Hybrid dynamic bright and black blood angiography by non-contrast-enhanced vessel selective saturation angiography.

The integrity of vessel walls and changes in blood flow are involved in many diseases, and information about these anatomical and physiological conditions is important for a diagnosis. There are several different angiography methods that can be used to generate images for diagnostic purposes, but often using different imaging techniques and MR sequences. The purpose of this study was to develop a method that allows time-resolved, vessel-selective simultaneous bright and black blood imaging by vesselselective blood saturation. Measurements in six volunteers were performed to evaluate the time-resolved bright blood angiography and the significance of the generated black blood contrast. It was shown that this method can be used to generate a black blood contrast with a sufficient signal difference to the surrounding gray matter in addition to the time-resolved and vessel-selective bright blood contrast. Using post-processing methods, whole brain angiograms can be calculated from the acquired data.

Child-centredness in paediatric magnetic resonance imaging: Information needs and experiences of children requiring magnetic resonance imaging and their parents.

BACKGROUND: Assessing patient experiences is essential to provide high quality health-care. The objectives of this study were to examine (1) child- and parent-reported information status before magnetic resonance imaging (MRI), (2) experiences during an MRI and (3) needs and suggestions for improvement. METHODS: Children (≥8 years) and parents answered questionnaires (before and after planned MRI examination) covering mental condition, information status/needs, preparation for MRI, and potential stressors. Before MRI n = 132 accompanying parents and n = 91 children provided data (after MRI: n = 93 parents; n = 71 children). The mean age of the children undergoing MRI was 10.5 years (SD = 4.9). Children had on average seven previous MRIs before our survey (Range: 1-33). Twenty-three percent of the children were to be sedated during the examination. RESULTS: Parents and children reported low to medium levels of burden, high knowledge and high information status. For the children, most stressful factors during the MRI were boredom and noise. Main information resources were the radiologists or self-searches. Parents of children with their first MRI reported higher anxiety levels in their children and stated a worse information status (main information source: self-searches/internet). Parents reported needs regarding organization of the MRI (e.g., reduction of waiting times), age-appropriate information and communication during the MRI. Children wished to visit the MRI room prior the examination (44%) and to get more information (44%). Children suggested improvements such as better sound quality of films/music, more transparency about the procedure, being in contact with a parent and shorter examinations. CONCLUSION: Results suggest that preparation, information provision and care is perceived positively by families. Needs and suggestions for improvement were, for example, higher transparency of procedures, better communication and reduction of stress. Findings indicate that preparation in routine-care should follow an individualized child-focused approach, should focus on families without previous MRIs and should address children with high anxiety levels.

Benefit and risk of intravenous alteplase in patients with acute large vessel occlusion stroke and low ASPECTS.

BACKGROUND: The benefit of best medical treatment including intravenous alteplase (IVT) before mechanical thrombectomy (MT) in patients with acute ischemic stroke and extensive early ischemic changes on baseline CT remains uncertain. The purpose of this study was to evaluate the benefit of IVT for patients with low ASPECTS (Alberta Stroke Programme Early CT Score) compared with patients with or without MT. METHODS: This multicenter study pooled consecutive patients with anterior circulation acute stroke and ASPECTS≤5 to analyze the impact of IVT on functional outcome, and to compare bridging IVT with direct MT. Functional endpoints were the rates of good (modified Rankin Scale (mRS) score ≤2) and very poor (mRS ≥5) outcome at day 90. Safety endpoint was the occurrence of symptomatic intracranial hemorrhage (sICH). RESULTS: 429 patients were included. 290 (68%) received IVT and 168 (39%) underwent MT. The rate of good functional outcome was 14.4% (95% CI 7.1% to 21.8%) for patients who received bridging IVT and 24.4% (95% CI 16.5% to 32.2%) for those who underwent direct MT. The rate of sICH was significantly higher in patients with bridging IVT compared with direct MT (17.8% vs 6.4%, p=0.004). In multivariable logistic regression analysis, IVT was significantly associated with very poor outcome (OR 2.22, 95% CI 1.05 to 4.73, p=0.04) and sICH (OR 3.44, 95% CI 1.18 to 10.07, p=0.02). Successful recanalization, age, and ASPECTS were associated with good functional outcome. CONCLUSIONS: Bridging IVT in patients with low ASPECTS was associated with very poor functional outcome and an increased risk of sICH. The benefit of this treatment should therefore be carefully weighed in such scenarios. Further randomized controlled trials are required to validate our findings.

