Unknown-onset strokes with anterior circulation occlusion treated by thrombectomy after DWI-FLAIR mismatch selection

Multicenter validation of synthetic FLAIR as a substitute for FLAIR sequence in acute ischemic stroke

PURPOSE

To evaluate performance of synthetic and real FLAIR for identifying early stroke in a multicenter cohort.

METHODS

This retrospective study was conducted using DWI and FLAIR extracted from the Endovascular Treatment in Ischemic Stroke image registry (2017-2021). The database was partitioned into subsets according to MRI field strength and manufacturer, and randomly divided into training set (70%) used for model fine-tuning, validation set (15%), and test set (15%). In test set, five readers, blinded to FLAIR sequence type, assessed DWI-FLAIR mismatch using real and synthetic FLAIR. Interobserver agreement for DWI-FLAIR rating and concordance between synthetic and real FLAIR were evaluated with kappa statistics. Sensitivity and specificity for identification of ⩽4.5 h AIS were compared in patients with known onset-to-MRI delay using McNemar's test.

RESULTS

1454 complete MRI sets (1172 patients, median (IQR) age: 73 years (62-82); 762 women) acquired on 125 MRI units were analyzed. In test set (207 MRI), interobserver reproducibility for DWI-FLAIR mismatch labeling was substantial for real and synthetic FLAIR (Fleiss κ = 0.79 (95%CI: 0.73-0.84) and 0.77 (95%CI: 0.71-0.82), respectively). After consensus, concordance between real and synthetic FLAIR was excellent (κ = 0.85 (95%CI: 0.78-0.92)). In 141 MRI sets with known onset-to-MRI delay, diagnostic performances for ⩽4.5 h AIS identification did not differ between real and synthetic FLAIR (sensitivity: 60/71 (85%) vs 59/71 (83%), p = .56; specificity: 65/70 (93%) vs 65/70 (93%), p > 0.99).

CONCLUSION

A deep-learning-based FLAIR fine-tuned on multicenter data can provide comparable performances to real FLAIR for early AIS identification. This approach may help reducing MR protocol duration and motion artifacts.

Characteristics and outcomes of unknown onset stroke: The Japan Stroke Data Bank

BACKGROUND

Clinical outcomes of unknown onset stroke (UOS) are influenced by the enlargement of the therapeutic time window for reperfusion therapy. This study aimed to investigate and describe the characteristics and clinical outcomes of patients with UOS.

METHODS

Patients with acute ischemic stroke (AIS) who were admitted within 24 h of their last known well time, from January 2017 to December 2020, were included. Data were obtained from a long-lasting nationwide hospital-based multicenter prospective registry: the Japan Stroke Data Bank. The co-primary outcomes were the National Institutes of Stroke Scale (NIHSS) scores on admission and unfavorable outcomes at discharge, corresponding to modified Rankin Scale (mRS) scores of 3-6.

RESULTS

Overall, 26,976 patients with AIS were investigated. Patients with UOS (N = 5783, 78 ± 12 years of age) were older than patients with known onset stroke (KOS) (N = 21,193, 75 ± 13 years of age). Age, female sex, higher premorbid mRS scores, atrial fibrillation, and congestive heart failure were associated with UOS in multivariate analysis. UOS was associated with higher NIHSS scores (median = 8 [interquartile range [IQR]: 3-19] vs. 4 [1-10], adjusted incidence rate ratio = 1.37 [95% CI: 1.35-1.38]) and unfavorable outcomes (52.1 vs. 33.6%, adjusted odds ratio = 1.27 [1.14-1.40]). Intergroup differences in unfavorable outcomes were attenuated among females (1.12 [0.95-1.32] vs. males 1.38 [1.21-1.56], P = 0.040) and in the subgroup that received reperfusion therapy (1.10 [0.92-1.33] vs. those who did not receive therapy 1.23 [1.08-1.39], P = 0.012).

CONCLUSIONS

UOS was associated with unfavorable outcomes but to a lesser degree among females and patients receiving reperfusion therapy.

