Focused Ultrasound Surgery Foundation

Funded project will develop temperature measuring techniques for treating breast and liver cancer with MR-guided focused ultrasound

Nick Todd, Ph.D. is the Foundation’s newest Research Award recipient

Nick Todd, Ph.D., and his colleagues at the University of Utah in Salt Lake City and the University of Geneva in Switzerland thrive on tackling difficult technical problems. Currently, they are developing MR temperature measuring techniques with the aim of overcoming the unique challenges of imaging the breast. Ultimately, their goal is to develop new, site-specific MR-guided focused ultrasound treatments for breast and liver cancer.

Todd, a post-doctoral researcher in the UU Department of Radiology, recently received a $100,000 Research Award from the Focused Ultrasound Surgery Foundation. Entitled, “Robust MR Thermometry for MRgHIFU in Breast and Liver: Joint Research between University of Utah and University of Geneva,” his project involves the development of temperature measuring techniques that accelerate data acquisition speed and are robust in the presence of motion.

Todd’s co-investigators are Dennis Parker, Ph.D., Professor of Radiology at UU and Rares Salomir, Ph.D., a research scientist at the University of Geneva. He describes details of the group’s research below.

Q. What prompted your interest in performing this research?

Our group has a four-year R01 grant from the NIH to develop a breast specific MR-guided high intensity focused ultrasound system. One of the challenges in this project is to develop MR temperature measurement techniques that overcome the unique set of problems posed by imaging in the breast. The solution will have to be able to measure temperature changes in adipose tissues, be robust to motion-related errors, and be able to image a large volume with high spatial and temporal resolution. We have submitted a separate proposal to the NIH to tackle the problem of measuring temperature changes in adipose tissues and the work to be done in this project takes on the remaining challenges of motion and volumetric imaging.

The research is interesting to us because it allows us to investigate a number of difficult problems regarding MR temperature measurements, and the results will be directly applicable to our larger goal of developing a breast specific MRgHIFU system.

Q. How could the temperature measurement techniques you are investigating accelerate the development of MR-guided FUS treatments for breast and liver tumors?

A lot of excellent work has been done in the past 10 to 15 years on MR thermometry, allowing non-invasive thermal therapies to be partially monitored and controlled in real time.

In our view, a few obstacles still need to be overcome before MR thermometry can provide the reliable and comprehensive monitoring of heat deposition that clinical applications require. These include measuring temperature changes in adipose tissues, robust handling of motion, and larger volume coverage at acceptable spatial and temporal resolution. If successful, the work done in this project will help to overcome the second and third of these challenges.

We are focusing on implementing our methods in the breast and liver but the techniques developed will be applicable to any organ.

Q.  Why is it important for these new techniques to be robust to motion-related errors?

Physiological motion, for example due to breathing or cardiac function, cannot be avoided during MRgHIFU treatments in certain organs. Image artifacts and misalignment will cause temperature errors when objects inside the imaging field of view are moving. And changes in the local magnetic field will cause temperature errors when objects outside of the imaging field of view are moving. Imaging in the liver is an example of the first type of motion-related error, and imaging in the breast is an example of the second type. If not corrected, these effects can lead to temperature measurement errors of 5°C to 10°C.

Q.  How could your findings be useful in developing MR-guided FUS treatments for other areas of the body?

The problems of motion detection and correction and of volumetric imaging that we are working on would be beneficial to all MRgHIFU treatments.  Motion can be a problem in a number of organs, and even in locations where physiological motion is not occurring, inadvertent patient motion can happen and must be detected. Additionally, monitoring temperature over a larger volume would be desirable for all applications.

Q.  Please describe the key steps of your research project and the specific roles being played by the University of Utah and the University of Geneva.

The research will progress in two phases.

In the first phase, we are testing novel motion detection and correction techniques against the current gold standards. We will implement the reference-less thermometry technique developed by Dr. Salomir at the University of Geneva for breast imaging and compare it to currently used reference-less techniques. We will also test a motion detection technique developed at the University of Utah against currently used techniques.

In the second phase of the project we will take the best reference-less and motion detection techniques and integrate them into the University of Utah’s method for 3-D volumetric imaging. The 3-D technique uses an under-sampled 3-D segmented EPI sequence and incorporates a biophysical model to reconstruct temperature maps with large volume coverage, good spatial resolution and high temporal resolution.

Q.  How will this research project tie-in to any other MR-guided FUS research being performed at UU or Geneva?

As mentioned above, this project will directly benefit the University of Utah’s NIH R01 grant for developing a breast-specific MR-guided HIFU system. It will also strengthen two NIH proposals that are now in review, and will lead to future proposals for additional research and collaborations with Geneva and other groups.

The HIFU research team at the University of Utah

Q.  How important to achieving your research goals is the research award received from the FUS Foundation?

The support that we have received from the FUS Foundation is critical to achieving our goals. In the short term, it has allowed the principal investigator, Nick Todd, to remain at the Utah Center for Advanced Imaging Research (UCAIR) as a postdoctoral research associate; will fund data acquisition for this project; will allow for travel between the University of Utah and the University of Geneva to facilitate the exchange of ideas and techniques; and will allow the investigators to present their findings at major scientific meetings.  In the longer term, we plan to use the results of this project to help with future applications for funding and intend to develop the relationship between the University of Utah and University of Geneva into a longstanding collaboration.

Q.  What other thoughts, insights or observations would you like to add?

We greatly appreciate the support from the FUS Foundation.  The peer review process is excellent and provides good feedback during the application process, and the funding is a key component of building a broad-based FUS research program.

Researchers are using new generation of MR-guided focused ultrasound equipment to treat patients with uterine fibroids and pain from metastatic bone tumors.

Paul Read, M.D., of UVA’s Department of Radiation Oncology, is principal investigator for two clinical trials related to pain resulting from metastatic bone tumors.

Dedicated in September 2009, the Foundation-sponsored Focused Ultrasound Center of Excellence at the University of Virginia Health System in Charlottesville has taken the first steps in building a robust, multi-disciplinary clinical trial program.

Recently launched, the center’s first clinical trial is a pivotal (Phase 3) study investigating the safety and efficacy of MR-guided focused ultrasound treatment for pain associated with metastatic bone tumors. Typically, pivotal studies support the submission of a premarket approval (PMA) application to the FDA for a new device or a new use of that device. In this case, research is supporting a new use of Insightec’s ExAblate 2000, which received FDA approval for the treatment of uterine fibroids in 2004.

The UVA center will begin two more clinical trials this summer. One will be a feasibility (pilot) study of the safety and initial efficacy of the new ExAblate 2100 Conformal Bone System in treating pain resulting from metastatic bone tumors. UVA will be one of two sites conducting this study, which is expected to enroll a total of 50 patients.

The second study will evaluate the safety of the ExAblate 2100 Uterine Fibroid V2 System in treating symptomatic uterine fibroids.

The studies are being funded by InSightec of Triat Carmel, Israel, manufacturer of ExAblate systems.

Alan Matsumoto,M.D., chair of UVA’s Department of Radiology, will be principal investigator of a clinical trial of a new generation ExAblate system for the treatment of uterine fibroids.

Now underway: