) and endovascular thrombectomy (EVT)].

Methods

Electronic databases PubMed and EMBASE were used to search relevant studies. Pooled odds ratio (OR) with 95% confidence interval (CI) were estimated.

Results

A total of 120 studies were included. Atrial fibrillation and NIHSS score were common predictors for any intracerebral hemorrhage (ICH) after reperfusion therapies (both IVT and EVT), while a hyperdense artery sign (OR = 2.605, 95% CI 1.212-5.599, I ² = 0.0%) and number of thrombectomy passes (OR = 1.151, 95% CI 1.041-1.272, I ² = 54.3%) were predictors of any ICH after IVT and EVT, respectively. Common predictors for symptomatic ICH (sICH) after reperfusion therapies were age and serum glucose level. Atrial fibrillation (OR = 3.867, 95% CI 1.970-7.591, I ² = 29.1%), NIHSS score (OR = 1.082, 95% CI 1.060-1.105, I ² = 54.5%) and onset-to-treatment time (OR = 1.003, 95% CI 1.001-1.005, I ² = 0.0%) were predictors of sICH after IVT. Alberta Stroke Program Early CT score (ASPECTS) (OR = 0.686, 95% CI 0.565-0.833, I ² =77.6%) and number of thrombectomy passes (OR = 1.374, 95% CI 1.012-1.866, I ² = 86.4%) were predictors of sICH after EVT.

Conclusion

Several predictors of ICH were identified, which varied by treatment type. Studies based on larger and multi-center data sets should be prioritized to confirm the results.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=268927, identifier: CRD42021268927.

Effects of Hyperferritinemia on Functional Outcome in Acute Ischemic Stroke Patients with Admission Hyperglycemia

INTRODUCTION

Hyperferritinemia, presented as elevated serum ferritin level, is an indicator of high iron status which plays roles in secondary brain injury after acute ischemic stroke (AIS). However, the effects of hyperferritinemia and poor outcomes remain uncertain. Additionally, admission hyperglycemia quite frequently accompanies AIS patients, which is associated with unfavorable outcome. Thus, we aimed to investigate the effects of hyperferritinemia on 3-month and 1-year functional outcomes in AIS patients and especially those with admission hyperglycemia.

METHODS

AIS patients within 24 h of onset were enrolled at West China Hospital from October 2016 to December 2019. Serum ferritin and blood glucose levels were tested on admission. Poor functional outcome at 3 months and 1 year was defined as modified Rankin Scale score ≥3. Multivariable analysis was used to investigate the associations between hyperferritinemia and 3-month and 1-year outcomes. Subgroup analysis was performed in patients with and without hyperglycemia.

RESULTS

Of 723 patients (mean age 68.11 years, 60.6% males) finally included, 347 (48.0%) had hyperferritinemia. The incidence of poor outcome was 45.2% at 3 months and 41.2% at 1 year. Patients with hyperferritinemia had a higher frequency of poor 3-month outcome (51.8% vs. 39.2%, p = 0.001) and poor 1-year outcome (46.8% vs. 36.1%, p = 0.004). In all AIS patients, hyperferritinemia was not independently associated with poor functional outcome at 3 months or 1 year after adjusting for confounders (all p > 0.05). In AIS patients with hyperglycemia, hyperferritinemia was an independent factor correlated with poor 3-month outcome (OR = 1.711, 95% CI 1.093-2.681, p = 0.019) but not with poor 1-year outcome (p > 0.05).

CONCLUSIONS

High iron status, presented as hyperferritinemia, is associated with poor 3-month functional outcome in AIS patients with hyperglycemia. Evaluating serum ferritin level may be conducive to assess the risk of short-term poor outcome in AIS patients with hyperglycemia. Further studies will be required to confirm our findings.

CT Hyperdense Artery Sign and the Effect of Alteplase in Endovascular Thrombectomy after Acute Stroke

Background Recent evidence suggests that presence of an intracranial arterial thrombus with a hyperdense artery sign (HAS) at noncontrast CT (NCCT) is associated with better response to intravenous alteplase. Patients with HAS may benefit more from combined intravenous alteplase and endovascular treatment (EVT). Purpose To investigate whether HAS at NCCT modifies the treatment effect of adding intravenous alteplase on clinical outcome in patients with acute large-vessel occlusion undergoing EVT. Materials and Methods This study is a secondary analysis of a prospective randomized trial (Direct Intra-arterial thrombectomy in order to Revascularize AIS patients with large-vessel occlusion Efficiently in Chinese Tertiary hospitals: A Multicenter randomized clinical Trial [DIRECT-MT]), which compared adding alteplase to EVT versus EVT alone in participants with acute large-vessel occlusion between February 2018 and July 2019. Participants with catheter angiograms and adequate NCCT for HAS evaluation were included. HAS was determined visually by two independent investigators at baseline NCCT. Treatment effect of intravenous alteplase administration according to presence of HAS on the primary clinical outcome (modified Rankin Scale [mRS] score at 90 days) and secondary and safety outcomes were assessed using adjusted multivariable regression models. Results Among 633 included participants (356 men [56%]; median age, 69 years), HAS was observed in 283 participants (45%): 142 of 313 participants (45%) in the EVT-only group and 141 of 320 participants (44%) in the group with added intravenous alteplase. Treatment-by-HAS interaction was observed for the primary outcome (P < .001), whereby a shift in favor of better outcomes with added intravenous alteplase occurred in participants with HAS (adjusted odds ratio [OR]: 1.82; 95% CI: 1.18, 2.79), while an adverse effect was seen in participants without HAS (adjusted OR: 0.62; 95% CI: 0.42, 0.91). This also held true for three secondary outcomes (excellent outcome [mRS score of 0-1 at 90 days], P = .005; good outcome [mRS score of 0-2 at 90 days], P = .008; final successful reperfusion, P = .04) in the adjusted models. Conclusion After acute ischemic stroke, presence of hyperdense artery sign (HAS) at baseline noncontrast CT indicated better outcomes when alteplase was added to endovascular treatment, but adding alteplase to endovascular treatment resulted in worse outcomes in participants without HAS. Clinical trial registration no. NCT03469206 © RSNA, 2022 Online supplemental material is available for this article.