Cytoskeletal protein breakdown and serum albumin extravasation in MRI DWI-T2WI mismatch area in acute murine cerebral ischemia

MRI diffusion-weighted imaging (DWI)-FLAIR mismatch is known as predictive of symptom onset within 4.5 h. This study assessed the breakdown of cytoskeletal protein and blood-brain barrier (BBB) in DWI-T2 mismatch. We employed occlusion of middle cerebral artery (MCAO) in C57BL/6 mice. We serially measured MRI including DWI and T2WI. After MRI, we prepared brain sections or samples and examined microtubule-associated protein 2 (MAP2) expression, alpha-fodrin degradation, extravasation of albumin and claudin-5 expression. In permanent or transient MCAO for 45 min, DWI hyperintensities was already found at 60 min without change of T2, showing DWI-T2 mismatch. In permanent MCAO, MAP2 expressions were preserved, and no extravasation of albumin was observed. In transient MCAO, MAP2 immunoreaction was already lost in the lateral part of the striatum. In both models, alpha-fodrin degradation was already detected. At 180 min, T2 hyperintensities appeared, where MAP2 signal was lost and albumin extravasation was found. At 24 h, hyperintensities of DWI and T2WI was found in the whole MCA territory, where MAP2 signal was completely lost with marked albumin extravasation and alpha-fodrin degradation. Immunoreaction for claudin-5 was preserved up to 180 min. DWI-T2 mismatch area may not always indicate intactness of cytoskeletal protein but shows preservation of BBB.

Outcome of Stroke Patients with Unknown Onset and Unknown Time Last Known Well Undergoing Endovascular Therapy

PURPOSE

Endovascular treatment (ET) in patients with large vessel occlusion stroke (LVOS) with unknown onset or an extended time window can be safe and effective if patients are selected by defined clinical and imaging criteria; however, it is unclear if these criteria should also be applied to patients with unknown onset and unknown time last known well. In this study, we aimed to assess whether absent information on the time patients were last known to be well impacts outcome in patients with unknown onset LVOS.

METHODS

We analyzed patients who were enrolled in the German Stroke Registry-Endovascular Treatment between 2015 and 2019. Patients with unknown onset and unknown time last known well (LKWu) were compared to patients with known onset (KO) and to patients with unknown onset but known time last known well (LKWk) regarding clinical and imaging baseline characteristics and outcome.

RESULTS

Out of 5909 patients, 561 presented with LKWu (9.5%), 1849 with LKWk (31.3%) and 3499 with KO (59.2%). At 90 days, functional independency was less frequent in LKWu (27.0%) compared to KO (42.6%) and LKWk patients (31.8%). These differences were not significant after adjusting for confounders. A main confounder was the initial Alberta stroke program early CT score.

CONCLUSION

The LKWu patients had a similar outcome after ET as KO and LKWk patients after adjusting for confounders. Thus, ET should not be withheld if the time last known well is unknown. Instead, LKWu patients may be selected for ET using the same criteria as in LKWk patients.

Three Dimensional-Arterial Spin Labeling Evaluation of Improved Cerebral Perfusion After Limb Remote Ischemic Preconditioning in a Rat Model of Focal Ischemic Stroke

Purpose

To investigate the application value of 3D arterial spin labeling (3D-ASL) for evaluating distal limb ischemic preconditioning to improve acute ischemic stroke (AIS) perfusion.

Materials and Methods

A total of 40 patients with AISs treated in our hospital from January 2020 to December 2020 were recruited, and 15 healthy individuals who were examined in our hospital during the same period were included as the control group; all of these participants were scored on the National Institutes of Health Stroke Scale (NIHSS) and examined by MRI. Sequences included conventional sequences, diffusion-weighted imaging (DWI), magnetic resonance angiography (MRA), and 3D-ASL, and cerebral infarct volume and cerebral blood flow (CBF) in the area of the infarct lesion were measured. After 3 months of treatment, patients with AIS were scored on the modified Rankin Scale (mRS) and divided into good prognosis and poor prognosis groups. In total, 55 adult male Sprague–Dawley rats were divided randomly into three groups: 20 in the middle cerebral artery occlusion (MCAO) group, 20 in the MCAO + limb remote ischemic preconditioning (LRP) group, and 15 in the sham group. In total, 48 h after the procedures, conventional MRI, DWI, and 3D-ASL sequence data were collected, and 2,3,5-trphenyltetrazolium chloride monohydrate (TTC) staining and behavioral scoring were performed. CBF was recorded in the infarct lesion area and the corresponding contralateral area, and the affected/contralateral relative values (rCBF) were calculated to compare the differences in rCBF between different groups. The pathological changes in brain tissues were observed by HE staining, and the expression of vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) in brain tissues was detected by immunofluorescence and real-time quantitative polymerase chain reaction (RT-qPCR). The protein expression of VEGF was detected by western blotting.