Low baseline ischemic water uptake is directly related to overestimation of CT perfusion-derived ischemic core volume.

Computed-tomography perfusion (CTP) is frequently used to screen acute ischemic stroke (AIS) patients for endovascular treatment (EVT), despite known problems with ischemic "core" overestimation. This potentially leads to the unfair exclusion of patients from EVT. We propose that net water uptake (NWU) can be used in addition to CTP to more accurately assess the extent and/or stage of tissue infarction. Patients treated for AIS between 06/2015 and 07/2020 were retrospectively analyzed. Baseline CTP-derived core volume (pCore) and NWU were determined. Logistic regression tested the relationship between baseline clinical and imaging variables and core-overestimation (primary outcome). The secondary outcomes comprised 90-day functional independence (modified Rankin score) and lesion growth. 284 patients were included. Median NWU was 7.2% (IQR 2.6-12.8). ASPECTS (RR 1.28, 95% CI 1.09-1.51), NWU (RR 0.94, 95% CI 0.89-0.98), onset to recanalization (RR 1.00, 95% CI 0.99-1.00) and imaging (RR 1.00, 95% CI 1.00-1.00) times, and pCore (RR 1.02, 95% CI 1.01-1.02) were significantly associated with core overestimation. Core-overestimation was more likely to occur in patients with large pCores and low NWU at baseline. NWU was significantly correlated with lesion growth. We conclude that NWU can be used as a supplemental tool to CTP during admission imaging to more accurately assess the extent of ischemia, particularly relevant for patients with large CTP-defined cores who would otherwise be excluded from treatment.

Impact of Woven EndoBridge Shape Modification on Aneurysm Recanalization at Short-Term Follow-up Digital Subtraction Angiography.

BACKGROUND: Woven EndoBridge (WEB) shape modification (WSM) is a frequently observed phenomenon after aneurysm embolization. OBJECTIVE: To test our hypothesis that WSM is associated with worse aneurysm occlusion on short-term angiographic follow-up images. METHODS: Patients with short-term follow-up digital subtraction angiography (DSA) available were included. Baseline patient characteristics, aneurysm morphometrics, and WEB dimensions ("conventional" parameters) and height and width WSM ("WSM" parameters) in the initial and the follow-up examination were analyzed. For ordinal regression analyses, aneurysm occlusion was graded according to the Bicêtre Occlusion Scale Score (BOSS; grades 0, 0', 1, 2, 3, and 1 + 3). Receiver operating characteristic curve analysis was used to distinguish adequately (BOSS 0, 0', and 1) from incompletely (BOSS 2, 3, and 1 + 3) occluded aneurysms. RESULTS: We included 93 patients with 96 aneurysms. Adequate occlusion was observed in 72 cases (75.0%). In univariate ordinal regression analysis, width WSM in anteroposterior DSA (odds ratio = 0.96, 95% CI: 0.94-0.99, P = .010) and in lateral DSA (odds ratio = 0.98, 95% CI: 0.97-0.99, P = .049) were significantly associated with the BOSS after 6 months. In multivariate regression analysis, WSM was not independently associated with aneurysm occlusion. Based on receiver operating characteristic curve analysis, the area under the curve (AUC) of the "conventional" model (AUC = 0.83, 95% CI 0.74-0.90) was higher than the AUC of the "WSM" model (WSM; AUC = 0.70, 95% CI 0.60-0.79). CONCLUSION: WSM was not independently associated with angiographic aneurysm occlusion status after 6 months. However, the "conventional" parameters including sex, rupture state, WEB type, WEB width, aneurysm width, height, and volume were associated with partial aneurysm recanalization in WEB-treated patients at the short-term follow-up.

