Accuracy and reliability of PBV ASPECTS, CBV ASPECTS and NCCT ASPECTS in acute ischaemic stroke: a matched-pair analysis.

BACKGROUND AND PURPOSE: To investigate the reliability and accuracy of Alberta Stroke Program Early Computed Tomography Scores (ASPECTS) derived from flatpanel detector computed tomography pooled blood volume maps compared to non-contrast computed tomography and multidetector computed tomography perfusion cerebral blood volume maps. METHODS: ASPECTS from pooled blood volume maps were evaluated retrospectively by two experienced readers for 37 consecutive patients with acute middle cerebral artery (MCA) M1 occlusion who underwent flatpanel detector computed tomography perfusion imaging before mechanical thrombectomy between November 2016 and February 2019. For comparison with ASPECTS from non-contrast computed tomography and cerebral blood volume maps, a matched-pair analysis according to pre-stroke modified Rankin scale, age, stroke severity, site of occlusion, time from stroke onset to imaging and final modified thrombolysis in cerebral infarction (mTICI) was performed in a separate group of patients who underwent multimodal computed tomography prior to mechanical thrombectomy between June 2015 and February 2019. Follow-up ASPECTS were derived from either non-contrast computed tomography or from magnetic resonance imaging (in seven patients) one day after mechanical thrombectomy. RESULTS: Interrater agreement was best for non-contrast computed tomography ASPECTS (w-kappa = 0.74, vs. w-kappa = 0.63 for cerebral blood volume ASPECTS and w-kappa = 0.53 for pooled blood volume ASPECTS). Also, accuracy, defined as correlation between acute and follow-up ASPECTS, was best for non-contrast computed tomography ASPECTS (Spearman ρ = 0.86 (0.65-0.97), P < 0.001), while it was lower and comparable for pooled blood volume ASPECTS (ρ = 0.58 (0.32-0.79), P < 0.001) and cerebral blood volume ASPECTS (ρ = 0.52 (0.17-0.80), P = 0.001). It was noteworthy that cases of relevant infarct overestimation by two or more ASPECTS regions (compared to follow-up imaging) were observed for both acute pooled blood volume and cerebral blood volume ASPECTS but occurred more often for acute pooled blood volume ASPECTS (25% vs. 5%, P = 0.02). CONCLUSION: Non-contrast computed tomography ASPECTS outperformed both pooled blood volume ASPECTS and cerebral blood volume ASPECTS in accuracy and reliability. Importantly, relevant infarct overestimation was observed more often in pooled blood volume ASPECTS than cerebral blood volume ASPECTS, limiting its present clinical applicability for acute stroke imaging.

Effect of treatment technique on radiation exposure in mechanical thrombectomy for acute ischaemic stroke: A matched-pair analysis.

OBJECTIVE: This study aimed to compare radiation exposure (RE) in patients receiving mechanical thrombectomy (MT) for large-vessel occlusions in the anterior circulation using direct thrombo-aspiration (DT) versus stent-retriever thrombectomy under continuous distal aspiration (STA). METHODS: This was a retrospective single-centre analysis of an Institutional Review Board-approved stroke database of a comprehensive stroke centre focusing on RE per dose area product, procedure time (PT) and fluoroscopy time (FT) in patients receiving MT. Patients who received MT with DT were matched with patients treated using STA according to occlusion location, mode of anaesthesia, manoeuvre count and sex. RESULTS: Apart from patient age (DT: M = 74 years (standard deviation (SD)=13 years); STA: M = 79 years (SD = 11 years); p = 0.023), there was no difference in baseline patient characteristics (n = 68 per group). PT (DT: median = 26 minutes (interquartile range (IQR) = 21-38 minutes); STA: median = 49 minutes (IQR 37-77 minutes); p < 0.0001) and FT (DT: median = 12 minutes (IQR 7-18 minutes); STA: median = 26 minutes (IQR 14-43 minutes); p < 0.0001) were shorter in patients who received MT using DT. RE (DT: median = 62.6 Gy·cm2 (IQR 41.7-89.4 Gy·cm2); STA: median = 89.8 Gy·cm2 (IQR 53.7-131.7 Gy·cm2); p = 0.034) was significantly lower in patients who received MT using DT. This represents a relative increase of RE, FT and PT by 43.6%, 116.6% and 88.5%, respectively, in patients who received MT using STA. CONCLUSION: MT using DT is associated with shorter FT and PT and lower RE compared to matched patients treated with STA.

