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Title:A signal processing approach to ultrasound localization microscopy
Author(s):Soylu, Ufuk
Advisor(s):Bresler, Yoram
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Ultrasound Localization Microscopy
Signal Processing
Velocity Filtering
Abstract:Ultrasound Localization Microscopy (ULM) offers a cost-effective modality for microvascular imaging by using intravascular contrast agents (microbubbles). However, ULM has a fundamental trade-off between acquisition time and spatial resolution, which makes clinical translation challenging. In this thesis, in order to circumvent the trade-off, we pose the localization problem as a signal processing problem and introduce a filtering operation that is capable of separating microbubble contrast agents into different subgroups based on their vector velocities while simultaneously offering blood velocity mapping at super resolution, without tracking individual microbubbles. We define the filtering operation in three-dimensional (3D) Fourier domain and provide rigorous theoretical analysis on the performance of the filtering operation. Numerical experiments validate that the proposed filtering method is able to separate the microbubbles with respect to the speed and direction of their motion. In combination with subsequent localization of microbubble centers, e.g. by matched filtering, velocity filter signicantly improves the quality of reconstructed vessel structure map and provides blood flow information. Overall, the proposed imaging pipeline in this thesis, eliminates the need of using diluted microbubble injections to improve image quality, thus helping to circumvent the trade-off between acquisition time and spatial resolution. Conveniently, because the velocity filtering operation can be implemented by fast Fourier transforms (FFTs) it admits fast, and potentially real-time realization. We believe that the proposed filtering method has the potential to pave the way to clinical translation of ULM.
Issue Date:2020-07-08
Rights Information:Copyright 2020 Ufuk Soylu
Date Available in IDEALS:2020-10-07
Date Deposited:2020-08

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