People

Graduate Student	Yibo Wu
Project Supervisor	Prof. Joseph Katz
Project Collaborator	Prof. Misun Hwang (Children’s Hospital of Philadelphia)

Introduction

Contrast Enhanced Ultrasound (CEUS) imaging, combined tracking of the microbubbles velocity using ultrasound localization microscopy (ULM), is widely used tool for assessing blood flows in various organs. Owing to the spatial variations in the size and shape of the (2-3um diameter) micro bubble images, their tracks should be calibrated. Here, we introduce a microcirculation phantom designed for simultaneous ultrasonic and optical tracking of the same microbubbles in physiologically relevant microchannels. The optical bubble tracking is performed using microscopic in-line holography. The phantom is constructed from a transparent polyacrylamide hydrogel, which replicates the acoustic properties of human tissues, including the speed of sound and acoustic impedance, and B/A. Microchannels with diameters of 10, 50, 125, 250 and 400 um are formed by installing and then extracting tungsten wires coated with Parylene-C inside the hydrogel matrix. The resulting parallel micro-channels have minimum spacings of 30 to 60 mm at realistic depth varying from 7 to 54 mm from the ultrasonic probes. The axis of the microscopic holography system is perpendicular to the CEUS scanning plane, enabling observations at any depth. The presentation will include details of the design and will discuss several algorithms for enhancing and detecting bubble trajectories.