The administration of rtPA before mechanical thrombectomy in acute ischemic stroke patients is associated with a significant reduction of the retrieved clot area but it does not influence revascularization outcome.

Both intravenous thrombolysis (IVT) and mechanical thrombectomy (MT) are evidence-based treatments for acute ischemic stroke (AIS) in selected cases. Recanalization may occur following IVT without the necessity of further interventions or requiring a subsequent MT procedure. IVT prior to MT (bridging-therapy) may be associated with benefits or hazards. We studied the retrieved clot area and degree of recanalization in patients undergoing MT or bridging-therapy for whom it was possible to collect thrombus material. We collected mechanically extracted thrombi from 550 AIS patients from four International stroke centers. Patients were grouped according to the administration (or not) of IVT before thrombectomy and the mechanical thrombectomy approach used. We assessed the number of passes for clot removal and the mTICI (modified Treatment In Cerebral Ischemia) score to define revascularization outcome. Gross photos of each clot were taken and the clot area was measured with ImageJ software. The non-parametric Kruskal-Wallis test was used for statistical analysis. 255 patients (46.4%) were treated with bridging-therapy while 295 (53.6%) underwent MT alone. By analysing retrieved clot area, we found that clots from patients treated with bridging-therapy were significantly smaller compared to those from patients that underwent MT alone (H1 = 10.155 p = 0.001*). There was no difference between bridging-therapy and MT alone in terms of number of passes or final mTICI score. Bridging-therapy was associated with significantly smaller retrieved clot area compared to MT alone but it did not influence revascularization outcome.

Per-pass analysis of acute ischemic stroke clots: impact of stroke etiology on extracted clot area and histological composition.

BACKGROUND: Initial studies investigating correlations between stroke etiology and clot composition are conflicting and do not account for clot size as determined by area. Radiological studies have shown that cardioembolic strokes are associated with shorter clot lengths and lower clot burden than non-cardioembolic clots. OBJECTIVE: To report the relationship between stroke etiology, extracted clot area, and histological composition at each procedural pass. METHODS: As part of the multi-institutional RESTORE Registry, the Martius Scarlett Blue stained histological composition and extracted clot area of 612 per-pass clots retrieved from 441 patients during mechanical thrombectomy procedures were quantified. Correlations with clinical and procedural details were investigated. RESULTS: Clot composition varied significantly with procedural passes; clots retrieved in earlier passes had higher red blood cell content (H4=11.644, p=0.020) and larger extracted clot area (H4=10.730, p=0.030). Later passes were associated with significantly higher fibrin (H4=12.935, p=0.012) and platelets/other (H4=15.977, p=0.003) content and smaller extracted clot area. Large artery atherosclerotic (LAA) clots were significantly larger in the extracted clot area and more red blood cell-rich than other etiologies in passes 1-3. Cardioembolic and cryptogenic clots had similar histological composition and extracted clot area across all procedural passes. CONCLUSION: LAA clots are larger and associated with a large red blood cell-rich extracted clot area, suggesting soft thrombus material. Cardioembolic clots are smaller in the extracted clot area, consistent in composition and area across passes, and have higher fibrin and platelets/other content than LAA clots, making them stiffer clots. The per-pass histological composition and extracted clot area of cryptogenic clots are similar to those of cardioembolic clots, suggesting similar formation mechanisms.

Large Artery Atherosclerotic Clots are Larger than Clots of other Stroke Etiologies and have Poorer Recanalization rates.

