Primary Pain Palliation and Local Tumor Control in Bone Metastases Treated With Magnetic Resonance-Guided Focused Ultrasound

Objectives: The objectives of this study were to evaluate the efficacy in pain management of magnetic resonance (MR)-guided focused ultrasound for the primary treatment of painful bone metastases and to assess its potential for local control of bone metastases. Materials and Methods: This was a prospective, single-arm research study with approval from the institutional review board. Eighteen consecutive patients (female, 8; male, 10; mean [SD] age, 62.7 [11.5] years) with painful bone metastases were enrolled. The patients were examined clinically for pain severity and pain interference in accordance with the Brief Pain Inventory-Quality of Life criteria before and at each follow-up visit. Computed tomography and MR imaging were performed before and at 1 and 3 months after the magnetic resonance-guided focused ultrasound treatment. The nonperfused volume (NPV) was calculated to correlate the extension of the ablated pathological tissue in the responder and nonresponder patients. Results: No treatment-related adverse events were recorded during the study. The evaluation of pain palliation revealed a statistically significant difference between baseline and follow-up values for pain severity and pain interference (P = 0.001, both evaluations). In the evaluation of local tumor control, we observed increased bone density with restoration of cortical borders in 5 of the 18 patients (27.7%). In accordance with the MD Anderson criteria, complete and partial responses were obtained in 2 of the 18 patients (11.1%) and 4 of the 18 patients (22.2%), respectively. Nonperfused volume values ranged between 20% and 93%. Mean NPV values remained substantially stable after the treatment (P = 0.08). There was no difference in the NPV values between the responder and nonresponder patients (46.7% [24.2%] [25%-90%] versus 45% [24.9%] [20%-93%]; P = 0.7). Conclusions: Magnetic resonance-guided focused ultrasound can be safely and effectively used as the primary treatment of pain palliation in patients with bone metastases and has a potential role in local tumor control.