Usefulness of maximum intensity projection images of non-enhanced CT for detection of hyperdense middle cerebral artery sign in acute thromboembolic ischemic stroke

PURPOSE

To compare the sensitivity of the hyperdense middle cerebral artery (MCA) sign between maximum intensity projection (MIP) and conventional averaged images in patients with acute focal neurological deficits with acute thromboembolic MCA occlusion (MCA occlusion group) and patients with acute focal neurological deficits without MCA occlusion (control group).

MATERIALS AND METHODS

Initial computed tomography (CT) scans on admission were reconstructed with 5 mm thickness at every 3 mm interval for averaged and MIP images from 1 mm thickness non-contrast axial source images. Images were obtained from 30 cases each in the MCA occlusion and control groups. The CT values in the region of interests (ROIs) on the affected and unaffected sides of the MCA were compared. To compare CT values among subjects, the CT values were normalized by obtaining a ratio on the affected and unaffected sides, and the normalized CT values were analyzed using the receiver operating characteristic (ROC) curve.

RESULTS

The hyperdense MCA sign was visually detected on MIP images in 90% cases and on 5 mm averaged images in only 57% cases in the MCA occlusion group. Based on the ROC analysis of the normalized ratio on the affected and unaffected sides, area under the curve of MIP image and averaged image was 0.941 and 0.655, respectively. On MIP images, the optimal threshold of the ratio on the affected and unaffected sides was 1.152 (sensitivity: 90.0%, and specificity: 93.3%).

CONCLUSION

The hyperdense MCA sign sensitivity on 5 mm MIP images was significantly higher than that on conventional 5 mm averaged CT images. This could be useful for the early initiation of proper therapy for patients with acute focal neurological deficits.

Hyperdense Artery Sign and Clinical Outcomes After Endovascular Treatment in Acute Basilar Artery Occlusion

Background

This study aimed to investigate the association between the hyperdense basilar artery sign (HBAS) on non-enhanced computed tomography (CT) and clinical outcomes in patients with acute basilar artery occlusion (BAO) who underwent endovascular treatment (EVT).

Methods

Eligible patients who underwent EVT due to acute BAO between January 2014 and May 2019 were divided into two groups based on HBAS. HBAS was assessed by two neuroradiologists using five grades on nonenhanced CT. The primary outcome was a favorable functional outcome (defined as a modified Rankin Scale [mRS] of 0-3) at 90 days. Secondary outcomes included successful recanalization and mortality within 90 days.

Results

Among 829 patients with BAO as assessed with CT angiography, magnetic resonance angiography, or digital subtraction angiography, 643 patients were treated with EVT. Of these, 51.32% (330/643) had HBAS. Patients with HBAS were older and had more severe neurological deficits and a higher frequency of atrial fibrillation than those without HBAS. There was no significant difference in favorable outcome (adjusted odds ratio [aOR]: 1.354, 95% confidence interval [CI]: 0.906-2.024; p = 0.14), successful recanalization (aOR: 0.926, 95% CI: 0.616--1.393; p = 0.71), and mortality (aOR: 1.193, 95% CI: 0.839-1.695; p = 0.33) between patients with or without HBAS. Subgroup analysis showed that the HBAS predicted a favorable outcome in patients aged <60 years (aOR: 2.574, 95% CI: 1.234-5.368; p = 0.01) and patients with vertebral artery-V4 segment occlusion (aOR: 3.738, 95% CI: 1.212-11.530; p = 0.02). In patients with HBAS, the baseline National Institutes of Health Stroke Scale (NIHSS) score, posterior circulation-Acute Stroke Prognosis Early Computed Tomography Score (pc-ASPECTS), and stent retriever were associated with successful recanalization.

Conclusions

Our study did not find a significant association between HBAS and favorable outcomes and successful recanalization in patients with BAO who underwent EVT. Moreover, large prospective studies are warranted to further investigate this relationship.

Mechanical Thrombectomy for Acute Ischemic Stroke in Patients With Cardiac Myxoma: A Case Series and Pooled Analysis

Background and Purpose

Acute ischemic stroke (AIS) is a common and life-threatening complication of patients with cardiac myxoma (CM). The role of the mechanical thrombectomy (MT) technique in CM-AIS patients remains unclear, and no guidelines exist for this population. Therefore, we conducted a case series study of MT in CM-AIS patients to investigate its safety and efficacy via a pooled analysis of published literature.

Methods

Eleven CM-AIS patients who underwent MT between 2016 and 2021 were screened from multicenter stroke databases. Clinical, procedural, and outcome data were obtained from medical records. A systematic review was conducted to identify additional cases from published studies by searching PubMed and China National Knowledge Infrastructure databases. We then performed a pooled analysis of the published cases.

Results

In the case series study, most patients were male (81.8%), with a median age of 51 years. All patients had CM located in the left atrium. The rate of successful reperfusion using the first-line thrombectomy technique was 100% with stent retriever (SR) and 66.7% with direct aspiration (DA), which resulted in overall successful reperfusion in 94.1% of all occlusions. The retrieved emboli of the five patients who underwent histopathology examination were identified as myxoma components. Hemorrhagic transformation was observed in five (45.5%) patients, of whom one was symptomatic (9.1%). Three-month favorable functional outcomes were achieved in five (45.5%) patients with a 3-month mortality rate of 18.2%. For the literature review, 35 cases with 51 target vessel occlusions were identified and included in the pooled analysis. The rate of successful reperfusion following first-line thrombectomy did not differ between SR (30 patients, 90.9%) and DA (10 patients, 83.3%). The overall successful reperfusion rate was 91.8% of all occlusions. Three-month favorable functional outcomes were achieved in 21 (60.0%) patients, and the mortality rate was 8.6%.

