Susceptibility Vessel Sign on MRI Predicts Favorable Clinical Outcome in Patients with Anterior Circulation Acute Stroke Treated with Mechanical Thrombectomy

Susceptibility weighted imaging for detection of thrombus in acute ischemic stroke: A cross-sectional study

Background and Aims

Susceptibility-weighted imaging (SWI) can help in the diagnosis of thrombus within the vessel in acute ischemic stroke, known as susceptibility vessel sign (SVS), and detection of SVS within the vessel can predict treatment modality and outcome. In this study, the purpose is to correlate the SVS on SWI with different parameters of stroke.

Methods

This prospective cross-sectional study enrolled consecutive stroke patients with vessel occlusion on magnetic resonance angiography (MRA) over 1 year. The relationship between SVS on SWI with risk factors, territory involved, and length of thrombus was correlated with the National Institutes of Health Stroke Scale (NIHSS).

Results

A total of 105 patients were enrolled in this study. Sixty-two percent (66 out of 105) of patients showed SVS on SWI with MRA-positive occlusion. A positive correlation was observed between SVS on SWI and the risk factor (p = 0.003, chi-square test), with 86% of patients with heart disease and 47% with hypertension exhibiting SVS. Additionally, a positive correlation was observed between SVS on SWI and territorial occlusion (p = 0.000, chi-square test). A moderate positive correlation was observed between the NIHSS and thrombus length (p = 0.002, Pearson's correlation coefficient), with a Pearson's coefficient of 0.367.

Conclusions

SWI can be useful in identifying the location of the thrombus, and NIHSS can determine the thrombus length in acute stroke. A higher incidence of SVS can be associated with risk factors, and it also depends upon the site of occlusion of the vessel.

Safety and efficacy of stent retrievers plus contact aspiration in patients with acute ischaemic anterior circulation stroke and positive susceptibility vessel sign in France (VECTOR): a randomised, single-blind trial

BACKGROUND

Positive susceptibility vessel sign (SVS) in patients with acute ischaemic stroke has been associated with friable red blood cell-rich clots and more effective recanalisation using stent retrievers versus contact aspiration. We compared the safety and efficacy of stent retrievers plus contact aspiration (combined technique) versus contact aspiration alone as the first-line thrombectomy technique in patients with acute ischaemic anterior circulation stroke and SVS-positive occlusions.

METHODS

Adaptive Endovascular Strategy to the Clot MRI in Large Intracranial Vessel Occlusion (VECTOR) was a prospective, randomised, open-label study with blinded evaluation. Patients with SVS-positive anterior circulation occlusions on pretreatment MRI and arterial puncture within 24 h of symptom onset were enrolled from 22 centres in France. A centralised web-based method was used by interventional neuroradiologists for dynamic randomisation by minimisation. Patients were randomly assigned 1:1 to the combined technique or contact aspiration alone. The primary outcome was expanded Thrombolysis in Cerebral Infarction (eTICI) grade 2c or 3 reperfusion after three or fewer passes on post-treatment angiogram, adjudicated by a blinded independent central imaging core laboratory. The intention-to-treat population was used to assess the primary and secondary outcomes. This trial is registered with ClinicalTrials.gov (NCT04139486) and is complete.

FINDINGS

Between Nov 26, 2019, and Feb 14, 2022, 526 patients were enrolled, of whom 521 constituted the intention-to-treat population (combined technique, n=263; contact aspiration alone, n=258). The median age of participants was 74·9 years (IQR 64·4-83·3); 284 (55%) were female and 237 (45%) male. The primary outcome did not differ significantly between groups (152 [58%] of 263 patients for the combined technique vs 135 [52%] of 258 for contact aspiration; odds ratio [OR] 1·27; 95% CI 0·88-1·83; p=0·19). Procedure-related adverse events occurred in 32 (12%) of 263 patients in the combined technique group and 27 (11%) of 257 in the contact aspiration group (OR 1·14; 0·65-2·00; p=0·65). The most common adverse event was intracerebral haemorrhage (146 [56%] of 259 patients for the combined technique vs 123 [49%] of 251 for contact aspiration; OR 1·32; 0·91-1·90; p=0·13). All-cause mortality at 3 months occurred in 57 (23%) of 251 patients in the combined technique group and 48 (19%) of 247 in the contact aspiration group (OR 1·19; 0·76-1·86; p=0·45), none of which was treatment-related.

INTERPRETATION

The results of the VECTOR trial do not show superiority of the combined stent retriever plus contact aspiration technique over contact aspiration alone in patients with SVS-positive occlusion with respect to achieving eTICI 2c-3 within three passes. These findings support the use of either the combined technique or contact aspiration alone as the initial thrombectomy strategy in patients with acute anterior circulation stroke with SVS on pretreatment MRI.

FUNDING

Cerenovus.

Susceptibility vessel sign, a predictor of long-term outcome in patients with stroke treated with mechanical thrombectomy

BACKGROUND

The absence of the susceptibility vessel sign (SVS) in patients treated with mechanical thrombectomy (MT) is associated with poor radiological and clinical outcomes after 3 months. Underlying conditions, such as cancer, are assumed to influence SVS status and could potentially impact the long-term outcome. We aimed to assess SVS status as an independent predictor of long-term outcomes in MT-treated patients.

METHODS

SVS status was retrospectively determined in consecutive MT-treated patients at a comprehensive stroke center between 2010 and 2018. Predictors of long-term mortality and poor functional outcome (modified Rankin Scale (mRS) ≥3) up to 8 years were identified using multivariable Cox and logistic regression, respectively.

RESULTS

Of the 558 patients included, SVS was absent in 13% (n=71) and present in 87% (n=487) on baseline imaging. Patients without SVS were more likely to have active cancer (P=0.003) and diabetes mellitus (P<0.001) at the time of stroke. The median long-term follow-up time was 1058 days (IQR 533-1671 days). After adjustment for active cancer and diabetes mellitus, among others, the absence of SVS was associated with long-term mortality (adjusted HR (aHR) 2.11, 95% CI 1.35 to 3.29) and poor functional outcome in the long term (adjusted OR (aOR) 2.90, 95% CI 1.29 to 6.55).

CONCLUSION

MT-treated patients without SVS have higher long-term mortality rates and poorer long-term functional outcome. It appears that this association cannot be explained by comorbidities alone, and further studies are warranted.

Impact of smoking on outcomes following endovascular therapy for acute ischemic stroke: A systematic review and meta-analysis

BACKGROUND

Smoking represents a leading risk factor for acute ischemic stroke (AIS). Previous literature has described a "smoking paradox", wherein smokers experience better outcomes following intravenous thrombolysis for AIS. It is unclear whether such a phenomenon exists in smokers undergoing endovascular therapy (EVT) for AIS. To assess outcomes in smokers following EVT for AIS, we conducted a systematic review and meta-analysis.

METHODS

Following the PRISMA guidelines, a systematic literature review of the English language literature was conducted using PubMed, Embase Web of Science, and Scopus. Outcomes of interest included 90-day modified Rankin Scale (mRS) 0-2, thrombolysis in cerebral infarction (TICI) score 2b-3, symptomatic intracranial hemorrhage (sICH), and mortality. We calculated mean difference (MD), pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CI).

RESULTS

Eight studies with 2633 patients comprised our analysis. On average, smokers were 10.14 years (MD  =  10.14, [95% CI  =  -14.49 to -5.79], P-value < 0.001) younger than non-smokers. Smokers achieved mRS 0-2 (OR =  1.82, [95% CI, 1.34-2.48], P-value < 0.001) and TICI 2b-3 (OR =  1.61, [95% CI, 1.19-2.19], P-value  =  0.002) at a higher rate than non-smokers. sICH rates were comparable between smokers and non-smokers (OR =  1.07, [95% CI, 0.62-1.85], P-value  =  0.81). Smokers had a lower rate of 90-day mortality than non-smokers (OR =  0.54, [95% CI, 0.41-0.71], P-value < 0.001).

CONCLUSIONS

In this meta-analysis of eight studies, we found that smokers with AIS undergoing EVT experienced better 90-day outcomes and higher rates of TICI 2b-3. This may be due to baseline differences between smokers and non-smokers, but future studies should explore alternative reasons that could explain this relationship between smoking and AIS treated with EVT.