Results

Hypertension and internal carotid atherosclerosis are high-risk factors for ischemic stroke, and CBF values in the infarct area are significantly lower than those in the corresponding areas on the contralateral side. NIHSS and mRS scores and CBF values have higher specificity and sensitivity for the prognosis of patients with AIS. LRP significantly reduces the infarct area, improves behavioral deficits in rats with cerebral ischemia, reduces neurological injury and histological damage, protects vascular structures, and promotes neovascularization. In addition, 3D-ASL showed a significant increase in brain tissue perfusion in the ischemic area after LRP, and the expression of VEGF and CD31 showed a significant positive correlation with CBF values.

Conclusion

Three dimensional (3D) ASL can be used to evaluate LRP to improve stroke perfusion, and its protective effect may be closely related to LRP-induced vascular regeneration.

Endovascular treatment for wake-up stroke and daytime unwitnessed stroke: A meta-analysis

BACKGROUND

Evidence from sources outside the typical clinical research setting, such as a real-world setting, may complement evidence from randomised controlled trials (RCTs). The aim of the present study was to carry out a meta-analysis of available real-world evidence that focused on the efficacy and safety of endovascular treatment in patients with wake-up stroke (WUS) or daytime unwitnessed stroke (DUS) compared to that in patients treated ≤ 6 h after the onset of an ischemic stroke.

METHODS

Data mining was conducted on 1 May 2021 from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials Cochrane Library. The study reviewed all published that assessed the effect of endovascular treatment in WUS and DUS compared to that received by patients with ischemic stroke. Relevant data were extracted and the narrative was reviewed and analysed. The results were expressed as odds ratios (ORs) with 95% confidence intervals (CIs).

FINDINGS

The meta-analysis showed no significant differences between the two groups in the rates of functional independence (OR, 0.81; 95% CI, 0.65-1.02; P = 0.07), symptomatic intracerebral haemorrhage (OR, 0.86; 95% CI, 0.57-1.30; P = 0.470), and all-cause mortality (OR, 0.92; 95% CI, 0.73-1.16; P = 0.50). There was also no heterogeneity between the trials.

CONCLUSION

The pooled analysis provided evidence to support the use of endovascular treatment in WUS and DUS with favourable perfusion imaging. The meta-analysis confirmed the main findings of RCTs of endovascular treatment in WUS and DUS in a real-world setting and therefore strengthens the validity of this treatment strategy.

Incidence, outcomes, and associated factors of isolated striatocapsular infarct after mechanical thrombectomy

OBJECTIVE

To describe baseline and procedural characteristics and clinical outcomes of isolated striatocapsular infarct (iSCI) after mechanical thrombectomy in patients with large-vessel occlusion of the anterior cerebral circulation and its clinical outcome.

METHODS

We performed a longitudinal study including all patients treated with mechanical thrombectomy at our centre between 2015 and 2017; patients were divided into 2 groups (iSCI and non-iSCI) according to whether they presented iSCI in a control CT scan at 24 hours.

RESULTS

Of the 83 patients identified, 22.9% developed an iSCI. There were no statically significant differences in baseline characteristics or in reperfusion times. Patients presenting iSCI showed better collateral circulation and better reperfusion rates in the bivariate analysis. No significant difference was observed for mortality at discharge or at 3 months, or for functional prognosis at 3 months.