Conclusions

Our findings suggest that MT is not only an effective technique but also a safe option for CM-AIS patients with large vessel occlusion. MT has several advantages for this population, which include a high recanalization rate, low bleeding risk, and the ability to evaluate the source of emboli and the etiology of stroke.

Prognostic capacity of hyperdense middle cerebral artery sign in anterior circulation acute ischaemic stroke patients receiving reperfusion therapy: a systematic review and meta-analysis

Pre-intervention CT imaging-based biomarkers, such as hyperdense middle cerebral artery sign (HMCAS) may have a role in acute ischaemic stroke prognostication. However, the clinical utility of HMCAS in settings of reperfusion therapy and the level of prognostic association is still unclear. This systematic review and meta-analysis investigated the association of HMCAS sign with clinical outcomes and its prognostic capacity in acute ischaemic stroke patients treated with reperfusion therapy. Prospective and retrospective studies from the following databases were retrieved from EMBASE, MEDLINE and Cochrane. Association of HMCAS with functional outcome, symptomatic intracerebral haemorrhage (sICH) and mortality were investigated. The random effect model was used to calculate the risk ratio (RR). Subgroup analyses were performed for subgroups of patients receiving thrombolysis (tPA), mechanical thrombectomy (EVT) and/or combined therapy (tPA + EVT). HMCAS significantly increased the rate of poor functional outcome by 1.43-fold in patients (RR 1.43; 95% CI 1.30-1.57; p < 0.0001) without any significant differences in sICH rates (RR 0.91; 95% CI 0.68-1.23; p = 0.546) and mortality (RR 1.34; 95% CI 0.72-2.51; p = 354) in patients with positive HMCAS as compared to negative HMCAS. In subgroup analyses, significant association between HMCAS and 90 days functional outcome was observed in patients receiving tPA (RR 1.53; 95% CI 1.40-1.67; p < 0.0001) or both therapies (RR 1.40; 95% CI 1.08-1.80; p = 0.010). This meta-analysis demonstrated that pre-treatment HMCAS increases risk of poor functional outcomes. However, its prognostic sensitivity and specificity in predicting long-term functional outcome, mortality and sICH after reperfusion therapy is poor.

Influence of Thrombocytopenia on the Outcome of Mechanical Thrombectomy in Patients with Acute Ischemic Stroke

OBJECTIVES

Mechanical thrombectomy (MT) has become leading treatment option for acute ischemic stroke (AIS) due to large vessels occlusion (LVO). Platelet counts may affect outcome in patients with AIS or transient ischemic attack. The aim of our study was to determine the influence of thrombocytopenia on the safety and efficacy of MT in patients with AIS due to anterior circulation LVO.

MATERIALS AND METHODS

This study included 127 consecutive adult patients with AIS due to anterior circulation LVO who underwent MT. The patients were divided into 2 groups based on initial platelet count: with thrombocytopenia (<150 × 10⁹/L) and without thrombocytopenia (≥150 × 10⁹/L). Primary safety outcome was symptomatic intracerebral haemorrhage (SICH), while secondary safety outcome was stroke-related mortality. Efficacy outcome was functional independence, defined as modified Rankin Scale (mRS) score 0-2. Follow- up time was 90 days.

RESULTS

Initial thrombocytopenia (<150 × 10⁹/L) was detected in 19 (15%) patients. Multivariable analysis showed that initial thrombocytopenia did not increase the risk of SICH and did not affect the short-term functional outcome (p = 0.587). However, initial thrombocytopenia increased the risk for stroke-related mortality (aOR 3.639, 95% CI 1.079-12.641, p = 0.037). The main cause of mortality in the group with thrombocytopenia was malignant cerebral infarction (44.4%).

CONCLUSIONS

Thrombocytopenia does not affect the efficacy and the risk of SICH in patients with AIS caused by anterior circulation LVO treated with MT. However, the risk of mortality is higher in patients with thrombocytopenia, mainly due to malignant cerebral infarction.

Implications of the Presence of Hyperdense Middle Cerebral Artery Sign in Determining the Subtypes of Stroke Etiology

Background

Identifying stroke subtypes is crucial in choosing appropriate treatment, predicting outcomes, and managing recurrent stroke prevention.

Objectives

To study the association of hyperdense middle cerebral artery sign (HMCAS) on noncontrast computed tomography (NCCT) brain and subtypes of stroke etiology.

Methods

This is a retrospective hypothesis testing study. Patients aged 18 or over who had middle cerebral artery occlusion symptoms with HMCAS with verification on brain NCCT and received intravenous thrombolysis between January 2016 and June 2019 were enrolled. The demographic data, clinical outcomes, stroke subtypes, and characteristics of HMCAS were collected from medical records.

Results

Ninety-nine out of 299 enrolled patients presented with HMCAS. The most common stroke subtype was cardioembolism (59%). Of the baseline characteristics, hypertension was more common in cases of large-artery atherosclerosis (LAA) (86.4%), and atrial fibrillation (AF) was the highest in cardioembolism (44.8%). HMCAS disappearance in cardioembolism was lowest compared to LAA and others (63% vs. 91% vs. 94.7%, respectively). The univariable analysis found that HMCAS disappearance is significantly associated with all stroke subtypes (Odds ratio, 95% confidence interval 10.58, 1.31-85.43; P = 0.027 for other and 5.88, 1.24-27.85; P = 0.026 for LAA). Multinomial logistic regression found that body weight and hypertension were associated with the LAA subtype. AF and intracranial hemorrhage (ICH) were associated with cardioembolism.