Negative susceptibility vessel sign might be predictive of complete reperfusion in patients with acute basilar artery occlusion managed with thrombectomy

OBJECTIVES

Negative susceptibility vessel sign (SVS) on pre-thrombectomy MRI has been linked to fibrin-rich thrombus and difficult retrieval in anterior ischemic stroke. However, its impact in posterior circulation-large vessel occlusion stroke (PC-LVOS) has not yet been elucidated. We aim to investigate the relationship of SVS parameters with stroke subtypes and their influence on angiographic and functional outcomes.

METHODS

Prospective thrombectomy registries at two-comprehensive stroke centers were retrospectively reviewed between January 2015 and December 2019 for consecutive MRI-selected patients with PC-LVOS. Two groups were assigned by two independent readers, based on the presence or absence of the SVS (SVS +, SVS -) on MRI-GRE sequence. Multivariate logistic regression analysis was utilized to study primarily the impact of the SVS on the rate of complete recanalization (defined as mTICI 2c/3) at the final series following endovascular thrombectomy (EVT) and whether or not it might influence the efficacy of the frontline EVT strategy. Secondarily, we studied whether the absence of the SVS was predictive of the rate of 90-day functional independence (defined as mRS score < 2). Lastly, both qualitative (SVS +, SVS-) and quantitative (SVS length and diameter) parameters of the SVS were analyzed in association with the puncture to recanalization interval and various stroke etiological subtypes based on TOAST criteria.

RESULTS

Among 1823 patients, 116 were qualified for final analysis (median age, 68 (59-75) years; male, 65%); SVS was detected in 62.9% (73/116) of cases. SVS length was an independent predictor of procedural duration (p = .01) whilst two-layered SVS was inversely associated with the atherosclerosis etiological subtype (aOR = 0.27, 95% CI 0.08-0.89; p = .03). Successful recanalization was achieved in 82% (60/73) vs. 86% (37/43), p = .80 of patients with SVS (+, -) respectively. Only in SVS (+), stentriever (RR 0.59 (0.4-0.88), p = .009), and contact-aspiration (RR 0.82 (0.7-0.96), p = .01) achieved a lower rate of successful recanalization compared to combined technique. SVS (-) was significantly associated with a higher rate of mTICI 2c/3 (aOR = 4.444; 95% CI 1.466-13.473; p = .008) and showed an indirect effect of 9% towards functional independence mediated by mTICI 2c/3.

CONCLUSION

SVS parameters in PC-LVOS might predict stroke subtype and indirectly influence the functional outcome by virtue of complete recanalization.

KEY POINTS

• Negative susceptibility vessel sign (SVS) in patients with basilar occlusion independently predict complete recanalization that indirectly instigated a 3-month favorable outcome following thrombectomy. • The longer the SVS, the higher likelihood of large artery atherosclerosis and the longer the thrombectomy procedure. • Two-layered SVS might be negatively associated with the presence of atherosclerosis, yet already-known limitations of TOAST classification and the absence of pathological analysis should be taken into consideration.

Impact of width of susceptibility vessel sign on recanalization following endovascular therapy

BACKGROUND AND PURPOSE

We aimed to investigate the relationship between arterial recanalization following endovascular therapy and the susceptibility vessel sign (SVS) length and width on susceptibility-weighted imaging.

METHODS

We retrospectively evaluated consecutive patients with anterior circulation ischemic stroke who underwent magnetic resonance imaging preceded endovascular therapy, and measured the SVS length and width. Successful recanalization was defined as expanded thrombolysis in cerebral infarction grade of 2b to 3. Logistic regression analysis was executed to determine the independent predictors of successful recanalization and first-pass reperfusion (FPR) after endovascular therapy.

RESULTS

Among 100 patients, successful recanalization and FPR were observed in 77 and 34 patients, respectively. The median SVS length and width were 10.3 mm (interquartile range, 6.8-14.1 mm) and 4.2 mm (interquartile range, 3.1-5.2 mm), respectively. In multivariate logistic regression analysis, SVS width was associated with successful recanalization (odds ratio, 1.88; 95% confidence interval, 1.14-3.07; p = 0.005) and FPR (odds ratio, 1.38; 95% confidence interval, 1.01-1.89; p = 0.039). The optimal cutoff value for the SVS width to predict successful recanalization and FPR were 4.2 mm and 4.0 mm, respectively.

CONCLUSIONS

Larger SVS width may predict successful recanalization and FPR following endovascular therapy.

Thrombus magnetic susceptibility is associated with recanalization and clinical outcome in patients with ischemic stroke

In acute ischemic stroke patients with large vessel occlusion, the characteristics of the occluding thrombus on neuroimaging may be associated with recanalization after endovascular thrombectomy (EVT); however, the relationship between magnetic susceptibility of thrombus and clinical outcome remains unclear. We utilized quantitative susceptibility mapping (QSM) MRI to assess the magnetic susceptibility of thrombus in acute ischemic stroke patients undergoing EVT, and to evaluate its relationship with recanalization and functional outcomes. Patients with documented intracranial artery occlusion were consecutively recruited from one research center of the RESCUE-RE study (a registration study for Critical Care of Acute Ischemic Stroke After Recanalization). All the recruited patients underwent a 3D multi-echo MRI scan on a 3.0 T scanner for both susceptibility-weighted imaging (SWI) and QSM quantification of the thrombus. Among 61 patients included in the analyses, 51 (75.0 %) patients achieved thrombolysis in cerebral infarction (TICI) 2b/3 and 22 (36.1 %) patients had favorable functional outcomes. Successful recanalization was significantly associated with a higher thrombus magnetic susceptibility mean value (0.27 ± 0.09 vs 0.20 ± 0.09 ppm, p = 0.020) and lower coefficient of variation (0.42 ± 0.12 vs 0.52 ± 0.19, p = 0.024). ROC curve analysis showed the optimal cutoff value for thrombus susceptibility for predicting good clinical outcomes was 0.25 ppm (sensitivity 86.4 %, specificity 69.2 %). In multivariable logistic regression analyses, increased thrombus magnetic susceptibility was independently and significantly associated with good functional outcomes (adjusted odds ratio 15.11 [95 % confidence interval 2.64-86.46], p = 0.002). This study demonstrated that the increased thrombus magnetic susceptibility is associated with successful recanalization and favorable functional outcomes for intracranial artery occluded stroke patients.

Stent-Based Retrieval Techniques in Acute Ischemic Stroke Patients with and Without Susceptibility Vessel Sign

BACKGROUND AND PURPOSE

Randomized controlled trials have challenged the assumption that reperfusion success after mechanical thrombectomy varies depending on the retrieval techniques applied; however, recent analyses have suggested that acute ischemic stroke (AIS) patients showing susceptibility vessel sign (SVS) may respond differently. We aimed to compare different stent retriever (SR)-based thrombectomy techniques with respect to interventional outcome parameters depending on SVS status.

METHODS

We retrospectively reviewed 497 patients treated with SR-based thrombectomy for anterior circulation AIS. Imaging was conducted using a 1.5 T or 3 T magnetic resonance imaging (MRI) scanner. Logistic regression analyses were performed to test for the interaction of SVS status and first-line retrieval technique. Results are shown as percentages, total values or adjusted odds ratio (aOR) with 95% confidence intervals (CI).

RESULTS

An SVS was present in 87.9% (n = 437) of patients. First-line SR thrombectomy was used to treat 293 patients, whereas 204 patients were treated with a combined approach (COA) of SR and distal aspiration. An additional balloon-guide catheter (BGC) was used in 273 SR-treated (93.2%) and 89 COA-treated (43.6%) patients. On logistic regression analysis, the interaction variable of SVS status and first-line retrieval technique was not associated with first-pass reperfusion (aOR 1.736, 95% CI 0.491-6.136; p = 0.392), overall reperfusion (aOR 3.173, 95% CI 0.752-13.387; p = 0.116), periinterventional complications, embolization into new territories, or symptomatic intracerebral hemorrhage. The use of BGC did not affect the results.

