Abstract WP95: Microct Data Can Distinguish Between in vitro Clot Types of Different Composition

Abstract

Introduction: Several clinical studies have demonstrated that thrombectomy leads to improved clinical outcome and extends the treatment window for patients with acute ischemic stroke. This has motivated an expansion of the arsenal of available thrombectomy devices and an increased interest in image-guided patient selection and treatment. In vitro and in vivo studies have shown that the choice of thrombectomy device may be optimized according to the composition of the occluding clot. Baseline imaging may, therefore, guide the thrombectomy device choice, provided that the composition of the clot can be determined by imaging. Due to the low soft tissue contrast of CT images, the extraction of image parameters may, however, be confounded by pooling of blood around the occlusion. Hypothesis: MicroCT images can be used to verify the x-ray density of the extracted clots in an unambiguous manner. These images may eventually be correlated to clinical baseline imaging to determine whether the x-ray density extracted from clinical images is representative of the clot or confounded by the pooling of blood around the occlusion. Methods: In this pilot study, we investigated whether the x-ray density, as measured with a microCT (Qunatum GX; Perkin Elmer), could be used to distinguish between clot analogs made from whole blood (n=1) and clots of blood constituents mixed to produce ratios of 95% : 5% (n=1) and 5% : 95% red blood cells : fibrin (n=1). After imaging, the compositions of the clots were histologically verified by H&E staining. Results: MicroCT data could be used to distinguish between red blood cell rich, whole blood and fibrinous clots with area-under-curve of receiver operating curves ranging between 0.64 and 0.82. The compositions of the red blood cell rich, the whole blood and the fibrinous clot were verified to contain 94% red blood cells and 6% fibrin, 70% red blood cells and 30 % fibrin, and 97% fibrin and 3% white blood cells respectively. Conclusions: X-ray density—as measured on a microCT— can be used to infer the composition of blood clots. Further studies will be performed to determine whether the x-ray density of patient-derived clots, as measured with the microCT, is representative of the appearance of the clots on clinical baseline imaging.