TMC PULSE

t m c » p u l s e | m ay 2 0 1 7 30 30 Small Robots, Big Jobs Researchers hope to harness MRI technology for noninvasive treatments B y C h r i s t i n e H a l l Solutions: TMC Innovations O ver the years, surgeries have shifted from inva- sive to minimally invasive—from cutting through the breastbone to get to the heart to inserting cathe- ters in the leg and snaking them up the torso to gain access to the heart. But Aaron Becker, Ph.D., who hopes to deploy millimeter-sized robots in the body's venous system to deliver drugs or break up harmful masses and growths, thinks surgeries could go even smaller. "Ideally, we want to shrink down the surgery," said Becker, assistant professor of electrical and computer engineering at the University of Houston. "Essentially, we are making a probe, but without the tether." Becker and a team that includes Nikolaos Tsekos, Ph.D., associate professor of computer science and director of the Medical Robotics Laboratory at UH, and Dipan J. Shah, M.D., a cardiologist and director of cardiovascular MRI at Houston Methodist Hospital, are developing control algorithms, imaging technology, ultrafast computational methods and human-machine immersion methods by harness- ing the force from a magnetic resonance imaging (MRI) scanner. The big idea is to use MRI, traditionally employed for noninvasive diagnosis, for noninvasive treatment. Becker is principal investigator for a $608,000 Synergy Award from the National Science Foundation (NSF) to develop robot prototypes. The current models measure as much as two cen- timeters, but Becker said the goal is to design robots that range from 0.5 millimeters to two millimeters. As a point of comparison, the average human hair is about 0.08 millimeters wide. "MRI is a wonderful methodology that gives you sight of soft tissue," he said. "We can use the MRI to do two things at once: Steer the robot through blood ves- sels in real time without penetrating tumors or other tissue, and see deep into the tissue." One example Becker likes to use is a cyst in the ventricular system inside the brain. A cyst in that location can block the flow of cerebral spinal fluid, which helps circulate chemicals and nutrients filtered from the brain, cushions the brain inside the skull and removes waste from the brain. Some of the robots, which look like small capsules, are outfitted with a self-assembling surgical tool, like a Gauss gun. Using the MRI, one robot with the tool can be steered up to the cyst, and then another robot can be pushed into the first one to break up the cyst. "If we can get the first one into the right spot, we can steer the others toward there," he said. "We are working on the miniaturization process through the NSF. We have some fun designs that will be neutrally buoyant [they don't sink or float in the liquid] to move through the body's fluids." Up next for the researchers is improving MRIs. Current scans have a lag time that doesn't allow for real-time control of the tiny robots. Becker and his team hope to speed up the scan time to a matter of milliseconds. Ultimately, the goal is to steer multiple miniature robots through the body at the same time. One robot could target a single lesion, while another could deliver chemotherapy or another type of intervention during late-stage cancer, Becker said. "Targeting delivery with dozens of microsurgeons is my goal," he said. Aaron Becker, Ph.D., assistant professor of electrical and computer engineering at the University of Houston, is currently testing robots of various sizes to see how they move around the body using MRI scanners. Credit: Carlos Landa, UH Cullen College of Engineering Dipan J. Shah, M.D., a cardiologist at Houston Methodist Hospital, is developing the MRI technology on the project.

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