Presence of the hyperintense acute reperfusion marker on MRI after mechanical thrombectomy for large vessel occlusion is associated with worse early neurological recovery

A CT texture-based nomogram for predicting futile reperfusion in patients with intraparenchymal hyperdensity after endovascular thrombectomy for acute anterior circulation large vessel occlusion

Background

Post-thrombectomy intraparenchymal hyperdensity (PTIH) in patients with acute anterior circulation large vessel occlusion is a common CT sign associated with a higher incidence of futile reperfusion (FR). We aimed to develop a nomogram to predict FR specifically in patients with PTIH.

Methods

We retrospectively collected information on patients with acute ischemic stroke who underwent endovascular thrombectomy (EVT) at two stroke centers. A total of 398 patients with PTIH were included to develop and validate the nomogram, including 214 patients in the development cohort, 92 patients in the internal validation cohort and 92 patients in the external validation cohort. The nomogram was developed according to the independent predictors obtained from multivariate logistic regression analysis, including clinical factors and CT texture features extracted from hyperdense areas on CT images within half an hour after EVT. The performance of the nomogram was evaluated with integrated discrimination improvement (IDI), category-free net reclassification improvement (NRI), the area under the receiver operating characteristic curve (AUC-ROC), calibration plots, and decision curve analyses for discrimination, calibration ability, and clinical net benefits, respectively.

Results

Our nomogram was constructed based on three clinical factors (age, NIHSS score and ASPECT score) and two CT texture features (entropy and kurtosis), with AUC-ROC of 0.900, 0.897, and 0.870 in the development, internal validation, and external validation cohorts, respectively. NRI and IDI further validated the superior predictive ability of the nomogram compared to the clinical model. The calibration plot revealed good consistency between the predicted and the actual outcome. The decision curve indicated good positive net benefit and clinical validity of the nomogram.

Conclusion

The nomogram enables clinicians to accurately predict FR specifically in patients with PTIH within half an hour after EVT and helps to formulate more appropriate treatment plans in the early post-EVT period.

Good outcome associated with blood-brain barrier disruption and lower blood pressure after endovascular therapy

OBJECTIVES

To evaluate the association between post-endovascular thrombectomy (EVT) blood-brain barrier (BBB) disruption on MRI or CT and average systolic blood pressure (SBP) with favorable 90-day functional outcome. Observational studies have found elevated SBP associated with worse outcomes post-EVT, while recent randomized trials found no difference in targeted BP reduction. There may be a subgroup of patients who benefit from targeted BP reduction post-EVT.

METHODS

This is a single-center study of 1) anterior large vessel occlusion stroke patients treated with EVT from 2015 to 2021, 2) achieved mTICI grade 2b or 3. Hyperintense acute reperfusion marker (HARM), hemorrhagic transformation (HT), and midline shift at 3 h post-EVT and 24 h imaging were assessed independently by multiple raters. Binary logistic regression models were used to determine the association of post-EVT SBP with outcomes. BBB disruption was defined as HT or HARM on 3h post-EVT imaging.

RESULTS

Of 103 patients, those with SBP 100-129 versus SBP 130-160 found no significant difference in favorable 90-day outcome (64% vs. 46%, OR 2.11, 95% CI 0.78-5.76, p=0.143). However, among 71 patients with BBB disruption, a significant difference in favorable outcome of 64% in SBP 100-129 vs. 39% in SBP 130-160 group (OR 5.93, 95% CI 1.50-23.45, p=0.011) was found. There was no difference in symptomatic ICH, 90-day mortality, midline shift (≥5 mm), and hemicraniectomy, between BP or BBB groups.

CONCLUSIONS

BBB disruption on 3h post-EVT imaging and lower SBP was associated with favorable outcome. This imaging finding may guide targeted BP therapy and suggests need for a randomized control trial.