The impact of the DWI-FLAIR-mismatch in the ECASS-4 trial - A post hoc analysis.

INTRODUCTION: To investigate the impact of a mismatch between diffusion-weighted imaging (DWI) and fluid attenuated inversion recovery (FLAIR) on functional outcome in patients with acute stroke in a prolonged time window or unknown time of symptom onset randomized to intravenous thrombolysis or placebo. PATIENTS AND METHODS: We performed a post-hoc analysis of the European Cooperative Acute Stroke Study-4 (ECASS-4) trial. ECASS-4 was an investigator driven, phase 3, multi-center, double-blind, placebo-controlled study which randomized ischemic stroke patients presenting within 4.5 and 9h of stroke onset or unknown time-window to either rt-PA or placebo after MR-imaging. Two subgroups "no mismatch" (nMM) and "any mismatch" (aMM) were created by applying a DWI-FLAIR-mismatch criterion. We calculated frequency of nMM and aMM and performed a univariate analysis (Fisher's Test) for excellent clinical outcome (mRS 0-1) and mortality (mRS=6). RESULTS: MR-Imaging of n=111/119 (93.2%) patients was suitable for this analysis. DWI-FLAIR mismatch was found in 49 patients (44.1%). Proportions of mismatch nMM and aMM were comparable in treatment-groups (aMM: Placebo 46.3%, Alteplase 42.1%; p=0.70). Patients with nMM showed no benefit of rt-PA-treatment (OR (95%CI) mRS 0-1: 0.95 (0.29-3.17)). Patients with aMM showed a point estimate of the odds ratio in favour of a treatment benefit of rt-PA (mRS 0-1: OR (95%CI) 2.62 (0.68-11.1)). Mortality within 90 days was not different in patients treated with rt-PA if nMM (15.2%) or aMM (12.5%) was present. DISCUSSION: In this analysis no significant evidence, but subtle indication towards patients treated with rt-PA in a prolonged time window reaching an excellent clinical outcome if a DWI-FLAIR-mismatch is present on initial stroke MR-imaging. CONCLUSION: A DWI-FLAIR mismatch in the region of ischemia as imaging based surrogate parameter for patient selection for i.v. rt-PA should be strongly pursued.

Effect of mode of anesthesia on radiation exposure in patients undergoing endovascular recanalization of anterior circulation embolic stroke.

PURPOSE: To determine the effect of general anesthesia (GA) versus conscious sedation (CS) on radiation exposure (RE), procedure time (PT), and fluoroscopy time (FT) in patients receiving endovascular stroke treatment (EST) for large vessel occlusions (LVOs) in the anterior circulation. METHODS: Retrospective analysis of an institutional review board-approved prospective stroke database of a comprehensive stroke center focusing on RE (as dose area product (DAP) in Gy.cm², median (IQR)), PT, and FT (in minutes, median (IQR)) in patients receiving EST for LVOs of the anterior circulation according to the mode of anesthesia during the intervention. RESULTS: Overall 544 patients were included in this analysis (GA: n=143, CS: n=401). For all included LVOs in the anterior circulation PTs (GA: 69 (44-100); CS: 59 (37-99); p=0.235), FTs (GA: 33 (20-56); CS: 29 (16-51); p=0.286), and RE (DAP, GA: 116.23 (73.47-173.41); CS: 110.5 (68.35-184.65); p=0.929) were comparable. In a subgroup analysis of occlusions of the middle cerebral artery (M1-segment; GA: n=80/544, 14.7%; CS: n=211/544, 38.8%), PTs (GA: 69 (37-101); CS: 54 (35 - 89); p=0.223), FTs (GA: 33 (19-55); CS: 25 (14-48); p=0.264), and RE (DAP, GA: 110.91 (66.8-169.12); CS: 103.8 (63.17-181); p=0.893) were similar. CONCLUSION: In this retrospective analysis, no effect of the mode of anesthesia on the radiation exposure during EST was detected as GA and CS showed comparable PT, FT, and DAPs.