Quantitative Lesion Water Uptake as Stroke Imaging Biomarker: A Tool for Treatment Selection in the Extended Time Window?

BACKGROUND AND PURPOSE: Patients presenting in the extended time window may benefit from mechanical thrombectomy. However, selection for mechanical thrombectomy in this patient group has only been performed using specialized image processing platforms, which are not widely available. We hypothesized that quantitative lesion water uptake calculated in acute stroke computed tomography (CT) may serve as imaging biomarker to estimate ischemic lesion progression and predict clinical outcome in patients undergoing mechanical thrombectomy in the extended time window. METHODS: All patients with ischemic anterior circulation stroke presenting within 4.5 to 24 hours after symptom onset who received initial multimodal CT between August 2014 and March 2020 and underwent mechanical thrombectomy were analyzed. Quantitative lesion net water uptake was calculated from the admission CT. Prediction of clinical outcome was assessed using univariable receiver operating characteristic curve analysis and logistic regression analyses. RESULTS: One hundred two patients met the inclusion criteria. In the multivariable logistic regression analysis, net water uptake (odds ratio, 0.78 [95% CI, 0.64-0.95], P=0.01), age (odds ratio, 0.94 [95% CI, 0.88-0.99]; P=0.02), and National Institutes of Health Stroke Scale (odds ratio, 0.88 [95% CI, 0.79-0.99], P=0.03) were significantly and independently associated with favorable outcome (modified Rankin Scale score ≤1), adjusted for degree of recanalization and Alberta Stroke Program Early CT Score. A multivariable predictive model including the above parameters yielded the highest diagnostic ability in the classification of functional outcome, with an area under the curve of 0.88 (sensitivity 92.3%, specificity 82.9%). CONCLUSIONS: The implementation of quantitative lesion water uptake as imaging biomarker in the diagnosis of patients with ischemic stroke presenting in the extended time window might improve clinical prognosis. Future studies could test this biomarker as complementary or even alternative tool to CT perfusion.

Woven EndoBridge (WEB) Width at the Aneurysm Neck Level Affects Early Angiographic Aneurysm Occlusion.

PURPOSE: Endovascular therapy with the Woven EndoBridge (WEB) device is a safe treatment approach, whereby neoendothelialization at the neck area is a crucial element for aneurysm occlusion. We hypothesized that WEB sizing at the aneurysmal neck level has an impact on early aneurysm occlusion. METHODS: Patients with short-term follow-up digital subtraction angiography following WEB treatment of unruptured aneurysms were included. Aneurysms were categorized according to the Bicêtre Occlusion Scale Score (BOSS) as adequately (BOSS 0, 0', 1) or partially occluded (BOSS 2, 3, 1 + 3). The WEB device dimensions, including the average aneurysm diameter (AADi) and the average neck diameter (ANDi) as well as baseline patient characteristics were documented. RESULTS: In this study 75 patients with 76 aneurysms were included and 65 aneurysms showed adequate occlusion at short-term follow-up (86%). In univariable logistic regression analysis, smaller differences in WEB size to ANDi (D-ANDi) were significantly associated with adequate aneurysm occlusion (odds ratio, OR = 0.41, 95% confidence interval, CI 0.23-0.71, p = 0.002). Receiver operating characteristic (ROC) curve analyses displayed higher discriminative power for the D­ANDi (AUC = 0.77, 95% CI 0.66-0.86, cut-off ≤2.9 mm) compared to the difference in WEB size to the average aneurysm diameter (D-AADi, AUC = 0.65, 95% CI 0.53-0.75, cut-off ≤1.0 mm). CONCLUSION: Smaller differences between the WEB width and ANDi were associated with adequate early aneurysm occlusion and might thus have a higher impact on the results than the traditional device sizing considering the mean aneurysm diameter. D­ANDi ≤2.9 mm served as an optimal cut-off to classify occlusion after WEB treatment at the short-term follow-up. Further external validation is warranted.

Persistent challenges in endovascular treatment decision-making for acute ischaemic stroke.

PURPOSE OF REVIEW: Although endovascular treatment (EVT) is the gold standard for treating acute stroke patients with large vessel occlusion (LVO), multiple challenges in decision-making for specific conditions persist. Recent evidence on a selection of patient subgroups will be discussed in this narrative review. RECENT FINDINGS: Two randomized controlled trials (RCTs) have been published in EVT of basilar artery occlusion (BAO). Large single arm studies showed promising results in Patients with low Alberta stroke program early CT score (ASPECTS) and more distal vessel occlusions. Recent data confirm patients with low National Institutes of Health Stroke Scale (NIHSS) despite LVO to represent a heterogeneous and challenging patient group. SUMMARY: The current evidence does not justify withholding EVT from BAO patients as none of the RCTs showed any signal of superiority of BMT alone vs. EVT. Patients with low ASPECTS, more distal vessel occlusions and patients with low NIHSS scores should be included into RCTs if possible. Without participation in a RCT, patients should be selected for EVT based on age, severity and type of neurological impairment, time since symptom onset, location of the ischaemic lesion and perhaps also results of advanced imaging.

Reversible Ischemic Lesion Hypodensity in Acute Stroke CT Following Endovascular Reperfusion.

BACKGROUND AND OBJECTIVES: In acute stroke, early ischemic lesion hypodensity on CT is considered the imaging hallmark of brain infarction, representing a state of irreversible tissue damage with a continual increase of net water uptake. This dogma, however, is challenged by rare cases of apparently reversed early lesion hypodensity after complete reperfusion. The purpose of this study was to investigate the occurrence of reversible ischemic edema after endovascular treatment. METHODS: One hundred eighty-four patients with acute ischemic anterior circulation stroke were included after consecutive screening. Ischemic brain edema was determined with quantitative lesion net water uptake (NWU) in admission CT and follow-up CT based on CT densitometry, and ΔNWU was calculated as the difference. The association of edema progression to imaging and clinical parameters was investigated. Clinical outcome was assessed with the modified Rankin Scale (mRS) scores at day 90. RESULTS: Of 184 patients, 27 (14.7%) showed edema arrest and 3 (1.6%) exhibited significant edema reversibility. Higher degree of recanalization (odds ratio [OR] 2.96, 95% confidence interval [CI] 1.46-6.01, p < 0.01) and shorter time from imaging to recanalization (OR per hour 0.32, 95% CI 0.18-0.54, p < 0.0001) were significantly associated with edema arrest or reversibility. Clinical outcome was significantly better in patients without edema progression (median mRS score 2 vs 5, p = 0.004). DISCUSSION: Although rare, lesion hypodensity considered to be representative of early infarct in acute stroke CT may be reversible after complete recanalization. Arrest of edema progression of acute brain infarct lesions may occur after successful rapid vessel recanalization, resulting in improved functional outcome. Future research is needed to investigate conditions in which early revascularization may halt or even reverse vasogenic edema of ischemic tissue.

Relationship between the degree of recanalization and functional outcome in acute ischemic stroke is mediated by penumbra salvage volume.

BACKGROUND: The presence of metabolically viable brain tissue that may be salvageable with rapid cerebral blood flow restoration is the fundament rationale for reperfusion therapy in patients with large vessel occlusion stroke. The effect of endovascular treatment (EVT) on functional outcome largely depends on the degree of recanalization. However, the relationship of recanalization degree and penumbra salvage has not yet been investigated. We hypothesized that penumbra salvage volume mediates the effect of thrombectomy on functional outcome. METHODS: 99 acute anterior circulation stroke patients who received multimodal CT and underwent thrombectomy with resulting partial to complete reperfusion (modified thrombolysis in cerebral infarction scale (mTICI) ≥ 2a) were retrospectively analyzed. Penumbra volume was quantified on CT perfusion and penumbra salvage volume (PSV) was calculated as difference of penumbra and net infarct growth from admission to follow-up imaging. RESULTS: In patients with complete reperfusion (mTICI ≥ 2c), the median PSV was significantly higher than the median PSV in patients with partial or incomplete (mTICI 2a-2b) reperfusion (median 224 mL, IQR: 168-303 versus 158 mL, IQR: 129-225; p < 0.01). A higher degree of recanalization was associated with increased PSV (+ 63 mL per grade, 95% CI: 17-110; p < 0.01). Higher PSV was also associated with improved functional outcome (OR/mRS shift: 0.89; 95% CI: 0.85-0.95, p < 0.0001). CONCLUSIONS: PSV may be an important mediator between functional outcome and recanalization degree in EVT patients and could serve as a more accurate instrument to compare treatment effects than infarct volumes.

