One-Stop Management of 230 Consecutive Acute Stroke Patients: Report of Procedural Times and Clinical Outcome

Flat-panel Detector Perfusion Imaging and Conventional Multidetector Perfusion Imaging in Patients with Acute Ischemic Stroke : A Comparative Study

PURPOSE

Flat-panel detector computed tomography (FDCT) is increasingly used in (neuro)interventional angiography suites. This study aimed to compare FDCT perfusion (FDCTP) with conventional multidetector computed tomography perfusion (MDCTP) in patients with acute ischemic stroke.

METHODS

In this study, 19 patients with large vessel occlusion in the anterior circulation who had undergone mechanical thrombectomy, baseline MDCTP and pre-interventional FDCTP were included. Hypoperfused tissue volumes were manually segmented on time to maximum (Tmax) and time to peak (TTP) maps based on the maximum visible extent. Absolute and relative thresholds were applied to the maximum visible extent on Tmax and relative cerebral blood flow (rCBF) maps to delineate penumbra volumes and volumes with a high likelihood of irreversible infarcted tissue ("core"). Standard comparative metrics were used to evaluate the performance of FDCTP.

RESULTS

Strong correlations and robust agreement were found between manually segmented volumes on MDCTP and FDCTP Tmax maps (r = 0.85, 95% CI 0.65-0.94, p < 0.001; ICC = 0.85, 95% CI 0.69-0.94) and TTP maps (r = 0.91, 95% CI 0.78-0.97, p < 0.001; ICC = 0.90, 95% CI 0.78-0.96); however, direct quantitative comparisons using thresholding showed lower correlations and weaker agreement (MDCTP versus FDCTP Tmax 6 s: r = 0.35, 95% CI -0.13-0.69, p = 0.15; ICC = 0.32, 95% CI 0.07-0.75). Normalization techniques improved results for Tmax maps (r = 0.78, 95% CI 0.50-0.91, p < 0.001; ICC = 0.77, 95% CI 0.55-0.91). Bland-Altman analyses indicated a slight systematic underestimation of FDCTP Tmax maximum visible extent volumes and slight overestimation of FDCTP TTP maximum visible extent volumes compared to MDCTP.

CONCLUSION

FDCTP and MDCTP provide qualitatively comparable volumetric results on Tmax and TTP maps; however, direct quantitative measurements of infarct core and hypoperfused tissue volumes showed lower correlations and agreement.

Simulation of transportation of acute stroke patients in border regions

Determining the optimal transportation for each stroke patient is critically important to achieve the best possible outcomes. In border regions the next comprehensive stroke center may be just across an international border, but bureaucratic and financial hurdles may prevent a simple transfer to the next stroke center. We hypothesized that in regions close to international borders, patients may benefit from an "open border, closed transfer scenario", meaning that patients in whom a large vessel occlusion (LVO) is detected in the primary stroke center will benefit from a transfer to the nearest stroke center offering endovascular thrombectomy-even if this may be across a national border. We used the Swiss-German-French trinational region as an example for a region with several international borders within close proximity to one another, and compared two feasible scenarios; (a) a "closed borders, open transfer" scenario, where the patient is transported to any center in the same country, (b) an "open border, closed transfer" scenario, where patients are always transported to the nearby primary stroke center first and then to the nearest comprehensive stroke center in either the same or a neighboring country and (c) and "open borders, open transfer" scenario. The outcome of interest was the predicted probability of acute ischemic stroke patients to achieve a good outcome using a conditional probability model which predicts the likelihood of excellent outcome (modified Rankin scale score of 0-1 at 90 days post-stroke) for patients with suspected LVO. Results were modeled in a virtual map from which the ideal transport concept emerged. For an exemplary LVO stroke patient in Germany, the probability of a good outcome was higher in an open border, closed transfer scenario than with closed borders, open transfer (33.1 vs. 30.1%). Moreover, time to EVT would decrease from 232 min in the first scenario to 169 min in an open border, closed transfer scenario. The catchment area of the University Hospital Basel was almost double the size in an open border, closed transfer scenario compared to closed borders (1674 km2 vs. 2897 km2) and would receive transfers from 3 primary stroke centers in other countries (2 in Germany and 1 in France). Stroke patients showed a higher likelihood of good outcome in the "open border" scenarios without transfer restrictions to a specific healthcare system. This probably has implications for stroke treatment in all border regions where EVT eligible stroke patients may benefit from transport to the closest EVT capable center whenever possible, regardless of whether this hospital is located in the same or a neighboring country/jurisdiction.

Cost-utility of direct transfer to angiography suite (DTAS) bypassing conventional imaging for patients with acute ischemic stroke in Spain: results from the ANGIOCAT trial

BACKGROUND

The ANGIOCAT trial showed a clinical benefit of direct to angiography suite (DTAS) for patients with large vessel occlusion (LVO) stroke admitted within 6 hours after symptom onset in decreased hospital workflow time and improved clinical outcome. However, the impact of DTAS implementation on hospital costs is unknown. This economic evaluation aims to assess the cost-utility of DTAS from the provider (hospital) perspective.

METHODS

A cost-utility analysis was applied to compare DTAS with the standard direct to CT (DTCT) suite approach using direct cost and health outcomes data. The time horizon was 90 days. One-way sensitivity analysis as well as probabilistic sensitivity analysis was performed, varying the model parameters by ±25%. Measures included costs, quality-adjusted life years, and incremental cost-effectiveness ratios. Health outcomes, classified according to the modified Rankin Scale, were obtained from the ANGIOCAT trial. Respective utilities were obtained from the literature.

RESULTS

DTAS is the dominant strategy. The incremental cost-effectiveness ratio is -€89 110 (-$97 600) with cost saving per patient of -€2848 (-$3120). The improved clinical outcome is directly related with a decrease in costs for the hospital, mainly due to the decrease in costs of hospital stay, improved clinical outcome and fewer complications.

CONCLUSIONS

For patients with LVO admitted within 6 hours after symptom onset, the DTAS not only improves clinical outcome but also decreases the costs (dominant option) compared with the standard DTCT. Multicentric international randomized clinical trials are ongoing to determine the replicability of our findings.

Current and future trends in acute ischemic stroke treatment: direct-to-angiography suite, middle vessel occlusion, large core, and minor strokes

Since the publication of the landmark thrombectomy trials in 2015, the field of endovascular therapy for ischemic stroke has been rapidly growing. The very low number needed to treat to provide functional benefits shown by the initial randomized trials has led clinicians and investigators to seek to translate the benefits of endovascular therapy to other patient subgroups. Even if the treatment effect is diminished, currently available data has provided sufficient information to extend endovascular therapy to large infarct core patients. Recently, published data have also shown that sophisticated imaging is not necessary for late time- window patients. As a result, further research into patient selection and the stroke pathway now focuses on dramatically reducing door-to-groin times and improving outcomes by circumventing classical imaging paradigms altogether and employing a direct-to-angio suite approach for selected large vessel occlusion patients in the early time window. While the results of this approach mainly concern patients with severe deficits, there are further struggles to provide evidence of the efficacy and safety of endovascular treatment in minor stroke and large vessel occlusion, as well as in patients with middle vessel occlusions. The current lack of good quality data regarding these patients provides significant challenges for accurately selecting potential candidates for endovascular treatment. However, current and future randomized trials will probably elucidate the efficacy of endovascular treatment in these patient populations.

