Clot composition in retrieved thrombi after mechanical thrombectomy in strokes due to carotid web

2021 ◽  
pp. neurintsurg-2020-017112
Author(s):  
Sitara Koneru ◽  
Raul G Nogueira ◽  
Ehizele Osehobo ◽  
Gabriela Oprea-Ilies ◽  
Alhamza R Al-Bayati ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Blood Cells ◽  
Mechanical Thrombectomy ◽  
White Blood Cells ◽  
Case Series ◽  
Composition Analysis ◽  
Conventional Angiography ◽  
Vessel Occlusion ◽  
Ct Angiogram ◽  
Staining Techniques

BackgroundThe association of carotid webs (CaW) and ischemic stroke is being increasingly recognized. Data on the histologic clot architecture in strokes caused by CaW has not been previously described. Understanding thrombi histopathology may provide insight into the pathophysiology of CaW-related strokes.MethodsThis case series presents three patients with acute ischemic stroke thought to be caused by ipsilateral CaW. Thromboemboli were retrieved from the middle cerebral artery (MCA) by mechanical thrombectomy and histologic analysis was performed.ResultsThree patients aged between 41 and 55 years with few to no vascular risk factors presented with symptoms concerning for an acute MCA territory infarction (National Institutes of Health Stroke Scale (NIHSS) range 10–17). Non-contrast computed tomography (CT) Alberta Stroke Program Early CT Score (ASPECTS) range was 7–8 and all patients had hyperdense vessel sign. Initial CT angiogram was concerning for CaW with no superimposed thrombus, later confirmed with conventional angiography. All patients underwent thrombectomy with full reperfusion. Comprehensive stroke workup failed to reveal other etiologies besides ipsilateral CaW. The histopathologic appearance was of typical fresh mixed thrombi. Qualitative thrombus composition analysis of clot from Case #1 yielded 42.5% fibrin, 50.0% red blood cells (RBC), and 7.5% white blood cells (WBC); Case #2 yielded 46.9% fibrin, 43.4% RBC, and 9.7% WBC; and Case #3 yielded 61.5% fibrin, 31.8% RBC, and 6.7% WBC.ConclusionsThe clot composition of large vessel occlusion strokes from CaW is comparable to the histopathology of previously reported clots from other stroke etiologies. Advanced staining techniques may aid in further characterizing the thrombi of this poorly understood condition.

Abstract W P37: Accuracy Of CT Angiography In The Localization Of Carotid Occlusion Sites In Acute Ischemic Stroke

Stroke ◽  
2015 ◽  
Vol 46 (suppl_1) ◽  
Author(s):  
Marcelo Rocha ◽  
William T Delfyett ◽  
Amin Aghaebrahim ◽  
Ashutosh Jadhav ◽  
Tudor Jovin
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Ct Angiography ◽  
Target Lesion ◽  
Carotid Occlusion ◽  
Conventional Angiography ◽  
Vessel Occlusion ◽  
Cerebral Vessel ◽  
Ct Angiogram ◽  
Comprehensive Stroke Center

Background and Purpose: CT angiography yields rapid detection of a major cerebral vessel occlusion during the evaluation of patients with acute ischemic stroke leading to its widespread use in rapidly triaging for IA trial enrollment. In such trials, patients who have an extracranial carotid occlusion in tandem to the intracranial target lesion are typically excluded. However, ICA terminus occlusions may be misidentified as cervical carotid occlusions on CTA. The goal of this study is to determine the accuracy of CTA in identifying ICA terminus occlusions from tandem carotid occlusions (cervical and intracranial segments). Methods: Retrospective review of a prospectively maintained database containing patients treated at our comprehensive stroke center between 1996 and 2014 in whom catheter angiogram and CT angiogram were available on PACS. A Neuroradiologist, blinded to catheter angiographic results reviewed the CT angiography identifying the presence of intracranial stenoses and concomitant cervical carotid occlusions. Results: Of 196 patients presenting with intracranial carotid occlusions on catheter based angiogram, 101 patients were identified with good quality CT angiography and subsequent catheter angiograms. Mean ages for identified patients was 65 +/- 14, of which 52% women and 48% men. Forty-four percent of patients had an ASPECT score of 9-10. The overall rate of agreement between retrospective CTA and conventional angiography readings was 77%. Of 72 isolated intracranial occlusions on conventional angiography, CT angiography misidentified 23 cervical carotid occlusions. The sensitivity of CTA for detecting isolated carotid terminus occlusion was 68% in this cohort. Specific factors associated with CT and catheter based angiographic discrepancy are reviewed. Conclusions: The study raises systematic considerations for maximizing inclusion of patients with target arterial occlusions who are most likely to benefit from intra-arterial therapy in future clinical trials. Future steps will include determination of specificity, predictive value of CTA for localization of specific carotid occlusion sites. Clinical variables associated with lower CTA accuracy will also be examined.

scholarly journals Histologic differences between in situ and embolized carotid web thrombi: a case report

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Qun Gao ◽  
Shen Hu ◽  
Ximeng Yang ◽  
Junjie Wang ◽  
Jun Lu ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Blood Cells ◽  
Histological Analysis ◽  
White Blood Cells ◽  
Vessel Occlusion ◽  
Research Directions ◽  
Case Presentation ◽  
Hematoxylin And Eosin ◽  
New Research

Abstract Background The significance of carotid webs (CaWs) in ischemic stroke is becoming acknowledged. Histological features of clot composition in situ and secondary cerebrovascular embolized thrombi caused by CaW have not been described concurrently. Understanding clots’ histological composition is essential for understanding the pathophysiology of clot formation in CaW. Case presentation A 50-year-old male patient with acute ischemic stroke, which was believed to be caused by ipsilateral CaW, was admitted to the hospital. Mechanical thrombectomy was used to retrieve thromboemboli from the middle cerebral artery. One month thereafter, the patient underwent carotid endarterectomy, and in situ CaW thrombi were retrieved. Histological analysis by hematoxylin and eosin staining revealed that histopathologic embolized thrombi appeared as typical mixed thrombi, 46.03% fibrin/platelet ratio, 48.12% RBCs, and 5.85% white blood cells. In situ thrombi had a higher fibrin/platelet ratio (68.0%), fewer RBCs (17.2%), and 14.8% white blood cells. Conclusion The histopathology of large vessel occlusion stroke embolized thrombi by CaW is similar to that of other stroke etiologies. However, the clot composition of embolized thrombi significantly differs from that of in situ thrombi. CaW’s in situ thrombi showed predominantly fibrin, and embolized thrombi had equivalent contents of red blood cells and fibrin/platelets. Histopathological differences between in situ and embolized thrombi suggest new research directions for the etiology of embolization. Further studies are required to confirm these results.

scholarly journals Endovascular treatment of ischemic large-vessel stroke due to infective endocarditis: case series and review of the literature

2020 ◽  
Vol 41 (12) ◽  
pp. 3517-3525
Author(s):  
Lucio D’Anna
Keyword(s):  
Ischemic Stroke ◽  
Infective Endocarditis ◽  
Acute Ischemic Stroke ◽  
Mechanical Thrombectomy ◽  
Case Series ◽  
Large Vessel ◽  
Controlled Trials ◽  
Large Vessel Occlusion ◽  
Review Of The Literature ◽  
Vessel Occlusion

Abstract Background Mechanical thrombectomy is the standard of care, in selected patients, for acute ischemic stroke with large vessel occlusion but its use in patients with stroke secondary to infective endocarditis is controversial. We report three cases of acute ischemic stroke treated by mechanical thrombectomy and we propose an extensive review of the literature to evaluate the clinical safety and efficacy of thrombectomy in patients with stroke secondary to infective endocarditis. Methods A comprehensive literature search was performed following a pre-specified protocol of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Case reports, cases series, cross-sectional studies, case control studies, randomized controlled trials or nonrandomized controlled trials were considered that included endocarditis-related acute ischemic stroke patients who underwent mechanical thrombectomy. Results The database search yielded 431 relevant records published until January 2020. Nineteen articles fulfilled the eligibility criteria that described thirty patients. After the thrombectomy, 13.3% of the patients experienced intracranial haemorrhage. After the procedure, the median National Institutes of Health Stroke Scale score dropped from 15 (IQR 7) to 2.5 (IQR 5.75). At 90 days, mortality was 23.3% while 46.7% of the patients were functionally independent (mRS ≤ 2). Discussion Based on our review, the use of mechanical thrombectomy in patients with large vessel occlusion due to endocarditis-associated stroke might improve patient outcome but it should be considered on a case by case base as the safety has not been well established yet. Further research on risk stratification is needed to drive clinician during the decision-making process.