Computed tomography-based triage of extensive baseline infarction: ASPECTS and collaterals versus perfusion imaging for outcome prediction.

BACKGROUND: Patients presenting with large baseline infarctions are often excluded from mechanical thrombectomy (MT) due to uncertainty surrounding its effect on outcome. We hypothesized that computed tomography perfusion (CTP)-based selection may be predictive of functional outcome in low Alberta Stroke Program Early CT Score (ASPECTS) patients. METHODS: This was a double-center, retrospective analysis of patients presenting with ASPECTS≤5 who received multimodal admission CT imaging between May 2015 and June 2020. The predicted ischemic core (pCore) was defined as a reduction in cerebral blood flow (rCBF), while mismatch volume was defined using time to maximum (Tmax). The pCore perfusion mismatch ratio (CPMR) was also calculated. These parameters (pCore, mismatch volume, and CPMR), as well as a combined radiological score consisting of ASPECTS and collateral status (ASCO score), were tested in logistic regression and receiver operating characteristic (ROC) analyses. The primary outcome was favorable modified Rankin Scale (mRS) at discharge (≤3). RESULTS: A total of 113 patients met the inclusion criteria. The median ischemic core volume was 74.1 mL (IQR 43.8-121.8). The ASCO score was associated with favorable outcome at discharge (aOR 3.7, 95% CI 1.8 to 10.7, P=0.002), while no association was observed for the CTP parameters. A model including the ASCO score also had significantly higher area under the curve (AUC) values compared with the CTP-based model (0.88 vs 0.64, P=0.018). CONCLUSIONS: The ASCO score was superior to the CTP-based model for the prediction of good functional outcome and could represent a quick, practical, and easily implemented method for the selection of low ASPECTS patients most likely benefit from MT.

Feasibility of a customizable training environment for neurointerventional skills assessment.

OBJECTIVE: To meet increasing demands to train neuroendovascular techniques, we developed a dedicated simulator applying individualized three-dimensional intracranial aneurysm models ('HANNES'; Hamburg Anatomic Neurointerventional Endovascular Simulator). We hypothesized that HANNES provides a realistic and reproducible training environment to practice coil embolization and to exemplify disparities between neurointerventionalists, thus objectively benchmarking operators at different levels of experience. METHODS: Six physicians with different degrees of neurointerventional procedural experience were recruited into a standardized training protocol comprising catheterization of two internal carotid artery (ICA) aneurysms and one basilar tip aneurysm, followed by introduction of one framing coil into each aneurysm and finally complete coil embolization of one determined ICA aneurysm. The level of difficulty increased with every aneurysm. Fluoroscopy was recorded and assessed for procedural characteristics and adverse events. RESULTS: Physicians were divided into inexperienced and experienced operators, depending on their experience with microcatheter handling. Mean overall catheterization times increased with difficulty of the aneurysm model. Inexperienced operators showed longer catheterization times (median; IQR: 47; 30-84s) than experienced operators (21; 13-58s, p = 0.011) and became significantly faster during the course of the attempts (rho = -0.493, p = 0.009) than the experienced physicians (rho = -0.318, p = 0.106). Number of dangerous maneuvers throughout all attempts was significantly higher for inexperienced operators (median; IQR: 1.0; 0.0-1.5) as compared to experienced operators (0.0; 0.0-1.0, p = 0.014). CONCLUSION: HANNES represents a modular neurointerventional training environment for practicing aneurysm coil embolization in vitro. Objective procedural metrics correlate with operator experience, suggesting that the system could be useful for assessing operator proficiency.