CONCLUSION

While previous analyses indicated that first-line SR thrombectomy may promise higher rates of reperfusion than contact aspiration in AIS patients with SVS, our data show no superiority of any particular SR-based retrieval technique regardless of SVS status.

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

Background and Purpose

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

Methods

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

Results

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

Conclusion

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

Selecting the Appropriate First-Line Strategy Based on Hyperdense Vessel Sign in Acute Ischemic Stroke Increases First Pass Recanalization: A Tertiary Center Experience

Background:  The data pertaining to selecting an optimal first-line strategy (stent retriever [SR] vs. contact aspiration [CA]) based on noncontrast computed tomography (NCCT) in cases of acute ischemic stroke consequent to large vessel occlusion (LVO) is lacking.

Aims:  This article studies the influence of hyperdense vessel sign (HVS) in selecting optimal first-line strategy, with intention of increasing first-pass recanalization (FPR).

Methods:  Upfront approach at our center is SR technique with rescue therapy (CA) adoption consequent to three failed SR attempts to achieve successful recanalization. Data of patients with acute LVO who underwent mechanical thrombectomy from June 2017 to May 2020 was retrospectively analyzed. Patients were classified into HVS (+) and HVS (−) cohort. Rate of successful recanalization (first pass, early, and final) and efficacy of rescue therapy was assessed between the two cohorts.

Results:  Of 52 patients included, 28 and 24 were assigned to the HVS (+) and HVS (−) cohort, respectively. FPR was observed in 50% of HVS (+) and 20.9% of HVS (−) ( p  = 0.029). Early recanalization was documented in 64.2% of HVS (+) and 37.5% of HVS (−) ( p  = 0.054). Rescue therapy need was higher in patients not demonstrating HVS ( p  = 0.062). Successful recanalization was achieved with rescue therapy in 50% of HVS (−) group.

Conclusion:  A higher FPR is achievable following individualized first-pass strategy (based on NCCT appearance of clot), instead of a generalized SR first-pass approach. This CT imaging-based strategy is a step closer to achieving primary angiographic goal of FPR.

Quantitative time-of-flight MR angiography for simultaneous luminal and hemodynamic evaluation of the intracranial arteries

PURPOSE

To report a quantitative time-of-flight (qTOF) MRA technique for simultaneous luminal and hemodynamic evaluation of the intracranial arteries.

METHODS

Implemented using a thin overlapping slab 3D stack-of-stars based 3-echo FLASH readout, qTOF was tested in a flow phantom and for imaging the intracranial arteries of 10 human subjects at 3 Tesla. Display of the intracranial arteries with qTOF was compared to resolution-matched and scan time-matched standard Cartesian 3D time-of-flight (TOF) MRA, whereas quantification of mean blood flow velocity with qTOF, done using a computer vision-based inter-echo image analysis procedure, was compared to 3D phase contrast MRA. Arterial-to-background contrast-to-noise ratio was measured, and intraclass correlation coefficient was used to evaluate agreement of flow velocities.

RESULTS

For resolution-matched protocols of similar scan time, qTOF portrayed the intracranial arteries with good morphological correlation with standard Cartesian TOF, and both techniques provided superior contrast-to-noise ratio and arterial delineation compared to phase contrast (20.6 ± 3.0 and 37.8 ± 8.7 vs. 11.5 ± 2.2, P < .001, both comparisons). With respect to phase contrast, qTOF showed excellent agreement for measuring mean flow velocity in the flow phantom (intraclass correlation coefficient = 0.981, P < .001) and good agreement in the intracranial arteries (intraclass correlation coefficient = 0.700, P < .001). Stack-of-stars data sampling used with qTOF eliminated oblique in-plane flow misregistration artifacts that were seen with standard Cartesian TOF.

CONCLUSION

qTOF is a new 3D MRA technique for simultaneous luminal and hemodynamic evaluation of the intracranial arteries that provides significantly greater contrast-to-noise ratio efficiency than phase contrast and eliminates misregistration artifacts from oblique in-plane blood flow that occur with standard 3D TOF.

Susceptibility vessel sign as a predictor for recanalization and clinical outcome in acute ischaemic stroke: A systematic review and meta-analysis

OBJECTIVE

To assess the prognostic values of susceptibility vessel sign (SVS) on T2*-weighted MRI using GRE and SWI sequences for recanalization status and clinical outcomes in patients with acute ischaemic stroke undergoing different therapies.

METHODS

Literature search on PubMed, EMBASE databases and other sources from inception up to 01 June 2021 was conducted. 11 studies which reported SVS, recanalization and clinical outcomes were included in qualitative synthesis and meta-analysis.

RESULTS

Pooled analysis demonstrated significant association between good clinical outcome and SVS-positive patients who underwent mechanical thrombectomy (RR = 1.34, 95% CI = 1.07-1.67, p = 0.01), which is in line with higher recanalization rate in SVS-positive patients who were treated with mechanical thrombectomy compared to intravenous thrombolysis only. No statistically significant association was demonstrated between presence of SVS and successful recanalization, likely due to limitations in the recruited studies.

CONCLUSIONS

Presence of SVS in patients with acute ischaemic stroke who underwent mechanical thrombectomy is associated with good clinical outcome. SVS-positive patients treated with mechanical thrombectomy also shows better recanalization rate comparing to intravenous thrombolysis only, although not statistically significant. MRI assessment of the clot content using SVS is useful in selection of reperfusion strategy for acute ischaemic stroke and prognostication.

SWI Susceptibility Vessel Sign in Patients Undergoing Mechanical Thrombectomy for Acute Ischemic Stroke

BACKGROUND AND PURPOSE

The frequency and clinical significance of the susceptibility vessel sign in patients with acute ischemic stroke remains unclear. We aimed to assess its prevalence in patients with acute ischemic stroke undergoing mechanical thrombectomy and to analyze its association with interventional and clinical outcome parameters in that group.

MATERIALS AND METHODS

Six hundred seventy-six patients with acute ischemic stroke and admission MR imaging were reviewed retrospectively. Of those, 577 met the eligibility criteria for further analysis. Imaging was performed using a 1.5T or 3T MR imaging scanner. Associations between baseline variables, interventional and clinical outcome parameters, and susceptibility vessel sign were determined with multivariable logistic regression models. Results are shown as adjusted ORs with 95% CIs.

RESULTS

The susceptibility vessel sign was present in 87.5% (n = 505) of patients and associated with tandem occlusion (adjusted OR, 3.3; 95% CI, 1.1-10.0; P = .032) as well as successful reperfusion, defined as an expanded TICI score of ≥2b (adjusted OR, 2.4; 95% CI, 1.28-4.6; P = .007). The susceptibility vessel sign was independently associated with functional independence (mRS ≤ 2: adjusted OR, 2.1; 95% CI, 1.1-4.0; P = .028) and lower mortality (adjusted OR, 0.4; 95% CI, 0.2-0.7; P = .003) at 90 days, even after adjusting for successful reperfusion. The susceptibility vessel sign did not influence the number of passes performed during mechanical thrombectomy, the first-pass reperfusion, or the risk of peri- or postinterventional complications.

CONCLUSIONS

The susceptibility vessel sign is an MR imaging phenomenon frequently observed in patients with acute ischemic stroke and is associated with successful reperfusion after mechanical thrombectomy. However, superior clinical functional outcome and lower mortality noted in patients showing the susceptibility vessel sign could not be entirely attributed to higher reperfusion rates.

Absence of susceptibility vessel sign is associated with aspiration-resistant fibrin/platelet-rich thrombi

BACKGROUND

The composition of the thrombus influences its retrievability by mechanical thrombectomy.

PURPOSE

Our study aimed to report on thrombi resistant to aspiration, regarding susceptibility vessel sign and histologic composition.

METHODS

This observational study was based on a prospective database of acute anterior circulation ischemic strokes treated by mechanical thrombectomy. Endovascular first-line strategy was aspiration and in case of failure, combined therapy-rescue was performed. The positivity of susceptibility vessel sign (SVS+) or its negativity (SVS-) was assessed on T2* sequences. The thrombus composition was analyzed with hematoxylin eosin staining.

