Flat-panel detector CT assessment in stroke to reduce times to intra-arterial treatment: A study of multiphase computed tomography angiography in the angiography suite to bypass conventional imaging

Sine Spin flat detector CT can improve cerebral soft tissue imaging: a retrospective in vivo study

BACKGROUND

Flat detector computed tomography (FDCT) is frequently applied for periinterventional brain imaging within the angiography suite. Novel technical developments such as the Sine Spin FDCT (S-FDCT) may provide an improved cerebral soft tissue contrast. This study investigates the effect of S-FDCT on the differentiation between gray and white matter compared to conventional FDCT (C-FDCT) and multidetector computed tomography (MDCT).

METHODS

A retrospective analysis of a prospectively maintained patient database was performed, including patients who underwent mechanical thrombectomy in our institution and received S-FDCT or C-FDCT as well as MDCT. Differentiation between gray and white matter on the contralateral hemisphere to the ischemic stroke was analyzed quantitatively by contrast-to-noise ratio (CNR) and qualitatively (5-point ordinal scale).

RESULTS

In a cohort of 109 patients, MDCT demonstrated the best differentiation between gray and white matter compared to both FDCT techniques (p ≤ 0.001). Comparing both generations of FDCT, S-FDCT provided better visibility of the basal ganglia (p = 0.045) and the supratentorial cortex (p = 0.044) compared to C-FDCT both in quantitative and qualitative analyses. Median CNR were as follows: S-FDCT 2.41 (interquartile range [IQR] 1.66-3.21), C-FDCT 0.96 (0.46-1.70), MDCT 3.43 (2.83-4.17). For basal ganglia, median score and IQR were as follows: S-FDCT 2.00 (2.00-3.00), C-FDCT 1.50 (1.00-2.00), MDCT 5.00 (4.00-5.00).

CONCLUSIONS

The novel S-FDCT improves the periinterventional imaging quality of cerebral soft tissue compared to C-FDCT. Thus, it may improve the diagnosis of complications within the angiography suite. MDCT provides the best option for x-ray-based imaging of the brain tissue.

RELEVANCE STATEMENT

Flat detector computed tomography is a promising technique for cerebral soft tissue imaging, while the novel Sine Spin flat detector computed tomography technique improves imaging quality compared to conventional flat detector computed tomography and thus may facilitate periinterventional diagnosis of gray and white matter.

KEY POINTS

• Flat detector computed tomography (FDCT) is frequently applied for periinterventional brain imaging. • The potential of novel Sine Spin FDCT (S-FDCT) is unknown so far. • S-FDCT improves the visibility of cerebral soft tissue compared to conventional FDCT. • Multidetector computed tomography is superior to both FDCT techniques. • S-FDCT may facilitate the evaluation of brain parenchyma within the angiography suite.

Hemodynamic Characteristics of Intracranial Atherosclerotic Stenosis: A Pilot Study of Contrast Enhancement Time-Density Curves Based on Regions of Interest

OBJECTIVE

The present study aimed to analyze the hemodynamic characteristics of occluded vessels responsible for acute ischemic stroke and to diagnose the occlusion types.

METHODS

Multimodal computed tomography (CT) was used to accurately identify the range of occlusion of large intracranial vessels. Regions of interest (ROI 1-3 ) were manually delineated at sites 2 mm away from the proximal, middle, and distal portions of each occlusion, generating 3 contrast enhancement time-density curves. The peak CT attenuation values, or Hounsfield units (H 1-3 ), and time-to-peak values (T 1-3 ) were extracted from each curve. H 0 and T 0 of the time-density curve, based on ROI 0 of the automatically recognized input artery, were used as the baseline values with which the odds ratios of each parameter, H 1-3/0 and T 1-3/0 , were obtained. The present study aimed to establish prediction models for intracranial atherosclerotic stenosis (ICAS) based on each ROI's time-density curve.

RESULTS

Among the 33 acutely occluded intracranial vessels, 10 were found to have ICAS, whereas 23 did not, based on the diagnostic criteria. Significant differences were observed in patient sex, neutrophil-to-lymphocyte ratio upon admission, Alberta Stroke Program Early CT Score 24-48 hours after reperfusion therapy, and H 1/0 , H 3/0 , and T 3/0 between the ICAS and non-ICAS groups ( P < 0.05). The prediction model (model 3) based on the ROI 3 time-density curve showed the best performance for the diagnosis of ICAS (area under the curve, 0.944; 95% confidence interval, 0.854-1.000). The prediction models based on ROI 1 (model 1) and ROI 2 (model 2) showed moderate diagnostic performance (area under the curve, 0.817 vs 0.822, respectively). The best visualization for proximal occlusions was in the first phase (arterial phase) of multiphase CT angiography, and in the second phase (early venous phase) for distal occlusions.

