MR Guided Focused Ultrasound for the Palliation of Bone Metastases: Clinical Procedures and Outcome

Lili Chen, Joshua Meyer, Gary Freedman, Andre Konski and C-M Ma

Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, USA
Department of Radiation Oncology, Perelman Center for Advanced Medicine, Philadelphia, USA
Department of Radiation Oncology, The Chester County Hospital, West Chester, USA

^*Correspondance to: Lili Chen 

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Abstract:

Purpose: The purpose of this paper is to report our initial clinical experience with MR Guided Focused Ultrasound (MRgFUS) for the palliative treatment of bone metastases with a focus on patient treatment workflow and Quality Assurance (QA) procedures to ensure the safe and effective operation of MRgFUS.Methods: In addition to the monthly, annual QA and Preventive Maintenance (PM), pre-treatment machine QA was performed one week before and on the day prior to patient treatment to test the machine hardware, imaging and treatment software and patient safety devices. The geometrical ultrasound focal spot between the planning focal spot and treatment focal spot was registered with an acoustic phantom using MR thermometry. The QA procedures were verified through patient treatments. Seven patients (recruited in the multicenter Phase III clinical trial, BM004) with scapula, humeral head, sacrum, ilium, pubic ramus and acetabular bone metastases were treated using a FDA approved clinical focused ultrasound system under MR guidance. Patients were treated with a frequency of 1 MHz; acoustic power of 32W ± 4.0W to 96W ± 11W with a duration of 20-30 seconds for each sonication resulting in an energy of 628J ± 78J to1859J ± 338J. MR phase images were used to monitor the temperature changes at focal spots in real-time. Based on the temperature feedback, the acoustic power can be adjusted to reach designed temperatures (≥600C) for individual sonications. The effectiveness of the treatment was evaluated by pain score using the visual analog scale (0-10VAS).Results: Our data showed that all seven patients tolerated the MRgFUS treatment well. No skin toxicity or other complications were observed during or after treatment. The patient pain rating was significantly reduced from 8.0 ± 1.1 before treatment to 4.7 ± 3.0, 3.0 ± 1.5, 3.2 ± 2.8 and 3.4 ± 1.5 at one day, one month, two months and three months after treatment, respectively.Conclusions: Our clinical data suggests that with appropriate treatment and QA procedures, MRgFUS is a safe and effective treatment modality for the noninvasive palliation of bone metastases.

Keywords:

Quality assurance; MR guided focused ultrasound; Bone metastases

Cite the Article:

Chen L, Meyer J, Freedman G, Konski A, Ma C-M. MR Guided Focused Ultrasound for the Palliation of Bone Metastases: Clinical Procedures and Outcome. Clin Oncol. 2017; 2: 1287.