Cost-effectiveness of Direct Transfer to Angiography Suite of Patients With Suspected Large Vessel Occlusion

BACKGROUND AND OBJECTIVES

Patients with acute ischemic stroke due to large vessel occlusion (LVO) deemed eligible for endovascular thrombectomy (EVT) are transferred from the emergency room to the angiography suite to undergo the procedure. Recently, the strategy of direct transfer of patients with suspected LVO to the angiography suite (DTAS) has been shown to improve functional outcomes. This study aims to evaluate the cost-effectiveness of the DTAS strategy vs initial transfer of patients with suspected LVO (Rapid Arterial Occlusion Evaluation score >4 and NIH Stroke Scale >10) to the emergency room (ITER).

METHODS

A decision-analytic Markov model was developed to estimate the cost-effectiveness of the DTAS strategy vs the ITER strategy from a Dutch health care perspective with a 10-year time horizon. The primary outcome was the incremental cost-effectiveness ratio (ICER) using Dutch thresholds of $59,135 (€50,000) and $94,616 (€80,000) per quality-adjusted life year (QALY). Uncertainty of input parameters was assessed using 1-way sensitivity analysis, scenario analysis, and probabilistic sensitivity analysis.

RESULTS

The DTAS strategy yielded 0.65 additional QALYs at an additional $16,089, resulting in an ICER of $24,925/QALY compared with the ITER strategy. The ICER varied from $27,169 to $38,325/QALY across different scenarios. The probabilistic sensitivity analysis showed that the DTAS strategy had a 91.8% and 97.0% likelihood of being cost-effective at a decision threshold of $59,135/QALY and $94,616/QALY, respectively.

DISCUSSION

The cost-effectiveness of the DTAS strategy over ITER is robust for patients with suspected LVO. Together with recently published clinical results, this means that implementation of the DTAS strategy may be considered to improve the workflow and outcome of EVT.

Direct to angiosuite strategy versus standard workflow triage for endovascular therapy: systematic review and meta-analysis

BACKGROUND

Reducing stroke workflow times when performing endovascular thrombectomy is associated with improvement in clinical outcomes. We compared outcomes among large vessel occlusion (LVO) stroke patients following the direct to angiosuite (DTAS) strategy versus standard workflow (SW) when undergoing endovascular therapy.

METHODS

We conducted a systematic review and meta-analysis to compare rates of functional outcomes, reperfusion, symptomatic intracranial hemorrhage (sICH) and stroke workflow metrics. We included observational studies and clinical trials that compared the DTAS strategy versus SW, and at least one outcome of interest was assessed. Clinical, methodological and statistical heterogeneity were measured, and a random-effects model was used.

RESULTS

12 studies were included in the systematic review and 8 in the meta-analysis (n=2890). The DTAS strategy was associated with significant higher odds of good functional outcome at 90 days (47.3% vs 34.9%; OR 1.58, 95% CI 1.16 to 2.14) and a significant average reduction of door-to-puncture (mean differences (MD) -35.09, 95% CI -49.76 to -20.41) and door-to-reperfusion times (MD -32.88, 95% CI -50.75 to -15.01). We found no differences in sICH (OR 0.80, 95% CI 0.53 to 1.20), mortality (OR 1.00, 95% CI 0.60 to 1.67) or successful reperfusion rates (OR 1.37, 95% CI 0.82 to 2.29). Moreover, the DTAS strategy was associated with greater odds of dramatic clinical improvement at 24 hours (OR 1.79, 95% CI 1.15 to 2.79).

CONCLUSION

Patients undergoing the DTAS strategy had a significant reduction in door-to-puncture and door-to-reperfusion times. This resulted in an increased rate of early neurological and 90-day functional recovery without compromising safety in LVO patients undergoing endovascular thrombectomy.

Current Status of and Future Developments in Acute Stroke Management

Stroke treatment has advanced rapidly over the last few years [...].

Extended Multimodal Flat Detector CT Imaging in Acute Ischemic Stroke: A Pilot Study

By using Flat detector computed tomography (FD-CT), a one-stop-shop approach in the diagnostic workup of acute ischemic stroke (AIS) might be achieved. Although information on upstream vessels is warranted, dedicated FD-CT protocols which include the imaging of the cervical vasculature are still lacking. We aimed to prospectively evaluate the implementation of a new multimodal FD-CT protocol including cervical vessel imaging in AIS patients. In total, 16 patients were included in this study. Eight patients with AIS due to large vessel occlusion (LVO) prospectively received a fully multimodal FD-CT imaging, including non-enhanced flat detector computed tomography (NE-FDCT), dynamic perfusion flat detector computed tomography (FD-CTP) and flat detector computed tomography angiography (FD-CTA) including cervical imaging. For comparison of time metrics and image quality, eight AIS patients, which received multimodal CT imaging, were included retrospectively. Although image quality of NE-FDCT and FD-CTA was rated slightly lower than NE-CT and CTA, all FD-CT datasets were of diagnostic quality. Intracerebral hemorrhage exclusion and LVO detection was reliably possible. Median door-to-image time was comparable for the FD-CT group and the control group (CT:30 min, IQR27-58; FD-CT:44.5 min, IQR31-55, p = 0.491). Door-to-groin-puncture time (CT:79.5 min, IQR65-90; FD-CT:59.5 min, IQR51-67; p = 0.016) and image-to-groin-puncture time (CT:44 min, IQR30-50; FD-CT:14 min, IQR12-18; p < 0.001) were significantly shorter, when patients were directly transferred to the angiosuite, where FD-CT took place. Our study indicates that using a new fully multimodal FD-CT approach including imaging of cervical vessels for first-line imaging in AIS patients is feasible and comparable to multimodal CT imaging with substantial potential to streamline the stroke workflow.

Access to and application of recanalizing therapies for severe acute ischemic stroke caused by large vessel occlusion

BACKGROUND

Groundbreaking study results since 2014 have dramatically changed the therapeutic options in acute therapy for severe ischemic stroke caused by large vessel occlusion (LVO). The scientifically proven advances in stroke imaging and thrombectomy techniques have allowed to offer the optimal version or combination of best medical and interventional therapy to the selected patient, yielding favorable or even excellent clinical outcomes within time windows unheard of before. The provision of the best possible individual therapy has become a guideline-based gold standard, but remains a great challenge. With geographic, regional, cultural, economic and resource differences worldwide, optimal local solutions have to be strived for.

AIM

This standard operation procedure (SOP) is aimed to give a suggestion of how to give patients access to and apply modern recanalizing therapy for acute ischemic stroke caused by LVO.

METHOD

The SOP was developed based on current guidelines, the evidence from the most recent trials and the experience of authors who have been involved in the above-named development at different levels.

RESULTS

This SOP is meant to be a comprehensive, yet not too detailed template to allow for freedom in local adaption. It comprises all relevant stages in providing care to the patient with severe ischemic stroke such as suspicion and alarm, prehospital acute measures, recognition and grading, transport, emergency room workup, selective cerebral imaging, differential treatment by recanalizing therapies (intravenous thrombolysis, endovascular stroke treatmet, or combined), complications, stroke unit and neurocritical care.

CONCLUSIONS

The challenge of giving patients access to and applying recanalizing therapies in severe ischemic stroke may be facilitated by a systematic, SOP-based approach adapted to local settings.

Evaluation of time-resolved whole brain flat panel detector perfusion imaging using RAPID ANGIO in patients with acute stroke: comparison with CT perfusion imaging

BACKGROUND

In contrast to conventional CT perfusion (CTP) imaging, flat panel detector CT perfusion (FD-CTP) imaging can be acquired directly in the angiosuite.

