Mid-term efficacy grading evaluation and predictive factors of magnetic resonance–guided focused ultrasound surgery for painful bone metastases: a multi-center study

Objectives MR imaging–guided focused ultrasound surgery (MRgFUS) is an emerging non-invasive treatment. It is helpful in investigating the mid-term grading efficacy and safety of MRgFUS, and possible risk factors in participants with painful bone metastases. Methods This four-center prospective study enrolled 96 participants between June 2016 and May 2019 with painful bone metastases. The Numerical Rating Scale (NRS), Brief Pain Inventory-Quality of Life (BPI-QoL) score, morphine equivalent daily dose (MEDD), and the adverse events (AEs) were recorded before and at 1 week, 1 month, 2 months, and 3 months after MRgFUS. The repeated ANOVA tests were used to analyze the change in NRS and BPI-QoL, and logistic regression analysis was used to analyze the possible risk factors. Results A total of 82 participants completed the 3-month follow-up period. And 16 (19.5%) participants were complete responders (CR), 46 (56.1%) participants were effective responders (ER), and the other 20 (24.4%) participants were non-responders (NR). The NRS (2.67 ± 2.47 at 3 months compared to 6.38 ± 1.70 before treatment) and BPI-QoL score (3.11 ± 2.51 at 3 months compared to 5.40 ± 1.85 before treatment) significantly decreased after the treatment at all time points ( p < 0.001). Eleven adverse events were recorded and they were all cured within 1 to 52 days after treatment. The non-perfused volume (NPV) ratio ( p = 0.001) and the bone metastases lesion type ( p = 0.025) were the key risk factors. Conclusions MRgFUS can be used as a non-invasive, effective, and safe modality to treat painful bone metastases. NPV ratio and the lesion type may be used as affecting factors to predict the mid-term efficacy of MRgFUS. Key Points • MRgFUS can be considered a non-invasive, effective, and safe modality to treat painful bone metastases. • The NRS and BPI-QoL score at 1 week, 1 month, 2 months, and 3 months all decreased significantly (p < 0.001) after receiving MRgFUS. Among 82 participants, 16 (19.5%) were complete responders, 46 (56.1%) were effective responders, and the other 20 (24.4%) were non-responders. • According to logistic regression analysis, non-perfused volume ratio and the bone metastases lesion type were the affecting factors to predict the mid-term efficacy of MRgFUS. The adjusted OR of non-perfused volume ratio was 0.86 (p = 0.001), and osteoblastic lesion type was 0.06 (p = 0.025).