Acute Stroke Management During the COVID-19 Pandemic: Does Confinement Impact Eligibility for Endovascular Therapy?

During the coronavirus disease 2019 (COVID-19) pandemic, the World Health Organization recommended measures to mitigate the outbreak such as social distancing and confinement. Since these measures have been put in place, anecdotal reports describe a decrease in the number of endovascular therapy (EVT) treatments for acute ischemic stroke due to large vessel occlusion. The purpose of our study was to determine the effect on EVT for patients with acute ischemic stroke during the COVID-19 confinement. In this retrospective, observational study, data were collected from November 1, 2019, to April 15, 2020, at 17 stroke centers in countries where confinement measures have been in place since March 2020 for the COVID-19 pandemic (Switzerland, Italy, France, Spain, Portugal, Germany, Canada, and United States). This study included 1600 patients treated by EVT for acute ischemic stroke. Date of EVT and symptom onset-to-groin puncture time were collected. Mean number of EVTs performed per hospital per 2-week interval and mean stroke onset-to-groin puncture time were calculated before confinement measures and after confinement measures. Distributions (non-normal) between the 2 groups (before COVID-19 confinement versus after COVID-19 confinement) were compared using 2-sample Wilcoxon rank-sum test. The results show a significant decrease in mean number of EVTs performed per hospital per 2-week interval between before COVID-19 confinement (9.0 [95% CI, 7.8-10.1]) and after COVID-19 confinement (6.1 [95% CI, 4.5-7.7]), (P<0.001). In addition, there is a significant increase in mean stroke onset-to-groin puncture time (P<0.001), between before COVID-19 confinement (300.3 minutes [95% CI, 285.3-315.4]) and after COVID-19 confinement (354.5 minutes [95% CI, 316.2-392.7]). Our preliminary analysis indicates a 32% reduction in EVT procedures and an estimated 54-minute increase in symptom onset-to-groin puncture time after confinement measures for COVID-19 pandemic were put into place.

Evaluation of a modular in vitro neurovascular procedure simulation for intracranial aneurysm embolization.

BACKGROUND: Rapid development in endovascular aneurysm therapy continuously drives demand for suitable neurointerventional training opportunities. OBJECTIVE: To investigate the value of an integrated modular neurovascular training environment for aneurysm embolization using additively manufactured vascular models. METHODS: A large portfolio of 30 patient-specific aneurysm models derived from different treatment settings (eg, coiling, flow diversion, flow disruption) was fabricated using additive manufacturing. Models were integrated into a customizable neurointerventional simulator with interchangeable intracranial and cervical vessel segments and physiological circuit conditions ('HANNES'; Hamburg ANatomic Neurointerventional Endovascular Simulator). Multiple training courses were performed and participant feedback was obtained using a questionnaire. RESULTS: Training for aneurysm embolization could be reliably performed using HANNES. Case-specific clinical difficulties, such as difficult aneurysm access or coil dislocation, could be reproduced. During a training session, models could be easily exchanged owing to standardized connectors in order to switch to a different treatment situation or to change from 'treated' back to 'untreated' condition. Among 23 participants evaluating hands-on courses using a five-point scale from 1 (strongly agree) to 5 (strongly disagree), HANNES was mostly rated as 'highly suitable for practicing aneurysm coil embolization' (1.78±0.79). CONCLUSION: HANNES offers a wide variability and flexibility for case-specific hands-on training of intracranial aneurysm treatment, providing equal training conditions for each situation. The high degree of standardization offered may be valuable for analysis of device behavior or assessment of physician skills. Moreover, it has the ability to reduce the need for animal experiments.

Early clinical course after aneurysmal subarachnoid hemorrhage: comparison of patients treated with Woven EndoBridge, microsurgical clipping, or endovascular coiling.