OBJECTIVE

To evaluate time-resolved whole brain FD-CTP imaging and assess clinically important qualitative and quantitative perfusion parameters in correlation with previously acquired conventional CTP using the new RAPID for ANGIO software.

METHODS

We included patients with internal carotid artery occlusions and M1 or M2 occlusions from six centers. All patients underwent mechanical thrombectomy (MT) with preinterventional conventional CTP and FD-CTP imaging. Quantitative performance was determined by comparing volumes of infarct core, penumbral tissue, and mismatch. Eligibility for MT according to the perfusion imaging criteria of DEFUSE 3 was determined for each case from both conventional CTP and FD-CTP imaging.

RESULTS

A total of 20 patients were included in the final analysis. Conventional relative cerebral blood flow (rCBF) <30% and FD-CTP rCBF <45% showed good correlation (R²=0.84). Comparisons of conventional CTP Tmax >6 s versus FD-CTP Tmax >6 s and CTP mismatch versus FD-CTP mismatch showed more variability (R²=0.57, and R²=0.33, respectively). Based on FD-CTP, 16/20 (80%) patients met the inclusion criteria for MT according to the DEFUSE 3 perfusion criteria, in contrast to 18/20 (90%) patients based on conventional CTP. The vessel occlusion could be correctly extrapolated from the hypoperfusion in 18/20 cases (90%).

CONCLUSIONS

In our multicenter study, time-resolved whole brain FD-CTP was technically feasible, and qualitative and quantitative perfusion results correlated with those obtained with conventional CTP.

Image quality improvements for brain soft tissue in neuro-endovascular treatments: A novel dual-axis "butterfly" trajectory for optimized Cone-Beam CT

PURPOSE

Cone-beam computed tomography (CBCT) is useful in the diagnosis of complications after neuro-endovascular treatment. However, the image quality of conventional CBCT is inferior to that of conventional CT. To solve this problem, a dual-axis butterfly CBCT available with an angiography suite has been developed. This study aimed to evaluate the image quality of this dual-axis butterfly CBCT compared to the conventional CBCT in the same patient.

METHOD

We prospectively included patients who underwent scheduled neuro-endovascular treatment and performed conventional CBCT and novel dual-axis butterfly CBCT as a postoperative examination. We evaluated artifacts, brain contrast, and cortico-medullary junctions on a scoring system using a 5-point scale in which lower scores indicate better image quality. In addition, the white matter/gray matter ratio was calculated in selected brain lobe regions.

RESULTS

Forty-seven cases (94 paired images) were enrolled. The novel dual-axis butterfly CBCT had significantly fewer supratentorial and infratentorial artifacts in the artifact evaluation. Similarly, contrast and cortico-medullary junction discrimination in the cerebral hemispheres scored significantly better in the butterfly scan in all regions. The white matter/gray matter ROI ratio was significantly higher in the novel dual-axis butterfly CBCT in the frontal and occipital lobes but not in the temporal lobe.

CONCLUSIONS

Compared to conventional CBCT, the novel dual-axis butterfly CBCT showed supratentorial and infratentorial artifact reduction as well as improved contrast with the brain parenchyma and cerebrospinal fluid space and white matter/gray matter discrimination ability.

Evaluation of direct-to-angiography suite (DTAS) and conventional clinical pathways in stroke care: a simulation study

BACKGROUND

Rapid time to reperfusion is essential to minimize morbidity and mortality in acute ischemic stroke due to large vessel occlusion (LVO). We aimed to evaluate the workflow times when utilizing a direct-to-angiography suite (DTAS) pathway for patients with suspected stroke presenting at a comprehensive stroke center compared with a conventional CT pathway.

METHODS

We developed a discrete-event simulation (DES) model to evaluate DTAS workflow timelines compared with a conventional CT pathway, varying the admission NIHSS score treatment eligibility criteria. Model parameters were estimated based on 2 year observational data from our institution. Sensitivity analyses of simulation parameters were performed to assess the impact of patient volume and baseline utilization of angiography suites on workflow times utilizing DTAS.

RESULTS

Simulation modeling of stroke patients (SimStroke) demonstrated door-to-reperfusion time savings of 0.2-3.5 min (p=0.05) for a range of DTAS eligibility criteria (ie, last known well to arrival <6 hours and National Institutes of Health Stroke Scale ≥6-11), when compared with the conventional stroke care pathway. Sensitivity analyses revealed that DTAS time savings is highly dependent on baseline utilization of angiography suites.

CONCLUSIONS

The results of the SimStroke model showed comparable time intervals for door-to-reperfusion for DTAS compared with a conventional stroke care pathway. However, the DTAS pathway was very sensitive to baseline angiography suite utilization, with even a 10% increase eliminating the advantages of DTAS compared with the conventional pathway. Given the minimal time savings modeled here, further investigation of implementing the DTAS pathway in clinical care is warranted.

Correlation of Collateral Scores Derived from Whole-Brain Time-Resolved Flat Panel Detector Imaging in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Flat panel detector CT imaging allows simultaneous acquisition of multiphase flat panel CTA and flat panel CTP imaging directly in the angio suite. We compared collateral assessment derived from multiphase flat panel CTA and flat panel CTP with collateral assessment derived from DSA as the gold-standard.

MATERIALS AND METHODS

We performed a retrospective analysis of patients with occlusion of the first or second segment of the MCA who underwent pre-interventional flat panel detector CT. The hypoperfusion intensity ratio as a correlate of collateral status was calculated from flat panel CTP (time-to-maximum > 10 seconds volume/time-to-maximum > 6 seconds volume). Intraclass correlation coefficients were calculated for interrater reliability for the Calgary/Menon score for multiphase flat panel CTA and for the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) score for DSA collateral scores. Correlations of the hypoperfusion intensity ratio, multiphase flat panel CTA score, and the ASITN/SIR score were calculated using the Spearman correlation.

RESULTS

From November 2019 to February 2020, thirty patients were included. Moderate interrater reliability was achieved for the ASITN/SIR DSA score (0.68; 95% CI, 0.50-0.82) as well as for the Calgary/Menon multiphase flat panel CTA score (0.53; 95% CI, 0.29-0.72). We found a strong correlation between the ASITN/SIR DSA and Calgary/Menon multiphase flat panel CTA score (ρ = 0.54, P = .002) and between the hypoperfusion intensity ratio and the Calgary/Menon multiphase flat panel CTA score (ρ = -0.57, P < .001). The correlation was moderate between the hypoperfusion intensity ratio and the ASITN/SIR DSA score (ρ = -0.49, P = .006). The infarct core volume correlated strongly with the Calgary/Menon multiphase flat panel CTA score (ρ = -0.66, P < .001) and the hypoperfusion intensity ratio (ρ = 0.76, P < .001) and correlated moderately with the ASITN/SIR DSA score (ρ = -0.46, P = .01).

CONCLUSIONS

The Calgary/Menon multiphase flat panel CTA score and the hypoperfusion intensity ratio correlated with each other and with the ASITN/SIR DSA score as the gold-standard. In our cohort, the collateral scoring derived from flat panel detector CT was clinically reliable.

Effective Dose Measurements of the Latest-Generation Angiographic System in Patients with Acute Stroke: A Comparison with the Newest Multidetector CT Generation

BACKGROUND AND PURPOSE

Patients with acute ischemic stroke are increasingly triaged with one-stop management approaches, resulting in baseline imaging with a flat detector CT scanner. This study aimed to estimate the effective dose to a patient of a novel cervical and intracranial flat detector CT angiography and a flat detector CT perfusion protocol and to compare it with the effective dose of analogous multidetector row CT protocols.