CONCLUSIONS

The contrast enhancement time-density curves of the ROIs at all evaluated portions of the acute ischemic stroke occlusions provided a visual display of the blood flow characteristics of the responsible vessels. The time-density curve of the ROI placed 2 mm from the distal occlusion was a combined effect of residual blood flow and collateral establishment, thus providing good performance for the diagnosis of ICAS.

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.

Clinical Applications of Conebeam CTP Imaging in Cerebral Disease: A Systematic Review

BACKGROUND

Perfusion imaging with multidetector CT is integral to the evaluation of patients presenting with ischemic stroke due to large-vessel occlusion. Using conebeam CT perfusion in a direct-to-angio approach could reduce workflow times and improve functional outcome.

PURPOSE

Our aim was to provide an overview of conebeam CT techniques for quantifying cerebral perfusion, their clinical applications, and validation.

DATA SOURCES

A systematic search was performed for articles published between January 2000 and October 2022 in which a conebeam CT imaging technique for quantifying cerebral perfusion in human subjects was compared against a reference technique.

STUDY SELECTION

Eleven articles were retrieved describing 2 techniques: dual-phase (n = 6) and multiphase (n = 5) conebeam CTP.

DATA ANALYSIS

Descriptions of the conebeam CT techniques and the correlations between them and the reference techniques were retrieved.

DATA SYNTHESIS

Appraisal of the quality and risk of bias of the included studies revealed little concern about bias and applicability. Good correlations were reported for dual-phase conebeam CTP; however, the comprehensiveness of its parameter is unclear. Multiphase conebeam CTP demonstrated the potential for clinical implementation due to its ability to produce conventional stroke protocols. However, it did not consistently correlate with the reference techniques.

LIMITATIONS

The heterogeneity within the available literature made it impossible to apply meta-analysis to the data.

CONCLUSIONS

The reviewed techniques show promise for clinical use. Beyond evaluating their diagnostic accuracy, future studies should address the practical challenges associated with implementing these techniques and the potential benefits for different ischemic diseases.

Characterizing Fast and Slow Progressors in Anterior Circulation Large Vessel Occlusion Strokes

BACKGROUND AND PURPOSE

Infarct growth rate (IGR) in acute ischemic stroke is highly variable. We sought to evaluate impact of symptom-reperfusion time on outcomes in patients undergoing mechanical thrombectomy (MT).

METHODS

A prospectively maintained database from January,2012-August,2020 was reviewed. All patients with isolated MCA-M1 occlusion who achieved complete reperfusion(mTICI2C-3), had a witnessed symptom onset and follow-up MRI were included. IGR was calculated as final infarct volume (FIV)(ml)/symptom onset to reperfusion time(hours) and was dichotomized according to the median value into slow-(SP) versus fast-progressors (FP). The primary analysis aimed to evaluate the impact of symptom-reperfusion time on 90-day mRS in SP and FP. Secondary analysis was performed to identify predictors of IGR.

RESULTS

A total of 137 patients were eligible for analysis. Mean age was 63 ± 15.4 years and median IGR was 5.13ml/hour. SP(n = 69) had higher median ASPECTS, lower median rCBF<30% lesion volume, higher proportion of favorable collaterals and hypoperfusion intensity ratio (HIR)<0.4, higher minimal mean arterial blood pressure before reperfusion, and lower rates of general anesthesia compared to FP(n = 68). Symptom-reperfusion time was comparable between both groups. SP had higher rates of 90-day mRS0-2(71.9%vs.38.9%,aOR;7.226,95%CI[2.431-21.482],p < 0.001) and lower median FIV. Symptom-reperfusion time was associated with 90-day mRS0-2 in FP (aOR;0.541,95%CI[0.309-0.946],p = 0.03) but not in SP (aOR;0.874,95%CI[0.742-1.056],p = 0.16). On multivariable analysis, high ASPECTS and favorable collaterals in the NCCT/CTA model, and low rCBF<30% and HIR<0.4 in the CTP model were independent predictors of SP.

CONCLUSIONS

The impact of symptom-reperfusion time on outcomes significantly varies across slow-versus fast-progressors. ASPECTS, collateral score, rCBF<30%, and HIR define stroke progression profile.

