No real-time monitoring
According to Stang “Although ablation is becoming increasingly popular, there is still no thermal imaging technology in regular clinical use to monitor these procedures in real time and ensure that the correct thermal dose is delivered the first time”.
In absence of real-time monitoring, surgeons and interventional radiologists rely on the guidance provided by ultrasound, CT, or MRI to perform life-saving operations and a follow-up imaging study is needed to confirm proper treatment. This increases risks, time and costs in the operating room.
“Without real-time monitoring, there is the potential for both under-treatment and over-treatment,” said co-researcher Mahta Moghaddam. “If there is under-treatment, doctors must perform additional rounds of thermal ablation until all of the tumor is destroyed. Each repeat ablation carries increased risk of infection or other complications and takes up more time in the operating room.”
Surrounding healthy tissue are at increased risk of collateral damage, in case of over-treatment. This can be especially dangerous when the tumor is located close to sensitive structures, near a blood vessel or deep in the skull.
“With our technology, however, we can guide the treatment and focus on a very specific area,” Stang said. “A microwave antenna array is placed around the region to be treated, with room left open for the surgeon to insert an ablation probe.”
Giving doctors a live temperature map
During the procedure, microwave signals are continuously transmitted and received into the treatment area. From these signals and information from a prior imaging study, like an MRI, Moghaddam and Stang produce a 3D thermal image of the region in real-time, giving doctors a quantitative temperature map of the region they’re operating on.
“In in vitro experimental validation studies, our system was able to achieve one-degree Celsius accuracy at a refresh rate of one frame per second,” Stang said.
One issue they have to contend with is the resolution of their thermal image is not as high as that of MRI. But Stang sees a world in which this real-time thermal image feed can be overlaid on a high-resolution MRI enabling doctors to precisely deliver the right dose to the right location, without the need for follow-up imaging studies.
For the next phase, their procedure will undergo animal testing later this year, specifically looking at liver cancer with support from the USC Alfred E. Mann Institute for Biomedical Engineering and in collaboration with the USC Keck School of Medicine.
“Assuming we get good results, we may be three to five years away from clinical trials,” said researcher Mahta Moghaddam.
“This time, our environment is the human body and we make maps which are smaller. It’s a microcosm of the larger terrestrial picture.”
For further information click on the link: 10.1109/TBME.2017.2702182