MATERIALS AND METHODS

We estimated the effective dose to the patient according to the International Commission on Radiological Protection 103 using an anthropomorphic phantom with metal oxide semiconductor field effect transistor dosimeters. Placement was according to the organ map provided by the phantom manufacturer. We used 100 measurement points within the phantom, and 18 metal oxide semiconductor field effect transistor dosimeters were placed on the surface of the phantom. All protocols followed the manufacturer's specifications, and patient positioning and collimation were performed as in routine clinical practice. Measurements were obtained on the latest-generation angiography and multidetector row CT systems with identical placement of the metal oxide semiconductor field effect transistor dosimeters.

RESULTS

The estimated effective doses of the investigated perfusion protocols were 4.52 mSv (flat detector CT perfusion without collimation), 2.88 mSv (flat detector CT perfusion with collimation), and 2.17 mSv (multidetector row CT perfusion). A novel protocol called portrait flat detector CT angiography that has a z-axis coverage area comparable with that of multidetector row CT angiography had an estimated effective dose of 0.91 mSv, while the dose from multidetector row CT was 1.35 mSv.

CONCLUSIONS

The estimated effective dose to the patient for flat detector CT perfusion and angiography on a modern biplane angiography system does not deviate substantially from that of analogous multidetector row CT protocols.

Diagnostic performance of intraoperative cone beam computed tomography compared with postoperative magnetic resonance imaging for detecting hemorrhagic transformation after endovascular treatment following large vessel occlusion

OBJECTIVES

Early detection of hemorrhagic transformation (HT) in patients with large vessel occlusion (LVO) after endovascular treatment is important for postoperative patient management. We investigated the diagnostic performance of intraoperative cone beam computed tomography (CBCT) with reference standard magnetic resonance imaging (MRI) for detecting HT.

MATERIALS AND METHODS

Consecutive patients with LVO treated by endovascular treatment who underwent intraoperative CBCT and postoperative MRI were included. Two observers evaluated all images for the presence of HT. Sensitivity and specificity for detecting HT were calculated with MRI as reference standard. The observers classified HT according to the European Cooperative Acute Stroke Study (ECASS). Inter-method and inter-rater agreement for the detection of HT and for the ECASS classification were assessed using kappa or weighted Brennan-Prediger (wBP) statistics.

RESULTS

Images of 106 procedures (94 for anterior circulation) were analyzed. The sensitivity and specificity for detecting HT on CBCT were 0.77 and 0.83, respectively, for all procedures and 0.83 and 0.8, respectively, for anterior circulation. The inter-method agreement for HT detection (κ = 0.63 overall, κ = 0.69 anterior circulation) and ECASS classification (wBP = 0.67 overall, wBP = 0.77 anterior circulation) were substantial. The inter-rater agreement for HT detection (κ = 0.87 overall, κ = 0.85 anterior circulation) and for ECASS classification (wBP = 0.95 overall, wBP = 0.92 anterior circulation) were almost perfect.

CONCLUSIONS

The diagnostic performance of CBCT for the detection of HT in stroke patients treated for LVO was acceptable with excellent inter-rater agreement. Intraoperative CBCT may be useful to trigger early interventions if HT is detected, although detailed classifications of HT may be difficult.

A novel use of time separation technique to improve flat detector CT perfusion imaging in stroke patients

BACKGROUND

CT perfusion imaging (CTP) is used in the diagnostic workup of acute ischemic stroke (AIS). CTP may be performed within the angio suite using flat detector CT (FDCT) to help reduce patient management time.

PURPOSE

In order to significantly improve FDCT perfusion (FDCTP) imaging, data-processing algorithms need to be able to compensate for the higher levels of noise, slow rotation speed, and a lower frame rate of current FDCT devices.

METHODS

We performed a realistic simulation of FDCTP acquisition based on CTP data from seven subjects. We used the time separation technique (TST) as a model-based approach for FDCTP data processing. We propose a novel dimension reduction in which we approximate the time attenuation curves by a linear combination of trigonometric functions. Our goal was to show that the TST can be used even without prior assumptions on the shape of the attenuation profiles.

RESULTS

We first demonstrated that a trigonometric basis is suitable for dimension reduction of perfusion data. Using simulated FDCTP data, we have shown that a trigonometric basis in the TST provided better results than the classical straightforward processing even with additional noise. Average correlation coefficients of perfusion maps were improved for cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT) maps. In a moderate noise scenario, the average Pearson's coefficient for the CBF map was improved using the TST from 0.76 to 0.81. For the MTT map, it was improved from 0.37 to 0.45. Furthermore, we achieved a total processing time from the reconstruction of FDCTP data to the generation of perfusion maps of under 5 min.

CONCLUSIONS

In our study cohort, perfusion maps created from FDCTP data using the TST with a trigonometric basis showed equivalent perfusion deficits to classic CT perfusion maps. It follows, that this novel FDCTP technique has potential to provide fast and accurate FDCTP imaging for AIS patients.

Digital subtraction angiography in cerebrovascular disease: current practice and perspectives on diagnosis, acute treatment and prognosis

Digital Subtraction Angiography (DSA) is the gold-standard imaging modality in acute cerebrovascular diagnosis. The role of DSA has become increasingly prominent since the incorporation of endovascular therapy in standards of care for acute ischemic stroke. It is used in the assessment of cerebral vessel patency; however, the therapeutic role of DSA from a prognostic standpoint merits further investigation. The current paper provides an update on current practice on diagnostic, therapeutic and prognostic use of DSA in acute cerebrovascular diseases and various indications and perspectives that may apply, or limit its use, in ongoing surveillance or prognosis. Pre-clinical and clinical studies on the aspects, including but not limited to the morphology of cerebrovasculature in acute ischaemic stroke, are required to delineate and inform its prognostic role.

Direct to Angiosuite Versus Conventional Imaging in Suspected Large Vessel Occlusion: A Systemic Review and Meta-Analysis

BACKGROUND

There is growing evidence to suggest that the direct transfer to angiography suite (DTAS) approach for patients with suspected large vessel occlusion stroke potentially requiring mechanical thrombectomy shortens treatment times and improves outcomes compared with the direct transfer to conventional imaging (DTCI) model. Therefore, we conducted this meta-analysis to compare both approaches to build more concrete evidence to support this innovative treatment concept.

METHODS

All potentially relevant studies published in 4 electronic databases/search engines (PubMed, Web of Science, Cochrane Library, and Scopus) from inception to November 2021 were reviewed. Eligible studies were included if they enrolled ≥10 patients in both groups, were published in English, and reported baseline and procedural characteristics and outcomes. Relevant data were then extracted and analyzed.

RESULTS

Among 4514 searched studies, 7 qualified for the analysis with 1971 patients (DTAS=675, DTCI=1296). Times from door to puncture (mean difference, -30.76 minutes [95% CI, -43.70 to -17.82]; P<0.001) as well as door-to-reperfusion (mean difference=-33.24 minutes [95% CI, -51.82 to -14.66]; P<0.001) were significantly shorter and the rates of functional independence (modified Rankin Scale score, 0-2: risk ratio [RR], 1.25 [95% CI, 1.02-1.53]; P=0.03) at 90 days were higher in the DTAS versus the DTCI approach. There was no difference across the DTAS and DTCI groups in terms of the rates of successful reperfusion (modified Thrombolysis in Cerebral Infarction score 2B-3: RR, 1.03 [95% CI, 0.95-1.12]; P=0.42), near-complete/full reperfusion (modified Thrombolysis in Cerebral Infarction 2C-3: RR, 0.89 [95% CI, 0.74-1.08]; P=0.23), symptomatic intracranial hemorrhage (RR, 0.81 [95% CI, 0.56-1.17]; P=0.26), or fair outcomes (modified Rankin Scale score, 0-3: RR, 1.14 [95% CI, 0.88-1.47]; P=0.32) or mortality (RR, 0.98 [95% CI, 0.67-1.44]; P=0.93) at 90 days. Subgroup analysis showed no significant difference in 90-day functional independence across approaches in transfer patients (RR, 1.20 [95% CI, 0.96-1.51]; P=0.11).