Conclusion

The most likely diagnosis from the presence of HMCAS is cardioembolism, but the definite stroke etiologic subtype can not be identified. Combining the patient risk factors, including body weight, hypertension, and AF, with HMCAS and its characteristics will predict stroke subtypes more accurately.

Thrombus Composition, Imaging, and Outcome Prediction in Acute Ischemic Stroke

BACKGROUND AND OBJECTIVES

New imaging techniques have advanced our ability to capture thrombus characteristics and burden in real time. An improved understanding of recanalization rates with thrombolysis and endovascular thrombectomy based on thrombus characteristics has spurred interest in new therapies for acute stroke.

METHODS AND RESULTS

This article reviews the biochemical, structural, and imaging characteristics of intracranial thrombi in acute ischemic stroke; the relationship between thrombus composition and response to lytic and endovascular therapies; and current and future directions for improving outcomes in patients with acute stroke based on thrombus characteristics.

DISCUSSION

Thrombus composition, size, location, and timing from stroke onset correlate with imaging findings in acute ischemic stroke and are associated with clinical outcome. Further research across multiple domains could assist in better applying our knowledge of thrombi to patient selection and individualization of acute therapies.

Preprocedural Imaging : A Review of Different Radiological Factors Affecting the Outcome of Thrombectomy

BACKGROUND

Endovascular treatment (EVT) has strong evidence for its effectiveness in treatment of acute ischemic stroke (AIS); however, up to half of the patients who undergo EVT still do not have good functional outcomes. Various prethrombectomy radiological factors have been shown to be associated with good clinical outcomes and may be the key to better functional outcomes, reduced complications, and reduced mortality. In this paper, we reviewed the current literature on these imaging parameters so they can be employed to better estimate the probability of procedural success, therefore allowing for more effective preprocedural planning of EVT strategies. We reviewed articles in the literature related to imaging factors which have been shown to be associated with EVT success. The factors which are reviewed in this paper included: anatomical factors such as 1) the type of aortic arch and its characteristics, 2) the characteristics of the thrombus such as length, clot burden, permeability, location, 3) the middle cerebral artery features including the tortuosity and underlying intracranial stenosis, 4) perfusion scans estimating the volume of infarct and the penumbra and 5) the effect of collaterals on the procedure. The prognostic effect of each factor on the successful outcome of EVT is described. The identification of preprocedural thrombectomy imaging factors can help to improve the chances of recanalization, functional outcomes, and mortality. It allows the interventionist to make time-sensitive decisions in the treatment of acute ischemic stroke.

Hyperdense middle cerebral artery sign and response to combination of mechanical Thrombectomy plus intravenous thrombolysis in acute stroke patients

BACKGROUND AND PURPOSE

Combining intra-arterial mechanical thrombectomy (IAMT) and intravenous thrombolysis (IVT) has shown to have an excellent recanalization rate and better clinical outcome in acute ischemic stroke (AIS) patients. Hyperdense middle cerebral artery sign (HMCAS) on pretreatment non-contrast head CT scan of AIS patients is one of the early ischemic radiological findings in middle cerebral artery territory AIS. We aimed to evaluate whether the presence of HMCAS predicts the outcome of AIS patients receiving combination therapy with IAMT and IVT.

METHODS

We retrospectively reviewed medical records and cerebrovascular images of the patients treated with IAMT and IVT for AIS in our center. Patients with occlusion in the terminal internal carotid artery or middle cerebral artery on pretreatment CT angiogram of the head were included. Clinical outcome was compared between subjects with HMCAS and those without. Modified Rankin Score (mRS) and symptomatic intracranial hemorrhage (sICH) were used as measures of efficacy and safety, respectively.

RESULTS

Of 93 patients, 46 (49%) had HMCAS on their initial head CT scan. Both groups had comparable baseline characteristics and stroke severity. After adjusting for age, NIHSS score, time from symptom onset to starting IVT, and history of diabetes mellitus in multivariate logistic regression analysis, there was no difference in terms of a poor outcome (mRS >2) (OR = 0.5 [CI 0.2-1.4], p = 0.188) or rate of sICH (OR = 3.3 [CI 0.6-19.0], p = 0.190) between the two groups.

CONCLUSIONS

HMCAS is not a predictor of poor outcome in AIS patients receiving combination therapy with IAMT and IVT and does not affect treatment safety.

Histological composition behind CT-based thrombus density and perviousness in acute ischemic stroke

BACKGROUND

Clot composition could impact recanalization outcomes of thrombectomy, and preoperative imaging markers may help know about the histological components of thrombus.

METHODS

Consecutive patients who underwent thrombectomy from June 2017 to December 2019 were reviewed. The mean Hounsfield unit (HU) of thrombus (aHU) and contralateral artery (cHU) were recorded based on non-enhanced CT. The relative thrombus density was calculated (dHU=aHU-cHU). Hyperdense artery sign (HAS) was identified if dHU≥ 4HU. The clot perviousness was evaluated via thrombus attenuation increase (δHU) on contrast-enhanced CT compared to non-enhanced CT. Pervious clots were identified when δHU≥ 11HU. Tissue quantification for thrombus was based on Martius Scarlet Blue staining, using the Orbit Imaging Analysis Software. Spearman rank correlations was used to detect the association between imaging markers and clot composition. The differences in clinical characteristics were compared according to the presence of HAS or pervious clots.

