Efficacy of thrombus density on noninvasive computed tomography neuroimaging for predicting thrombus pathology and patient outcome after mechanical thrombectomy in acute ischemic stroke

Abstract

Background and Purpose: The aim of this study was to investigate the efficacy of thrombus density on noninvasive computed tomography (CT) neuroimaging for predicting thrombus pathology and patient outcome after mechanical thrombectomy in acute ischemic stroke. Materials and Methods: This retrospective chart and imaging review included patients that were treated by mechanical thrombectomy at Siriraj Hospital according to the American Heart Association/American Stroke Association guidelines for the early management of patients with acute ischemic stroke from March 2010 to February 2015 study period. Preintervention noncontrast CT (NCCT), CT angiography (CTA), and/or contrast-enhanced CT (CECT) images were interpreted using CT densitometry. Pathology results were classified as white, red, or mixed thrombi. The result of treatment was evaluated by the modified Rankin Scale at 90 days after treatment. Results: From 97 included patients – 97 NCCT images, 48 CTA images, 48 CECT images, and 54 pathologic results of cerebral thrombi were included in the final analysis. Mean clot Hounsfield unit values on NCCT, CTA, and CECT were significantly different between red and white thrombus ( P = 0.001 on NCCT, P = 0.03 on CTA, and P = 0.001 on CECT), and between red and mixed thrombus ( P = 0.043 on NCCT and P = 0.002 on CTA). However, no significant difference was observed between white thrombus and mixed thrombus ( P = 0.09 on NCCT, P = 1.00 on CTA, and P = 0.054 on CECT). There was no significant correlation between type of cerebral thrombus or clot density and the result of treatment. Conclusion: Thrombus density on CT was found to be a significant predictor of thrombus pathology; however, no significant association was observed between thrombus type or clot density and patient outcome after mechanical thrombectomy.

Histopathological Composition of Thrombus in Acute Ischemic Stroke May Vary Even Within the Same Patient: A Preliminary Study Examining Clots According to Their Area of Retrieval

“…In terms of imaging findings, the hyperdense artery sign has been associated with RBC-rich thrombi. [1][2][3] Furthermore, one study previously reported that clot permeability, assessed on non-contrast CT and CT angiography, was associated with higher RBC density, 4) while another report showed that permeable thrombi strongly correlated with lower fractions of RBC and more F/P conglomerations. 5) As for treatment outcomes, some studies have shown that high RBC composition was associated with successful recanalization, 6,7) whereas another study reported that a clot with a high number of RBCs had a higher risk of migration, which could lead to worse outcomes.…”

“…Many of these studies have measured the areas occupied by red blood cells (RBCs), fibrin/platelets (F/Ps), and white blood cells (WBCs), and examined the relationship between clot composition and clinical characteristics. [1][2][3][4][5][6][7][8][9][10][11][12] However, it is unknown whether the histopathological findings of one cross-section represent the overall composition of the clot. Histopathological composition may differ according to the site of the observed cross-section, even in the same thrombus.…”

Histological analysis of thrombi retrieved after acute ischemic stroke from large vessel occlusion: from research to clinical practice

“…Computed tomography angiography (CTA) of supra-aortic and intracranial vessels is a sensitive and specific tool to detect LVO, and it is now a standard procedure in the diagnostic workflow of AIS. We found 12 articles reporting an association between clot characteristic on CT and histological composition both on retrieved thrombi and on clot analogs [8,16,42,[76][77][78][79][80][81][82][83][84] .…”

“…Hyperdense middle cerebral artery sign (HMCAS) is a well-known sign of LVO in AIS on baseline NCCT. Its presence was proved to be related with higher content of RBCs in thrombi [8,42,76,85] , while its absence is related to platelet-rich clots [77,78] .…”

“…Main finding in thrombus HMCAS: ↑ RBC and ↓ fibrin content [8,42,[76][77][78]85] Thrombus attenuation: directly correlated with RBC content and inversely correlated with fibrin content [8,16,79,83,84] Thrombus permeability: ↑ fibrin content [81,84] Non contrast CT and CT angiography Thrombus permeability: ↑ RBC and ↓ fibrin and WBC content [82] MRI Susceptibility vessel sign: ↑ RBC and ↓ fibrin content [17,76] (D) Other clinical variables Clinical feature Main finding on thrombus Basilar artery occlusion: ↑ RBC content [96] Site of occlusion Internal carotid artery occlusion: larger thrombi compared to middle cerebral artery occlusion [97] Worse 90 days functional outcome: larger clot area [33] Worse 90 days functional outcome: ↑ polyhedral RBC content and clustered WBC [14] Admission NIHSS > 10: ↑ polyhedral RBC, platelets, and fibrin bundles content Admission NIHSS ≤ 10: fibrin sponge [14] Stroke severity and clinical outcome Admission NIHSS > 10: layered thrombus [33] RBC: Red blood cell; FP: fibrin and platelet; WBC: white blood cell; CE: cardioembolic; LAA: large artery atherosclerosis; CS: cryptogenic stroke; NETs: neutrophil extracellular traps; CT: computed tomography; MRI: magnetic resonance imaging; HMCAS: hyperdense middle cerebral artery sign.…”