MR Guided Focused Ultrasound vs Radiotherapy for Palliative Pain Tx in Bone Metastases

This is a prospective, single-center, randomized study directly comparing outcomes after MR guided high intensity focused ultrasound (MR HIFU) or external beam radiation therapy (EBRT) treatment of painful bone metastases.

The primary purpose of this study is to see if MR guided high intensity focused ultrasound (MR-HIFU) treats bone pain faster than the standard radiation therapy (External beam radiation therapy: EBRT) and to evaluate the patient's pain experience 14 days after completion of the treatment. The secondary purpose is to evaluate the outcomes of the pain, side effects, and quality of life and survival in the first 6 months after treatment.

Eligibility Criteria:
Inclusion Criteria:

1. Age ≥ 18 years
2. Painful metastatic bone lesions, with NRS \> 4 documented at screening visit
3. Pain from target lesion is distinguishable from other lesions\*
4. Target lesion lovation is accessible for MR-HIFU and EBRT\*\*
5. Target lesion is visible om MR or CT imaging obtained \< 3 months prior to screening, with a maximum diameter of 8 cm.
6. Reasonable performance score (KPS \> 50% or ECOG \<3)
7. Life expectancy \> 3 months as determined by the study PI or referring oncologist
8. Ability to understand and the willingness to personally sign the written IRB-approved informed consent document

   * Solitary painful metastatic bone lesion or multiple metastatic lesions with one predominantly painful target lesion (≥2 points higher pain score than other lesions).

     * e.g.: Extremities, pelvis (os pubis, os ilium, os ischium, sacrum, acetabulum), shoulders, in selected cases ribs and sternum

Exclusion Criteria:

1. Previous surgery, radiation, HIFU, or other local therapy on the target location
2. Neurological symptoms due to nerve involvement of target lesion
3. Need for surgery of targeted location due to (impending) pathological fracture
4. Unavoidable critical structures or dense tissues in target area\*
5. Curative intention of treatment plan
6. Patients with contraindication for MR imaging such as implanted metallic devices that are not MRI - safe, size limitations, claustrophobia, etc.
7. Patients with known intolerance or allergy to MR contrast agent (gadolinium chelates) including advanced kidney disease (GFR \<30mL/min/1.73 m\^2) or on dialysis
8. Pregnant and nursing patients will be excluded from the study because of a contraindication to administering MRI contrast agents to these patients
9. Patients unable to receive general anesthesia, as determinded by anesthesiologist, study PI or referring oncologist
10. Individuals who are not able or willing to tolerate the required prolonged stationary position during treatment (can be up to 4 hrs of total table time) via self report
11. Participant enrolled in another clinical interventional study related to bone metastases treatment or pain relief treatment
12. Clinically relevant medical history or physical findings that could interfere with the patient's safety as judged by the treating physician

    * as judged by the operator. e.g.: nerve bundles, skin, extensive scarring, non-targeted bones, air (e.g. hollow viscera), (external) fixation device