BACKGROUND: The Woven EndoBridge (WEB) device has been increasingly used for the treatment of intracranial aneurysms after aneurysmal subarachnoid hemorrhage (SAH). Still, recent major clinical trials on patient management after SAH have defined WEB embolization as an exclusion criterion. In an analysis of an unselected patient cohort, we evaluate the early clinical course of SAH patients after WEB treatment compared to those treated with endovascular coiling or surgical clipping. METHODS: Data of all patients with proven SAH who were either treated with a WEB device, coil embolization, or neurosurgical clipping between March 2015 and August 2018 was systematically reviewed. Clinical parameters on intensive care unit (ICU), medical history and mortality rates were evaluated and compared between the different treatment approaches. RESULTS: Of all 201 patients included, 107 patients received endovascular coil embolization, 56 patients were treated with clipping and in 38 cases a WEB device was placed. The overall mortality was 17.9%. Thirteen patients (34.2%) in the WEB group had a Hunt and Hess grade > 3. Essential medical factors showed no clinically relevant differences between the treatment groups, and the analyzed blood parameters were predominantly within physiological limits without any relevant outliers. The Hunt and Hess grade but not the treatment modality was identified as independent risk-factor associated with ICU-mortality in the overall cohort (p < 0.001). CONCLUSION: In this study, there was no difference in the early clinical course between those treated with WEB embolization, coil embolization, or neurosurgical clipping. Since WEB embolization is a valuable treatment alternative to coiling, it seems not justified to exclude this procedure from upcoming clinical SAH trials, yet the clinical long-term outcome, aneurysm occlusion, and retreatment rates have to be analyzed in further studies. CLINICAL TRIAL REGISTRATION NUMBER: not applicable.

Current status of training environments in neuro-interventional practice: are animal models still contemporary?

PURPOSE: Several different training environments for practicing neurointerventional procedures have been realized in silico, in vitro, and in vivo. We seek to replace animal-based training with suitable alternatives. In an effort to determine present training model distribution and preferences, we interviewed interventional neuroradiologists from 25 different countries about their experience in distinct training environments. METHODS: A voluntary online survey comprising 24 questions concerning the different training facilities was designed and electronically conducted with the members of the European Society for Minimally Invasive Neurological Therapy. RESULTS: Seventy-one physicians with an average experience of 11.8 (±8.7) years completed the survey. The majority of participants had experience with animal-based training (eg, stroke intervention: 36; 50.7%). Overall, animal-based training was rated as the most suitable environment to practice coil embolization (20 (±6)), flow diverter placement (13 (±7)), and stroke intervention (13.5 (±9)). In-vitro training before using a new device in patients was supported by most participants (35; 49.3%). Additionally, preference for certain training models was related to the years of experience. CONCLUSION: This survey discloses the preferred training modalities in European neurointerventional centers with the majority of physicians supporting the general concept of in-vitro training, concomitantly lacking a standardized curriculum for educating neurointerventional physicians. Most suitable training modalities appeared to be dependent on procedure and experience. As animal-based training is still common, alternate artificial environments meeting these demands must be further developed.

A new method to statistically describe microcatheter tip position in patient-specific aneurysm models.

BACKGROUND AND PURPOSE: Evidence on how to select microcatheters to facilitate aneurysm catheterization during coil embolization is sparse. We developed a new method to define microcatheter tip location inside a patient-specific aneurysm model as a 3-dimensional probability map. We hypothesized that precision and accuracy of microcatheter tip positioning depend on catheter tip shape and aneurysmal geometry. MATERIALS AND METHODS: Under fluoroscopic guidance two to three operators introduced differently shaped microcatheters (straight, 45°, 90°) into eight aneurysm models targeting the anatomic center of the aneurysm. Each microcatheter position was recorded with flat-panel CT, and 3-dimensional probability maps of the microcatheter tip positions were generated. Maps were assessed with histogram analyses and compared between tip shapes, aneurysm locations and operators. RESULTS: Among a total of 530 microcatheter insertions, the precision (mean distance between catheter positions) and accuracy (mean distance to target position) were significantly higher for the 45° tip (1.10±0.64 mm, 3.81±1.41 mm, respectively) than for the 90° tip (1.27±0.57 mm, p=0.010; 4.21±1.60 mm p=0.014, respectively). Accuracy was significantly higher in posterior communicating artery aneurysms (3.38±1.20 mm) than in aneurysms of the internal carotid artery (4.56±1.54 mm, p<0.001). CONCLUSION: Our method can be used tostatistically describe statistically microcatheter behavior in patient-specific anatomy, which may improve the available evidence guiding microcatheter shape selection. Experience increases the ability to reach the intended position with a microcatheter (accuracy) that is also dependent on the aneurysm location, whereas catheter tip choice determines the variability of catheter tip placements versus each other (precision). Clinical validation is required.