RESULTS

Histological analysis was performed on 102 clots. Thrombi with SVS- were significantly richer in fibrin/platelets, p = 0.04. Out of 210 mechanical thrombectomy, aspiration first pass strategy was performed in 131/210 (62%) patients. Combined therapy-rescue was needed in 37% of aspiration first pass strategy cases (n = 131). Clots retrieved combined therapy-rescue were richer in fibrin/platelets 63.9% versus 50.8% for aspiration first pass strategy, p = 0.03. Logistic regression analysis showed that fibrin/platelet-poor clots (<60%) were significantly more likely to be recanalized by aspiration first pass strategy compared to fibrin/platelet-rich clots (>60%) that were more likely recanalized by combined therapy-rescue after aspiration first pass strategy failure (OR = 3.5; 95% CI = 1.2-10.8; p = 0.0054).

CONCLUSIONS

Our results confirm that SVS- clots are rich in fibrin/platelets and suggest that these "white clots" are less likely to be retrieved by aspiration alone and more often require the use of combined therapy.

Hyperdense vessel sign as a potential guide for the choice of stent retriever versus contact aspiration as first-line thrombectomy strategy

BACKGROUND

The first-pass effect (FPE) has emerged as a key metric for efficacy in mechanical thrombectomy (MT). The hyperdense vessel sign (HDVS) on non-contrast head CT (NCCT) indicates a higher clot content of red blood cells.

OBJECTIVE

To assess whether the HDVS could serve as an imaging biomarker for guiding first-line device selection in MT.

METHODS

A prospective MT database was reviewed for consecutive patients with anterior circulation large vessel occlusion stroke who underwent thrombectomy with stent retriever (SR) or contact aspiration (CA) as first-line therapy between January 2012 and November 2018. Pretreatment NCCT scans were evaluated for the presence of HDVS. The primary outcome was FPE (modified Thrombolysis in Cerebral Infarction score 2c/3). The primary analysis was the interaction between HDVS and thrombectomy modality on FPE. Secondary analyses aimed to evaluate the predictors of FPE.

RESULTS

A total of 779 patients qualified for the analysis. HDVS and FPE were reported in 473 (60.7%) and 286 (36.7%) patients, respectively. The presence of HDVS significantly modified the effect of thrombectomy modality on FPE (p=0.01), with patients with HDVS having a significantly higher rate of FPE with a SR (41.3% vs 22.2%, p=0.001; adjusted OR 2.11 (95% CI 1.20 to 3.70), p=0.009) and non-HDVS patients having a numerically better response to CA (41.4% vs 33.9%, p=0.28; adjusted OR 0.58 (95% CI 0.311 to 1.084), p=0.088). Age (OR 1.01 (95% CI 1.00 to 1.02), p=0.04) and balloon guide catheter (OR 2.08 (95% CI 1.24 to 3.47), p=0.005) were independent predictors of FPE in the overall population.

CONCLUSION

Our data suggest that patients with HDVS may have a better response to SRs than CA for the FPE. Larger confirmatory prospective studies are warranted.

Association of Time From Stroke Onset to Groin Puncture With Quality of Reperfusion After Mechanical Thrombectomy: A Meta-analysis of Individual Patient Data From 7 Randomized Clinical Trials

Importance

Reperfusion is a key factor for clinical outcome in patients with acute ischemic stroke (AIS) treated with endovascular thrombectomy (EVT) for large-vessel intracranial occlusion. However, data are scarce on the association between the time from onset and reperfusion results.

Objective

To analyze the rate of reperfusion after EVT started at different intervals after symptom onset in patients with AIS.

Design, Setting, and Participants

We conducted a meta-analysis of individual patient data from 7 randomized trials of the Highly Effective Reperfusion Using Multiple Endovascular Devices (HERMES) group. This is a multicenter cohort study of the intervention arm of randomized clinical trials included in the HERMES group. Patients with anterior circulation AIS who underwent EVT for M1/M2 or intracranial carotid artery occlusion were included. Each trial enrolled patients according to its specific inclusion and exclusion criteria. Data on patients eligible but not enrolled (eg, refusals or exclusions) were not available. All analyses were performed by the HERMES biostatistical core laboratory using the pooled database. Data were analyzed between December 2010 and April 2015.

Main Outcomes and Measures

Successful reperfusion was defined as a modified thrombolysis in cerebral infarction score of 2b/3 at the end of the EVT procedure adjusted for age, occlusion location, pretreatment intravenous thrombolysis, and clot burden score and was analyzed in relation to different intervals (onset, emergency department arrival, imaging, and puncture) using mixed-methods logistic regression.

Results

Among the 728 included patients, with a mean (SD) age of 65.4 (13.5) years and of whom 345 were female (47.4%), decreases in rates of successful reperfusion defined as a thrombolysis in cerebral infarction score of 2b/3 were observed with increasing time from admission or first imaging to groin puncture. The magnitude of effect was a 22% relative reduction (odds ratio, 0.78; 95% CI, 0.64-0.95) per additional hour between admission and puncture and a 26% relative reduction (odds ratio, 0.74; 95% CI, 0.59-0.93) per additional hour between imaging and puncture.

Conclusions and Relevance

Because the probability of reperfusion declined significantly with time between hospital arrival and groin puncture, we provide additional arguments for minimizing the intervals after symptom onset in anterior circulation acute ischemic stroke.

"Adaptative endovascular strategy to the CloT MRI in large intracranial vessel occlusion" (VECTOR): Study protocol of a randomized control trial

A correlation between the susceptibility vessel sign (SVS) and red thrombi has been identified in MRI. We hypothesized that the Embotrap allow better retrieving of SVS+ thrombi. The AdaptatiVe Endovascular strategy to the CloT MRI in large intracranial vessel Occlusion (VECTOR) trial is a multicenter, prospective and randomized study designed to compare a first-line strategy combining Embotrap added to contact aspiration (CA) versus CA alone in patients with SVS+ occlusions.

A Direct Aspiration First Pass Technique vs Standard Endovascular Therapy for Acute Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

The direct aspiration first pass technique (ADAPT) is a recent endovascular treatment for ischemic stroke due to large vessel occlusion that has been gaining popularity due to the rapidity of the technique and the potential for cost savings in comparison to standard thrombectomy methods such as stent retrievers. However, few studies have directly compared these 2.

OBJECTIVE

To compare ADAPT with stent retrievers for thrombectomy via systematic review and meta-analysis.

METHODS

Ovid Medline, PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, ACP Journal Club, and Database of Abstracts of Review of Effectiveness limited to English through September 2016 were systematically searched. Eligible studies included those in which patient cohorts underwent ADAPT for acute stroke. Recanalization efficiency, clinical outcomes, and complication rates of ADAPT were compared with the current standard of endovascular thrombectomy techniques.

RESULTS

Seventeen studies on ADAPT and 5 randomized controlled trials on endovascular therapy were included. ADAPT achieved higher rates of complete revascularisation (89.4% vs 71.7%, P < .001) but similar clinical outcomes compared to front-line endovascular therapy. Seventy-one point four percent of ADAPT cases were successfully recanalized with aspiration alone, and a trend towards reduced time from groin puncture to recanalization time was noted (44.77 vs 61.46 min, P = .088).

CONCLUSION

The pooled results are comparable with recent randomized studies that demonstrate the benefit of endovascular therapy over intra-arterial medical therapy. Future direct comparative studies and randomized trials are required to confirm the benefit of the ADAPT strategy compared to standard endovascular therapy for acute ischemic stroke.

Meta-analysis of the Smoker’s Paradox in Acute Ischemic Stroke Patients Receiving Intravenous Thrombolysis or Endovascular Treatment

Introduction

The existence of the smoker’s paradox is controversial and potential mechanisms have not been explained. We aimed to explore the association between cigarette smoking and functional outcome at 3 months in patients with acute ischemic stroke who were treated with intravenous thrombolysis (IVT) or endovascular treatment (EVT).

Methods

This meta-analysis was conducted in accordance with the PRISMA guidelines. Studies exploring the association between smoking and good functional outcome (modified Rankin Scale score ≤ 2) following IVT or EVT were searched via the databases of PubMed, Embase, and the Cochrane Library from inception to August 8, 2018. Information on the characteristics of included studies was independently extracted by two investigators. Data were pooled using a random-effects or fixed-effects meta-analysis according to the heterogeneity of included studies.

