Focused ultrasound appears to be able to selectively destroy liver tumors, new research from an EU project shows.
Preliminary results of this new method, developed as part of the TRANS-FUSIMO EU project, were presented as part of an industry symposium at the European Congress of Radiology March 1-5 in Vienna, Austria.
Although ultrasound is widely used in diagnosis, its application as a form of treatment therapy is relatively new. Highly concentrated ultrasound waves were able to destroy tumor cells and make them harmless. Until now, focused ultrasound has been approved to treat prostate cancer, bone metastasis, and uterine myomas (noncancerous growths of the uterus that often appear during childbearing years).
The important benefits of focused ultrasound are that it is noninvasive, it doesn’t require anesthesia, and it doesn’t cause surgery wounds. However, this method offers limited applicability to treat organs that move with breathing, such as the liver. For this purpose, patients would need to be under anesthesia or be able to hold their breath.
To overcome this limitation, scientists working in the TRANS-FUSIMO EU project, coordinated by the Fraunhofer Institute for Medical Image Computing (MEVIS) in Bremen, Germany, refocused the ultrasound beam to the movement of the liver to selectively target tumor cells while healthy tissue is spared. The scientists now have the fundamental technology to pursue this approach.
During the procedure, the patient lies in an MRI scanner. The scanner will produce an image of the current position of the liver every tenth of a second. The ultrasound transducer, a device containing more than 1,000 small ultrasound transmitters that can be directed to a point as small as a grain of rice, is placed on the patient’s stomach. The ultrasound waves are then targeted at the tumor cells, leading to their destruction. The temperature in the liver and the correct heating of the targets are controlled by the MRI.
“Generating an image of the liver’s position every tenth of a second is not fast enough to reliably direct the ultrasound beam. This is why we developed software that can see into the immediate future and calculate the next position of the treated region,” Sabrina Haase, mathematician at Fraunhoher MEVIS and TRANS-FUSIMO EU project manager, said in a press release.
The software must be able to guarantee real-time performance, with precise targeting of liver tumors while the patient breathes. And, to avoid damaging the ribs, the researchers had to deactivate ultrasound transmitters whose waves might hit the ribs.
“We have completed the technical development phase and have already run preliminary tests,” Haase said. In the tests, focused ultrasound was targeted at a gel model moved by a robotic arm to simulate the liver movement while breathing. The MRI scanner monitored temperature distribution. “The results match our expectations,” Haase added. “Now, we can pursue the next steps.”
The first tests on patients are planned for mid-2018. If successful, in cooperation with an industry partner, medical product certification can be addressed. As a long-term goal, this method shows promise to treat other organs that move with breathing, such as the kidney, pancreas, or lungs.