CONCLUSIONS

Even if successful reperfusion is achieved, iSCI is a common sequela, independently of reperfusion time, especially in patients with good collateral circulation.

Incidence, outcomes, and associated factors of isolated striatocapsular infarct after mechanical thrombectomy

OBJECTIVES

To describe baseline and procedural characteristics and clinical outcomes of isolated striatocapsular infarct (iSCI) after mechanical thrombectomy in patients with large-vessel occlusion of the anterior cerebral circulation andits clinical outcome.

METHODS

We performed a longitudinal study including all patients treated with mechanical thrombectomy at our centre between 2015 and 2017; patients were divided into 2 groups (iSCI and non-iSCI) according to whether they presented iSCI in a control CT scan at 24h.

RESULTS

Of the 83 patients identified, 22.9% developed an iSCI. There were no statically significant differences in baseline characteristics or in reperfusion times. Patients presenting iSCI showed better collateral circulation and better reperfusion rates in the bivariate analysis. No significant difference was observed for mortality at discharge or at 3 months, or for functional prognosis at 3 months.

CONCLUSIONS

Even if successful reperfusion is achieved, iSCI is a common sequela, independently of reperfusion time, especially in patients with good collateral circulation.

Synthetic FLAIR as a Substitute for FLAIR Sequence in Acute Ischemic Stroke

Background In acute ischemic stroke (AIS), fluid-attenuated inversion recovery (FLAIR) is used for treatment decisions when onset time is unknown. Synthetic FLAIR could be generated with deep learning from information embedded in diffusion-weighted imaging (DWI) and could replace acquired FLAIR sequence (real FLAIR) and shorten MRI duration. Purpose To compare performance of synthetic and real FLAIR for DWI-FLAIR mismatch estimation and identification of patients presenting within 4.5 hours from symptom onset. Materials and Methods In this retrospective study, all pretreatment and early follow-up (<48 hours after symptom onset) MRI data sets including DWI (b = 0-1000 sec/mm²) and FLAIR sequences obtained in consecutive patients with AIS referred for reperfusion therapies between January 2002 and May 2019 were included. On the training set (80%), a generative adversarial network was trained to produce synthetic FLAIR with DWI as input. On the test set (20%), synthetic FLAIR was computed without real FLAIR knowledge. The DWI-FLAIR mismatch was evaluated on both FLAIR data sets by four independent readers. Interobserver reproducibility and DWI-FLAIR mismatch concordance between synthetic and real FLAIR were evaluated with κ statistics. Sensitivity and specificity for identification of AIS within 4.5 hours were compared in patients with known onset time by using McNemar test. Results The study included 1416 MRI scans (861 patients; median age, 71 years [interquartile range, 57-81 years]; 375 men), yielding 1134 and 282 scans for training and test sets, respectively. Regarding DWI-FLAIR mismatch, interobserver reproducibility was substantial for real and synthetic FLAIR (κ = 0.80 [95% CI: 0.74, 0.87] and 0.80 [95% CI: 0.74, 0.87], respectively). After consensus, concordance between real and synthetic FLAIR was almost perfect (κ = 0.88; 95% CI: 0.82, 0.93). Diagnostic value for identifying AIS within 4.5 hours did not differ between real and synthetic FLAIR (sensitivity: 107 of 131 [82%] vs 111 of 131 [85%], P = .2; specificity: 96 of 104 [92%] vs 96 of 104 [92%], respectively, P > .99). Conclusion Synthetic fluid-attenuated inversion recovery (FLAIR) had diagnostic performances similar to real FLAIR in depicting diffusion-weighted imaging-FLAIR mismatch and in helping to identify early acute ischemic stroke, and it may accelerate MRI protocols. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Carroll and Hurley in this issue.