Abstract WP43: Anti-Coagulation Therapy Prior to Mechanical Thrombectomy is Associated With Reduced Procedure Time and Low Proportion of Fibrin in Retrieved Thrombus

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Kota Maekawa ◽  
Kobayashi Kazuto ◽  
Sano Takanori ◽  
Shibata Masunari ◽  
Yabana Tadashi ◽  
...  
Keyword(s):  
Blood Cells ◽  
Mechanical Thrombectomy ◽  
White Blood Cells ◽  
Recombinant Tissue Plasminogen Activator ◽  
Large Vessel ◽  
Large Vessel Occlusion ◽  
Procedure Time ◽  
Vessel Occlusion ◽  
Coagulation Therapy

Introduction: Very few studies have investigated the relationship between the histopathology of the retrieved thrombus by mechanical thrombectomy for large vessel occlusion and anti-coagulation agents before mechanical thrombectomy. A study in vitro showed that clots of patients with anti-coagulation agents were dissolved easily compared to those of patients with aspirin. Hypothesis: Anti-coagulation therapy prior to mechanical thrombectomy is associated with reduced procedure time and low proportion of fibrin in retrieved thrombus. Methods: All retrieved thrombus was stained with hematoxylin-eosin. Embolic debris underwent quantitative analysis to quantify three main components: red blood cells, white blood cells and fibrin, by color based segmentation. Patients were assingned to receive either mechanical thrombectomy with anti-coagulation agents (AC-MT group) or mechanical thrombectomy alone (MT group). Considering influence by stroke etiology, patients with non-cardioembolism were excluded. Results: From August 2015 to Dec 2018, 226 consecutive patients were treated in our hospital by MT for acute large vessel occlusion. Histopathologic analysis of retrieved thrombus from 119 patients with acute stroke. 92 patients with cardioembolism were included. Patients were assigned to AC-MT group (n=35) or MT group (n=57). Clinical backgrounds were not significantly different. PT-INR was higher in AC-MT group. (1.32 vs 1.06; p<0.01) The proportion of patients with recombinant tissue plasminogen activator was not significantly different (26% vs 43%; p=0.12). AC-MT group had shorter puncture to recanalization time (median 38 vs 54 minutes; p<0.01) and tendency to reduce number of maneuvers [median 2 (range 1-4) vs 2 (range 1-6); p=0.06]. AC-MT group had lower proportion of fibrin in retrieved thrombus (44.3% vs 77.3%, p<0.01). Conclusion: Anti-coagulation therapy prior to mechanical thrombectomy is associated with reduced procedure time and low proportion of fibrin in retrieved thrombus.

Abstract WP31: Fibrin Rich Thrombus versus Erythrocyte Rich Thrombus in Acute Large Vessel Occlusion

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Kota Maekawa ◽  
Masunari Shibata ◽  
Masaru Seguchi ◽  
Kazuto Kobayashi ◽  
Hidetaka Nakajima ◽  
...  
Keyword(s):  
Blood Cells ◽  
Mechanical Thrombectomy ◽  
Clinical Laboratory ◽  
White Blood Cells ◽  
Functional Independence ◽  
Large Vessel ◽  
Basilar Artery Occlusion ◽  
Large Vessel Occlusion ◽  
Vessel Occlusion ◽  
Significant Difference

Objective: The aim of this study was to evaluate thrombus composition and its association with clinical, laboratory, and neurointerventional findings in patients treated by mechanical thrombectomy due to acute large vessel occlusion. Methods: From August 2015 to June 2016, 72 patients were treated in our hospital by mechanical thrombectomy using stent retriever and/or aspiration catheter. Retrieved thrombi underwent semiquantitative analysis to quantify red blood cells, white blood cells, and fibrin by area. We divided patients into two groups as fibrin rich group or erythrocyte rich group according to predominant composition in thrombus. Two groups were compared with respect to imaging, clinical, and neurointerventional data. Results: Histopathologic analysis of retrieved thrombus from 37 patients with acute stroke due to internal carotid artery, middle cerebral artery, or basilar artery occlusion was performed. Erythrocyte rich thrombi were present in 13 (35%) of cases, and fibrin rich thrombi in 24 (65%). Cardioembolic etiology was significantly more in patients with fibrin rich thrombi than those with erythrocyte rich thrombi (79% vs. 38%; p=0.01). All other clinical and laboratory characteristics did not differ. Patients with fibrin rich thrombi had greater number of recanalization maneuvers (2.8 ± 1.2 vs. 1.8 ± 1.6, p=0.04) and longer interval time between puncture and recanalization (62 ± 33.6 minutes vs. 42 ± 21.3 minutes; p=0.04). There is no significant difference in occluded vessels and mechanical thrombectomy devices between two groups. Patients with fibrin rich thrombi were lower rate of functional independence (mRS score, 0-2) at 90 days (33% vs. 75%; p=0.04). Conclusion: This study showed that fibirin rich thrombus was associated with extended procedure time, unfavorable clinical outcome and cardioembolic etiology.

Abstract 1122‐000171: Unusual Multicompartmental Intracranial Hemorrhage After Tenecteplase Administration

2021 ◽  
Vol 1 (S1) ◽  
Author(s):  
Abdallah Amireh ◽  
Muhammad Nagy ◽  
Hassan Ali ◽  
Siddhart Mehta ◽  
Haralabos Zacharatos ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Intracranial Hemorrhage ◽  
Mechanical Thrombectomy ◽  
University Hospital ◽  
Vascular Lesions ◽  
Intracranial Hemorrhages ◽  
Conventional Angiography ◽  
Vessel Occlusion ◽  
Early Management ◽  
Ct Head

Introduction : The 2019 AHA/ASA updated Guidelines for the Early Management of Patients with Acute Ischemic Stroke mention tenecteplase (TNK) as a reasonable therapy in patients without contraindications for IV fibrinolysis who are also eligible to undergo mechanical thrombectomy. We describe a case of acute left MCA ischemic stroke treated with IV TNK (IV bolus of 0.25 mg/kg) followed by mechanical thrombectomy with subsequent multicompartmental intracranial hemorrhages unrelated to area of infraction. Methods : A retrospective review at a single center university hospital was performed for all intravenous TNK administrations outside of a clinical trial setting from October 2020 to July 2021. Results : A 61‐year‐old male with history of HTN and cardiomyopathy (EF<20%). Presented with sudden onset right sided weakness, aphasia and left gaze. Presenting NIHSS was 28. CT head with hyperdense left MCA sign and ASPECTS score of 10. CTA confirmed proximal left MCA M1 segment occlusion. IV TNK was given within 01:23 hours of symptoms onset. Subsequently, patient underwent emergent mechanical thrombectomy for disabling large vessel occlusion stroke. Spontaneous near complete recanalization of left MCA occlusion was noted on initial angiography run with small non flow limiting distal thrombi visualized in the distal MCA territories. Immediate post procedure CT head was negative for any intracranial hemorrhage. Patient’s exam was noted to improve to NIHSS of 2. Approximately 6 hours after the TNK administration, patient became acutely unresponsive with NIHSS of 26. With Glasgow Coma Scale 7 patient required emergent intubation. CT head revealed bilateral cerebellar intraparenchymal hemorrhages, extensive subarachnoid hemorrhage in basal cisterns and within the sulci in bilateral frontotemporal regions, as well as subdural hemorrhages along the falx and tentorial dural folds. Hypertonic saline was administered followed by emergent extraventricular drain placement. Tranexamic acid 1000 mg was given as emergent reversal, fibrinogen level was 155 mg/dL. Despite aggressive medical management and over following 24 hours, exam worsened with loss of pupillary reflexes. Patient was terminally extubated 2 days after initial presentation in accordance with his advance directives. Conclusions : Tenecteplase was a reasonable choice in this case given LVO and disabling stroke. The patient’s neurological exam improved significantly after TNK with evidence of spontaneous recanalization. However, patient’s multicompartmental intracranial hemorrhages unrelated to area of infraction were unusual in the absence of any vascular lesions to predispose hemorrhage based on CT and conventional angiography. Further observational studies are warranted to evaluate similar complications of Tenecteplase administration and their occurrence rates.