CONCLUSIONS

Our meta-analysis showed that the DTAS approach seems to be associated with improved time metrics and functional outcomes with comparable safety to the DTCI approach. Ongoing multicenter randomized clinical trials will hopefully provide more definite data about this promising approach.

Direct to angiography suite approaches for the triage of suspected acute stroke patients: a systematic review and meta-analysis

Background:

Increasing evidence suggests improved time metrics leading to better clinical outcomes when stroke patients with suspected large vessel occlusion (LVO) are transferred directly to the angiography suite (DTAS) compared with cross-sectional imaging followed by transfer to the angiography suite. We performed a systematic review and meta-analysis on the efficacy and safety of DTAS approaches.

Methods:

We searched Embase, Medline, Scopus, and clinicaltrials.gov for studies comparing outcomes of DTAS and conventional triage. Eligible studies were assessed for risk of bias. We performed a random-effects meta-analysis on the differences of median door-to-groin and door-to-reperfusion times between intervention and control group. Secondary outcomes included good outcome at 90 days (modified Rankin Scale ⩽ 2) rate of symptomatic intracranial hemorrhage (sICH) and mortality within 90 days.

Results:

Eight studies (one randomized, one cluster-randomized trial and six observational studies) with 1938 patients were included. Door-to-groin and door-to-reperfusion times in the intervention group were on median 29.0 min [95% confidence interval (CI): 14.3–43.6; p < 0.001] and 32.1 min (95% CI: 15.1–49.1; p < 0.001) shorter compared with controls. Prespecified subgroup analyses for transfer (n = 1753) and mothership patients (n = 185) showed similar reductions of the door-to-groin and door-to-reperfusion times in response to the intervention. The odds of good outcome did not differ significantly between both groups but were numerically higher in the intervention group (odds ratio: 1.38, 95% CI: 0.97–1.95; p = 0.07). There was no significant difference for mortality and sICH between the groups.

Conclusion:

DTAS approaches for the triage of suspected LVO patients led to a significant reduction in door-to-groin and door-to-reperfusion times but an effect on functional outcome was not detected. The subgroup analysis showed similar results for transfer and mothership patients.

Registration: This study was registered in PROSPERO (CRD42020213621).

Endovascular thrombectomy for acute ischemic stroke

This review describes the evolution of endovascular treatment for acute ischemic stroke, current state of the art, and the challenges for the next decade. The rapid development of endovascular thrombectomy (EVT), from the first attempts into standard of care on a global scale, is one of the major achievements in modern medicine. It was possible thanks to the establishment of a scientific framework for patient selection, assessment of stroke severity and outcome, technical development by dedicated physicians and the MedTech industry, including noninvasive imaging for patient selection, and radiological outcome evaluation. A series of randomized controlled trials on EVT in addition to intravenous thrombolytics, with overwhelmingly positive results for anterior circulation stroke within 6 h of onset regardless of patient characteristics with a number needed to treat of less than 3 for any positive shift in outcome, paved the way for a rapid introduction of EVT into clinical practice. Within the "extended" time window of 6-24 h, the effect has been even greater for patients with salvageable brain tissue according to perfusion imaging with a number needed to treat below 2. Even so, EVT is only available for a small portion of stroke patients, and successfully recanalized EVT patients do not always achieve excellent functional outcome. The major challenges in the years to come include rapid prehospital detection of stroke symptoms, adequate clinical and radiological diagnosis of severe ischemic stroke cases, enabling effective recanalization by EVT in dedicated angiosuites, followed by personalized post-EVT stroke care.

Comparison of Mobile Stroke Unit With Usual Care for Acute Ischemic Stroke Management: A Systematic Review and Meta-analysis

IMPORTANCE

So far, uncertainty remains as to whether there is sufficient cumulative evidence that mobile stroke unit (MSU; specialized ambulance equipped with computed tomography scanner, point-of-care laboratory, and neurological expertise) use leads to better functional outcomes compared with usual care.

OBJECTIVE

To determine with a systematic review and meta-analysis of the literature whether MSU use is associated with better functional outcomes in patients with acute ischemic stroke (AIS).

DATA SOURCES

MEDLINE, Cochrane Library, and Embase from 1960 to 2021.

STUDY SELECTION

Studies comparing MSU deployment and usual care for patients with suspected stroke were eligible for analysis, excluding case series and case-control studies.

DATA EXTRACTION AND SYNTHESIS

Independent data extraction by 2 observers, following the PRISMA and MOOSE reporting guidelines. The risk of bias in each study was determined using the ROBINS-I and RoB2 tools. In the case of articles with partially overlapping study populations, unpublished disentangled results were obtained. Data were pooled in random-effects meta-analyses.

MAIN OUTCOMES AND MEASURES

The primary outcome was excellent outcome as measured with the modified Rankin Scale (mRS; score of 0 to 1 at 90 days).

RESULTS

Compared with usual care, MSU use was associated with excellent outcome (adjusted odds ratio [OR], 1.64; 95% CI, 1.27-2.13; P < .001; 5 studies; n = 3228), reduced disability over the full range of the mRS (adjusted common OR, 1.39; 95% CI, 1.14-1.70; P = .001; 3 studies; n = 1563), good outcome (mRS score of 0 to 2: crude OR, 1.25; 95% CI, 1.09-1.44; P = .001; 6 studies; n = 3266), shorter onset-to-intravenous thrombolysis (IVT) times (median reduction, 31 minutes [95% CI, 23-39]; P < .001; 13 studies; n = 3322), delivery of IVT (crude OR, 1.83; 95% CI, 1.58-2.12; P < .001; 7 studies; n = 4790), and IVT within 60 minutes of symptom onset (crude OR, 7.71; 95% CI, 4.17-14.25; P < .001; 8 studies; n = 3351). MSU use was not associated with an increased risk of all-cause mortality at 7 days or at 90 days or with higher proportions of symptomatic intracranial hemorrhage after IVT.

CONCLUSIONS AND RELEVANCE

Compared with usual care, MSU use was associated with an approximately 65% increase in the odds of excellent outcome and a 30-minute reduction in onset-to-IVT times, without safety concerns. These results should help guideline writing committees and policy makers.

