Abstract Number ‐ 169: Intraprocedural angiographic sign for assessing the stent‐clot interaction during mechanical thrombectomy

Introduction The characteristics of the occlusive clot affect the clot integration with a stent retriever (SR). This relationship, stent‐clot interaction, is considered to be a major factor in the technical success of mechanical thrombectomy. To date, numerous studies analyzing the retrieved clots have shown that both soft erythro‐rich clots and hard fibrin‐rich clots make clot retrieval challenging. Several studies have successfully obtained information on this interaction using three‐dimensional (3D) rotational angiography. However, these 3D imaging technologies have not been utilized in clinical practice due to the time‐consuming nature of image acquisition and processing. Our previous clinical study demonstrated that the angiographic findings about the deployed stent morphology obtained from conventional two‐dimensional (2D) angiography could predict recanalization (1). The greater stent expansion at the occlusion was strongly associated with recanalization after the procedure. This intraprocedural angiographic sign allows us to know the stiffness of the clots in real‐time and to choose the optimal technique. The purpose of this study was to evaluate whether the stent expansion assessed by a 2D angiographical image reflects the actual stent dilation at the occlusion (Figure). We investigated the correlations between 2D images and 3D structures of the deployed SR using an experimental occlusion model. Methods Using occlusion models created with pseudo‐clot with 9 hardness levels (n = 3/clot type), images of the deployed Trevo SR were obtained by cone‐beam computed tomography.As the measurement metric for the 2D images, we used the degree of stent expansion obtained from a plane along the long axis of the device. In clinical practice, however, this 2‐D image is usually obtained from one viewing angle. Therefore, to investigate the difference in measurement by viewing angle, different angle 2D images were created to evaluate the stent expansion. For the 3D structures, we used the stent area obtained from the short‐axis plane of the vascular model, considering this as a surrogate for actual stent expansion. We evaluated the correlation between the 2D images and the 3D structure. Results A total of 27 model image sets were obtained, showing graduated stent expansion (range: 21–79%) depending on the clot type. The median variation in the degree of stent expansion for each model measured at different angles, which means the differences by viewing angles, was 9% (range: 5–20%). The median degree of stent expansion was strongly correlated with the stent area (Pearson’s coefficient: 0.98), indicating that the degree of stent expansion could reflect the 3D structure. Conclusions This study showed that the stent expansion on 2D angiography, even assessed from one direction, could be used as the approximation of the actual stent dilatation at the occlusion. This angiographic sign provides real‐time feedback on the clot characteristics at the occlusion

Abstract Number ‐ 23: In vitro evaluation of thrombectomy techniques: What is the most efficient combined technique?

Introduction A combined technique with contact aspiration and stent retriever is widely used for the treatment of patients with acute ischemic stroke due to the potential synergistic effect of the two technologies. However, there are no large studies that conclude the combined technique is more efficient compared to stent retriever only or contact aspiration. One of the issues in combined techniques may be the complexity, and multiple variations of combined techniques exist. We performed an in vitro study using three‐dimensional (3D) flow models and performed clot retrieval in order to explore effective and safe techniques for mechanical thrombectomy. Methods In a 3D silicone flow model with moderate tortuosity, we compared several techniques: 1. a pinching combination method (pull out stent retriever and aspiration catheter as a unit) with several variations of aspiration catheter locations; 2. an ingestion combination method (stent retriever removal through aspiration catheter); 3. stent retriever only; and 4. contact aspiration. We evaluated the success retrieval rates of a thrombus in the M2 branch. In addition, we measured pulling force during each technique to determine the amount of force exerted on the distal MCA vessel. Results The highest clot retrieval rate was achieved with a pinching combination technique with close contact with an aspiration catheter. The pulling force on the distal MCA vessel was high with the techniques that had high clot retrieval rates and low with the techniques that had low success rates. The pulling force was higher when the stent retriever was fully deployed compared with a pinching technique with a stent partially covered with an aspiration catheter. Conclusions In our in vitro model, the pinching combination method showed the highest clot retrieval rate when the aspiration catheter was advanced to the clot and the stent retriever. The pulling force experiments suggested the shorter stent retriever may decrease the rate of subarachnoid hemorrhage due to low pulling force

Devices and Techniques.

This extensive review explores the intricacies of the three principal mechanical thrombectomy techniques: the stent retriever technique, contact aspiration technique, and a combined approach, and their application in managing acute ischemic stroke. Each technique operates uniquely on the thrombus, leading to differences in their efficacy. Factors including clot size, clot stiffness, vessel tortuosity, and the angle of interaction between the aspiration catheter and the clot significantly influence these differences. Clinical trials and meta-analyses have shown the overall equivalency of these techniques for the treatments of large vessel occlusion and distal medium vessel occlusions. However, there are nuanced differences that emerge under specific clinical circumstances, highlighting the absence of a one-size-fits-all strategy in acute ischemic stroke management. We emphasize the need for future investigations to elucidate these nuances further, aiming to refine procedural strategies and individualize patient care for optimal outcomes

Water content for clot composition prediction in acute ischemic stroke.