A Semi-Supervised Learning Framework to Leverage Proxy Information for Stroke MRI Analysis

Treating acute ischemic stroke (AIS) patients is a time-sensitive endeavor, as therapies target areas experiencing ischemia to prevent irreversible damage to brain tissue. Depending on how an AIS is progressing, thrombolytics such as tissue-plasminogen activator (tPA) may be administered within a short therapeutic window. The underlying conditions for optimal treatment are varied. While previous clinical guidelines only permitted tPA to be administered to patients with a known onset within 4.5 hours, clinical trials demonstrated that patients with signal intensity differences between diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) sequences in an MRI study can benefit from thrombolytic therapy. This intensity difference, known as DWI-FLAIR mismatch, is prone to high inter-reader variability. Thus, a paradigm exists where onset time serves as a weak proxy for DWI-FLAIR mismatch. In this study, we sought to detect DWI-FLAIR mismatch in an automated fashion, and we compared this to assessments done by three expert neuroradiologists. Our approach involved training a deep learning model on MRI to classify tissue clock and leveraging time clock as a weak proxy label to supplement training in a semi-supervised learning (SSL) framework. We evaluate our deep learning model by testing it on an unseen dataset from an external institution. In total, our proposed framework was able to improve detection of DWI-FLAIR mismatch, achieving a top ROC-AUC of 74.30%. Our study illustrated that incorporating clinical proxy information into SSL can improve model optimization by increasing the fidelity of unlabeled samples included in the training process.

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.

Clinical feasibility of single-shot fluid-attenuated inversion recovery with wide inversion recovery pulse designed to reduce cerebrospinal fluid and motion artifacts for evaluation of uncooperative patients in acute stroke protocol

Fluid-attenuated inversion recovery (FLAIR) imaging is a key sequence for stroke assessment. Motion artifact reduction with short acquisition time is still challenging, but necessary in the magnetic resonance (MR) stroke protocol, especially for uncooperative patients suspected of stroke. The aim of this study is to investigate the feasibility of modified single-shot FLAIR with wide inversion recovery pulses for use in stroke patients. This is a prospective study, which included 30 patients clinically suspected of stroke who were examined by MR stroke protocol from January 2018 to September 2018. A 1.5 T, multi-shot-turbo spin-echo (TSE) conventional FLAIR, and single-shot-TSE-FLAIR with wide inversion recovery pulse were used. Modified single-shot FLAIR was obtained for 30 patients with suspected stroke who moved during conventional FLAIR scan. Motion artifacts were randomly and independently scored using a 5-grade scale by three radiologists in blinded fashion. Whether the FLAIR vessel hyperintensity sign was present was visually evaluated. Statistical tests included Wilcoxon-signed rank test and weighted Cohen's kappa statistics. The motion artifact score was significantly lower in single-shot FLAIR than in conventional FLAIR (0.37 ± 0.56 vs. 1.83 ± 1.18; p < 0.05. The vessel hyperintensity sign was visualized in 6 and 5 patients on single-shot and conventional FLAIR images, respectively. This study demonstrates the value of single-shot FLAIR for stroke assessment. Single-shot FLAIR reduced motion artifact and visualized vessel hyperintensity sign more than conventional FLAIR. LEVEL OF EVIDENCE: 2. TECHNICAL EFFICACY STAGE: 2.

Diffusion-Weighted Imaging-Fluid-Attenuated Inversion Recovery Mismatch Is Associated with 90-Day Functional Outcomes in Patients Undergoing Mechanical Thrombectomy

BACKGROUND AND PURPOSE

Diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch is an early sign of acute ischemic stroke. DWI-FLAIR mismatch was reported to be valuable to select patients with unknown onset stroke who are eligible to receive intravenous thrombolysis (IVT), but its utility is less studied in patients undergoing mechanical thrombectomy (MT) for acute large vessel occlusion (LVO). We thus investigated the functional outcomes at 90 days between patients with DWI-FLAIR mismatch and those with match who underwent MT for LVO.

METHODS

We conducted a historical cohort study in consecutive patients who were evaluated by magnetic resonance imaging for suspected stroke at a single center. We enrolled patients with occlusion of internal carotid artery or horizontal or vertical segment of middle cerebral artery who underwent MT within 24 h after they were last known to be well. DWI-FLAIR mismatch was defined when a visible acute ischemic lesion was present on DWI without traceable parenchymal hyperintensity on FLAIR. Image analysis was done by 2 stroke neurologists independently. We estimated the adjusted odds ratio (OR) of DWI-FLAIR mismatch relative to DWI-FLAIR match for moderate outcome defined as modified Rankin Scale (mRS) 0-3, favorable outcome defined as mRS 0-2 and mortality at 90 days after the onset, and symptomatic intracranial hemorrhage (sICH) within 72 h after the onset.

