Author : Kayvan Samimi
Publisher :
ISBN 13 :
Total Pages : 206 pages
Book Rating : 4.:/5 (13 download)
Book Synopsis Quantitative Ultrasound Imaging During Ablation Procedures by : Kayvan Samimi
Download or read book Quantitative Ultrasound Imaging During Ablation Procedures written by Kayvan Samimi and published by . This book was released on 2017 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conventional ultrasound imaging (i.e. B-mode sonogram) is a qualitative mode of imaging based on visualizing the relative echogenicity of different tissue types within the body. This useful mode of imaging has aided clinicians for more than 50 years. However, B-mode imaging does not capture any of the frequency-dependent information that is contained within the ultrasound echo signal. Additionally, due to its qualitative nature, there is much inter-system and inter-observer variability with regard to generation and interpretation of B-mode images. Quantitative Ultrasound (QUS) methods have been developed to extract additional information by estimating acoustic properties of tissue from the frequency-domain representation of echo signals. These estimates can be converted to color-coded maps that are visualized along with conventional B-mode images to form enhanced ultrasound images. Such images can potentially provide valuable diagnostic and prognostic information to medical professionals. Some of the more important acoustic parameters of interest in QUS and tissue characterization are the ultrasonic attenuation coefficient and the backscatter coefficient. Attenuation has been studied as a potential classifier of normal and pathological liver tissue. In addition to providing pathological information for diagnosis, monitoring these QUS parameters during therapeutic procedures such as tumor ablation can lead to targeted and optimized treatment. The goals of this dissertation are to theoretically model and analyze current methods of acoustic attenuation estimation; improve attenuation estimation algorithms to enhance the quality of subsequent QUS images; and correlate changes in QUS parameter values with progression of thermally ablative procedures for ex-vivo and in-vivo liver ablations. Although QUS imaging may be used to assist clinicians in various stages of diagnosis and treatment of diseases in a multitude of bodily organs and tissue types, this dissertation focuses on thermal ablation of primary or metastatic liver tumors in order to showcase the possible benefits of the proposed estimation methods and to compare their performance with existing estimation techniques. Additionally, simulated and physical tissue-mimicking (TM) phantoms with known acoustic properties are used to statistically test and compare the accuracy and precision of these methods. Theoretical analysis and experimental results suggest that our proposed method for estimation of the ultrasonic attenuation coefficient based on measurement of frequency shifts in a normalized power-spectral representation of the ultrasonic echo signal is best suited to in-vivo QUS imaging in clinical settings and provides estimates with standard deviations that are at least three times smaller than was previously possible with other methods.