MRI-Guided Focused Ultrasound Effective Option for Bone Metastasis Pain Relief

MRI-guided focused ultrasound (US) can be a highly effective tool for pain relief from bone metastases, particularly among women, according to new research.

In a study published on Aug. 26 in Investigative Radiology, researchers from Stanford University shared their results that showed this strategy can be a good option for localized pain relief treatment. In particular, they determined that three variables contributed most of the reduction – energy density on the bone surface (EDBS), the presence of post-procedural periosteal devascularization, and being female.

Currently, radiation therapy is most commonly used for relieving localized metastatic bone pain, and it has a good response rate at 59 percent. But, subsequent treatments expose patients to additional radiation, potentially setting them up for future complications. To help control that exposure, MRI-guided focused US has been gaining popularity.

“MRI-guided focused ultrasound is an emerging treatment that has proven effective for the treatment of painful bone metastases,” wrote the team, led by Rachel Bitton, Ph.D., a senior research scientist.

To determine how well this treatment works, the team conducted a randomized sham-controlled multi-center trial from July 2008 to May 2012 that included 99 patients with an average age of 59. All patients had tumors that were painful and had targeted bone metastases that were visible by non-contrast MRI located at least 1 cm from the skin or any major nerve bundles.

The team captured non-contrast CT scans prior to treatment. In addition, they obtained T2-weighed and pre-gadolinium and post-gadolinium contrast-enhanced T1-weighted fat-suppressed images on a 1.5T or 3T MRI. Those MRI images were taken before, during, and after three months post-treatment. From the MRI images, the team pinpointed a feature they dubbed black band (BB), a devascularization of the periosteum around the tumor. BB was a hypointensity along the periosteum, they said, that was greater than or equip to 5 mm wide and at least 75 percent more hypointense than skeletal muscle tissue.

Based on the comparison of images between groups and patient response, Bitton’s team determined that patients in the active treatment group had a 64-percent response rate to the therapy at three months while only 20 percent of the sham group experienced pain relief. The response was even higher among women who also had EDBS and BB – they had a 93-percent response rate. Patients who had none of those factors experiences a 0-percent response rate.

“The results of our study suggest that, when increasing EDBS is used during treatment and when BB+ is present immediately after treatment, MRI-guided focused US achieves the desired response of meaningful pain relief and should be offered to patients not responding to radiation therapy,” the team concluded. “In particular, high EDBS can be implemented in the design of a treatment plan more likely to results in durable pain relief.”

Additional study is needed to for a greater understanding of the role MRI-guided focused US can play in treating bone metastasis pain.