Results

Among 20 identified studies, 15 reported functional outcomes following IVT, and five reported functional outcomes following EVT. Unadjusted analyses showed that smoking increased the odds of good functional outcomes with a pooled odds ratio (OR) of 1.48 (95% confidence interval [CI]: 1.36–1.60) after IVT and 2.10 (95% CI: 1.47–3.20) after EVT. Of IVT studies, only eight reported outcomes adjusted for covariates and none of the EVT studies reported adjusted outcomes. After adjustment, the relation between smoking and good functional outcome following IVT lost statistical significance (OR 1.14 [95% CI: 0.81–1.59]).

Conclusion

Our meta-analysis suggested that smoking was not associated with good functional outcome (mRS ≤ 2) at 3 months in patients with acute ischemic stroke who were treated with intravenous thrombolysis.

Implications

The existence of the smoker’s paradox is controversial. A previous letter by Plas et al. published in 2013 reported a positive result for the association between smoking and good functional outcome at 3 months in acute ischemic stroke patients who received intravenous thrombolysis (IVT). However, a major limitation of their meta-analysis was that the process of data synthesis was based on unadjusted data. Therefore, we conducted this meta-analysis to investigate the association based on adjusted data and a larger sample size. Our meta-analysis suggested that smoking was not associated with good functional outcome after adjusting for covariates.

[Reperfusion therapy in patients with minor or mild ischemic stroke]

A significant number of patients with minor or mild stroke symptoms on initial presentation subsequently develop neurological deterioration and poor clinical outcomes at hospital discharge. The presence of an underlying large vessel occlusion is a strong predictor of both clinical worsening and poor outcome. Although patients with a low baseline National Institutes of Health Stroke Scale (NIHSS) could have been included in some randomized controlled trials, the benefits of the mechanical thrombectomy for patients with a low NIHSS score are unknown. The causes of neurological deterioration in patients with underlying large vessel occlusion are heterogeneous, but include collateral failure, and no straightforward mechanisms are found in the majority of cases. Patients with internal carotid artery occlusion, but with a patent middle cerebral artery (MCA), can occasionally have good collateral circulation and develop only minor or mild stroke. These patients exhibit collateral MCA flow via the circle of Willis despite ipsilateral internal carotid artery occlusion. However, thrombus migration may cause occlusion of collateral MCA flow, leading to dramatic neurological deterioration. Careful observation and detailed assessment are required for the management of these patients. Recent studies have examined the efficacy and optimal timing of thrombolysis or mechanical thrombectomy for patients with minor or mild stroke. Herein, we review the mechanisms of neurological deterioration, and the efficacy of reperfusion therapy, for patients with minor or mild stroke.

The different clinical value of susceptibility vessel sign in acute ischemic stroke patients under different interventional therapy: A systematic review and meta-analysis

Acute ischemic stroke (AIS) subtype, one of the most important factors for selecting therapeutic strategies, is difficult to be accurately diagnosed at admission sometimes. The magnetic susceptibility effect of deoxygenated hemoglobin in red thrombi appeared as hypointense signals in magnetic resonance imaging (MRI) scans. The prognostic value of susceptibility vessel sign (SVS) for stroke subtype, recanalization and outcomes in AIS patients will be comprehensively determined in the present study. A comprehensive search of databases was conducted including the PubMed, Embase, and Cochrane Library from inception up to August 2017. Statistical tests were performed to check for heterogeneity and publication bias. Subgroup and sensitivity analysis were also conducted to evaluate the robustness of the conclusions. Overall, 21 studies including 1832 patients were identified. The presence of SVS was significantly associated with cardioembolic stroke than absence of SVS (RR = 1.53, 95% CI = 1.30-1.81, p < 0.001). The patients with SVS were less likely to achieve recanalization (RR = 0.70, 95% CI = 0.56-0.88, p = 0.002) and poor functional outcome (RR = 1.68, 95% CI = 1.44-1.97, p < 0.001) after intravenous thrombolysis (IVT), whereas it was similar between two group after endovascular treatment (EVT) (p = 0.990 and p = 0.335). The SVS length was smaller in recanalization group than that in non-recanalization group (RR = -0.49, 95% CI = -0.72 to -0.27, p < 0.001), however, no significant difference between SVS width and recanalization rate was found. The presence of SVS appears to be a stronger predictor of cardioembolic stroke. Furthermore, the SVS was associated with a decreasing recanalization rate and poor outcome in AIS patients after IVT but not after EVT. Which offered a practical information to select optimal therapeutic strategies for stroke patients with SVS though the level of evidence seems to be quite shaky.

Effect of Clot Stiffness on Recombinant Tissue Plasminogen Activator Lytic Susceptibility in Vitro

The lytic recombinant tissue plasminogen activator (rt-PA) is the only drug approved by the Food and Drug Administration for treating ischemic stroke. Less than 40% of patients with large vessel occlusions who are treated with rt-PA have improved blood flow. However, up to 6% of all patients receiving rt-PA develop intracerebral hemorrhage. Predicting the efficacy of rt-PA treatment a priori could help guide therapeutic decision making, such that rt-PA is administered only to those individuals who would benefit from this treatment. Clot composition and structure affect the lytic efficacy of rt-PA and have an impact on elasticity. However, the relationship between clot elasticity and rt-PA lytic susceptibility has not been adequately investigated. The goal of this study was to quantify the relationship between clot elasticity and rt-PA susceptibility in vitro. Human and porcine highly retracted and mildly retracted clots were fabricated in glass pipettes. The rt-PA lytic susceptibility was evaluated in vitro using the percent clot mass loss. The Young's moduli of the clots were estimated using ultrasound-based single-track-location shear wave elasticity imaging. The percent mass loss in mildly retracted porcine and human clots (28.9 ± 6.1% and 45.2 ± 7.1%, respectively) was significantly higher (p < 0.05) than in highly retracted porcine and human clots (10.9 ± 2.1% and 25.5 ± 10.0%, respectively). Furthermore, the Young's moduli of highly retracted porcine and human clots (5.33 ± 0.92 and 3.21 ± 1.97 kPa, respectively) were significantly higher (p < 0.05) than those of mildly retracted porcine and human clots (2.66 ± 0.55 and 0.79 ± 0.21 kPa, respectively). The results revealed an inverse relationship between the percent clot mass loss and Young's modulus. These findings motivate continued investigation of ultrasound-based methods to assess clot stiffness in order to predict rt-PA thrombolytic efficacy.

Validation of overestimation ratio and TL-SVS as imaging biomarker of cardioembolic stroke and time from onset to MRI

OBJECTIVE

We aimed to determine in the "THRACE" trial, the clinical and MRI technical parameters associated with the two-layered susceptibility vessel sign (TL-SVS) and the overestimation ratio (overR).

MATERIALS AND METHODS

Patients with pre-treatment brain gradient echo (GRE) sequence and an etiological work-up were identified. Two readers reviewed TL-SVS, i.e., a SVS with a linear low-intense signal core surrounded by a higher intensity and measured the overR as the width of SVS divided by the width of the artery. Binomial and ordinal logistic regression respectively tested the association between TL-SVS and quartiles of overR with patient characteristics, cardioembolic stroke (CES), time from onset to imaging, and GRE sequence parameters (inter slice gap, slice thickness, echo time, flip angle, voxel size, and field strength).

RESULTS

Among 258 included patients, 102 patients were examined by 3 Tesla MRI and 156 by 1.5 Tesla MRI. Intra- and inter-reader agreements for quartiles of overR and TL-SVS were good to excellent. The median overR was 1.59 (IQR, 1.30 to 1.86). TL-SVS was present in 101 patients (39.2%, 95%CI, 33.1 to 45.1%). In multivariate analysis, only CES was associated with overR quartiles (OR, 1.83; 95%CI, 1.11 to 2.99), and every 60 min increase from onset to MRI time was associated with TL-SVS (OR, 1.72; 95%CI, 1.10 to 2.67). MRI technical parameters were statistically associated with neither overR nor TL-SVS.

CONCLUSION

Independent of GRE sequence parameters, an increased overR was associated to CES, while the TL-SVS is independently related to a longer time from onset to MRI.

