BOSTON—Since MR-guided focused ultrasound (MRgFUS) can achieve therapeutic results with relatively low energy, the procedure has the potential to provide an effective alternative for palliation of pain caused by bone metastases, according to a poster presentation from the 50th annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO).
According to the study’s co-author David Gianfelice, MD, division head of VIR at the University Health Network in Toronto, they evaluated the safety and initial efficacy of for the palliation of pain caused by bone metastases in patients where standard available treatments have been ineffective or not feasible. On study completion, they performed an additional analysis of the data to optimize required acoustic parameters and evaluate procedure load on the facility in terms of MR time and medical team.
Eleven patients (seven female; average age 58.6 years) with pain related to bony metastases were treated with MRgFUS. Treatment efficacy was evaluated by changes in VAS pain scale as well as reduction in the analgesics intake. During each treatment the parameters of every acoustic pulse were automatically recorded, as well as the time log of the procedure, starting from patient entering the MR room and up to the time of transferring the patient to medical imaging day unit for recovery.
Twelve lesions were treated in eleven patients. All patients reported progressive decrease in pain in the treated regions in the ensuing three-month follow-up period along with similar reduction in the pain medication usage. No serious device related adverse events were recorded, the researchers said.
Pain scores on VAS pain scale averaged 6 prior to treatment and decreased to 0.5 at three months (decrease in pain scores 92 percent).
According to the investigators, total procedure time averaged two hours, 44 minutes, while actual energy delivery took only averaged 60 minutes out of that time. In all but one case, only one procedure was sufficient for successful pain palliation. Patients were examined and questioned immediately after the procedure for any adverse events, monitored for one to two hours following treatment and discharged in the care of a companion.
Gianfelice and colleagues wrote that since the energy used in MRgFUS is non-ionizing, the treatment can be repeated as many times as needed with no upper dose limit. Furthermore, the need for only one session, short treatment duration, using of conscious sedation only, suggest that “MRgFUS may be a viable economic option for the palliative treatment of painful bone metastases,” they wrote.