BACKGROUND: Mechanical thrombectomy (MT) has become the gold standard care for treating acute ischemic stroke (AIS) due to large vessel occlusion. Emerging evidence suggests that understanding the composition of clots prior to intervention could be useful for the selection of neuroendovascular techniques, potentially improving the efficacy of treatments. However, current imaging modalities lack the ability to distinguish clot composition accurately and reliably. Since water content can influence signal intensity on CT and MRI scans, its assessment may provide indirect clues about clot composition. This study aimed to elucidate the correlation between water content and clot composition using human clots retrieved from stroke patients and experimentally generated ovine clots. MATERIALS AND METHODS: This study involved an analysis of ten clots retrieved from patients with AIS undergoing MT. Additionally, we created ten red blood cells (RBC)-rich and ten fibrin-rich ovine blood clots, which were placed in a human intracranial vascular model under realistic flow conditions. The water content and compositions of these clots were evaluated, and linear regression analyses were performed to determine the relationship between clot composition and water content. RESULTS: The regression analysis in human stroke clots revealed a significant negative association between RBC concentration and water content. We also observed a positive correlation between water content and both fibrin and platelets in ovine blood clots. Conclusion

Focal hyperintensity in the dorsal brain stem of patients with cerebellopontine angle tumor: A high-resolution 3 T MRI study

Focal hyperintensity (FHI) in the dorsal brain stem on T2-weighted images of patients with cerebellopontine angle (CPA) tumor was thought to indicate degeneration of the vestibular nucleus and to be specific to vestibular schwannoma. The purpose of this study was to evaluate FHI by using high-resolution 3 Tesla magnetic resonance imaging (3 T MRI) and the relation to clinical characteristics. We retrospectively reviewed the clinical data and MRI of 45 patients with CPA tumors (34 vestibular schwannomas and 11 other tumors). FHI in the dorsal brain stem was found in 25 (55.6%) patients (20 vestibular schwannomas and 5 other tumors). For the vestibular schwannomas, the factors contributing to positive FHI were age (p = 0.025), max CPA (p = < 0.001), hearing ability (P = 0.005), and canal paresis (p = < 0.001) in the univariate analysis. Multivariate regression analysis showed that max CPA (p = 0.029) was a significant factor of positive FHI. In other CPA tumors, these factors were not significant predictors. With the use of 3 T MRI, FHI was observed more frequently than previously reported. Our results suggest that FHI is not a specific indicator of vestibular schwannoma and is related to not only vestibular function but also other factors

Subarachnoid hemorrhage associated with cerebral hyperperfusion syndrome after simultaneous carotid endarterectomy and coronary artery bypass grafting procedures: A case report and review of the literature

Background: Intracranial hemorrhage associated with cerebral hyperperfusion syndrome (CHS) is a potentially devastating complication of carotid endarterectomy (CEA) or carotid artery stenting. Intracranial hemorrhage can comprise of intracerebral hemorrhage or subarachnoid hemorrhage (SAH), but SAH after CEA is rare. We report a case of SAH associated with CHS that followed simultaneous CEA and coronary artery bypass grafting (CABG). Case description: A 78-year-old man developed left-sided hemiparesis and was admitted to our institution. A preoperative study showed severe stenosis of the right carotid artery associated with markedly reduced cerebral blood flow (CBF), and a CEA was scheduled after initiating medical treatment. However, the patient developed unstable angina requiring an emergency CABG before undergoing an elective CEA. Given the risk of stroke associated with performing CABG alone, simultaneous CEA and CABG were urgently performed. The patient received dual antiplatelet therapy preoperatively and anticoagulation intraoperatively for the CABG procedure, and the anticoagulation was continued postoperatively due to the development of atrial fibrillation. Three days after the surgery, the patient developed a headache and magnetic resonance imaging demonstrated right-sided cortical SAH. Single-photon emission computed tomography revealed a significantly increased CBF. Therefore, the SAH appears to have been associated with CHS after the CEA. The hemorrhage was managed conservatively and resolved without an associated neurological deficit. Conclusion: SAH after CEA is rare clinical manifestation of CHS. Simultaneous CEA and CABG, or aggressive perioperative antithrombotic therapy, may increase the risk of its occurrence. Early diagnosis and careful management are important for favorable outcomes