RESULTS

Of the 380 patients who received MT, 202 were included. Patients with DWI-FLAIR mismatch (146 [72%]) had significantly higher baseline National Institutes of Health Stroke Scale (median 16 vs. 13, p = 0.01), more transferred-in (78 vs. 63%, p = 0.02), more IVT (45 vs. 18%, p = 0.0003), more cardioembolism (69 vs. 54%, p = 0.03), and shorter onset-to-hospital door times (median 175 vs. 371 min, p < 0.0001) than patients with DWI-FLAIR match. Patients with DWI-FLAIR mismatch had more moderate outcome than those with DWI-FLAIR match (61 vs. 52%, p = 0.24), and the adjusted OR was 3.12 (95% confidence interval [CI]: 1.35-7.19, p = 0.008). sICH within 72 h was less frequent in the DWI-FLAIR mismatch group (10 vs. 20%, p = 0.06), with an adjusted OR of 0.36 (95% CI: 0.13-0.97, p = 0.044). The adjusted ORs for favorable outcome and mortality were 0.87 (95% CI: 0.39-1.94, p = 0.73) and 0.63 (95% CI: 0.20-2.05, p = 0.44), respectively.

CONCLUSIONS

DWI-FLAIR mismatch was associated with more moderate outcome and less sICH in the adjusted analysis in patients receiving MT for acute LVO. DWI-FLAIR mismatch could be useful to select patients with unknown onset stroke who are eligible to receive MT for acute LVO.

Endovascular treatment for ischemic stroke beyond the time window: A meta-analysis

Currently, endovascular treatment has been proven to be effective when conducted within 6 hours of symptom onset. However, when patients have symptoms for more than 6 hours, have a daytime-unwitnessed stroke (DUS) or wake up with a stroke (wake-up stroke, WUS), the safety and efficacy of endovascular treatment need to be further elucidated. Therefore, we performed a systematic review and meta-analysis to compare the clinical outcomes of endovascular treatment in patients with ischemic stroke beyond the time window with that ≤6 hours. PubMed, EMBASE, and Ovid MEDLINE were searched from inception to November 2018. The following outcomes were evaluated by a random-effects model: efficacy outcomes, that is, functional independence and successful recanalization, and safety outcomes, that is, symptomatic intracranial hemorrhage and mortality. Subgroup analyses were also performed to examine whether patient or study characteristics were associated with the outcomes. Nine observational studies, including 5192 patients (1414 patients with extended time windows [ETWs]; 3778 patients ≤6 hours), were eligible for analysis. The overall analysis demonstrated that the functional independence was worse in patients with ETWs vs those ≤6 hours (OR, 0.78; 95% CI, 0.68-0.90, P = .0006). However, subgroup analysis showed that there was no significant difference in functional independence between the two groups when patients were selected for a perfusion mismatch by imaging (OR, 1.00; 95% CI, 0.70-1.43, P = 1.000). Therefore, compared with a window ≤6 hours, endovascular treatment with ETWs for ischemic stroke may not result in poor outcomes when patients are typically selected by perfusion techniques.

Cerebral ischaemia with unknown onset: Outcome after recanalization procedure

BACKGROUND

Stroke of unknown time of onset (UTOS) accounts for one-third of contra-indications for revascularization procedures. With modern neuroimaging techniques it is possible to differentiate the core infarcts and the presence of penumbra.

OBJECTIVE

To evaluate outcomes in patients with UTOS, treated with intravenous (i.v.) recombinant tissue-plasminogen activator (rt-PA), mechanical thrombectomy (MT), or both.

METHOD

We conducted this observational study in patients treated by i.v. rt-PA, MT, or both, selected by a diffusion-weighted image/fluid-attenuated inversion recovery mismatch. We evaluated outcomes with the modified Rankin scale (mRS) at 3 months.