Evaluation of Sine Spin flat detector CT imaging compared with multidetector CT

BACKGROUND

Flat detector computed tomography (FDCT) is widely used for periprocedural imaging in the angiography suite. Sine Spin FDCT (SFDCT) is the latest generation of cone beam CT using a double oblique trajectory for image acquisition to reduce artefacts and improve soft tissue brain imaging. This study compared the effective dose, image quality and diagnostic performance of the latest generation of SFDCT with multidetector CT (MDCT).

METHODS

An anthropomorphic phantom equipped with MOSFET detectors was used to measure the effective dose of the new 7sDCT Sine Spin protocol on a latest generation biplane angiographic C-arm system. Diagnostic performance was evaluated on periprocedurally acquired SFDCT for depiction of anatomical details, detection of hemorrhage, and ischemia and was compared with preprocedurally acquired MDCT. Inter- and intra-rater correlation as well as sensitivity and specificity were calculated.

RESULTS

Both modalities showed equal diagnostic performance in the supratentorial ventricular system. SFDCT provided inferior image quality in grey-white matter differentiation and infratentorial structures. Intraventricular, subarachnoid and parenchymal hemorrhages were diagnosed with a sensitivity of 83.3%, 84.2% and 75% and a specificity of 97.3%, 80.0% and 100%, respectively; early ischemic lesions with a sensitivity of 73.3% and specificity 94.7%. The effective dose measured for the 7sDCT Sine Spin protocol was 2 mSv.

CONCLUSIONS

Our findings confirm the high diagnostic sensitivity and specificity of SFDCT in detecting intracranial hemorrhage and early ischemic lesions. The delineation of grey-white matter differentiation and infratentorial structures remains a limiting factor. In comparison to previous studies, the new 7sDCT Sine Spin protocol showed a lower effective dose.

Efficacy of Emergency Room Skip Strategy in Patients Transferred for Mechanical Thrombectomy

Objective

Time to recanalization is directly linked to cerebral infarction prognosis. However, patients transferred from another hospital take longer to arrive than those transported directly. To minimize time to recanalization, the emergency room (ER) skip strategy for hospital transfers was executed and reviewed.

Methods

From April 2019, patients transferred from another hospital for mechanical thrombectomy were carried into the angio-suite using emergency service stretchers. Results for these patients (ER skip group) were compared with those for patients transported directly to our hospital (Direct group).

Results

Among 108 cases in 32 months, 99 patients (91.7%) had major cerebral artery occlusion and underwent endovascular treatment. No differences in age, baseline National Institutes of Health Stroke Scale score, effective recanalization rate, or proportion of posterior circulation cases were seen between groups. The ER skip group (26 patients) showed significantly longer median time from onset to arrival (240 vs. 120 min; p = 0.0001) and significantly shorter median time from arrival to groin puncture (11 vs. 69 min; p = 0.0000). No significant differences were evident in time from groin puncture to recanalization (39 vs. 45 min), time from onset to recanalization (298 vs. 244 min), or rate of modified Rankin Scale score 0-2 after 90 days (42.3% vs. 32.9%). Median time from alarm to recanalization (266 vs. 176 min; p = 0.0001) was significantly longer in the ER skip group. Door-to-puncture (DTP) time for the Direct group gradually fell as the number of cases increased, reaching 40 min by the end of study period. In contrast, DTP time for the ER skip group remained extremely short and did not change further. The proportion of patients who underwent both CT and MRI before endovascular treatment was significantly lower in the Direct group (30.1%) than in the ER skip group (57.7%). In the ER skip group, median length of stay in the primary hospital was 119 min, and the median duration of interhospital transfer was 16 min.

Conclusion

The ER skip strategy for patients transferred with large vessel occlusion achieved favorable outcomes comparable to that for direct transport cases. Direct transport to a thrombectomy-capable stroke center remains ideal, however, because the time to intervention is improving for direct transport cases each year.

Neuroimaging in Pediatric Stroke

Pediatric stroke is unfortunately not a rare condition. It is associated with severe disability and mortality because of the complexity of potential clinical manifestations, and the resulting delay in seeking care and in diagnosis. Neuroimaging plays an important role in the multidisciplinary response for pediatric stroke patients. The rapid development of adult endovascular thrombectomy has created a new momentum in health professionals caring for pediatric stroke patients. Neuroimaging is critical to make decisions of identifying appropriate candidates for thrombectomy. This review article will review current neuroimaging techniques, imaging work-up strategies and special considerations in pediatric stroke. For resources limited areas, recommendation of substitute imaging approaches will be provided. Finally, promising new techniques and hypothesis-driven research protocols will be discussed.