Multiparametric MRI of intracranial aneurysms treated with the Woven EndoBridge (WEB): a case of Faraday's cage?

OBJECTIVE: To evaluate multiparametric MRI including non-contrast and contrast-enhanced morphological and angiographic techniques for intracranial aneurysms treated with the single-layer Woven EndoBridge (WEB) embolization system applying simultaneous digital subtraction angiography (DSA) as the reference of standard. MATERIALS AND METHODS: We retrospectively identified all patients with incidental and acute ruptured intracranial aneurysms treated with a WEB device (WEB SL and WEB SLS) between March 2014 and June 2016 in our neurovascular center with early (within 7 days) postinterventional multiparametric MRI as well as mid-term (5-8 months) follow-up MRI and DSA available. Occlusion rates were recorded both in DSA and MR angiography (MRA). In MRI, signal intensities within the WEB as well as in the occluded dome distal to the WEB, if present, were measured by region-of-interest (ROI) analysis. RESULTS: Twenty-five patients fulfilled the inclusion criteria. Rates of complete/adequate occlusion at mid-term follow-up were 84% with both MRA and DSA. A strong signal loss within the WEB was observed in all MR sequences at initial and follow-up examinations. ROI analysis did not reveal significant differences in non-contrast (P=0.946) and contrast-enhanced imaging (P=0.377). A T1-hyperintense thrombus in the non-WEB-carrying dome was a frequent observation. CONCLUSIONS: Signal intensity measurements in multiparametric MRI suggest that neither contrast-enhanced MRA nor morphological sequences are capable of revealing reliable information on the WEB lumen, presumably due to radio frequency shielding. MRI is therefore not suitable for confirming complete thrombus formation within the WEB.

Intra-aneurysmal flow disruption after implantation of the Medina® Embolization Device depends on aneurysm neck coverage.

BACKGROUND AND PURPOSE: Flow disruption achieved by braided intrasaccular implants is a novel treatment strategy for cerebrovascular aneurysms. We hypothesized that the degree of intra-aneurysmal flow disruption can be quantified in vitro and is influenced by device position across the aneurysm neck. We tested this hypothesis using the Medina® Embolization Device (MED). METHODS: Ten different patient-specific elastic vascular models were manufactured. Models were connected to a pulsatile flow circuit, filled with a blood-mimicking fluid and treated by two operators using a single MED. Intra-aneurysmal flow velocity was measured using conventional and high-frequency digital subtraction angiography (HF-DSA) before and after each deployment. Aneurysm neck coverage by the implanted devices was assessed with flat detector computed tomography on a three-point Likert scale. RESULTS: A total of 80 individual MED deployments were performed by the two operators. The mean intra-aneurysmal flow velocity reduction after MED implantation was 33.6% (27.5-39.7%). No significant differences in neck coverage (p = 0.99) or flow disruption (p = 0.84) were observed between operators. The degree of flow disruption significantly correlated with neck coverage (ρ = 0.42, 95% CI: 0.21-0.59, p = 0.002) as well as with neck area (ρ = -0,35, 95% CI: -0.54 --0.13, p = 0.024). On multiple regression analysis, both neck coverage and total neck area were independent predictors of flow disruption. CONCLUSIONS: The degree of intra-aneurysmal flow disruption after MED implantation can be quantified in vitro and varies considerably between different aneurysms and different device configurations. Optimal device coverage across the aneurysm neck improves flow disruption and may thus contribute to aneurysm occlusion.