KEY POINTS

• An imaging biomarker would be useful to predict the etiology of stroke in order to adapt secondary prevention of stroke. • The two-layered susceptibility vessel sign and the overestimation ratio are paramagnetic effect derived markers that vary according to the MRI machines and sequence parameters. • Independent of sequence parameters, an increased overestimation ratio was associated to cardioembolic stroke, while the two-layered susceptibility vessel sign is independently related to a longer time from onset to MRI.

Characteristic Signs on T2*-Based Imaging and Their Relationship with Results of Reperfusion Therapy for Acute Ischemic Stroke: A Systematic Review and Evidence to Date

PURPOSE

Characteristic signs - the susceptibility vessel sign (SVS) and the prominent hypointense vessel sign (PHVS) - on T2*-based magnetic resonance imaging (T2*MRI) can be seen for acute ischemic stroke with large artery occlusion. In this study, we investigated the evidence to support our hypothesis that these findings may help to predict outcomes after reperfusion therapy.

MATERIALS AND METHODS

We searched for papers describing SVS and PHVS in patients treated with reperfusion therapy for acute ischemic stroke, and their functional/radiologic outcomes were systematically reviewed.

RESULTS

Nine studies on the SVS and six studies on the PHVS were included. The pooled odds ratio (OR) of recanalization after intravenous thrombolysis or mechanical thrombectomy was not significantly different with the presence of SVS (OR, 0.615; 95% confidence interval [CI], 0.335-1.131 and OR, 0.993; 95% CI, 0.629-1.567). The OR of favorable functional outcome after reperfusion therapy in terms of the presence of PHVS varied (0.083 to 1.831) by study.

CONCLUSION

Our meta-analysis of the published data showed that a SVS was not a predictive factor for recanalization after reperfusion therapy for acute ischemic stroke. Currently, the data available on T2*MRI are too limited to warrant reperfusion therapy in routine practice. More data are needed from studies with randomized treatment allocation to determine the role of T2*MRI.

Susceptibility vessel sign on MRI predicts better clinical outcome in patients with anterior circulation acute stroke treated with stent retriever as first-line strategy

BACKGROUND

Susceptibility vessel sign (SVS) can be a useful MRI biomarker of an occlusion but its relationship with clinical outcomes of acute ischemic stroke (AIS) is yet to be fully elucidated.

OBJECTIVE

To investigate SVS in relation to the clinical outcomes after mechanical thrombectomy using a stent retriever (SR) as first-line approach in patients with AIS.

MATERIAL AND METHODS

We included patients with a first-line SR approach for anterior AIS from the the Contact Aspiration vs Stent Retriever for Successful Revascularization (ASTER) and THRombectomie des Artères CErebrales (THRACE) trials when both baseline imaging of SVS and 90-day modified Rankin Scale (mRS) scores were available. Patients were assigned to two groups based on the presence of an SVS (independent core laboratory), and the overall distributions of the mRS score at 90 days (shift analysis) and clinical independence (mRS score ≤2) were compared.

RESULTS

217 patients were included and SVS was diagnosed in 76.0% of cases (n=165, 95% CI 70.4% to 81.7%). After adjustment for potential confounders, SVS+ was significantly associated with 90-day mRS improvement (adjusted common OR=2.75; 95% CI 1.44 to 5.26) and favorable outcome (adjusted common OR=2.76; 95% CI 1.18 to 6.45).

CONCLUSION

Based on results for patients of the ASTER and THRACE trials receiving first-line SR treatment, SVS was associated with lower disability at 3 months. Large prospective studies using MRI-based thrombus evaluation are warranted.

Susceptibility Vessel Sign and Cardioembolic Etiology in the THRACE Trial

PURPOSE

The susceptibility vessel sign (SVS) has been described on gradient echo (GRE) magnetic resonance imaging (MRI) in acute ischemic stroke patients by large vessel occlusion. The presence of SVS (SVS+) was associated with treatment outcome and stroke etiology with conflicting results. Based on multicenter data from the THRombectomie des Artères CErebrales (THRACE) study, we aimed to determine if the association between SVS and cardioembolic etiology (CE) was independent of GRE sequence parameters.

MATERIAL AND METHODS

Patients with a pretreatment brain GRE sequence were identified. Logistic regression tested the association between SVS+, CE, time from onset to imaging and GRE sequence parameters (e.g. echo time, voxel size, field strength). We calculated the sensitivity, specificity, positive and negative predictive values (PPV and NPV) for the SVS to predict a stroke from a CE.

RESULTS

An SVS+ was observed in 237 out of 287 (83%) patients. In the univariate analysis, there was a significant association between SVS+ and a CE with an odds ratio (OR) and 95% confidence interval (95% CI) of 2.10 (1.02-4.29), respectively (p = 0.04) but not with GRE sequence parameters. In multivariate analysis, there was an independent relationship between SVS+ and CE (OR [95% CI]: 2.14 [1.02-4.45], p = 0.04). Sensitivity and specificity of SVS+ to predict CE were 0.89 and 0.21, respectively. The PPV and NPV of SVS+ were 0.44 and 0.78, respectively.

CONCLUSION

The presence of SVS is associated to CE, independent of GRE sequence parameters. While the specificity and the PPV of the sign were low, CE seems less likely in the absence of an SVS.

Susceptibility Vessel Sign in the ASTER Trial: Higher Recanalization Rate and More Favourable Clinical Outcome after First Line Stent Retriever Compared to Contact Aspiration

Background and Purpose

In the Aspiration vs. Stent Retriever for Successful Revascularization (ASTER) trial, which evaluated contact aspiration (CA) versus stent retriever (SR) use as first-line technique, the impact of the susceptibility vessel sign (SVS) on magnetic resonance imaging (MRI) was studied to determine its influence on trial results.

Methods

We included patients having undergone CA or SR for M1 or M2 occlusions, who were screened by MRI with T2^* gradient recalled echo. Occlusions were classified as SVS (+) or SVS (–) in each randomization arm. Modified thrombolysis in cerebral infarction (mTICI) 2b, 2c, or 3 revascularization rates were recorded and clinical outcomes assessed by the overall distribution of modified Rankin scale (mRS) at 90 days.

Results

Among the 202 patients included, 143 patients were SVS (+) (70.8%; 95% confidence interval [CI], 64.5% to 77.1%). Overall, there was no difference in angiographic and clinical outcomes according to SVS status. However, compared to SR, CA achieved a lower mTICI 2c/3 rate in SVS (+) patients (risk ratio [RR] for CA vs. SR, 0.60; 95% CI, 0.51 to 0.71) but not in SVS (–) (RR, 1.11; 95% CI, 0.69 to 1.77; P for interaction=0.018). A significant heterogeneity in favor of superiority of first-line SR strategy in SVS (+) patients was also found regarding the overall mRS distribution (common odds ratio for CA vs. SR, 0.40 vs. 1.32; 95% CI, 0.21 to 0.74 in SVS (+) vs. 95% CI, 0.51 to 3.35 in SVS (–); P for interaction=0.038).

Conclusions

As a first line strategy, SR achieved higher recanalization rates and a more favourable clinical outcome at 3 months compared to CA when MRI shows SVS within the thrombus.

Procedural and clinical outcomes of endovascular recanalization therapy in patients with cancer-related stroke

Objective Embolism due to coagulopathy might be the main pathomechanism underlying cancer-related stroke (CRS). CRS patients with a large artery occlusion could be candidates for endovascular recanalization therapy (ERT), although its procedural and clinical outcomes are not well known. This study aimed to investigate the procedural and clinical outcomes of ERT in CRS patients and the characteristics associated with outcomes compared with those of conventional stroke patients. Methods A registry of consecutive acute ischemic stroke patients who underwent ERT between January 2011 and October 2015 was retrospectively reviewed. CRS patients are described as those who had (a) cryptogenic stroke with advanced or metastatic cancer; (b) no other possible causes of stroke such as cardioembolism (CE) and large artery atherosclerosis (LAA); and (c) elevated D-dimer levels or diffusion-restricted lesions in multiple vascular territories. We compared procedural and clinical outcomes at discharge among CRS, CE, and LAA patients. Results A total of 329 patients were finally enrolled in this study; of these, 19 were CRS patients. The rate of successful recanalization, defined as modified treatment in cerebral infarction grade 2b or 3, was lower in the CRS group than in the LAA and CE groups (63% versus 84% versus 84%, p = .06). CRS subtype was an independent predictor for successful recanalization after ERT in the multivariate analysis (odds ratio, 0.317; 95% confidence interval, 0.116-0.867; p < .001). No significant difference in the rate of good clinical outcomes at discharge was observed among groups. Conclusions Although clinical outcomes at discharge were similar for CE and LAA patients, complete recanalization seemed more difficult to achieve in CRS patients than in conventional stroke patients.

