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BME PhD Thesis Defense| Advanced Imaging in the Neurointerventional Treatment of Stroke by Robert King| Via Zoom

Tuesday, April 27, 2021
3:00 pm to 4:00 pm

Abstract: There are over 15 million cases of stroke each year worldwide, with approximately 1/3 of these resulting in death, and another 1/3 in serious disability. Within the United States stroke has become the leading cause of permanent disability. The two major subtypes of stroke are hemorrhagic, a bleed, and ischemic, a blockage of flow. Endovascular treatment for both causes of stroke, especially post 2015 for ischemic stroke, has become a leading method of treatment, as a much less invasive method compared to surgery. With the development of Optical Coherence Tomography (OCT) and more recently High Frequency OCT (HF-OCT), we sought the leverage this powerful tool in the prediction and monitoring of healing after endovascular treatment of aneurysms.

More explicitly we hypothesized that OCT would allows for the imaging of apposition of flow diverters and use this as a tool for occlusion prognostication. We found that poor apposition, specifically confined to the neck of the aneurysm, that we named Communicating malapposition (CM), was highly predictive of failed early occlusion. Once the device has been implanted, measuring the volume of acute thrombus formation could enlighten the use of antiplatelet therapy. Here we found that independently new surface coatings on flow diverters, and the use of antiplatelet drugs would reduce acute clot burden, and in combination virtually eliminated it. Finally, if an intrasaccular device is used, any gaps in the coverage of the neck would lead to a failed treatment. We were able to show that any gap larger that 1mm2, or roughly the size of a microcatheter, would be too large, and allow an aneurysm to remain patent.

Animal model are often tailored to a specific need, a common model for endovascular device testing is the rabbit elastase aneurysm model. A drawback to this model is the aneurysm stability, it will not rupture spontaneously. By including a decellularization step during aneurysm construction, we were able to modify the aneurysm such that it could exhibit both inflammation and growth of aneurysms, key hallmarks of rupture.

With all the advances in endovascular treatment of ischemic stroke, rates of successful embolus removal have reached over 85%; however, the number of patients who have a good clinical outcome remains at under 40%. In order to develop new therapeutics animal models that closely mimic the natural progression within the human populations must be developed. Here we have designed a method for analyzing MR imaging data to identify both the final volume and rate of progression within a canine model of large vessel occlusion. From here we have successfully applied this new model and analysis technique to a novel oxygen carrier therapy that can reduce the rate of infarct progression, allowing for more time for intervention.

Defense Committee:

Matthew Gounis, PhD, Professor, Department of Radiology, UMass Medical School (Thesis Advisor)
Kris Billiar, PhD, Professor, Department of Biomedical Engineering, WPI (Chair)
Sonbgai Ji, PhD, Associate Professor, Department of Biomedical Engineering, WPI
Mohammed Salman Shazeeb, PhD, Assistant Professor, Department of Radiology, UMass Medical School
Adnan Siddiqui, MD, PhD, Vice-Chairman and Professor, Department of Neurosurgery, University at Buffalo Neurosurgery

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Department of Biomedical Engineering
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