Correlation of imaging and histopathology of thrombi in acute ischemic stroke with etiology and outcome

Abstract

Mechanical thrombectomy has become the stand of care for patients with large vessel occlusions, yet major improvements in thrombectomy speed, efficacy, and completeness can still be achieved. High rates of clot fragmentation and failure to remove the clot resulting in poor neurological outcomes suggest that in order to further advance the field of stroke intervention we must turn our attention towards understanding the science of clot. Accurately identifying the composition of the occlusive clot prior to intervention could significantly influence the success of the revascularization strategy used to treat them. Numerous features of thromboemboli could be studied and characterized, including quantitative histomorphometry and diagnostic imaging characteristics. Each of these features might logically predict superior thrombectomy outcomes with one device or another. This article aims to review the current literature on histopathological composition of acute ischemic stroke clots, with a particular focus on the correlation between clot composition and diagnostic imaging, stroke etiology and revascularization outcomes.

Figure 1:. Commonly used histological stain in acute ischemic stroke clot assessment.

A&E are gross photographs of clots removed from two different patients that had suffered an acute ischemic stroke with an area of suspected calcification in E highlighted with a red box. B&F are examples of H&E stained slides from the corresponding clots showing Red Blood Cells (Red), White Blood Cells (Purple) and Fibrin/Platelets (Pink). C&G are examples of MSB stained slides showing Red Blood Cells (Yellow), White Blood Cells (Purple), Fibrin (Red) and Platelets/Other (Grey). D&H are examples of Masson’s Trichrome stained slide showing Red Blood Cells (Red), White Blood Cells (Purple) and Fibrin/Platelets (Purple). I is an example of a von Kossa stained slide confirming the presence of calcification (Brown).

Figure 2:. Histologic and Immunohistochemical Analysis of an acute ischemic stroke clot.

(A) is a gross photograph a ‘White’ clot retrieved from a patient using a mechanical thrombectomy procedure. (B) is an example of an MSB stained slide from the same clot showing the presence of Red Blood Cells (Yellow), White Blood Cells (Purple), Fibrin (Red) and Platelets/Other (Grey). (C) is an example of an immunohistochemically stained slide demonstrating the presence of Platelets in the clot (CD42b=Red). (D) is an example of an immunohistochemically stained slide demonstrating the presence of von Willebrand factor (Red).