Kim Butts Pauly's Lab

MRgFUS Overview

Investigators throughout the world are currently applying MR-guided focused ultrasound (MRgFUS) for non-invasive treatments of a variety of diseases and disorders. Typically, focused ultrasound uses a large area ultrasound transducer array outside the body, focused either geometrically or electronically, to a point within the body. The amplification provided by focusing (which can be on the order of 1000-fold) provides the means to generate significant ultrasound intensities deep within the body, with insignificant ultrasound intensities in the intervening tissue. We are working with InSightec who makes a variety of systems that are integrated into General Electric MR-scanners. For brain applications, InSightec has a hemisphere array, which is currently in clinical trials.

Fus

Magnetic resonance imaging provides the means to target the ultrasound beam to the tissue of interest, monitor the therapy with MR thermometry, and assess the treatment through the variety of contrast mechanisms available with MRI. While some targeting and assessment could alternatively be done with ultrasound, MRI is the only imaging modality that provides quantitative temperature mapping over a wide range of temperatures. The key to MR thermometry is the change in hydrogen bonding with temperature, which results in a change in the electron shielding of water protons, and changes the resonant frequency by approximately -0.01 ppm/°C. In practice, temperature images are calculated from the change in phase on gradient echo images.

Temperature

 

Clinical Trials

There are several clinical applications of MRgFUS in the body. The first is the ablation of uterine fibroids. This application has regulatory approval in a number of countries, including by the FDA in the United States. With 24 month follow-up, MRgFUS provides a durable relief of symptoms. Stanford provides MRgFUS for uterine fibroids.

** Stanford's MRgFUS Treatment for Uterine Fibroids**


The palliation of painful bone metastases with MRgFUS is another exciting application. The ultrasound beam destroys the periosteum lining the bone, resulting in decreased pain. This treatment has also been approved by the FDA. Stanford provides MRgFUS for the palliation of painful bone metastases.

** Stanford's MRgFUS Treatment for Painful Bone Metastases**

Stanford is also participating in a clinical trial of MRgFUS for essential tremor.


** Stanford's MRgFUS Treatment for Essential Tremor **

MRgFUS Research

Our lab is doing research in many areas of MRgFUS. Technical areas of research to support clinical applications include improved thermometry and monitoring (especially in moving organs), focal spot visualization, MR-based phase aberration correction, and workflow improvements. In addition, basic science research in ultrasound-based neuromodulation is showing that ultrasound can modulate neuronal firing. More details on our research can be found in these webpages. The future of MRgFUS holds new non-invasive treatments for a variety of diseases and disorders and also an exciting array of technical and scientific innovations.

Footer Links:

http://stanfordhealthcare.org/medical-treatments/m/mr-guided-focused-ultrasound/procedures/uterine-fibroids.html