RESULTS

Fifty-three patients were included. The dHU was positively correlated with erythrocyte fractions (r = 0.337, p = 0.014), while there was no significant association between aHU and erythrocyte components (r = 0.146, p = 0.296). HAS (+) patients showed a comparable proportion of modified Thrombolysis In Cerebral Infarction (mTICI) 2b-3 (94.6% vs. 87.5%, p = 0.740) and modified Rankin Scale score (mRS) 0-2 (35.1% vs. 56.3%, p = 0.152) compared with those HAS (-). Forty-seven cases were available for the analysis of clot perviousness. Clot perviousness was negatively associated with platelet fractions (r = -0.577, p < 0.001). Patients with pervious clots also showed a comparable proportion of mTICI 2b-3 (86.2% vs. 100%, p = 0.283) and mRS 0-2 (37.9% vs. 50.0%, p = 0.416) compared with impervious clots.

CONCLUSIONS

This study suggests that relative thrombus density was positively correlated with erythrocyte fractions, while clot perviousness showed a negative relationship with platelet components. Yet, the presence of HAS or pervious clots did not show significant associations with recanalization and clinical outcomes. The conclusions should be drawn with caution.

Diagnostic and prognostic computed tomography imaging markers in basilar artery occlusion (Review)

Acute ischemic stroke treatment has been revolutionized by the addition of mechanical and aspiration thrombectomy. Randomized controlled trials have proven beyond doubt, the substantial clinical impact of endovascular interventions in anterior circulation territory strokes. Unfortunately, patients with vertebrobasilar ischemic stroke could not be included in these early trials due to inherent clinical, radiological, and prognostic particularities of posterior circulation ischemia; thus, indications for the treatment of posterior fossa strokes and basilar artery occlusion (BAO) are mainly based on retrospective studies and registries. BAO carries high morbidity and mortality, despite the new improvements in endovascular therapy. Identifying patients who will likely benefit from invasive treatment and have a good clinical outcome resides in discovering clinical, biological, or imaging markers, that have prognostic implications. Such imaging markers have been described, especially in the last decade. Hyperdense Basilar Artery Sign (HDBA), Posterior Circulations-Alberta Stroke Program Early CT Score (pc-ASPECTS), Pons-Midbrain Index (PMI), Posterior Circulation Collateral Score (pc-CS), Posterior Circulation CT Angiography Score (pc-CTA), and Basilar Artery on CT Prognostic Score (BATMAN), are computed tomography (CT) markers with properties that can aid the diagnosis of BAO and can independently predict clinical outcome. This paper aims to present a comprehensive review of these imaging signs to have a thorough understanding of their diagnostic and prognostic attributes.

3D dissimilar-siamese-u-net for hyperdense Middle cerebral artery sign segmentation

The hyperdense middle cerebral artery sign (HMCAS) representing a thromboembolus has been declared as a vital CT finding for intravascular thrombus in the diagnosis of acute ischemia stroke. Early recognition of HMCAS can assist in patient triage and subsequent thrombolysis or thrombectomy treatment. A total of 624 annotated head non-contrast-enhanced CT (NCCT) image scans were retrospectively collected from multiple public hospitals in Hong Kong. In this study, we present a deep Dissimilar-Siamese-U-Net (DSU-Net) that is able to precisely segment the lesions by integrating Siamese and U-Net architectures. The proposed framework consists of twin sub-networks that allow inputs of left and right hemispheres in head NCCT images separately. The proposed Dissimilar block fully explores the feature representation of the differences between the bilateral hemispheres. Ablation studies were carried out to validate the performance of various components of the proposed DSU-Net. Our findings reveal that the proposed DSU-Net provides a novel approach for HMCAS automatic segmentation and it outperforms the baseline U-Net and many state-of-the-art models for clinical practice.

Absent hyperdense middle cerebral artery sign is associated with poor functional outcome after mechanical thrombectomy

BACKGROUND

The hyperdense middle cerebral artery sign on computed tomography indicates proximal middle cerebral artery occlusion. Recent reports suggest an association between the hyperdense sign and successful reperfusion. The prognostic value of the hyperdense middle cerebral artery sign in patients receiving mechanical thrombectomy has not been extensively studied.

AIMS

Our study aims to evaluate the association between the hyperdense middle cerebral artery sign and functional outcome in patients with M1 occlusions that had undergone mechanical thrombectomy.

METHODS

We conducted a single-center retrospective observational cohort study of 102 consecutive patients presenting with acute M1 occlusions that had undergone mechanical thrombectomy. Patients were stratified into cohorts based on the presence of hyperdense middle cerebral artery sign visually assessed on computed tomography by two readers. The outcomes of interests were functional disability measured by the ordinal Modified Rankin Scale (mRS) at 90 days, mortality, reperfusion status and hemorrhagic conversion.

RESULTS

Out of the 102 patients with M1 occlusions, 71 had hyperdense middle cerebral artery sign. There was no significant difference between the cohorts in age, baseline mRS, NIHSS, ASPECTS, and time to reperfusion. The absence of hyperdense middle cerebral artery sign was associated with increased odds of being dependent or dying (higher mRS) (OR: 3.24, 95% CI: 1.30-8.06, p = 0.011) after adjusting for other significant predictors, including age, female sex, hypertension, presenting serum glucose, ASPECTS, CTA collateral score, and successful reperfusion.

CONCLUSION

The absence of hyperdense middle cerebral artery sign is associated with worse functional outcome in patients presenting with M1 occlusions undergoing thrombectomy.

