Travis Singh
BME MS Thesis Defense Presentation
Date: 2025-04-11
Time: 1:00 PM - 3:00 PM
Location / Meeting Link: IBB 3316 / https://gatech.zoom.us/j/96467528704?pwd=jmH28cC1diBRVMsQYI15F6p8yOhO0C.1

Committee Members:
Dr. Brooks Lindsey; Dr. Alessandro Veneziani; Dr. John Oshinski


Title: Forward-viewing intravascular ultrasound-derived wall shear stress for PCI optimization: Phantom and CFD studies

Abstract:
Percutaneous coronary intervention (PCI) is the current standard of care to relieve myocardial ischemia, with approximately 3 million PCI procedures performed annually. However, 25-33% of patients experience recurrent angina or major adverse cardiac events by the two-year follow-up due to restenosis. Wall shear stress (WSS) is a hemodynamic variable that has demonstrated incremental value in predicting plaque initiation, progression, and vulnerability. Thus, the ability to image WSS during PCI could optimize stent placement, reduce rates of restenosis post-PCI, and improve risk stratification. To determine the feasibility of forward-viewing intravascular ultrasound (FV-IVUS) to assess stent placement by imaging WSS surrounding the stent, a high frequency commercial linear array transducer in a forward-viewing position was used to acquire data in 9 different scenarios in 3D-printed vessel-mimicking phantoms (before stenting, with a malapposed stent, and with a fully-expanded stent for 3 unique geometries). A syringe pump was used to inject a microbubble solution (0.025%) at 20 ml/min through each phantom. The fluid flow velocity was estimated in both axial and lateral directions using Doppler methods with transverse oscillation. WSS was estimated from ultrasound velocity imaging data with a pseudo-spectral method and compared with CFD for validation. For all malapposed cases, imaging-derived WSS maps indicated significantly lower WSS in the proximal segment of the phantom compared to the stenotic and distal segments. In addition, spatial variation in WSS was significantly higher in the malapposed cases compared to the well-apposed cases. To our knowledge, this is the first investigation of US imaging-derived WSS in stented coronary artery geometries. When implemented with a forward-viewing 2D array, US-derived WSS could allow for real-time WSS estimation to improve risk stratification as well as patient outcomes post-PCI.