Intra-Arterial Injection of Thrombin as Rescue Therapy of Vessel Perforation during Mechanical Thrombectomy for Acute Ischemic Stroke

BACKGROUND

Vessel perforation during stent mechanical thrombectomy (MT) is a rare and disastrous complication. A routine rescue strategy includes balloon occlusion for tamponade, procedure suspension, and lowering or normalizing blood pressure. However, this complication is still associated with poor outcome and high mortality.

OBJECTIVE

We present our experience with intra-arterial injection of thrombin in the treatment of vessel perforation secondary to microcatheter/microwire perforation, which prevents further deterioration in clinical outcomes.

METHODS

Cases with intraprocedural vessel perforation during mechanical thrombectomy were included in the final analysis. Clinical data, procedural details, and radiographic and clinical outcomes were collected.

RESULTS

Four patients with intraprocedural vessel perforation were included. Intraprocedural perforations occurred at the distal middle cerebral artery in two cases: the A2 segment in one case and the internal carotid artery terminus in one case. The etiology of four cases was intracranial atherosclerotic stenosis (ICAS). The ruptured vessels were effectively occluded in all cases. Endovascular therapy was continued in three cases, and mTICI ≥ 2b recanalization was achieved in all cases. The culprit artery was kept patent on CTA for 72 h post-operation. No active bleeding was detected on follow-up CT post-operation. During the 90-day follow-up period, one patient died, modified Rankle Scare (mRS) 3 was observed in two patients, and mRS 4 was observed in one patient.

CONCLUSIONS

The key benefit of this method is occluding the ruptured vessel without affecting the following MT. We propose that intra-arterial injection of prothrombin may be simple yet effective in managing vessel perforation complications during MT.

Ipsilateral blooming of microbleeds after Hyperintense Acute Reperfusion Marker sign in an ischemic Stroke patient, a case report

Background

Hyperintense Acute Reperfusion Marker (HARM) is a hyperintense subarachnoid signal on FLAIR MRI sequence caused by gadolinium contrast leakage into the subpial space. While, on FLAIR, HARM may mimic subarachnoid hemorrhage, it is differentiated from it on computed tomography (CT) and SWAN MRI sequences. Cerebral microbleeds are black, rounded spots on SWAN caused by blood-products deposition following red blood cell leakage from small cerebral vessels brain. Both microbleeds and HARM carry important prognostic implication as they are associated with blood-brain barrier disruption and an increased risk of intracerebral hemorrhage.

Case presentation

A 79-year-old man presented with aphasia and right hemiparesis due to ischemic stroke with left middle cerebral artery occlusion. Admission NIHSS score was 7, and he was successfully treated by intravenous thrombolysis and mechanical thrombectomy. On day 1, his clinical condition worsened, and he had an urgent gadolinium-enhanced MRI. There was no evidence of early recurrence, nor of hemorrhage on SWAN or on FLAIR. Left middle cerebral artery was permeable. The patient was anticoagulated for newly diagnosed atrial fibrillation, and a second MRI following a generalized tonic-clonic seizure showed multiple left hemispheric diffusion-weighted imaging (DWI) hyperintense spots and a left hemispheric sub-arachnoid hyperintensity on FLAIR, compatible with a subarachnoid hemorrhage. This diagnosis was excluded by SWAN MRI sequence and a normal cerebral CT the same day. The diagnosis of HARM was retained. At day 9, patient’s condition improved, and a control MRI did not show evidence of HARM. However, numerous microbleeds were detected in the left hemisphere only (ipsilateral with HARM and stroke).

Conclusions

This case highlights first of all the importance of differentiating HARM and subarachnoid hemorrhage, especially in an anticoagulated patient with clinical aggravation. Secondly, it is crucial to identify microbleeds and understand their pathophysiology, as they are associated with higher risk of hemorrhage and stroke recurrence in ischemic stroke patients. Finally, the mono-hemispheric appearance of microbleeds in this case suggests for the first time that, in some acute ischemic stroke patients, a relationship between HARM and cerebral microbleeds may exist.