Jet-Like Appearance in Angiography as a Predictive Image Marker for the Occlusion of Intracranial Atherosclerotic Stenosis

Introduction: Identifying intracranial atherosclerotic stenosis-related occlusion (ICAS-O) in acute ischemic stroke has important clinical significance. Correct identification would help operators devise an optimal recanalization strategy. However, it is often hard to make accurate judgments in emergency situations before thrombectomy. Here, we propose a new image marker for ICAS-O based on the appearance of occluded vessels on baseline digital subtraction angiography. Materials and Methods: We retrospectively reviewed patients with acute ischemic stroke who underwent endovascular therapy from August 2017 to February 2020 at our center. ICAS-O was identified by residual focal stenosis at occluded vessels after successful recanalization. The jet-like appearance was defined as appearance of pencil-tip-like or line-linked contrast filling of the occlusion edge. A non-jet-like appearance was defined as appearance of convex, concave, or flat edge contrast filling. The proportion of jet-like appearance in different occlusion etiologies and occluded vessels was determined. The diagnostic value of jet-like appearance for ICAS-O was assessed. Results: A total of 164 patients diagnosed with ICAS-O were enrolled. Jet-like appearance was detected in 34 (20.7%) patients with younger age (68.0 ± 11.9 years vs. 62.7 ± 10.2, p = 0.019), patients with lower baseline NIHSS scores (16.6 ± 7.1 vs. 12.4 ± 6.5, p = 0.002) and patients with more past stroke or transit ischemic events (31.4 vs. 13.2%, p = 0.011). ICAS-O rate was higher in the jet-like appearance group (82.9 vs. 8.5%, p < 0.001), and rescue methods were more frequently used (74.3 vs. 12.4%, p < 0.001). Jet-like appearance was mostly found at the origin of the middle cerebral artery (MCA) (44.1%), followed by the first segment trunk of MCA (20.6%) and internal carotid artery (ICA) supraclinoid (11.8%). Logistic regression showed that jet-like appearance was independently associated with ICAS-O [OR 180.813, 95% CI (17.966, 1,819.733), p < 0.001]. The sensitivity, specificity, and accuracy values for predicting ICAS-O was 96, 78, and 83%. Conclusion: The jet-like appearance on the angiogram was an image marker for ICAS-O, with relatively high sensitivity and specificity, which could help operators predict underlying intracranial atherosclerotic stenosis in a timely manner and choose the optimal intervention strategy during endovascular therapy.

Utility of Leptomeningeal Collaterals in Predicting Intracranial Atherosclerosis-Related Large Vessel Occlusion in Endovascular Treatment

Earlier or preprocedural identification of occlusion pathomechanism is crucial for effective endovascular treatment. As leptomeningeal collaterals tend to develop well in chronic ischemic conditions such as intracranial atherosclerosis (ICAS), we investigated whether leptomeningeal collaterals can be a preprocedural marker of ICAS-related large vessel occlusion (ICAS-LVO) in endovascular treatment. A total of 226 patients who underwent endovascular treatment were retrospectively reviewed. We compared the pattern of leptomeningeal collaterals between patients with ICAS-LVO and without. Leptomeningeal collaterals were assessed by preprocedural computed tomography angiography (CTA) and basically categorized by three different collateral assessment methods. Better leptomeningeal collaterals were significantly associated with ICAS-LVO, although they were not independent for ICAS-LVO. When leptomeningeal collaterals were dichotomized to incomplete (<100%) and complete (100%), the latter was significantly more frequent in patients with ICAS-LVO (52.5% versus 20.4%) and remained an independent factor for ICAS-LVO (odds ratio, 3.32; 95% confidence interval, 1.52-7.26; p = 0.003). The area under the curve (AUC) value of complete leptomeningeal collateral supply was 0.660 for discrimination of ICAS-LVO. Incomplete leptomeningeal collateral supply was not likely ICAS-LVO, based on the high negative predictive value (88.6%). Considering its negative predictive value and the independent association between complete leptomeningeal collateral supply and ICAS-LVO, leptomeningeal collaterals could be helpful in the preprocedural determination of occlusion pathomechanism.

The Hyperdense Middle Cerebral Artery Sign in Drip-and-Ship Models of Acute Stroke Management

Background

Large vessel occlusion (LVO) leads to debilitating stroke and responds modestly to recombinant tissue plasminogen activator (rt-TPA). Early thrombectomy improves functional outcomes in selected patients with proximal occlusion but it is not available in all medical facilities. The best imaging modality for triage in an acute stroke setting in drip-and-ship models is still the subject of debate.

Objectives

We aimed to assess the diagnostic value of millimeter-sliced noncontrast computed tomography (NCCT) hyperdense middle cerebral artery sign (HMCAS) in itself or associated with clinical data for early detection of LVO in drip-and-ship models of acute stroke management.

Methods

NCCT of patients admitted to the Erasme Hospital, ULB, Brussels, Belgium, for suspicion of acute ischemic stroke between January 1 and July 31, 2017, were collected. Patients with brain hemorrhages were excluded, leading to 122 cases. The presence of HMCAS on NCCT was determined via visual assessment by 6 raters blinded to all other data. An independent rater assessed the presence of LVO on digital subtraction angiography imaging or contrast-enhanced CT angiography (CTA). The sensitivity, false-positive rate (FPR), and accuracy of HMCAS and the dot sign to detect LVO were calculated. The interobserver agreement of HMCAS was assessed using Gwet's AC1 coefficient. Then, on a separate occasion, the first 2 observers rereviewed all NCCT provided with clinical clues. The sensitivity, FPR, and accuracy of HMCAS were recalculated.

Results

HMCAS was found in 21% of the cases and a dot sign was found in 9%. The mean HMCAS sensitivity was 62% (95% CI 45–79%) and its accuracy was 86% (95% CI 79–92%) for detecting LVO. The interobserver reliability coefficient was 80% for HMCAS. Combined with clinical information, HMCAS sensitivity increased to 81% (95% CI 68–94; p = 0.041) and accuracy increased to 91% (95% CI 86–96%).

