MRI Confirms Focused Ultrasound Treatment for Facet Joint Pain
Lower back pain can become a chronic (ongoing) problem, affecting all aspects of a person’s day. In fact, it’s one of the leading causes of missing work. It is estimated that 5-15% of cases are due to worn out cartilage of the small spinal joints called facet joints. When cartilage becomes thin, or altogether worn away, not only is there pain from bone rubbing against bone, but the compressed space also results in nerve pain. In turn, nerve pain can radiate from the lower spine down toward the backs of the legs, and outward toward the hips. Ouch!
A new treatment called MRI-guided Focused Ultrasound (MRgFUS) relieves facet joint pain by deadening the painful nerves. Unlike injections of medication or insertion of radiofrequency probes, MRgFUS is noninvasive. Instead of needles or probes, many “beams” of ultrasound are simultaneously aimed precisely at the facet joint and nerve. When these beams converge on the target for several seconds at a time, they create enough heat to destroy the nerve tissue. Not only does the MRI identify the target, it also tracks tissue changes during the treatment by providing instant image-based feedback on temperature changes using special software called thermometry.
Confirming the treatment effect
A research team from the University of California/San Francisco raised the question of how well MRI is able to assess the effectiveness of MRgFUS after the treatment. They acknowledge the promise of MRgFUS as a “very safe and effective minimally invasive technique to treat facet joint pain caused by arthritis and other degenerative changes.”1 An essential component of the treatment process is verifying that the target tissue was successfully destroyed.
The way to do so is to use MRI imaging sequences that define characteristics of ablated tissue such as anatomy, density, and absence of blood flow. According to Krug, et al. “…the ideal imaging protocol should have the following two characteristics. First, it should be highly sensitive to acute tissue changes to allow for accurate evaluation of the treatment. Second, it should allow repetitions of the treatment if necessary.”2 The second criterion implies that no contrast agent can be used to assess blood flow, because the presence of the contrast agent rules out performing additional focused ultrasound treatment during the same session if part of the target was missed.
Therefore, the UCSF team tested various combinations of imaging sequences to find the optimal combination, without contrast agent, that would yield the most accurate evaluation of treatment effect. Without going into technical details, they ultimately recommended specific MRI pulse sequences that achieve their dual goal of sensitivity to immediate tissue changes after treatment while keeping the door open for repeat Focused Ultrasound if necessary during the same session.
MRgFUS at the Sperling Medical Group
The Sperling Medical Group offers MRgFUS to treat facet joint arthritis. Our state-of-the-art 3 Tesla magnet is integrated with a focused ultrasound delivery system and the advanced software to pinpoint the source of the pain, plan MRgFUS, and use thermometry to assure accuracy and effectiveness. In addition, our experienced radiologists provide correct imaging protocols and are experts at interpreting the scans before, during and after treatment.
For more information about this safe and successful treatment for facet joint pain, contact the Sperling Medical Group.
1Krug R, Do L, Rieke V, Wilson MW, Saeed M. Evaluation of MRI protocols for the assessment of lumbar facet joints after MR-guided focused ultrasound treatment. J Ther Ultrasound. 2016 Apr 6;4:14.
- Facet Pain