Clinical outcomes of first-pass effect after mechanical thrombectomy for acute ischemic stroke: A systematic review and meta-analysis

OBJECTIVE

The first-pass effect (FPE) during a mechanical thrombectomy for ischemic stroke results in favorable clinical outcomes and low symptomatic intracranial hemorrhage (sICH) rates according to individual observational studies. We performed an integrated study-level meta-analysis to compare the clinical outcomes and safety profiles of single (FPE group) and multiple passages (non-FPE group) of devices in patients who achieved successful recanalizations.

METHODS

A literature search of the PubMed, Embase, and Cochrane databases for FPE was conducted. We included studies comparing outcomes between patients with and without FPE for 90-day favorable outcome, mortality, and sICH. The results from the pooled analysis using the random-effects model were presented as odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Of the 8 selected studies comprising 2308 patients, the overall rates of the FPE were 40.3% (930/2308). The FPE was significantly associated with more 90-day favorable outcomes (OR: 1.31, 95% CI: 1.13-1.51) and lower mortality (OR: 0.53, 95% CI: 0.34-0.81), but there were no significant differences in sICH rates (OR: 0.80, 95% CI: 0.50-1.30). The results of the meta-regression analysis showed that there was no confounding effect of intravenous thrombolysis prior to thrombectomy.

CONCLUSION

Our findings indicated that patients who achieved the FPE would have more 90-day favorable outcomes and lower mortality compared with non-FPE patients. However, there was a limited association between the FPE and reduced sICH rates.

The Clinical Significance of the Hyperintense Acute Reperfusion Marker Sign in Subacute Infarction Patients

Purpose: The hyperintense acute reperfusion marker (HARM) is characterized by the delayed enhancement of the subarachnoid or subpial space observed on postcontrast fluid-attenuated inversion recovery (FLAIR) images, and is considered a cerebral reperfusion marker for various brain disorders, including infarction. In this study, we evaluated the cerebral distribution patterns of HARM for discriminating between an enhancing subacute infarction and an enhancing mass located in the cortex and subcortical white matter. Materials and methods: We analyzed consecutive patients who experienced a subacute ischemic stroke, were hospitalized, and underwent conventional brain magnetic resonance imaging including postcontrast FLAIR within 14 days from symptom onset, as well as those who had lesions corresponding to a clinical sign detected by diffusion-weighted imaging and postcontrast T1-weighted imaging between May 2019 and May 2021. A total of 199 patients were included in the study. Of them, 94 were finally included in the subacute infarction group. During the same period, 76 enhancing masses located in the cortex or subcortical white matter, which were subcategorized as metastasis, malignant glioma, and lymphoma, were analyzed. We analyzed the overall incidence of HARM in subacute ischemic stroke cases, and compared the enhancement patterns between cortical infarctions and cortical masses. Results: Among 94 patients with subacute stroke, 78 patients (83%) presented HARM, and among 76 patients with subcortical masses, 48 patients (63%) presented peripheral rim enhancement. Of 170 subcortical enhancing lesions, 88 (51.8%) showed HARM, and 78 (88.6%) were determined to be subacute infarction. Among 94 patients with subacute stroke, 48 patients (51%) had diffusion restrictions, and HARM was found in 39 patients (81.2%). Of the 46 patients (49%) without diffusion restriction, 39 patients (84.8%) showed HARM. Conclusions: The presence of HARM was significantly associated with subacute infarctions. For the masses, a peripheral rim enhancement pattern was observed around the mass rather than the cerebral sulci on postcontrast FLAIR.

The feasibility of dual-energy CT to predict the probability of symptomatic intracerebral haemorrhage after successful mechanical thrombectomy

AIM

To study the ability of dual-energy computed tomography (DECT) after successful mechanical thrombectomy (MT) to predict symptomatic intracerebral haemorrhage (sICH) in anterior circulation acute ischaemic stroke (AIS).

