Magnetic resonance-guided focused ultrasound surgery for treatment of painful osseous metastases

Magnetic resonance guided focused ultrasound surgery (MRgFUS) is an emerging technology that can non-invasively heat and ablate targeted tissue utilizing ultrasound energy. Use of MR imaging for treatment guidance provides several key advantages over more widely used ultrasound guidance for focused ultrasound ablation. MR allows for precise targeting, detailed beam path visualization, real time non-invasive temperature measurement, and treatment feedback to ensure therapeutic goals are achieved. In the realm of oncology, management of painful bone metastases is a common and daunting clinical problem. The Insightec ExAblate System has been shown in phase I/II trials for treatment of bone metastases to have an excellent safety profile and high rates of pain response. An international multi-center phase III trial for patients with painful bone metastases or multiple myeloma who are not candidates for radiation therapy is currently open. Patients are randomized 3:1 to MRgFUS or sham treatment with crossover to study treatment allowed for sham failures. The primary study endpoint is assessment of pain control over 3 months following treatment. In addition safety, quality of life, cost effectiveness analysis, and patient perceived clinical benefit are also being assessed. Details of the MRgFUS system, technical and clinical therapeutic parameters, use of real time non-invasive MR thermometry, and examples of patient treatments with use of MRgFUS to treat bone metastases will be discussed. New directions in use of MRgFUS including an update on development of a new mobile applicator and integration of MRgFUS in multimodality oncologic care will also be presented.