OUP accepted manuscript

Background: Time is brain! This paradigm is forcing the development of strategies with potential to shorten the time from symptom onset to recanalization. One of these strategies is to transport select patients with acute ischaemic stroke directly to an angio-suite equipped with flat-detector computed tomography (FD-CT) to exclude intracranial haemorrhage, followed directly by invasive angiography and mechanical thrombectomy if large-vessel occlusion (LVO) is confirmed. Aim: To present existing published data about the direct transfer (DT) of stroke patients to angio-suites and to describe our initial experience with this stroke pathway. Methods: We performed a systematic PubMed search of trials that described DT of stroke patients to angio-suites and summarized the results of these trials. In January 2020, we implemented a new algorithm for acute ischaemic stroke care in our stroke centre. Select patients suitable for DT (National Institute of Health Stroke Scale score ≥10, time from symptom onset to door <4.5 h) were referred by neurologists directly to an angio-suite equipped with FD-CT. Patients treated using this algorithm were analysed and compared with patients treated using the standard protocol including CT and CT angiography in our centre. Results: We identified seven trials comparing the DT protocol with the standard protocol in stroke patients. Among the 628 patients treated using the DT protocol, 104 (16.5%) did not have LVO and did not undergo endovascular treatment (EVT). All the trials demonstrated a significant reduction in door-to-groin time with DT, compared with the standard protocol. This reduction ranged from 22 min (DT protocol: 33 min; standard protocol: 55 min) to 59 min (DT protocol: 22 min; standard protocol: 81 min). In three of five trials comparing the 90-day modified Rankin scale scores between the DT and standard imaging groups, this reduction in ischaemic time translated into better clinical outcomes, whereas the two other trials reported no such difference in scores. Between January 2020 and October 2021, 116 patients underwent EVT for acute ischaemic stroke in our centre. Among these patients, 65 (56%) met the criteria for DT (National Institutes of Health Stroke Scale score >10, symptom onset-to-door time <4.5 h), but only 7 (10.8%) were transported directly to the angio-suite. The reasons that many patients who met the criteria were not transported directly to the angio-suite were lack of personnel trained in FD-CT acquisition outside of working hours, ongoing procedures in the angio-suite, contraindication to the DT protocol due to atypical clinical presentation, and neurologist’s decision for obtain complete neurological imaging. All seven patients who were transported directly to the angio-suite had LVOs. The median time from door-to-groin-puncture was significantly lower with the DT protocol compared with the standard protocol {29 min [interquartile range (IQR): 25–31 min] vs. 71 min [IQR: 55–94 min]; P < 0.001}. None of the patients had symptomatic intracranial haemorrhage in the DT protocol group, compared with 7 (6.4%) patients in the standard protocol group. Direct transfer of acute ischaemic stroke patients to the angio-suite equipped with FD-CT seems to reduce the time from patient arrival in the hospital to groin puncture. This reduction in the ischaemic time translates into better clinical outcomes. However, more data are needed to confirm these results.

Evaluating the cost-utility of a direct transfer to angiosuite protocol within 6 h of symptom onset in suspected large vessel occlusion patients

INTRODUCTION

A direct transfer to angiosuite (DTAS) protocol has shown to be effective and safe by shortening in-hospital workflows and encouraging long-term outcome benefits. To implement DTAS at a new facility, a large organizational effort is necessary. We performed a cost-utility analysis and budget impact analysis (BIA) of the operation of a new angiosuite, primarily dedicated to stroke patients, that allows facilities to approximate the cost implications of utilizing a DTAS pathway.

METHODS

Sixty-one patients who underwent endovascular treatment (EVT) following DTAS were matched for baseline variables to 117 patients who underwent a conventional imaging protocol at a hospital in Catalonia, Spain. An economic model, based on actual data from these patients, was developed to assess the short- and long-term clinical and economic implications of DTAS. In the BIA, the DTAS scenario was gradually implemented for 20% of patients each year until reaching a plateau at 80% of patients in the DTAS pathway. Initial investment and additional organizational costs, €4 million, were taken into consideration to compare the budget impact of the DTAS scenario with no organizational changes over five years.

RESULTS

DTAS was associated with better patient functional independence rates (mRS 0-2: 50.9% vs. 41.0%) and a quality-adjusted life-years gain of 0.82 per patient. Despite the additional initial investment, DTAS development was associated with an estimated 10.2% reduction (€14.7 million) of the total costs (€144.5 million). Cost savings were mainly due to long-term associated costs related to patient disability (€13.2 million).

LIMITATIONS

The study relies on data obtained from a single-center, and therefore it may be difficult to generalize the findings.

CONCLUSIONS

Our economic model predicts that the implementation of a DTAS program is cost-effective compared with no organizational changes. Our model also predicts better clinical outcomes for patients in terms of functional independence and quality-adjusted life years.

Direct Transfer to Angiosuite in Acute Stroke: Why, When, and How?

Time to reperfusion is one of the strongest predictors of functional outcome in acute stroke due to a large vessel occlusion (LVO). Direct transfer to angiography suite (DTAS) protocols have shown encouraging results in reducing in-hospital delays. DTAS allows bypassing of conventional imaging in the emergency room by ruling out an intracranial hemorrhage or a large established infarct with imaging performed before transfer to the thrombectomy-capable center in the angiography suite using flat-panel CT (FP-CT). The rate of patients with stroke code primarily admitted to a comprehensive stroke center with a large ischemic established lesion is <10% within 6 hours from onset and remains <20% among patients with LVO or transferred from a primary stroke center. At the same time, stroke severity is an acceptable predictor of LVO. Therefore, ideal DTAS candidates are patients admitted in the early window with severe symptoms. The main difference between protocols adopted in different centers is the inclusion of FP-CT angiography to confirm an LVO before femoral puncture. While some centers advocate for FP-CT angiography, others favor additional time saving by directly assessing the presence of LVO with an angiogram. The latter, however, leads to unnecessary arterial punctures in patients with no LVO (3%-22% depending on selection criteria). Independently of these different imaging protocols, DTAS has been shown to be effective and safe in improving in-hospital workflow, achieving a reduction of door-to-puncture time as low as 16 minutes without safety concerns. The impact of DTAS on long-term functional outcomes varies between published studies, and randomized controlled trials are warranted to examine the benefit of DTAS.

Performance characterization of a prototype dual-layer cone-beam computed tomography system

PURPOSE

Conventional cone-beam computed tomography CT (CBCT) provides limited discrimination between low-contrast tissues. Furthermore, it is limited to full-spectrum energy integration. A dual-energy CBCT system could be used to separate photon energy spectra with the potential to increase the visibility of clinically relevant features and acquire additional information relevant in a multitude of clinical imaging applications. In this work, the performance of a novel dual-layer dual-energy CBCT (DL-DE-CBCT) C-arm system is characterized for the first time.

METHODS

A prototype dual-layer detector was fitted into a commercial interventional C-arm CBCT system to enable DL-DE-CBCT acquisitions. DL-DE reconstructions were derived from material-decomposed Compton scatter and photoelectric base functions. The modulation transfer function (MTF) of the prototype DL-DE-CBCT was compared to that of a commercial CBCT. Noise and uniformity characteristics were evaluated using a cylindrical water phantom. Effective atomic numbers and electron densities were estimated in clinically relevant tissue substitutes. Iodine quantification was performed (for 0.5-15 mg/ml concentrations) and virtual noncontrast (VNC) images were evaluated. Finally, contrast-to-noise ratios (CNR) and CT number accuracies were estimated.

RESULTS

The prototype and commercial CBCT showed similar spatial resolution, with a mean 10% MTF of 5.98 cycles/cm and 6.28 cycles/cm, respectively, using a commercial standard reconstruction. The lowest noise was seen in the 80 keV virtual monoenergetic images (VMI) (7.40 HU) and the most uniform images were seen at VMI 60 keV (4.74 HU) or VMI 80 keV (1.98 HU), depending on the uniformity measure used. For all the tissue substitutes measured, the mean accuracy in effective atomic number was 98.2% (SD 1.2%) and the mean accuracy in electron density was 100.3% (SD 0.9%). Iodine quantification images showed a mean difference of -0.1 (SD 0.5) mg/ml compared to the true iodine concentration for all blood and iodine-containing objects. For VNC images, all blood substitutes containing iodine averaged a CT number of 43.2 HU, whereas a blood-only substitute measured 44.8 HU. All water-containing iodine substitutes measured a mean CT number of 2.6 in the VNC images. A noise-suppressed dataset showed a CNR peak at VMI 40 keV and low at VMI 120 keV. In the same dataset without noise suppression applied, a peak in CNR was obtained at VMI 70 keV and a low at VMI 120 keV. The estimated CT numbers of various clinically relevant objects were generally very close to the calculated CT number.