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).

Change your Angle of View : Sinusoidal C-Arm Movement in Cranial Flat-panel CT to Improve Image Quality

BACKGROUND

Artifacts from surrounding bony structures, especially from the petrous bones, regularly impair soft tissue computed tomography (CT) imaging of the middle and posterior fossa. This affects flat-panel CT in particular. Sinusoidal movement of the C‑arm during acquisition (i.e. craniocaudal tilting along with semicircular rotation) is supposed to reduce artifacts, thus enhancing soft tissue imaging quality.

METHODS

In the work-up of ischemic stroke or subarachnoid hemorrhage 40 patients underwent multi-slice CT (MS-CT) and either plain circular (cFP-CT; n = 20) or sinusoidal (sFP-CT; n = 20) flat-panel CT within a short interval. Two independent readers analyzed MS-CT and FP-CT datasets for recognizability of eight different brain structures and three typical types of artifacts according to a predetermined score.

RESULTS

Interrater reliability was moderate for cFP-CT (κ = 0.575) and good to very good for ratings of MS-CT and sFP-CT (κ = 0.651 to κ = 1). MS-CT was rated to be significantly better than cFP-CT and sFP-CT (p < 0.0001) in the overall score. Yet, sFP-CT was rated to be significantly superior to cFP-CT (overall p < 0.0001) regarding most anatomical regions and petrous bone artifacts.

CONCLUSION

Compared to a standard circular protocol, sinusoidal C‑arm movement in cranial FP-CT can significantly reduce artifacts in the posterior fossa and, moreover, can improve visualization of most supratentorial and infratentorial anatomical structures.

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.

Ghost infarct core following endovascular reperfusion: A risk for computed tomography perfusion misguided selection in stroke

BACKGROUND

Computed tomography perfusion (CTP) has been increasingly used for patient selection in mechanical thrombectomy for stroke. However, previous studies suggested that CTP might overestimate the infarct size. The term ghost infarct core (GIC) has been used to describe an overestimation of the final infarct volumes by pre-treatment CTP of >10 ml.

AIM

We sought to study the frequency and predictors of GIC.

METHODS

A prospectively collected mechanical thrombectomy database at a comprehensive stroke center between September 2010 and August 2020 was reviewed. Patients were included if they had a successful reperfusion (mTICI2b-3), a pre-procedure CTP, and final infarct volume measured on follow-up magnetic resonance imaging. Uni- and multivariable analyses were performed to identify predictors of GIC.

RESULTS

Among 923 eligible patients (median [IQR] age, 64 [55-75] years; NIHSS, 16 [11-21]; onset to reperfusion time, 436.5 [286-744.5] min), GIC was identified in 77 (8.3%) of the overall patients and in 14% (47/335) of those reperfused within 6 h of symptom onset. The median overestimation volume was 23.2 [16.4-38.3] mL. GIC was associated with higher NIHSS score, larger areas of infarct core and tissue at risk on CTP, unfavorable collateral scores, and shorter times from onset to image acquisition and to reperfusion as compared to non-GIC. Patients with GIC had smaller median final infarct volumes (10.7 vs. 27.1 ml, p < 0.001), higher chances of functional independence (76.2% vs. 55.5%, adjusted odds ratio (aOR) 3.829, 95% CI [1.505-9.737], p = 0.005), lower disability (one-point-mRS improvement, aOR 1.761, 95% CI [1.044-2.981], p = 0.03), and lower mortality (6.3% vs. 15%, aOR 0.119, 95% CI [0.014-0.984], p = 0.048) at 90 days. On multivariable analysis, time from onset to reperfusion ≤6 h (OR 3.184, 95% CI [1.743-5.815], p < 0.001), poor collaterals (OR 2.688, 95% CI [1.466-4.931], p = 0.001), and higher NIHSS score (OR 1.060, 95% CI [1.010-1.113], p = 0.018) were independent predictors of GIC.

CONCLUSION

GIC is a relatively common entity, particularly in patients with poor collateral status, higher baseline NIHSS score, and early presentation, and is associated with more favorable outcomes. Patients should not be excluded from reperfusion therapies on the sole basis of CTP findings, especially in the early window.

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.

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.

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.