MATERIALS AND METHODS

From June 2018 to February 2020, 102 AIS patients with DECT performed immediately after successful MT were enrolled prospectively. According to the presence of iodine contrast media extravasation (ICME) on DECT and subsequent sICH development, patients were classified into four groups. The neurological outcome was compared among groups. Imaging parameters, together with clinical factors, were investigated for sICH prediction based on a linear logistic regression model after class-imbalance resolved by Synthetic Minority Sampling Technique (SMOTE) method.

RESULTS

Among 102 patients, patients (14.7%, 15/102) with the presence of sICH experienced worse outcomes than others without sICH (p<0.001). No case without ICME was observed with sICH development (0/102). The parameters derived from DECT have excellent performance for sICH prediction after successful MT, which is better than clinical predictive model boosted data (area under the curve [AUC]: DECT 0.87 versus clinical prediction 0.65), cross-validation results (AUC: DECT 0.87 versus clinical prediction 0.65), and original data (AUC: DECT 0.85 versus clinical prediction 0.68). By combining clinical and radiological parameters, the predictive performance for sICH could be further improved with an AUC of 0.90 (95% CI: 0.85-0.96).

CONCLUSIONS

Based on DECT parameters acquired immediately after successful MT, the present model was more efficient than the clinical model for accurate prediction of sICH. Rho and ICME volume appeared to be the best parameters for predicting sICH using DECT.

CSF enhancement on post-contrast fluid-attenuated inversion recovery images; a systematic review

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CSF enhancement on post-contrast FLAIR images is a novel marker for BBB leakage.

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This neuroradiological marker is frequently observed in neurological diseases.

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Post-contrast FLAIR CSF enhancement is associated with higher age and brain atrophy.

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There is large methodological heterogeneity between studies that use this technique.

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We provide recommendations for future methodological standardization.

Cerebrospinal fluid (CSF) enhancement on T2-weighted post-contrast fluid-attenuated inversion recovery (pcT2wFLAIR) images is a relatively unknown neuroradiological marker for gadolinium-based contrast agent extravasation due to blood–brain barrier (BBB) disruption. We systematically reviewed human studies reporting on CSF enhancement on pcT2wFLAIR images to provide a comprehensive overview of prevalence of this new biomarker in healthy and diseased populations as well as its etiology and optimal detection methodology. We extracted information on the prevalence of CSF enhancement, its vascular risk factor and neuroimaging correlates, and methodological attributes of each study. Forty-four eligible studies were identified. By pooling data, we found that the prevalence of CSF enhancement was 82% (95% confidence interval (CI) 80–89) in meningitis (4 studies, 65 patients), 73% (95%CI 62–81) in cases with (post-) acute intracerebral hemorrhage (2 studies, 77 cases), 64% (95% CI 54–73) in cases who underwent surgery for aneurysm treatment (2 studies, 99 patients), 40% (95% CI 30–51) in cases who underwent surgery for carotid artery disease treatment (3 studies, 76 patients), 27% (95% CI 25–30) in cases with acute ischemic stroke (9 studies, 1148 patients), 21% (95% CI 17–23) in multiple sclerosis (6 studies, 897 patients), and 13% (95% CI 7–21) in adult controls (4 studies, 112 cases). Presence of CSF enhancement was associated with higher age in eleven studies, with lobar cerebral microbleeds in one study, and with cerebral atrophy in four studies. PcT2wFLAIR imaging represents a promising method that can provide novel perspectives on BBB leakage into CSF compartments, with the potential to reveal important new insights into the pathophysiological mechanisms of varying neurological diseases.

Computed Tomography Perfusion After Thrombectomy

Background and Purpose—

Despite recanalization, almost 50% of patients undergoing endovascular treatment (EVT) experience poor outcome. We aim to evaluate the value of computed tomography perfusion as immediate outcome predictor postendovascular treatment.