CONCLUSIONS

The performance of a prototype dual-layer dual-energy C-arm CBCT system was characterized. Spatial resolution and noise were comparable with a commercially available C-arm CBCT system, while offering dual-energy capability. Iodine quantifications, effective atomic numbers, and electron densities were in good agreement with expected values, indicating that the system can be used to reliably evaluate the material composition of clinically relevant tissues. The VNC and monoenergetic images indicate a consistent ability to separate clinically relevant tissues. The results presented indicate that the system could find utility in diagnostic, interventional, and radiotherapy planning settings.

Non-contrast head CT alone for thrombectomy in acute ischemic stroke: analysis of the ANGEL-ACT registry

BACKGROUD

The goal of this study was to determine if the choice of imaging paradigm performed in the emergency department influences the procedural or clinical outcomes after mechanical thrombectomy (MT).

METHODS

This is a retrospective comparative outcome study which was conducted from the ANGEL-ACT registry. Comparisons were made between baseline characteristics and clinical outcomes of patients with acute ischemic stroke undergoing MT with non-contrast head computed tomography (NCHCT) alone versus patients undergoing NCHCT plus non-invasive vessel imaging (NVI) (including CT angiography (with or without CT perfusion) and magnetic resonance angiography). The primary outcome was the modified Rankin Scale (mRS) score at 90 days. Secondary outcomes included change in mRS score from baseline to 90 days, the proportions of mRS 0-1, 0-2, and 0-3, and dramatic clinical improvement at 24 hours. The safety outcomes were any intracranial hemorrhage (ICH), symptomatic ICH, and mortality within 90 days.

RESULTS

A total of 894 patients met the inclusion criteria; 476 (53%) underwent NCHCT alone and 418 (47%) underwent NCHCT + NVI. In the NCHCT alone group, the door-to-reperfusion time was shorter by 47 min compared with the NCHCT + NVI group (219 vs 266 min, P<0.001). Patients in the NCHCT alone group showed a smaller increase in baseline mRS score at 90 days (median 3 vs 2 points; P=0.004) after adjustment. There were no significant differences between groups in the remaining clinical outcomes.

CONCLUSIONS

In patients selected for MT using NCHCT alone versus NCHCT + NVI, there were improved procedural outcomes and smaller increases in baseline mRS scores at 90 days.

Direct to Angiography Suite Without Stopping for Computed Tomography Imaging for Patients With Acute Stroke: A Randomized Clinical Trial

Importance

Direct transfer to angiography suite (DTAS) for patients with suspected large vessel occlusion (LVO) stroke has been described as an effective and safe measure to reduce workflow time in endovascular treatment (EVT). However, it is unknown whether DTAS improves long-term functional outcomes.

Objective

To explore the effect of DTAS on clinical outcomes among patients with LVO stroke in a randomized clinical trial.

Design, Setting, and Participants

The study was an investigator-initiated, single-center, evaluator-blinded randomized clinical trial. Of 466 consecutive patients with acute stroke screened, 174 with suspected LVO acute stroke within 6 hours of symptom onset were included. Enrollment took place from September 2018 to November 2020 and was stopped after a preplanned interim analysis. Final follow-up was in February 2021.

Interventions

Patients were randomly assigned (1:1) to follow either DTAS (89 patients) or conventional workflow (85 patients received direct transfer to computed tomographic imaging, with usual imaging performed and EVT indication decided) to assess the indication of EVT. Patients were stratified according to their having been transferred from a primary center vs having a direct admission.

Main Outcomes and Measures

The primary outcome was a shift analysis assessing the distribution of the 90-day 7-category (from 0 [no symptoms] to 6 [death]) modified Rankin Scale (mRS) score among patients with LVO whether or not they received EVT (modified intention-to-treat population) assessed by blinded external evaluators. Secondary outcomes included rate of EVT and door-to-arterial puncture time. Safety outcomes included 90-day mortality and rates of symptomatic intracranial hemorrhage.

Results

In total, 174 patients were included, with a mean (SD) age of 73.4 (12.6) years (range, 19-95 years), and 78 patients (44.8%) were women. Their mean (SD) onset-to-door time was 228.0 (117.9) minutes, and their median admission National Institutes of Health Stroke Scale score was 18 (interquartile range [IQR], 14-21). In the modified intention-to-treat population, EVT was performed for all 74 patients in the DTAS group and for 64 patients (87.7%) in the conventional workflow group (P = .002). The DTAS protocol decreased the median door-to-arterial puncture time (18 minutes [IQR, 15-24 minutes] vs 42 minutes [IQR, 35-51 minutes]; P < .001) and door-to-reperfusion time (57 minutes [IQR, 43-77 minutes] vs 84 minutes [IQR, 63-117 minutes]; P < .001). The DTAS protocol decreased the severity of disability across the range of the mRS (adjusted common odds ratio, 2.2; 95% CI, 1.2-4.1; P = .009). Safety variables were comparable between groups.

Conclusions and Relevance

For patients with LVO admitted within 6 hours after symptom onset, this randomized clinical trial found that, compared with conventional workflow, the use of DTAS increased the odds of patients undergoing EVT, decreased hospital workflow time, and improved clinical outcome.

Trial Registration

ClinicalTrials.gov Identifier: NCT04001738.

[Border areas of thrombectomy]

Die mechanische Thrombektomie (MT) hat sich als Standardverfahren für die Behandlung akuter ischämischer Schlaganfälle aufgrund eines Verschlusses einer großen, proximalen Hirnarterie der vorderen Zirkulation etabliert. Dennoch sind nach aktuellen Guidelines noch große Patientenkollektive von dieser hocheffektiven Behandlungsmethode ausgeschlossen. Diese Arbeit gibt daher einen Überblick über mögliche Erweiterungen der Behandlungsindikationen für die MT, wie z. B. Patienten im erweiterten Zeitfenster, mit distalen Verschlüssen, mit großem Infarktkern oder auch für sehr alte (> 90 Jahre) und junge (0–17 Jahre) Patienten. Zusätzlich besprechen wir neue Entwicklungen in der interventionellen Behandlung von Schlaganfällen, wie z. B. neue Triage-Konzepte oder die Fragestellung, ob die zusätzliche intravenöse Thrombolyse bei MT-Patienten notwendig ist. Abschließend geben wir für die besprochenen Behandlungsindikationen unsere Einschätzungen basierend auf der aktuellen Literatur und unserer klinischen Erfahrung.