RESULTS

Of 992 consecutive patients (522 women, 52.6%; median age 76 years; median baseline national institutes of health stroke scale [NIHSS] 10), 153 (15.4%) had UTOS, including 101 with wake-up strokes. Compared to other patients, they were more likely to have pre-existing mRS scores >2 (P=0.022), multiple infarcts (P<0.001), middle cerebral artery occlusions (P=0.023), and to undergo MT (P=0.003), and less likely to receive i.v. rt-PA (P<0.001). They had higher NIHSS scores (P<0.001) and longer discovery to treatment initiation times (P<0.001). They were more likely to develop pulmonary (P=0.001) and urinary (P=0.006) infections, and pulmonary embolism (P=0.019), and tended to have a higher mortality rate (P=0.052) within 7 days. After adjustment, there was no association of UTOS with any of these outcome measures anymore.

CONCLUSION

Patients with UTOS have more severe strokes and more comorbidities, but after adjustment, their outcomes did not differ from those of other patients.

Mechanical thrombectomy for recurrent large vessel occlusion

Although mechanical thrombectomy (MT) has been shown in numerous trials to be a successful treatment option for patients with large vessel occlusion (LVO), there is limited information on the safety and effectiveness of the technique in cases of recurrent LVO. To this end, we performed a retrospective review of our prospectively maintained database to identify all patients that had undergone more than one MT procedure January 2008 and January 2018. The data collected on these patients included baseline demographics and any history of diabetes mellitus, hypercholesterolaemia, hypertension, atrial fibrillation or smoking. We also recorded when the symptoms had started, the patient's NIHSS and ASPECT scores, the number of passes taken, the patient's final TICI score, any complications which arose and the patient's mRS at 90 days. Our dataset encompassed 25 patients (of which 17 (68%) were female) who had undergone a total number of 52 MT's. Average age at 1st presentation was 70 ± 12.8 years. The median time between one stroke and the next was 71 days (range 1-1059, IQR 183 days). The majority of the strokes were deemed cardioembolic (86.5%) in origin. There was no significant difference in the procedure times, number of passes or TICI scores. There was a significant difference in the mRS after the 1st and 2nd events (p = 0.014) but no significant difference if the 2nd event occurred contralateral to the 1st event (p = 0.66) (n = 22). It is therefore concluded that recurrent thrombectomy can be safely performed with no significant difference in the technical aspects of the procedure.

Gadolinium-Enhanced Extracranial MRA Prior to Mechanical Thrombectomy Is Not Associated With an Improved Procedure Speed

Objectives: To assess whether performing a pre-intervention gadolinium-enhanced extracranial magnetic resonance angiogram (MRA) in addition to intracranial vascular imaging is associated with improved thrombectomy time metrics. Methods: Consecutive patients treated by MT at a large comprehensive stroke center between January 2012 and December 2017 who were screened using pre-intervention MRI were included. Patients characteristics and procedural data were collected. Univariate and multivariate analysis were performed to compare MT speed, efficacy, complications, and clinical outcomes between patients with and without pre-intervention gadolinium-enhanced extracranial MRA. Results: A total of 912 patients were treated within the study period, including 288 (31.6%) patients with and 624 (68.4%) patients without extracranial MRA. Multivariate analysis showed no significant difference between groups in groin puncture to clot contact time (RR = 0.93 [0.85-1.02], p = 0.14) or to recanalization time (RR = 0.92 [0.83-1.03], p = 0.15), rates of successful recanalization (defined as a mTICI 2b or 3, RR = 0.93 [0.62-1.42], p = 0.74), procedural complications (RR = 0.81 [0.51-1.27], p = 0.36), and good clinical outcome (defined by a mRS ≤ 2 at 3 months follow-up, RR = 1.05 [0.73-1.52], p = 0.79). Conclusion: Performing a pre-intervention gadolinium-enhanced extracranial MRA in addition to non-contrast intracranial MRA at stroke onset does not seem to be associated with a delay or shortening of procedure times.