Perfusion imaging using power doppler ultrasound without contrast enhancement to diagnose peripheral artery disease

Babaei, Somaye

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https://hdl.handle.net/2142/124157 Copy

Description

Title

Perfusion imaging using power doppler ultrasound without contrast enhancement to diagnose peripheral artery disease

Author(s)

Babaei, Somaye

Issue Date

2024-04-02

Director of Research (if dissertation) or Advisor (if thesis)

Insana, Michael

Doctoral Committee Chair(s)

Insana, Michael

Committee Member(s)

• Sutton, Brad
• Dobrucki, Wawrzyniee
• Philips, Heidi
• Lam, Fan
• Amos, Jenny

Department of Study

Bioengineering

Discipline

Bioengineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Power Doppler Ultrasound
• Perfusion Imaging
• Registration
• Peripheral Artery Disease (PAD)
• Singular Value Decomposition (SVD).

Abstract

This thesis delves into the exploration of non-contrast Power-Doppler ultrasound (PD-US) for monitoring blood perfusion in peripheral tissues, with a specific focus on its ability to track spatiotemporal changes in muscle perfusion. The research initiates with a thorough investigation of spatial registration techniques combined with Principal Components Analysis (PCA)-based clutter filtering. This approach substantially improves the efficiency of narrowing the eigen-spectrum of tissue clutter, optimizing the efficacy of PCA filters. It is imperative to note that the success of the clutter filter hinges on the spatial patterns of blood cell motion. The results demonstrate a successful reduction of in-plane clutter motion, enhancing the overall precision of the imaging process. However, challenges associated with out-of-plane movement persist, resulting in clutter-filter leakage. These issues can be addressed through simple adjustments in scanning techniques and implementing spatial averaging procedures. The scope of the study expands to validate PD-US measurements through a comparative analysis with laser speckle contrast imaging (LSCI) in pre-clinical rodent studies. The combination of spatial registration and clutter filtering techniques enables consistent tracking of blood perfusion in skeletal muscle while modulating hindlimb blood flow. The research encompasses invasive and non-invasive studies, with PD-US measurements compared with LSCI under various conditions, including short-term arterial clamping and prolonged hindlimb ischemia induction. Simultaneous B-mode imaging and PD-US are employed to assess flow-mediated dilation (FMD) of the femoral artery and downstream muscle perfusion, quantifying reactive hyperemia (RH). Measurements are conducted on adult male and female mice and rats, including those subjected to exercise conditioning, to explore potential biological variables. The results validate the efficacy of non-contrast PD-US through comparisons with LSCI, revealing no significant differences between sexes or fitness levels in FMD or RH estimates. Encouragingly, post-ischemic perfusion improvements are observed with exercise conditioning, suggesting variations in hyperemic responses between the conduit and resistive vessels. The research further examines the effectiveness of PD-US for monitoring shifts in muscle perfusion over time, emphasizing changes relevant to biological variables, specifically diabetes. Experiments include the induction of short and long-term ischemia in healthy and type II diabetic male and female mice, with and without exercise. Perfusion measurements are taken during and after 5-minute ischemic periods and throughout four-week recovery phases following irreversible femoral ligation. The results reveal differences in perfusion recovery times between diabetic and non-diabetic mice. Additionally, measurements of FMD in conduit arteries and the RH index in resistive vessels indicate a decline in sedentary diabetic mice compared to sedentary non-diabetic mice. The reproducibility of perfusion measurements is primarily affected by the ability to consistently select the same muscle region and effectively filter out tissue clutter. This study underscores the capability of PD-US measurements to accurately track site-specific changes in skeletal muscle perfusion over time, particularly in the context of diabetes. These findings offer promise in addressing the crucial need for techniques to monitor atherosclerotic changes leading to ischemic cardiovascular pathologies regularly. Extending beyond murine models, this research adopts a translational approach with porcine subjects. The method utilizes a low-frequency ultrasound pulse and a handheld transducer to explore muscle perfusion at greater depths. An ischemia model induced by an ameroid ring constrictor (ARC) is introduced, emphasizing gradual arterial constriction, resembling the extended development of atherosclerosis in peripheral artery disease (PAD) patients, in contrast to the acute ligation often used in murine models. The results confirm that PD-US, without contrast enhancement, effectively monitors temporal changes in a human-scale phantom using low-frequency probes. In conclusion, these findings support the advancement of non-contrast PD-US as a robust tool for assessing blood perfusion alterations and enhancing patient care in the context of peripheral artery disease.

Graduation Semester

2024-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2024 Somaye Babaei

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