1108. Hemodynamic comparison of carotid endarterectomy patch versus no-patch repair phantoms using 4-D flow imaging with MRI

Authors: Sang-Hyung Lee, MD PhD; Seungbin Ko; Simon Song, PhD; Doosang Kim, MD, PhD (Seoul , Republic of Korea)

Introduction: Carotid artery stenosis is widely accepted as a major concern, especially in symptomatic patients and results in cerebrovascular accident. Methods: We performed in-vitro experiments with pre- and post-operative carotid stenosis phantoms to elucidate and compare the hemodynamic characteristics of carotid artery atherosclerosis with and without a patch repair using 4-D flow imaging with MRI. Real-size, solid phantoms were fabricated with a 3D printer, and the phantom shapes were obtained from the CT images of two patients. We visualized the pulsatile flow patterns by 4-D flow imaging and calculated wall shear stress (WSS), oscillatory shear index (OSI). to study the hemodynamic characteristics. Results: Aa strong jet emitting at the stenotic area impinges on the outer carotid wall of the pre-operative phantom for both patients. Their WSS is high not only near the stenosis but also the entire carotid relatively to their counterpart of post-operative phantoms. OSI was high in the outer wall of both post-operative phantoms. A glance of flow visualization results as well as the CT images might mislead one as if both post-operative phantoms relieved hemodynamic flow resistance. However, detailed studies on the hemodynamic feature of the flows revealed that the post-operative phantom with a patch has a higher WSS in the inner wall of the fork despite its wider lumen than the one without a patch. This is attributed to the presence of a strong recirculation zone induced in the opposite (outer) wall of the fork. The recirculation is necessarily caused with a sudden expansion of the lumen due to the patch repair and this kind of low shear, highly oscillatory region is thought to stimulate the growth of the atherosclerosis. The comprehension of these hemodynamic studies will help the management of pre- and post-operative carotid stenosis patients.