Three-dimensional black blood contrast enhanced magnetic resonance imaging in patients with acute ischemic stroke and negative susceptibility vessel sign

PURPOSE

The purpose of this study was to evaluate the enhancement patterns of three-dimensional (3D) black blood (BB) contrast enhanced magnetic resonance (MR) imaging in acute stroke patients with negative susceptibility vessel sign (SVS).

MATERIALS AND METHODS

From January 2014 to August 2016 we retrospectively reviewed MR imaging and MR angiography findings of patients who presented with acute stroke symptoms of less than 24 h duration. For the 394 patients enrolled, we assessed the frequency of patients who exhibited negative SVS on susceptibility weighted MR imaging (SWI) and positive enhancement in 3D BB contrast enhanced MR imaging. We subdivided the enrolled group according to whether the MR angiography findings suggested stenosis (stenosis group) or occlusion (occlusion group). Enhancement patterns on BB contrast enhanced MR imaging were compared between the two groups according to several qualitative parameters: intensity (weak or strong), morphology (linear/eccentric or round/concentric), length (focal or segmental) and multiplicity (single or multiple).

RESULTS

Sixty-two of 394 patients (15.7%) showed positive findings on BB contrast-enhanced MR imaging with negative SVS. Forty-two patients were classified into the stenosis group, and 20 patients were assigned to the occlusion group. Enhancement patterns of the stenosis group showed weak intensity, linear or eccentric morphology and focal lesion length on BB contrast enhanced MR imaging, compared to the occlusion group (P < 0.001). In contrast, enhancement patterns of the occlusion group showed strong intensity, round or concentric morphology and longer segmental lesion length, compared to the stenosis group (P < 0.001).

CONCLUSION

Three-dimensional BB contrast enhanced MR imaging in acute stroke patients with stenotic lesions and negative SVS shows enhancement patterns of linear or eccentric morphology and shorter, more focal lesions.

Erythrocyte Fraction Within Retrieved Thrombi Contributes to Thrombolytic Response in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Recent advent of endovascular thrombectomy (EVT) enables us to provide a new perspective on the use of tPA (tissue-type plasminogen activator) through histological analysis of retrieved thrombus. We investigated the responsiveness of intravenous thrombolysis (IVT) according to the thrombus composition in EVT-attempted patients with acute ischemic stroke.

METHODS

We reviewed 92 consecutive patients with anterior circulation stroke who received combined IVT and EVT for 2 years. IVT responsiveness is defined as any decrease in the clot burden from baseline computed tomographic angiography to digital subtraction angiography during EVT. We histologically analyzed the relative fractions of red blood cells (RBCs), congregated fibrin and platelets, and white blood cells in the retrieved thrombi using semiautomated color-based segmentation method. Clinical characteristics according to the RBC fraction were investigated, and associated factors with IVT responsiveness were explored.

RESULTS

Fifty-two patients with histological analyses were stratified into lowest, middle, and highest tertiles of RBC fraction. Toward higher RBC fraction, there was more common susceptibility vessel signs on magnetic resonance imaging (50.0% versus 66.7% versus 91.7%; P=0.022) and prevalent IVT responsiveness (25.0% versus 41.7% versus 75.0%; P=0.010). IVT-responsive group (n=23) had higher RBC fraction (45.7±15.5% versus 35.9±12.2%; P=0.010), lower fibrin and platelet (50.4±14.0% versus 58.5±11.1%; P=0.027), and lower white blood cells fraction (3.9±2.1% versus 5.5±3.0%; P=0.027) than IVT-unresponsive group (n=29). After adjusting for potential variables, RBC fraction (odds ratio, 1.05; 95% confidence interval, 1.01-1.10) remained only independent determinant of IVT responsiveness.

CONCLUSIONS

In EVT-attempted patients with acute ischemic stroke, IVT responsiveness would be closely associated with RBC fraction.

Is bridging therapy still required in stroke due to carotid artery terminus occlusions?

INTRODUCTION

Studies comparing endovascular stroke treatment using mechanical thrombectomy (MT) with or without prior IV tissue plasminogen activator (tPa) have included only 30% of internal carotid artery terminus occlusions (ICA-O), a known predictor of recanalization failure with IV tPa.

OBJECTIVE

To carry out a retrospective multicenter analysis of prospectively collected data of consecutive patients to investigate the impact of intravenous thrombolysis on ICA-O by comparing patients treated with MT alone or bridging therapy (BT).

MATERIAL AND METHODS

Patients with ICA-O treated with MT alone or BT were retrospectively examined and compared. Demographic data, vascular risk factors, treatment modalities, complications, technical and clinical outcomes were recorded. A propensity score (PS) analysis was used to compare modified Rankin Scale (mRS) score at 3 months and intracerebral hemorrhage (ICH) between groups.

RESULTS

141 consecutive patients (60% BT/40% MT) were included between January 2014 and June 2016. Baseline characteristics did not differ between the groups. There was no significant difference in the rate of Thrombolysis in Cerebral Infarction 2b/3, distal emboli, and median number of passes between the groups. There was a significant difference between BT and MT groups in the median time between imaging and groin puncture (median 97 min vs 75, p=0.007), the rate of ICH (44% vs 27%, p=0.05), but not for symptomatic ICH (18% vs 13%, p=0.49). With PS, there was a trend towards a higher rate of ICH (OR=2.3, 95% CI 0.9 to 5.9, p=0.09) in the BT group compared with the MT alone group, with no difference in mRS score ≤2 at 3 months (OR=1.6, 95% CI 0.7 to 3.7, p=0.29).

CONCLUSION

There was no significant difference in clinical outcomes between patients receiving bridging therapy versus direct thrombectomy. Bridging therapy delayed time to groin puncture and increased ICH rate.

Can clot density predict recanalization in acute ischemic stroke treated with intravenous tPA?

Stroke has become an absolute emergency that is treated by additional endovascular means or by replacing pharmacological options. Modern neuroradiological techniques such as computed tomography (CT) allow us to examine multiple parameters of the diseased brain. These focused on the parenchyma and hemodynamics for pretherapeutic decisions. However, it has become evident that the clot is the current target for interventional measures. Clot length is established as a marker for recanalization. The dense artery sign is known as an acute CT sign of stroke that is readily visible on acute nonenhanced CT. The rationale behind our study was to study if clot density might represent clot vulnerability or resistance to treatment. We conducted a prospective study of all consecutive stroke patients admitted to our hospital over 1 year, who presented with signs of acute middle cerebral artery stroke within the therapeutic window, and who underwent either intravenous or combined intravenous and intra-arterial thrombolysis. All patients were evaluated with a complete stroke CT protocol, transcranial color-coded duplex sonography monitoring, and clinical evaluation with the National Institutes of Health Stroke Scale (NIHSS) score. We measured clot length using planimetry on unenhanced CT and measured Hounsfield units in the clots on the same images. A total of 31 patients were included in the study (19 men, 12 women, aged 35–90 years). We found that patients with a longer clot on the unenhanced CT had a higher NIHSS score, confirming previous literature. However, we found that patients with a lower clot density recanalized to a more marked degree and had a better clinical outcome. Patients who did not recanalize had a higher clot density (49 Hounsfield units) than those who did recanalize (23 Hounsfield units). Overall, measuring the clot seems to be an important additional parameter to be taken into account. In our study, CT clot density seems to correlate with clinical outcome and recanalization. The higher density seems to represent a higher red blood cell content. This is evidence that clot composition could play a much more important role in acute stroke than thought until now and characterizing it with imaging may help in choosing the adequate treatment modality. Higher density seems to reflect erythrocyte content. Therefore, patients with a longer and denser clot may necessitate direct thrombectomy.