Methods—

Consecutive patients receiving endovascular treatment who achieved recanalization (modified Thrombolysis in Cerebral Ischemia [mTICI] 2a-3) underwent computed tomography perfusion within 30 minutes from recanalization (CTPpost). Hypoperfusion was defined as the Tmax>6 second volume; hyperperfusion as visually increased cerebral blood flow/cerebral blood volume with reduced Tmax compared with unaffected hemisphere. Dramatic clinical recovery (DCR) was defined as 24-hour National Institutes of Health Stroke Scale score ≤2 or ≥8 points drop. Delayed recovery was defined as no-DCR with favorable outcome (modified Rankin Scale score 0–2) at 3 months.

Results—

We included 151 patients: median National Institutes of Health Stroke Scale score 16 (interquartile range, 10–21), median admission ASPECTS 9 (interquartile range, 8–10). Final recanalization was the following: mTICI2a 11 (7.3%), mTICI2b 46 (30.5%), and mTICI3 94 (62.3%). On CTPpost, 80 (52.9%) patients showed hypoperfusion (median Tmax>6 seconds: 4 cc [0–25]) and 32 (21.2%) hyperperfusion. There was an association between final TICI and CTPpost hypoperfusion(median Tmax>6: 91 [56–117], 15 [0–37.5], and 0 [0–7] cc, for mTICI 2a, 2b, and 3, respectively, P <0.01). Smaller hypoperfusion volumes on CTPpost were observed in patients with DCR (0 cc [0–13] versus non-DCR 8 cc [0–56]; P <0.01) or favorable outcome (modified Rankin Scale score 0–2: 0 cc [0–13] versus 7 [0–56] cc; P <0.01). No associations were detected with hyperperfusion pattern. An hypoperfusion volume <3.5 cc emerged as independent predictor of DCR (OR, 4.1 [95% CI, 2.0–8.3]; P <0.01) and 3 months favorable outcome (OR, 3.5 [95% CI, 1.6–7.8]; P <0.01).

Conclusions—

Hypoperfusion on CTPpost constitutes an immediate accurate surrogate marker of success after endovascular treatment and identifies those patients with delayed recovery and favorable outcome.

Frequency of Blood-Brain Barrier Disruption Post-Endovascular Therapy and Multiple Thrombectomy Passes in Acute Ischemic Stroke Patients

Background and Purpose- The high prevalence of hyperintense acute reperfusion marker (HARM) seen after endovascular therapy is suggestive of blood-brain barrier disruption and hemorrhage risk and may be attributable to multiple thrombectomy passes needed to achieve recanalization. Methods- Patients with acute stroke were included if they were screened from January 2015 through February 2019, received an acute ischemic stroke diagnosis involving the anterior circulation, treated with or without IV tPA (intravenous tissue-type plasminogen activator), consented to the NINDS Natural History Study, and imaged with a baseline magnetic resonance imaging before receiving endovascular therapy. Consensus image reads for HARM and hemorrhagic transformation were performed. Good clinical outcome was defined as 0-2 using the latest available modified Rankin Scale score. Results- Eighty patients met all study criteria and were included in the analyses. Median age was 65 years, 64% female, 51% black/African American, median admit National Institutes of Health Stroke Scale=19, 56% treated with IV tPA, and 84% achieved Thrombolysis in Cerebral Infarction score of 2b/3. Multiple-pass patients had significantly higher rates of severe HARM at 24 hours (67% versus 29%; P=0.001), any hemorrhagic transformation (60% versus 36%; P=0.04) and poor clinical outcome (67% versus 36%; P=0.008). Only age (odds ratio, 1.1; 95% CI, 1.01-1.12; P=0.022) and severe HARM at 24 hours post-endovascular therapy were significantly associated with multiple passes (odds ratio, 7.2; 95% CI, 1.93-26.92; P=0.003). Conclusions- In this exploratory study, multiple thrombectomy passes are independently associated with a significant increase in blood-brain barrier disruption detected at 24 hours. Patients with HARM post-endovascular therapy had a >7-fold increase in the odds of having multiple- versus single-pass thrombectomy. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT00009243.

