| Author: | Huang, Zihao |
| Title: | Liver fibrosis assessment using a palm-sized transient elastography system : performance evaluation and examination standards |
| Advisors: | Zheng, Yong-ping (BME) |
| Degree: | Ph.D. |
| Year: | 2025 |
| Department: | Department of Biomedical Engineering |
| Pages: | xxiii, 194 pages : color illustrations |
| Language: | English |
| Abstract: | Background: Chronic liver disease (CLD) is a major public health issue worldwide. Liver fibrosis is the common pathway for CLD of various etiologies, culminating in cirrhosis and liver cancer. Transient elastography (TE), endorsed by the WHO, is an established method for assessing liver fibrosis via liver stiffness measurement (LSM). However, technical barriers remain toward an efficient examination and point-of-care application, as conventional TE relies on wired connections, possesses a bulky size, has high unreliable and failure rates, and necessitates extensive training. Chapter 1 provides a systematic review to consolidate existing evidence on these TE-specific limitations, attributing them to the (1) absence of a standardized measurement protocol and (2) inadequacy of visual guidance during the TE procedure. Objectives: This thesis comprises a series of three integrated studies, aiming to bridge the above-mentioned gaps from technical and clinical perspectives. Methods and Findings: Chapter 2 aims to offer a technical remedy by incorporating point-of-care ultrasound (POCUS) and anatomical imaging guidance into TE. Specifically, we introduced a palm-sized wireless TE system with real-time B-mode imaging guidance. A methodological study was conducted to evaluate the performance of this newly developed system in eight reference phantoms and 121 adult patients with various CLDs. Results demonstrated the feasibility of employing a fully integrated phased array probe to provide accurate, reliable, and valid LSM. Its small footprint, along with B-mode guidance capability, can greatly facilitate the uptake of liver fibrosis screening. Chapter 3 aims to offer a practical guideline via establishing a standardized TE measurement protocol for clinical implementation. Specifically, we sought to identify an ideal site and respiratory condition for TE probe placement by investigating the morphological and biomechanical characteristics of different intercostal spaces (ICSs) overlying the liver. This observational study involving 89 participants employed a combination of ultrasound techniques, including 2D B-mode, 2D elasticity, and 3D ultrasound imaging. Results suggested the 8th ICS on the mid-axillary line as the preferred measurement site, owing to its greater width, smaller width-change, greater angle, lower stiffness, and smaller abdominal wall thickness. Additionally, performing TE at end-inspiration is recommended to minimize interferences from ribs and subcutaneous fat. These recommendations can serve as a guide for novices to shorten learning curve and improve examination efficiency. Chapter 4 presents an observational study (n=62) to further scrutinize into the effects of supine, seated, and standing postures on liver stiffness, as well as on the feasibility and reliability of TE. Results showed the postural dependency of liver stiffness, which was exhibited differently in healthy controls and patients with varying fibrosis stages. Different postures did not influence the success rate and reliability metrics of TE. Consequently, body positioning should be standardized and cautiously considered when interpreting LSM results. Conclusions: This thesis advocates for technical improvements and clinical procedural standardization in TE, which can provide actionable insights into addressing challenging cases and scaling up liver fibrosis assessment. Specifically, the key findings may advance TE technique in the long run, ultimately eliminating the failure and unreliable results, alleviating the training burden of TE practitioners, and streamlining the examination procedure in clinical settings. |
| Rights: | All rights reserved |
| Access: | open access |
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