A highlight of the FUS Foundation’s 2010 International Symposium on MR-guided Focused Ultrasound was the presence of our Young Investigators, ten early-career scientists selected to present their work during oral or poster sessions. The spirit and enthusiasm of these individuals provided a special spark that energized the entire symposium.
During a recent interview, one of those Young Investigators – Urvi Vyas, PhD – provided an update on her focused ultrasound activities. The excitement and positive expectancy with which she spoke were truly inspirational.
Vyas, who is now a post-doctoral fellow at Stanford University, earned her PhD in bioengineering at the University of Utah. Professionally, her main interests are ultrasound beam propagation and MR-guided focused ultrasound surgery. Like many of the unsung heroes in the field of focused ultrasound, she is working behind the scenes to address technical issues and challenges that will make new patient treatments possible.
After completing her undergraduate degree in bioengineering at Shree Govindram Institute of Technology and Science in India, Vyas joined Utah’s bioengineering program where she helped develop an NIH-funded focused ultrasound system for breast cancer. That project enabled her to learn from three individuals she describes as mentors: ultrasound expert Douglas Christensen, PhD, MR leader Dennis Parker, PhD, and biothermal specialist Robert Roemer, PhD.
“I think this is an exciting field because you need so many people to come together to make a system work. You need temperature measurements. You need the ultrasound to work. You need to control the ultrasound. Not only that, you need to control the heating and so you need somebody that knows the bioheat transfer equation,” Vyas observes.
Focused ultrasound system for the breast
In creating a focused ultrasound system for the breast, the Utah team had to break new ground in a number of areas: measuring temperature in the breast, planning patient treatments and designing a transducer. “Where I came in was the ultrasound part of all of this,” says Vyas.
She worked on developing fast simulations for ultrasound beam propagation. “We went from a time scale of a couple of hours to simulate one beam propagation pattern to a few seconds. This was on a grad student laptop, so this was really exciting. Once we had that working, we could then design patient-specific treatment plans. We’d take an MR image of the patient and then design a treatment plan that would fit this particular patient,” she explains.
After helping to reduce treatment planning time, Vyas got involved in designing an ultrasound transducer for the breast. “We designed various configurations and figured out that the side-shooting transducer would work best for the breast,” she says.
Inverse problem-solving
Her next task was using fast beam propagation simulation to solve an inverse problem. “In the forward problem, I can simulate where the beam is going to be. I can also do the inverse problem. I can see the temperature and figure out what the tissue properties for this particular person are because it’s very hard to measure acoustic properties of a human being without cutting the human being open,” she says.
Solving the inverse problem lead to a first-time in vivo study in which the Utah team demonstrated that the acoustic properties of muscle could be measured noninvasively with focused ultrasound. This work qualified Vyas for the FUS Foundation’s Young Investigator Award and for an award from the Society for Thermal Medicine.
At Stanford, Vyas is working with Kim Butts Pauly, PhD, a leader in MR thermometry. Her energies are now being directed to correcting trans-cranial phase aberration. “When you put the ultrasound beam through the skull, there are a lot of aberrations because of the skull having different thicknesses,” Vyas explains. “The plan is to use the acoustic radiation force imaging and figure out how to better correct these aberrations in the brain.”
Although the clinical applications of this approach have not yet been determined, Vyas hopes it will be widely useful. “I think what we want to do is give the field a very efficient, fast way of doing phase aberration correction and just share it with everybody,” she says.
Vyas is inspired by the thought of patients benefitting from her work. “When you’re in a lab typing code on a computer, you don’t realize what it may lead to,” she says. Attending the FUS Foundation’s recent Brain Workshop gave her a glimpse of the impact her work could have on patients. There, she heard doctors talking about treatment envelopes based on simulations she helped develop. “These treatments are going to be in clinics really soon, and it’s very exciting,” she exclaims.
Written by Ellen C., McKenna