Usefulness of hyperintense acute reperfusion marker sign in patients with transient neurologic symptom

It aimed to investigate the incidence and final diagnosis of hyperintense acute reperfusion marker (HARM) signs in patients initially suspected of having a transient ischemic attack (TIA).In retrospective manner, a series of consecutive series of patients who arrived at the emergency department and was initially assessed as TIA within 12 hours of symptom onset between July 2015 and December 2016 were enrolled. Conventional magnetic resonance imaging protocol including diffusion-weighted imaging (DWI) and pre- and post-contrast fluid attenuation inversion recovery imaging (FLAIR) was conducted to evaluate the ischemic lesion and prognosis. Through the review of medical records and imaging studies, their final diagnosis and its association with HARM signs on post-contrast FLAIR were investigated.A total of 174 subjects were enrolled (mean age, 64.0 ± 12.9 years old; male, 54.6%; DWI lesion, 17.8%). HARM signs were observed in 18 (10%) patients, and their final diagnoses were classified as true TIA (n = 11, 61%), seizure (2, 11%), posterior reversible encephalopathy (2, 11%), reversible cerebral vascular constriction (1, 6%) and unclassified encephalopathy (2, 11%). The co-occurrence of HARM and DWI lesions were observed in 7 subjects which were 6 subjects of true TIA (ischemic stroke) and 1 subject with RCVS related ischemic stroke.The observation of HARM sign would be helpful to confirm the ischemic insult and distinguish the other disease.

What to Look for on Post-stroke Neuroimaging

The most feared complication after acute ischemic stroke is symptomatic or asymptomatic hemorrhagic conversion. Neuroimaging and clinical criteria are used to predict development of hemorrhage. Seizures after acute ischemic stroke or stroke-like symptoms from seizures are not common but may lead to confusion in the peristroke period, especially if seizures are repetitive or evolve into status epilepticus, which could affect neuroimaging findings. Malignant infarction develops when cytotoxic edema is large enough to lead to herniation and death. Post-stroke neuroimaging prognosticators have been described and should be assessed early so that appropriate treatment is offered before herniation leads to additional tissue injury.

Complete Restitution of the Ischemic Penumbra after Successful Thrombectomy : A Pilot Study Using Quantitative MRI

PURPOSE

Endovascular thrombectomy is highly effective in patients with proximal large artery occlusion but the relevance of reperfusion injury after recanalization is a matter of debate. The aim of this study was to investigate potential residual metabolic distress and microstructural tissue damage or edema after reperfusion using quantitative oxygen-sensitive T2' and T2-mapping in patients successfully treated by thrombectomy.

METHODS

Included in this study were 11 patients (mean age 70 ± 11.4 years) with acute ischemic stroke due to internal carotid artery and/or middle cerebral artery occlusion. Quantitative T2 and T2' (1/T2' = 1/T2* - 1/T2) were determined within the ischemic core and hypoperfused but salvaged tissue with delayed time-to-peak (TTP) in patients before and after successful thrombectomy and compared to a control region within the unaffected hemisphere.

RESULTS

Decreased T2' values within hypoperfused tissue before thrombectomy showed a normalization after recanalization (p < 0.01). In formerly hypoperfused but salvaged tissue, T2 values increased significantly after thrombectomy (p < 0.05) but did not differ from reference values in the control region. In salvaged tissue, increases of quantitative T2' and T2 to follow-up were more pronounced in areas with severe TTP delay.

CONCLUSION

After successful recanalization, T2' re-increased back to normal in formerly hypoperfused areas as a sign of prompt normalization of oxygen metabolism. Furthermore, quantitative T2 in the formerly hypoperfused tissue did not differ from reference values in unaffected tissue. These results indicate complete restitution of salvaged tissue after reperfusion and support the overall safety of endovascular thrombectomy with respect to microstructural tissue integrity.