Conclusion

When clinical data are provided, detection of HMCAS on thinly sliced NCCT could be enough to decide on transfer for thrombectomy in drip-and-ship models of acute stroke management, especially in situations where CTA is less available and referral centers for thrombectomy fewer and further apart.

Intravenous thrombolysis for ischemic stroke with hyperdense middle cerebral artery sign: A meta-analysis

Hyperdense middle cerebral artery sign (HMCAS) on admitting to neuroimaging is reported to have prognostic value for poor outcomes after thrombolysis, while evidence from studies comprising a sufficiently large sample size is limited. To detect prognostic predictors after thrombolysis could help improve therapeutic clinical strategies for acute ischemic stroke. We included prospective and retrospective studies of stroke patients that were treated with intravenous thrombolysis, in which functional outcomes (ie, a modified Rankin scale [mRS]) and systematic intracranial hemorrhage (sICH) were assessed in relation to HMCAS during pretreatment head CT. Random-effects models were used to calculate pooled risk ratios (RR) of poor outcomes and sICH for HMCAS patients as compared to patients without HMCAS. Eleven studies permitted identification of 11 818 patients. The risk of poor outcome at 3 months in the HMCAS-positive group was 1.56-fold the negative group (RR, 1.56; 95% CI 1.50-1.62; P < .001). The sICH risk when comparing both groups was found to be non-significant. Sensitivity analysis regarding studies performing thrombolysis within 3 hours also exhibited significant differences in their functional outcomes (RR, 1.56, 95% CI 1.49-1.62; P < .001) in patients with HMCAS as compared to non-HMCAS patients, although this was true for sICH risk. The presence of HMCAS on pretreatment CT predicts a poor outcome at 3 months after intravenous thrombolysis, while its relationship with the incidence of sICH was found to have no statistic value. Our study implies that more aggressive treatment should be considered for HMCAS patients.

Risk of secondary embolism events during mechanical thrombectomy for acute ischemic stroke: A single-center study based on histological analysis

OBJECTIVE

Secondary embolism (SE) is a common adverse event during mechanical thrombectomy (MT) for acute intracranial large vessel occlusion, which could lead to incomplete revascularization and increased maneuvers. However, the mechanisms behind SE are still unclear. In this study, we aimed to investigate the risk factors of SE, with a focus on clot composition.

PATIENTS AND METHODS

Consecutive patients with retrieved clots were reviewed. Histologic examination for thrombus included Hematoxylin and eosin, Martius Scarlet Blue, immunohistochemistry for von Willebrand factor (VWF). Patients included were assigned to SE or no SE group. The differences in histological composition and clinical characteristics were compared, and logistic regression was conducted for predictors of SE.

RESULTS

Fifty-four patients were included, of which 19 were identified as having an SE. For patients with SE, there was more history of stroke or transient cerebral ischemia (TIA) (57.9 % vs. 28.6 %, p = 0.035), more occlusion located in terminal internal carotid artery (ICA) (63.2 % vs. 25.7 %, p = 0.007), relatively more contact aspiration used as frontline strategy (68.4 % vs. 45.7 %, p = 0.110), and less eTICI2c-3 recanalization achieved (52.6 % vs. 91.4 %, p = 0.003). As for histologic composition, the clots in SE group showed a higher proportion of erythrocyte fractions (42.9 % vs. 26.8 %, p = 0.045), while the other components were comparable with the non-SE group. Multivariate analysis suggested that a history of stroke or TIA (OR 6.45, 95 %CI 1.41-29.44, p = 0.016) and ICA occlusion (OR 8.05, 95 %CI 1.80-36.10, p = 0.006) could independently predict SE.

CONCLUSION

History of TIA or stroke and occlusion in the terminal ICA were found to be independent predictors for SE. Thrombus with a higher erythrocyte fractions might be more fragile. Further studies are needed.

Association Between Thrombus Density and Reperfusion Outcomes Using Different Thrombectomy Strategies: A Single-Center Study and Meta-Analysis

Background: For patients with acute ischemic stroke (AIS), the thrombus density on non-enhanced CT (NECT) indicates the composition of the thrombus, a characteristic that impacts the efficacy of mechanical thrombectomy (MT). A previous meta-analysis suggested a correlation between higher thrombus density and successful reperfusion, but some new studies have drawn different conclusions. This single-center study and meta-analysis aimed to detect the association between thrombus density and reperfusion outcomes based on various thrombectomy strategies.

Methods: We reviewed AIS patients who underwent MT at our center between July 2015 and May 2019. Thrombus density was recorded as mean Hounsfield Unit (HU) value on 1-mm reconstructed NECT, and expanded Thrombolysis In Cerebral Infarction (eTICI) scale was used to evaluate the reperfusion grade. The difference in thrombus density was examined according to reperfusion outcomes. Then, we systematically searched relevant literature on this issue. The random effect model was used to calculate standardized mean difference (SMD), and subgroup analysis was conducted according to MT strategies employed, including stent retriever (SR), contact aspiration (CA), Solumbra (a combination of SR and aspiration), and multiple thrombectomy modalities.

Results: Sixty-four patients with anterior circulation AIS were included in our single-center study with 57 (89.1%) achieving successful reperfusion (eTICI2b-3). Retrospective analysis showed no significant difference in thrombus density between eTICI2b-3 and eTICI0-2a reperfusion (65.27 vs. 62.19, p = 0.462). As for systematic review, 11 studies were included in qualitative analysis, among which 6 had data available for meta-analysis. Pooled result showed that a comparable thrombus density between eTICI2b-3 and eTICI0-2a reperfusion (SMD 0.14, 95%CI −0.28 to 0.57, p = 0.50). Interestingly, in the SR subgroup, eTICI2b-3 reperfusion showed a significant higher thrombus density (SMD 0.53, 95%CI 0.10 to 0.96, p = 0.02), while an inverse trend was observed in the CA subgroup (SMD −0.48, 95%CI −0.88 to −0.07, p = 0.02).