Abstract 177: Absent Collateral Flow on CT Angiogram Predicts Acute Hemorrhagic Transformation in Ischemic Stroke

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
Richard Burgess ◽  
Esteban Cheng Ching ◽  
Delora Wisco ◽  
Shumei Man ◽  
Ken Uchino ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Ct Angiography ◽  
Hemorrhagic Transformation ◽  
Collateral Flow ◽  
Stroke Patients ◽  
Conventional Angiography ◽  
Vessel Occlusion ◽  
Post Procedure ◽  
Ct Angiogram

Background: In patients with a large vessel occlusion, the degree of collateral vascular supply to an ischemic territory has been shown to be a predictor of stroke outcome. Prior studies have focused on the correlation between collateral flow measured on conventional digital subtraction angiography and outcome measures, including the presence of hemorrhagic conversion. CT/CTA is more widely available and more quickly accomplished than MR or conventional angiography. In this work we demonstrate that the absence of CT angiographic collaterals predicts hemorrhage transformation in acute ischemic stroke patients that have persistent vessel occlusion. Methods: Retrospective review of patient data from a prospectively acquired database identified acute ischemic stroke patients who underwent CT angiography followed by cerebral angiography, and post procedure non-contrast CT scans. Blinded evaluators independently assessed CT angiogram collaterals, angiographic TICI scores, and the presence and severity of post procedure hemorrhagic transformation. Fishers exact test was used to compare proportions between groups. Results: 146 patients were included. The mean age was 67. The median NIHSS was 15.5 (range 0-32). 34% of patients had any type of hemorrhagic conversion. Of patients with no collaterals on CT angiography, 63% had hemorrhagic conversion versus 23%, 33%, and 38% for patients with grades 1, 2, and 3 collaterals (p<0.05 for comparisons). Patients with TICI scores of 0 or 1 and no CTA collaterals all had hemorrhagic transformation. Conclusion: The absence of collateral flow on CT angiography in patients without recanalization strongly predicts the acute development of hemorrhagic conversion.

scholarly journals Erythrocyte-Rich Thrombus Is Associated with Reduced Number of Maneuvers and Procedure Time in Patients with Acute Ischemic Stroke Undergoing Mechanical Thrombectomy

2018 ◽  
Vol 8 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Kota Maekawa ◽  
Masunari Shibata ◽  
Hideki Nakajima ◽  
Akane Mizutani ◽  
Yotaro Kitano ◽  
...  
Keyword(s):  
Blood Cells ◽  
Mechanical Thrombectomy ◽  
Clinical Laboratory ◽  
White Blood Cells ◽  
Artery Occlusion ◽  
Basilar Artery Occlusion ◽  
Time Interval ◽  
Procedure Time ◽  
Vessel Occlusion ◽  
Computed Tomography Images

Background: Only few studies have investigated the relationship between the histopathology of retrieved thrombi and clinical outcomes. This study aimed to evaluate thrombus composition and its association with clinical, laboratory, and neurointerventional findings in patients treated by mechanical thrombectomy due to acute large vessel occlusion. Methods: At our institution, 79 patients were treated by mechanical thrombectomy using a stent retriever and/or aspiration catheter between August 2015 and August 2016. The retrieved thrombi were quantitatively analyzed to quantify red blood cells, white blood cells, and fibrin by area. We divided the patients into two groups – a fibrin-rich group and an erythrocyte-rich group – based on the predominant composition in the thrombus. The groups were compared for imaging, clinical, and neurointerventional data. Results: The retrieved thrombi from 43 patients with acute stroke from internal carotid artery, middle cerebral artery, or basilar artery occlusion were histologically analyzed. Erythrocyte-rich thrombi were present in 18 cases, while fibrin-rich thrombi were present in 25 cases. A cardioembolic etiology was significantly more prevalent among the patients with fibrin-rich thrombi than among those with erythrocyte-rich thrombi. Attenuation of thrombus density as shown on computed tomography images was greater in patients with erythrocyte-rich thrombi than in those with fibrin-rich thrombi. All other clinical and laboratory characteristics remained the same. Patients with erythrocyte-rich thrombi had a smaller number of recanalization maneuvers, shorter procedure times, a shorter time interval between arrival and recanalization, and a higher percentage of stent retrievers in the final recanalization procedure. The occluded vessels did not differ significantly. Conclusions: In this study, erythrocyte-rich thrombus was associated with noncardioembolic etiology, higher thrombus density, and reduced procedure time.