OBJECTIVES: There is a paucity of knowledge in the literature relating to the extent of clot burden and stroke etiology. In this study, we measured the Extracted Clot Area (ECA) retrieved during endovascular treatment (EVT) and investigated relationships with suspected etiology, administration of intravenous thrombolysis and recanalization. MATERIALS AND METHODS: As part of the multi-institutional RESTORE registry, the ECA retrieved during mechanical thrombectomy was quantified using ImageJ. The effect of stroke etiology (Large-artery atherosclerosis (LAA), Cardioembolism, Cryptogenic and other) and recombinant tissue plasminogen activator (rtPA) on ECA and recanalization outcome (mTICI) was assessed. Successful recanalization was described as mTICI 2c-3. RESULTS: A total of 550 patients who underwent EVT with any clot retrieved were included in the study. The ECA was significantly larger in the LAA group compared to all other etiologies. The average ECA size of each etiology was; LAA=109 mm2, Cardioembolic=52 mm2, Cryptogenic=47 mm2 and Other=52 mm2 (p=0.014*). LAA patients also had a significantly poorer rate of successful recanalization (mTICI 2c-3) compared to all other etiologies (p=0.003*). The administration of tPA was associated with a smaller ECA in both LAA (p=0.007*) and cardioembolic (p=0.035*) groups. CONCLUSION: The ECA of LAA clots was double the size of all other etiologies and this is associated with a lower rate of successful recanalization in LAA stroke subtype. rtPA administration prior to thrombectomy was associated with reduced ECA in LAA and CE clots.

Platelet-rich emboli are associated with von Willebrand factor levels and have poorer revascularization outcomes.

BACKGROUND AND AIMS: Platelets and von Willebrand factor (vWF) are key factors in thrombosis and thus are likely key components of acute ischemic stroke (AIS) emboli. We aimed to characterize platelet and vWF levels in AIS emboli and to assess associations between their expression levels and clinical and procedural information. MATERIALS AND METHOD: Histopathological and immunohistochemical analysis of emboli collected as part of the multi-institutional RESTORE registry was performed. The composition of the emboli was quantified using Orbit Image Analysis machine learning software. Correlations between clot components and clinical and procedural information were assessed using the χ2 test. RESULTS: Ninety-one emboli samples retrieved from 63 patients were analyzed in the study. The mean platelet (CD42b) content of the clots was 33.9% and the mean vWF content of the clots was 29.8%. There was a positive correlation between platelet and vWF levels (ρ=0.564, p<0.001*, n=91). There was an inverse correlation between both platelets and vWF levels and percentage of red blood cells (RBCs) in the emboli (CD42b vs RBC: ρ=-0.535, p<0.001*, n=91; vWF vs RBC: ρ=-0.366, p<0.001*, n=91). Eighty-one percent of patients in the low platelet group had a good revascularization outcome (Thrombolysis in Cerebral Infarction 2c/3) compared with 58% in the high platelet group (χ2=5.856, p=0.016). CONCLUSION: Platelet and vWF levels in AIS emboli correlate with each other and both have an inverse relationship with RBC composition. Patients with platelet-rich clots have poorer revascularization outcomes.

Performance and inter-observer variability of prostate MRI (PI-RADS version 2) outside high-volume centres.

Objective: Despite the growing trend to embrace pre-biopsy MRI in the diagnostic pathway for prostate cancer (PC), its performance and inter-observer variability outside high-volume centres remains unknown. This study aims to evaluate sensitivity of and variability between readers of prostate MRI outside specialized units with radical prostatectomy (RP) specimen as the reference standard.Materials and methods: Retrospective study comprising a consecutive cohort of all 97 men who underwent MRI and subsequent RP between January 2012 and December 2014 at a private hospital in Sweden. Three readers, blinded to clinical data, reviewed all images (including 11 extra prostate MRI to reduce bias). A tumour was considered detected if the overall PI-RADS v2 score was 3-5 and there was an approximate match (same or neighbouring sector) of tumour sector according to a 24 sector system used for both MRI and whole mount sections.Results: Detection rate for the index tumour ranged from 67 to 76%, if PI-RADS 3-5 lesions were considered positive and 54-66% if only PI-RADS score 4-5 tumours were included. Detection rate for aggressive tumours (GS ≥ 4 + 3) was higher; 83.1% for PI-RADS 3-5 and 79.2% for PI-RADS 4-5. The agreement between readers showed average [Formula: see text] values of 0.41 for PI-RADS score 3-5 and 0.51 for PI-RADS score 4-5.Conclusions: Prostate MRI evidenced a moderate detection rate for clinically significant PC with a rather large variability between readers. Clinics outside specialized units must have knowledge of their performance of prostate MRI before considering omitting biopsies in men with negative MRI.