Acute reperfusion therapies for acute ischemic stroke patients with unknown time of symptom onset or in extended time windows: an individualized approach

Recent randomized controlled clinical trials (RCTs) have revolutionized acute ischemic stroke care by extending the use of intravenous thrombolysis and endovascular reperfusion therapies in time windows that have been originally considered futile or even unsafe. Both systemic and endovascular reperfusion therapies have been shown to improve outcome in patients with wake-up strokes or symptom onset beyond 4.5 h for intravenous thrombolysis and beyond 6 h for endovascular treatment; however, they require advanced neuroimaging to select stroke patients safely. Experts have proposed simpler imaging algorithms but high-quality data on safety and efficacy are currently missing. RCTs used diverse imaging and clinical inclusion criteria for patient selection during the dawn of this novel stroke treatment paradigm. After taking into consideration the dismal prognosis of nonrecanalized ischemic stroke patients and the substantial clinical benefit of reperfusion therapies in selected late presenters, we propose rescue reperfusion therapies for acute ischemic stroke patients not fulfilling all clinical and imaging inclusion criteria as an option in a subgroup of patients with clinical and radiological profiles suggesting low risk for complications, notably hemorrhagic transformation as well as local or remote parenchymal hemorrhage. Incorporating new data to treatment algorithms may seem perplexing to stroke physicians, since treatment and imaging capabilities of each stroke center may dictate diverse treatment pathways. This narrative review will summarize current data that will assist clinicians in the selection of those late presenters that will most likely benefit from acute reperfusion therapies. Different treatment algorithms are provided according to available neuroimaging and endovascular treatment capabilities.

How to Improve the Management of Acute Ischemic Stroke by Modern Technologies, Artificial Intelligence, and New Treatment Methods

Stroke remains one of the leading causes of death and disability in Europe. The European Stroke Action Plan (ESAP) defines four main targets for the years 2018 to 2030. The COVID-19 pandemic forced the use of innovative technologies and created pressure to improve internet networks. Moreover, 5G internet network will be helpful for the transfer and collecting of extremely big databases. Nowadays, the speed of internet connection is a limiting factor for robotic systems, which can be controlled and commanded potentially from various places in the world. Innovative technologies can be implemented for acute stroke patient management soon. Artificial intelligence (AI) and robotics are used increasingly often without the exception of medicine. Their implementation can be achieved in every level of stroke care. In this article, all steps of stroke health care processes are discussed in terms of how to improve them (including prehospital diagnosis, consultation, transfer of the patient, diagnosis, techniques of the treatment as well as rehabilitation and usage of AI). New ethical problems have also been discovered. Everything must be aligned to the concept of “time is brain”.

Expanding indications for endovascular thrombectomy-how to leave no patient behind

Endovascular thrombectomy (EVT) has become standard of care for large vessel occlusion strokes but current guidelines exclude a large proportion of patients from this highly effective treatment. This review therefore focuses on expanding indications for EVT in several borderline indications such as patients in the extended time window, patients with extensive signs of infarction on admission imaging, elderly patients and patients with pre-existing deficits. It also discusses the current knowledge on intravenous thrombolysis as an adjunct to EVT and EVT as primary therapy for distal vessel occlusions, for tandem occlusions, for basilar artery occlusions and in pediatric patients. We provide clear recommendations based on current guidelines and further literature.

Acute ischemic stroke endovascular therapy

Endovascular therapy (EVT) has become the standard treatment for large-vessel occlusion (LVO) acute ischemic stroke (AIS). EVT is now indicated in patients up to 24h from their last known well, provided that the patient meets specific clinical and imaging criteria. Improvements in thrombectomy devices, techniques, and operator experience have allowed successful EVT of ICA terminus, M1-MCA occlusions as well as proximal M2-MCA, basilar artery occlusions, and revascularization of tandem lesions. Mechanical thrombectomy failures still occur due to several factors, however, highlighting the need for further device and technical improvements. An ongoing debate exists regarding the need for pre-EVT thrombolytic agents, thrombectomy techniques, distal occlusions, anesthesia methods, the role of advanced neuroimaging, the treatment of patients with larger infarct core, and those presenting with milder stroke symptoms. Many of these questions are the subject of current or upcoming clinical trials. This review aims to provide an outline and discussion about the established recommendations and emerging topics regarding EVT for LVO AIS.

Automated Perfusion Calculations vs. Visual Scoring of Collaterals and CBV-ASPECTS : Has the Machine Surpassed the Eye?

Purpose

Use of automated perfusion software has gained importance for imaging of stroke patients for mechanical thrombectomy (MT). We aim to compare four perfusion software packages: 1) with respect to their association with 3‑month functional outcome after successful reperfusion with MT in comparison to visual Cerebral Blood Volume - Alberta Stroke Program Early CT Score (CBV-ASPECTS) and collateral scoring and 2) with respect to their agreement in estimation of core and penumbra volume.

Methods

This retrospective, multicenter cohort study (2015–2019) analyzed data from 8 centers. We included patients who were functionally independent before and underwent successful MT of the middle cerebral artery. Primary outcome measurements were the relationship of core and penumbra volume calculated by each software, qualitative assessment of collaterals and CBV-APECTS with 3‑month functional outcome and disability (modified Rankin scale >2). Quantitative differences between perfusion software measurements were also assessed.

Results

A total of 215 patients (57% women, median age 77 years) from 8 centers fulfilled the inclusion criteria. Multivariable analyses showed a significant association of RAPID core (common odds ratio, cOR 1.02; p = 0.015), CBV-ASPECTS (cOR 0.78; p = 0.007) and collaterals (cOR 0.78; p = 0.001) with 3‑month functional outcome (shift analysis), while RAPID core (OR 1.02; p = 0.018), CBV-ASPECTS (OR 0.77; p = 0.024), collaterals (OR 0.78; p = 0.007) and OLEA core (OR 1.02; p = 0.029) were significantly associated with 3‑month functional disability. Mean differences on core estimates between VEOcore and RAPID were 13.4 ml, between syngo.via and RAPID 30.0 ml and between OLEA and RAPID −3.2 ml.

Conclusion

Collateral scoring, CBV-ASPECTS and RAPID were independently associated with functional outcome at 90 days. Core and Penumbra estimates using automated software packages varied significantly and should therefore be used with caution.

Electronic supplementary material

The online version of this article (10.1007/s00062-020-00974-3) contains supplementary material, which is available to authorized users.

Updates in Stroke Treatment, Diagnostic Methods and Predictors of Outcome

In recent years, there have been outstanding achievements in stroke diagnosis and care [...].

Modeling the Optimal Transportation for Acute Stroke Treatment : Impact of Diurnal Variations in Traffic Rate

Purpose

Prolonged transfer times between the primary stroke center (PSC) and the comprehensive stroke center (CSC) are one of the major causes of treatment delay for endovascular stroke treatment. We aimed to analyze the effect of the diurnal variations in traffic rates at weekdays and weekends on the catchment area size of three transportation paradigms, i.e. mothership, drip-and-ship (DS) and drip-and-drive (DD).

Methods

A conditional probability model that predicts the probability of good outcome for patients with suspected large vessel occlusion was used to analyze the prehospital stroke triage in northwest Germany and produce catchment area maps. Transportation times were calculated during each hour of a weekday and a Sunday using Google Maps. For comparison, real DD transportation times from our CSC in Hamburg-Eppendorf (blinded for review) to a PSC in Lüneburg were prospectively recorded.

Result

On weekdays, the mothership catchment area was the largest (≥40,000 km², 63%) except for a decrease during morning rush hours, when the DD catchment area was highest (30,879 km², 48%). The DS catchment area was higher than the DD catchment area during the afternoon rush hours both during the week as well as on Sundays.

Conclusion

Our study showed a considerable impact of the diurnal variations in traffic rate and direction of travel on optimal stroke transportation. Stroke systems of care should take real time traffic information into account.

Electronic supplementary material

The online version of this article (10.1007/s00062-020-00933-y) contains supplementary material, which is available to authorized users.