Conclusions: Although the pooled result of meta-analysis did not show a significant association between thrombus density and successful reperfusion, subgroup analysis implicated that the SR technique might be prone to retrieve high-density thrombus, while the CA subgroup showed an opposite tendency. Further studies are needed to confirm these results and to investigate its role in the optimization of thrombectomy strategy.

Correlation of imaging and histopathology of thrombi in acute ischemic stroke with etiology and outcome

Mechanical thrombectomy has become the stand of care for patients with large vessel occlusions, yet major improvements in thrombectomy speed, efficacy, and completeness can still be achieved. High rates of clot fragmentation and failure to remove the clot resulting in poor neurological outcomes suggest that in order to further advance the field of stroke intervention we must turn our attention towards understanding the science of clot. Accurately identifying the composition of the occlusive clot prior to intervention could significantly influence the success of the revascularization strategy used to treat them. Numerous features of thromboemboli could be studied and characterized, including quantitative histomorphometry and diagnostic imaging characteristics. Each of these features might logically predict superior thrombectomy outcomes with one device or another. This article aims to review the current literature on histopathological composition of acute ischemic stroke clots, with a particular focus on the correlation between clot composition and diagnostic imaging, stroke etiology and revascularization outcomes.

Angiographical Identification of Intracranial, Atherosclerosis-Related, Large Vessel Occlusion in Endovascular Treatment

Identification of intracranial, atherosclerosis-related, large vessel occlusion (ICAS-LVO) is important to set up an optimal endovascular treatment strategy, as most ICAS-LVOs require specific endovascular modalities for efficient recanalization. However, there is currently no decisive way to identify ICAS-LVO for endovascular treatment. Instead of the few, non-specific, clinical and imaging findings that operators have depended on, this review focused on the occlusion type, one of angiographical methods to identify the ICAS-LVO. Occlusion type was originally devised for predicting procedural details and endovascular outcomes of ICAS-LVO. Among occlusion types, truncal-type occlusion is regarded as a surrogate marker for ICAS-LVO. Although rare, false positives or negatives in truncal-type occlusion are possible. Nonetheless, occlusion type was easy to apply and reliably predictive of procedural outcomes. Furthermore, occlusion type can be determined prior to the procedure, which could allow it to be more helpful in setting up an optimal strategy before starting endovascular treatment.

Endovascular Treatment of Acute Stroke Due to Intracranial Atherosclerotic Stenosis-Related Large Vessel Occlusion

Endovascular treatment (EVT) has become a standard treatment for acute ischemic stroke due to large vessel occlusion (LVO) in the anterior circulation. However, whether EVT tools used for intracranial atherosclerotic stenosis (ICAS)-related LVO are as safe and effective as for use in embolic LVO remains unclear. There have been only a few studies about EVT for ICAS-related LVO, and these studies revealed that mechanical thrombectomy with a stent retriever or contact aspiration was less effective and more time consuming in ICAS-related LVO than in embolic LVO. Because fast and successful recanalization (defined as modified Thrombolysis in Cerebral Ischemia grade, 2b or 3) is the most critical factor influencing favorable outcomes, it is important to determine the appropriate EVT strategy for fast recanalization of ICAS-related LVO. In this report, we review the results of mechanical thrombectomy using stent retriever or contact aspiration and rescue treatments after failure of mechanical thrombectomy for ICAS-related LVO. Finally, we propose the EVT strategy appropriate for ICAS-related LVO based on a literature review and our experience.

Correlation of imaging and histopathology of thrombi in acute ischemic stroke with etiology and outcome: a systematic review

BACKGROUND AND PURPOSE

Studying the imaging and histopathologic characteristics of thrombi in ischemic stroke could provide insights into stroke etiology and ideal treatment strategies. We conducted a systematic review of imaging and histologic characteristics of thrombi in acute ischemic stroke.

MATERIALS AND METHODS

We identified all studies published between January 2005 and December 2015 that reported findings related to histologic and/or imaging characteristics of thrombi in acute ischemic stroke secondary to large vessel occlusion. The five outcomes examined in this study were (1) association between histologic composition of thrombi and stroke etiology; (2) association between histologic composition of thrombi and angiographic outcomes; (3) association between thrombi imaging and histologic characteristics; (4) association between thrombi imaging characteristics and angiographic outcomes; and (5) association between imaging characteristics of thrombi and stroke etiology. A meta-analysis was performed using a random effects model.

RESULTS

There was no significant difference in the proportion of red blood cell (RBC)-rich thrombi between cardioembolic and large artery atherosclerosis etiologies (OR 1.62, 95% CI 0.1 to 28.0, p=0.63). Patients with a hyperdense artery sign had a higher odds of having RBC-rich thrombi than those without a hyperdense artery sign (OR 9.0, 95% CI 2.6 to 31.2, p<0.01). Patients with a good angiographic outcome had a mean thrombus Hounsfield unit (HU) of 55.1±3.1 compared with a mean HU of 48.4±1.9 for patients with a poor angiographic outcome (mean standard difference 6.5, 95% CI 2.7 to 10.2, p<0.001). There was no association between imaging characteristics and stroke etiology (OR 1.13, 95% CI 0.32 to 4.00, p=0.85).

CONCLUSIONS

The hyperdense artery sign is associated with RBC-rich thrombi and improved recanalization rates. However, there was no association between the histopathological characteristics of thrombi and stroke etiology and angiographic outcomes.