Improved Volumetric MR-HIFU Ablation by Robust Binary Feedback Control

• Published in: IEEE transactions on biomedical engineering Vol. 57; no. 1; pp. 103 - 113
• Main Authors: Enholm, Julia K., Kohler, Max O., Quesson, Bruno, Mougenot, Charles, Moonen, Chrit T. W., Sokka, Shunmugavelu D.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.01.2010; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Ablation; Algorithms; Animals; biomedical applications of acoustic radiation; Computer Simulation; Feedback; Feedback control; Heating; High-Intensity Focused Ultrasound Ablation - methods; Lesions; Magnetic resonance; Magnetic Resonance Imaging, Interventional - methods; Male; MRI; Performance evaluation; Robust control; Signal Processing, Computer-Assisted; Standard deviation; Swine; Temperature control; Temperature dependence; Timing; Ultrasonic imaging
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2009.2034636

Volumetric high-intensity focused ultrasound (HIFU) guided by multiplane magnetic resonance (MR) thermometry has been shown to be a safe and efficient method to thermally ablate large tissue volumes. However, the induced temperature rise and thermal lesions show significant variability, depending on exposure parameters, such as power and timing, as well as unknown tissue parameters. In this study, a simple and robust feedback-control method that relies on rapid MR thermometry to control the HIFU exposure during heating is introduced. The binary feedback algorithm adjusts the durations of the concentric ablation circles within the target volume to reach an optimal temperature. The efficacy of the binary feedback control was evaluated by performing 90 ablations in vivo and comparing the results with simulations. Feedback control of the sonications improved the reproducibility of the induced lesion size. The standard deviation of the diameter was reduced by factors of 1.9, 7.2, 5.0, and 3.4 for 4-, 8-, 12-, and 16-mm lesions, respectively. Energy efficiency was also improved, as the binary feedback method required less energy to create the desired lesion. These results show that binary feedback improves the quality of volumetric ablation by consistently producing thermal lesions of expected size while reducing the required energy as well.