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Real-time Control of Radiofrequency Thermal Ablation using Three-dimensional Ultrasound Echo Decorrelation Imaging Feedback

Grimm, Peter
http://orcid.org/0000-0001-8579-3369
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668635885850819

Abstract Details

2022, MS, University of Cincinnati, Engineering and Applied Science: Electrical Engineering.
Liver cancer is a significant public health burden; as of 2020, it is the second leading cause of cancer-related mortality worldwide. Hepatic resection is considered the gold standard for the treatment of liver malignancies. However, this procedure is only possible in a minority of patients, necessitating treatment modalities with comparatively worse performance, such as thermal ablation. Thermal ablation generally results in poorer clinical outcomes relative to resection, with a higher rate of recurrence and the potential for complications related to damage to healthy tissue near the ablation zone. Medical imaging techniques can improve thermal ablation procedures via assistance in preoperative planning, probe placement and postoperative evaluation, but clinicians lack a method to monitor and control thermal ablation while the procedure is ongoing. Echo decorrelation imaging is a pulse-echo ultrasound imaging technique that measures stochastic variations in echo signals arising from thermal treatment. The method has been shown to accurately predict thermal lesioning in in vivo and ex vivo studies of thermal ablation using conventional 2D ultrasound imaging. This thesis aims to apply the echo decorrelation methodology to volumetric ultrasound data to control RFA procedures in real-time. Feedback control is implemented as a bang-bang type controller that automatically stops thermal treatment if the spatial mean of the cumulative decorrelation map exceeds a set threshold. 3D echo decorrelation-based control was evaluated through a series of feedback- controlled and uncontrolled ablation trials on ex vivo bovine liver tissue using a clinical RFA system. The RFA system was set to target a 15 mm radius spherical region of tissue while decorrelation maps were computed from captured volumetric ultrasound data; if the control criterion was met, the procedure was automatically stopped using a custom- designed microcontroller circuit. Trials were divided into two groups, a preliminary group, which was used to evaluate the efficacy of the method in predicting local thermal lesioning as well as to inform parameter selection for later trials, and a final group, which was used to gauge the performance of the method in optimizing the size and geometry of the ablated region. In our feedback-controlled trials, we found moderately better conformance to the targeted region as measured by the Sorenson-Dice coefficient between the targeted region and sectioned tissue histology. A statistically significant difference in ablated volume was found between the uncontrolled and controlled groups, but no difference was found in the variance of ablated volume or the ablation rate. We found that 3D echo decorrelation imaging performed similarly to 2D echo decorrelation imaging in monitoring and controlling thermal lesioning, despite using a lower frame rate, lower number of samples and forgoing stochastic averaging. Overall, we have demonstrated a feedback control methodology for ex vivo radiofrequency ablation using 3D ultrasound echo decorrelation imaging that resulted in better conformance to our desired ablation region. This result shows promise for the utility of echo decorrelation imaging in optimizing thermal ablation procedures, which could potentially result in better clinical outcomes for patients with liver cancer.
T. Douglas Mast, Ph.D. (Committee Member)
Xuefu Zhou, Ph.D. (Committee Member)
Mehdi Norouzi, Ph.D. (Committee Member)
124 p.
Radiology
echo decorrelation imaging; ultrasound; Radiofrequency thermal ablation; 3d ultrasound imaging; real-time control; treatment monitoring

Recommended Citations

Citations

  • Grimm, P. (2022). Real-time Control of Radiofrequency Thermal Ablation using Three-dimensional Ultrasound Echo Decorrelation Imaging Feedback [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668635885850819

    APA Style (7th edition)

  • Grimm, Peter. Real-time Control of Radiofrequency Thermal Ablation using Three-dimensional Ultrasound Echo Decorrelation Imaging Feedback. 2022. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668635885850819.

    MLA Style (8th edition)

  • Grimm, Peter. "Real-time Control of Radiofrequency Thermal Ablation using Three-dimensional Ultrasound Echo Decorrelation Imaging Feedback." Master's thesis, University of Cincinnati, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668635885850819

    Chicago Manual of Style (17th edition)

ucin1668635885850819
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This open access ETD is published by University of Cincinnati and OhioLINK.