Diagnosing gastrointestinal disorders is an uncomfortable process. It might involve sticking a long tube with a camera attached down a patient’s throat, or inserting a small catheter through a patient’s nostril.
A team of researchers from the Massachusetts Institute of Technology, the California Institute of Technology, and New York University, looking to explore more comfortable options, has designed an ingestible device that doctors can monitor as it moves through the GI tract.
In a paper published by Nature Electronics on Monday, the researchers lay out their case for using their ingestible device in diagnosing GI disorders like constipation or acid reflux. In tests on pigs, the researchers proved that the device’s location measurements are similarly reliable to those of an X-ray. The hope is the device will allow doctors, armed with the exact location of a GI tract disruption, to better target care — and give patients a diagnostic option they can use at home.
“In principle, one could be evaluated at home and then you could see how something is moving in three dimensions in the GI tract to help map, for example, dysfunction in the rectum,” said researcher Gio Traverso, a GI doctor and engineer at MIT who focused on medical applications of the device.
In recent years, researchers have developed other less invasive diagnostics, like Medtronic’s “SmartPill,” which measures the pH, pressure, transit time, and temperature along the GI tract. Traverso acknowledged those advances, but said such options lack precise data about the capsule’s location. “It’s challenging to monitor how things are moving through the GI tract in real time,” Traverso said.
The device, cocooned by a capsule the width of a quarter, works by detecting a magnetic field generated by a coil outside the body. The approach is inspired by MRIs, but instead of localizing hydrogen atoms to create images, the team localizes the tiny device.
“You can imagine this as a GPS for the body, but we don’t need the triangulation technique, instead you’re using an MRI-inspired technique,” Caltech engineering professor Azita Emami, who has been working on the device for more than five years, said. “This allows us to achieve higher-resolution inside the body.”
The coil might be placed on a jacket for continuous monitoring, or on a toilet for intermittent snapshots. The coil needs to be close enough to the body to generate the magnetic field that enables location measurements. That data would then be fed via Bluetooth to another device, like a hospital computer or a patient’s phone.
The device has not been tested on humans yet. Emami’s lab has previously tested it in mice, and then in environments simulating the inside of the body. The Nature paper describes the device’s performance in pigs, requiring the researchers to build in a larger field of view. Maintaining high accuracy and resolution within a larger anatomy was challenging, Emami said. The researchers also had to extend the device’s battery life, as it needed to function throughout a long and arduous GI tract journey.
The team placed an ingestible sensor inside the pig, and tracked its movement throughout the GI tract using magnetic field-generating coils, which were placed in a chute for the pigs to walk through. The sensor’s measurements aligned with the researchers’ X-ray measurements within a margin of 5 to 10 millimeters. The researchers continued to capture the device’s progress over several days until it had passed through the digestive tract. It still worked upon excretion.
Leslie Chan, a biomedical engineer at Georgia Tech who was not involved in the research, said the paper demonstrates an exciting step forward in noninvasive disease detection. Her lab monitors biochemical changes in the GI tract, and this device could someday help her more accurately detect these changes. “This is, from our perspective, a really useful potential tool to monitor for GI disease,” Chan said.
One area the researchers might improve upon, Chan said, is the placement of the coils. Patients may have different preferences as to where they want the coils placed; a backpack, for example, might be impractical to carry around constantly. “These sorts of logistics need to be defined, and it might vary from patient to patient,” Chan said.
The immediate next step is seeing how the device performs in people. Then, Traverso said, the team will be able to see how it can help doctors guide potential drug or diet-related therapies. Emami would like to eventually use the device for targeted drug delivery or precision surgery. Chan is eager to see what functionality they add to the device, with a particular interest in the GI tract’s biochemical changes.