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University of Cincinnati

1. Abbass, Mohamed A., M.S. Real-time Control of Ultrasound Thermal Ablation using Echo Decorrelation Imaging Feedback.

Degree: PhD, Engineering and Applied Science: Biomedical Engineering, 2018, University of Cincinnati

Liver cancer, including hepatocellular carcinoma and colorectal metastases, is the second greatest cause of cancer-related death worldwide. Liver transplantation is considered the gold standard for hepatic cancer treatment. However, it is limited by the availability of liver donors and by cost. Hepatic resection is another treatment option that offers a high long-term survival rate. However, the overall resectability rate is low due to chronic liver disease and tumor location. Thermal ablation, including radiofrequency ablation as well as microwave and ultrasound ablation, has become an important alternative to liver resection and transplantation. To avoid incomplete treatments and cancer recurrence while reducing morbidity, a real-time monitoring and control approach, capable of providing consistent thermal ablation in minimal time, is needed. Echo decorrelation imaging has been successfully employed to monitor ultrasound ablation and radiofrequency ablation both <i>ex vivo</i> and <i>in vivo</i>. In this dissertation, its utility for real-time control of ultrasound ablation was assessed in <i>ex vivo</i> bovine liver and <i>in vivo</i> rabbit liver with VX2 tumor. Ultrasound exposures and echo decorrelation imaging were performed using 5 MHz linear image-ablate array. Sonications were automatically ceased when the minimum or average cumulative echo decorrelation within a control region of interest (ROI) exceeded a predetermined threshold, corresponding to high specificity for prediction of local tissue ablation or complete ROI ablation. Ablation outcomes, treatment time and prediction performance were statistically compared between controlled and uncontrolled groups. For controlling <i>ex vivo</i> focused ultrasound treatments, a small control ROI was placed at the focal zone and the selected control threshold corresponded to 90% specificity of local ablation prediction for preliminary <i>ex vivo</i> experiments. Controlled trials were compared to uncontrolled trials employing 2, 5 or 9 therapy cycles. For controlling <i>ex vivo</i> unfocused ultrasound treatments, an optimization approach was developed to determine stopping criteria for two series of controlled experiments using different echo decorrelation imaging feedback parameters and sonication sequences. Controlled trials were compared with uncontrolled trials employing 9 or 18 therapy cycles of matching sonication sequences. For controlling <i>in vivo</i> focused and unfocused ultrasound treatments, the selected control threshold corresponded to 90% specificity for tumor ablation prediction in previous <i>in vivo</i> experiments. Controlled trials were compared with a previous series of uncontrolled <i>in vivo</i> experiments employing focused and unfocused ultrasound ablation in rabbit liver and VX2 tumor. In general, controlled trials resulted in higher ablation rate, smaller lesion dimensions and treatment time compared to uncontrolled trials with longer duration. However, controlled trials showed equivalent lesion dimensions and treatment time,… Advisors/Committee Members: Mast, T. Douglas (Committee Chair).

Subjects/Keywords: Biomedical Research; echo decorrelation imaging; ultrasound; thermal ablation; real-time control; HIFU; liver cancer

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APA (6th Edition):

Abbass, Mohamed A., M. S. (2018). Real-time Control of Ultrasound Thermal Ablation using Echo Decorrelation Imaging Feedback. (Doctoral Dissertation). University of Cincinnati. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535468911083998

Chicago Manual of Style (16th Edition):

Abbass, Mohamed A., M S. “Real-time Control of Ultrasound Thermal Ablation using Echo Decorrelation Imaging Feedback.” 2018. Doctoral Dissertation, University of Cincinnati. Accessed November 17, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535468911083998.

MLA Handbook (7th Edition):

Abbass, Mohamed A., M S. “Real-time Control of Ultrasound Thermal Ablation using Echo Decorrelation Imaging Feedback.” 2018. Web. 17 Nov 2018.

Vancouver:

Abbass, Mohamed A. MS. Real-time Control of Ultrasound Thermal Ablation using Echo Decorrelation Imaging Feedback. [Internet] [Doctoral dissertation]. University of Cincinnati; 2018. [cited 2018 Nov 17]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535468911083998.

Council of Science Editors:

Abbass, Mohamed A. MS. Real-time Control of Ultrasound Thermal Ablation using Echo Decorrelation Imaging Feedback. [Doctoral Dissertation]. University of Cincinnati; 2018. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535468911083998

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