MRI quantitative T2* mapping on thrombus to predict recanalization after endovascular treatment for acute anterior ischemic stroke

BACKGROUND

In anterior acute ischemic stroke (AAIS) treated with endovascular treatment (EVT), the susceptibility vessel sign (SVS+ or SVS-) is related to recanalization results (TICI 2b/3) and clinical outcome. However, a binary qualitative assessment of thrombus using SVS does not reflect its complex composition. Our aim was to assess whether a quantitative MRI marker, Thrombus-T2* relaxation time, may be assessable in clinical routine and may to predict early successful recanalization after EVT, defined as a TICI 2b/3 recanalization obtained in 2 attempts or less.

MATERIAL AND METHODS

Thrombus-T2* relaxation time was prospectively obtained from consecutive AAIS patients treated by EVT (concomitant aspiration and stent retriever). Quantitative values were compared between early recanalization and late or unsuccessful recanalization.

RESULTS

Thirty patients with AAIS were included and Thrombus-T2* relaxation time was obtained in all patients. Earlier TICI 2b/3 recanalization were obtained in 22 patients (73%) and was significantly associated with SVS+ (1/8 vs. 16/22, P=0.01) and a shorter Thombus-T2* relaxation time (mean SD, range: 257, 18-50ms vs. 45 9, 35-60ms, P<0.001).

CONCLUSION

A new quantitative MRI biomarker, the Thrombus-T2* relaxation time is assessable in clinical routine. In a preliminary study of 30 patients, a shorter Thombus-T2* relaxation time is related to earlier recanalization after EVT using combination of stent retriever and aspiration.

Prediction of Stroke Subtype and Recanalization Using Susceptibility Vessel Sign on Susceptibility-Weighted Magnetic Resonance Imaging

Supplemental Digital Content is available in the text.

Background and Purpose—

The susceptibility vessel sign (SVS) is a hypointense signal visualized because of the susceptibility effect of thrombi, sensitively detected on susceptibility-weighted magnetic resonance imaging. The relationship of SVS parameters with the stroke subtype and recanalization status after endovascular treatment remains uncertain.

Methods—

The data from 89 patients with acute stroke caused by anterior circulation infarcts who underwent susceptibility-weighted magnetic resonance imaging before endovascular treatment were examined. Independent reviewers, blinded to the stroke subtype and recanalization status, measured the SVS diameter, length, and estimated volume. The intra- and interrater agreements of the SVS parameters were assessed.

Results—

The SVS was identified in 78% of the patients. SVS was more commonly associated with cardioembolism than with noncardioembolism (P=0.01). The SVS diameter (P<0.01) and length (P=0.01) were larger in the cardioembolism group. The SVS diameter was larger in the recanalization group (thrombolysis in cerebral infarction ≥2b) than in the nonrecanalization group (P=0.04). Multivariable analysis revealed that the SVS diameter was an independent predictor of cardioembolism (adjusted odds ratio, 1.97; 95% confidence interval, 1.34–2.90; P<0.01). There was no significant association between the SVS volume and the recanalization status (adjusted odds ratio, 1.003; 95% confidence interval, 0.999–1.006; P=0.12). The optimal cutoff value of the SVS diameter for the cardioembolism was 5.5 mm (sensitivity, 45.6%; specificity, 93.8%).

Conclusions—

Increased SVS diameter on susceptibility-weighted magnetic resonance imaging may predict cardioembolism. No clear association was found between SVS volume and endovascular recanalization.

Special Endovascular Treatment for Acute Large Artery Occlusion Resulting From Atherosclerotic Disease

BACKGROUND

Acute intracranial atherosclerotic disease (IAD)-related large artery occlusion (LAO) is typically refractory to mechanical thrombectomy. We evaluated the feasibility and safety of emergency balloon-assisted or stent-assisted angioplasty performed with tirofiban administration for acute IAD-related LAO.

METHODS

We identified, from among 55 consecutive patients who underwent endovascular treatment for LAO, 12 patients with acute IAD-related LAO who underwent balloon-assisted or stent-assisted angioplasty with (n = 3) or without passage of a stent retriever. The treatment included tirofiban administration. We obtained, from patients' clinical records, thrombolysis in cerebral infarction scores (to assess the extent of reperfusion), follow-up magnetic resonance angiography images (to assess patency of the responsive arteries), and 90-day modified Rankin (mRS) scores (to assess outcomes).

RESULTS

Temporary blood flow and severe stenosis were observed angiographically in all 12 patients, either when the stent retriever was deployed or when a microcatheter was advanced through the site of occlusion. Persistent recanalization was achieved in all patients, and there was no operative complication or arterial reocclusion. All 8 patients with an occluded major artery in the anterior circulation had a good outcome, with an mRS score of ≤2. Two of the 4 patients with basilar artery occlusion had a good outcome, with an mRS score of ≤2. One patient (25%) died within 72 hours after procedure.

CONCLUSIONS

Our data point to the safety and feasibility of emergency balloon-assisted or stent-assisted angioplasty performed with tirofiban administration and a single or no passage of the stent retriever for acute IAD-related LAO.

Patient Selection and Clinical Efficacy of Urgent Superficial Temporal Artery-Middle Cerebral Artery Bypass in Acute Ischemic Stroke Using Advanced Magnetic Resonance Imaging Techniques

BACKGROUND: Selected patients with acute ischemic stroke might benefit from superficial temporal artery-middle cerebral artery (STA-MCA) bypass, but the indications for urgent STA-MCA bypass are unknown.

OBJECTIVE: To report our experiences of urgent STA-MCA bypass in patients requiring urgent reperfusion who were ineligible for other reperfusion therapies, using advanced magnetic resonance imaging (MRI) techniques.

METHODS: The inclusion criteria for urgent STA-MCA bypass were as follows: acute infarct volume &lt;70 mL with a ratio of perfusion/diffusion lesion volume ≥1.2, and a regional cerebral blood volume ratio &gt;0.85. From January 2013 to October 2015, 21 urgent STA-MCA bypass surgeries were performed. The control group included 19 patients who did not undergo bypass surgery mainly due to refusal of surgery or the decision of the neurologist. Clinical and radiological data were compared between the surgery and control group.

RESULTS: The median age of the control group (70 years, interquartile range [IQR] 58-76) was higher than that of the surgery group (62 years, IQR 49-66), but the median preoperative diffusion and perfusion lesion volumes of the surgery group (13.8 mL, IQR 7.5-26.0 and 120.9 mL, IQR 84.9-176.0, respectively) were higher than those of the control group (5.6 mL, IQR 2.1-9.1 and 69.7 mL, IQR 23.9-125.3, respectively). Sixteen (76.2%) patients in the surgery group and 2 (10.5%) patients in the control group had favorable outcomes (P &lt; .001). Logistic regression analysis identified bypass surgery as the strongest predictive factor.

CONCLUSION: STA-MCA bypass can be used as a therapeutic tool for acute ischemic stroke. Advanced MRI techniques are helpful for selecting patients and for decision making.

ASL and susceptibility-weighted imaging contribution to the management of acute ischaemic stroke

Abstract

Magnetic resonance imaging (MRI) plays a central role in the early diagnosis of cerebral vascular events. Today, MRI is used not only for the detection of acute ischaemic lesions, but also to fine tune the diagnosis and improve patient selection for early therapeutic decision-making. In this perspective, new tools such as arterial spin labelling (ASL) and susceptibility-weighted imaging (SWI) sequences have been developed. These MRI sequences enable noninvasive assessment of brain damage, providing important diagnostic and prognostic information: evaluation of cerebral parenchymal perfusion; detection and aetiological assessment of thrombi; ruling out differential diagnoses. After a brief recall of the fundamental basis of these sequences, this article proposes an update on their current contribution to the early management of stroke victims.

Teaching Points

• These noninvasive sequences provide essential information for early management of acute stroke.

• They can detect zones of parenchymal hypoperfusion.

• Susceptibility-weighted sequences provide information on thrombus localisation and composition.

• ASL can identify certain aetiologies of stroke mimics.

• Post-therapeutic ASL perfusion status predicts outcome.