MR-Guided Focused Ultrasound Relieves Pain from Bone Metastases

Physicians are evaluating new ways to use magnetic resonance imaging (MRI) and ultrasound to relieve some of the extreme pain resulting from cancer that has metastasized to the bones.

"Bone metastases are one of the most common causes of pain for cancer patients," said Dr. King Li, chair of the department of radiology at the Methodist Hospital (Houston, TX, USA) and lead investigator for the trial. "Unfortunately, current treatments to relieve this intense pain are very limited."

Typical painkilling or palliative treatment includes invasive surgery that many late-stage cancer patients cannot tolerate, radiation that damages more tissue than necessary, or nerve ablation. In this study, MRI technology was used to visualize the patient's anatomy and then aims focused ultrasound waves at the targeted tissue, using low-level heat to ablate, or destroy it, reducing or eliminating the pain. This new method of using MR-guided focused ultrasound (MRgFUS) may provide a completely non-invasive way to relieve pain, according to Dr. Li.

In earlier clinical studies performed in Europe, most of the patients reported pain relief within days of treatment. "This is an important trial because 90% of patients with a progressive form of breast cancer have bone metastases, and almost all patients with metastatic prostate cancer have tumors that spread to the bones," Dr. Li said.

MRI scanning allows the clinician to monitor and continuously modify the treatment in real time. Due to inherent structural characteristics of the bone tissue, it is possible to use a low level of heat and achieve the desired effect, while minimizing damage to adjacent tissue.

The U.S. Food and Drug Administration (FDA) approved this technology, MRgFUS, to treat uterine fibroids in 2004. This same technology has shown promising effectiveness and safety results in pain-palliation feasibility studies in patients who have in-bone metastases, and researchers hope to validate those results though this larger investigational trial.

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