Correlation of Neutrophil to Lymphocyte Ratio with Expression of Neutrophil Extracellular Traps Within Stroke Emboli

2021 ◽  
pp. 159101992110655
Author(s):  
Jorge Arturo Larco ◽  
Mehdi Abbasi ◽  
Sarosh Irfan Madhani ◽  
Madalina Oana Mereuta ◽  
Yang Liu ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Blood Cells ◽  
White Blood Cells ◽  
Neutrophil Extracellular Traps ◽  
Vessel Occlusion ◽  
Average Percentage ◽  
Neutrophil Lymphocyte Ratio ◽  
Lymphocyte Ratio ◽  
Extracellular Traps

Background & Purpose It has been hypothesized that circulating neutrophils have a direct correlation with the composition of emboli in acute ischemic stroke (AIS). The aim of this study is to evaluate the association between neutrophil-lymphocyte ratio (NLR) in peripheral blood and the expression of neutrophil extracellular traps (NETs) within stroke emboli. Methods Consecutive patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO) that underwent mechanical thrombectomy (MT) were included. Patients were divided into two groups based on NLR median value. Retrieved thrombi were histologically analyzed using Martius Scarlett Blue (MSB) for main thrombus components including red blood cells (RBCs), white blood cells (WBCs), fibrin and platelet. Immunohistochemistry staining for von Willebrand Factor (vWF) and anti-citrullinated H3 (H3Cit; NETs marker) was also performed. Results Samples from a total of 84 patients were included. The average percentage of RBCs, WBCs, fibrin, platelet, H3Cit, and vWF components in thrombi were 45.1%, 3.5%, 21.8%, 29.6%, 19.7% and 14.8% respectively. When stratifying by NLR group [low (≤3.94) versus high (>3.95)], high NLR group had significantly more WBCs (4.5%), fibrin (24.2%), H3Cit (22.7%) and vWF (17.1%) thrombus fractions compared to low NLR group. Additionally, RBC content (38.8%) was lower in the high NLR group. Conclusions NLR is correlated with the amounts of WBCs, fibrin, NETs and vWF within the thrombi retrieved from AIS patients due to LVO.

scholarly journals Clot permeability and histopathology: is a clot’s perviousness on CT imaging correlated with its histologic composition?

2019 ◽  
Vol 12 (1) ◽  
pp. 38-42 ◽  
Author(s):  
John Charles Benson ◽  
Sean T Fitzgerald ◽  
Ramanathan Kadirvel ◽  
Collin Johnson ◽  
Daying Dai ◽  
...  
Keyword(s):  
Blood Cells ◽  
Mechanical Thrombectomy ◽  
White Blood Cells ◽  
Intravenous Thrombolysis ◽  
Large Vessel ◽  
Large Vessel Occlusion ◽  
Hounsfield Units ◽  
Vessel Occlusion ◽  
Favorable Clinical Outcome ◽  
Contrast Ct

BackgroundClot perviousness in large vessel occlusion has been shown to be associated with improved recanalization outcomes with mechanical thrombectomy and intravenous thrombolysis.ObjectiveTo evaluate the association between clot perviousness based on thrombus attenuation increase (TAI) on CT, and histologic composition of clots in acute ischemic stroke (AIS).MethodsA retrospective review was completed of patients with AIS secondary to large vessel occlusion, non-contrast CT (NCCT) and CT angiography (CTA) images, and histologic analysis of the retrieved clot. TAI was measured by subtracting clot attenuation on NCCT from the attenuation on CTA. Up to 3 regions of interest (ROIs) were evaluated on each clot; the average attenuation was used for analysis if multiple ROIs were assessed. Pervious clots were defined as TAI ≥10 Hounsfield units (HUs); impervious clots had TAI <10 HU. Histopathologic analyses of clots were assessed for relative compositions of red blood cells (RBCs), white blood cells (WBCs), fibrin, and platelets/other.Results57 patients were included. Pervious clots were more likely to be RBC rich (p=0.04); impervious clots were more likely to be fibrin and WBC rich (p=0.01 for both). Pervious clots also had greater RBC density than impervious clots (49.8% and 33.0%, respectively; p=0.006); fibrin density of pervious clots was lower than that of impervious clots (17.8% and 23.2%, respectively; p=0.02).ConclusionClot perviousness, assessed on NCCT and CTA imaging, is associated with higher RBC density and lower fibrin density, offering a possible explanation for the higher rates of successful thrombectomy and favorable clinical outcome seen in such patients.

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