To navigate catheters through blood vessels and apply stents or remove blood clots, doctors typically rely on X-rays for visualization. That has two downsides: Patients and physicians are exposed to radiation and the two-dimensional imaging can impede precise location of the catheter. Germany’s Fraunhofer Institute for Digital Medicine MEVIS (Bremen) has developed the IntelliCath system to remedy these issues.
|Researchers Torben Pätz and Jan Strehlow demonstrate how physicians using the IntelliCath system can observe positioning of the catheter in the patient.|
The new method uses a catheter equipped with a special optical fiber containing tiny mirrors, explained the institute in a press release. Light passing through the fiber is partially reflected by the mirrors. When the fiber bends, the reflected light changes color, which is then measured by sensors. “The signal from the sensors gives us information about the intensity and direction of the curvature,” explained Dr. Torben Pätz, a mathematician at the institute.
To enable precise navigation through the vascular system, physicians obtain CT or MR images of the patient prior to the procedure. Based on this data, software creates a 3D model of the vessel system and displays it on a monitor. During the endovascular procedure, live data from the fiber navigation is fed into the model, allowing the doctor to see on the monitor how the device is moving through the vascular labyrinth live and in 3D.
Thus far, MEVIS experts have used a prototype to test the method’s feasibility. “We connected several silicone hoses into a curved labyrinth,” said Pätz. “Then, we inserted our device containing an optical fiber into the labyrinth.” On the monitor, the researchers were able to locate the catheter’s position in real time at precision approaching five millimeters. They have already applied for two patents.
Although several medical device companies are working on similar projects, “they expend a great deal of technical effort into trying to reconstruct the shape of the entire catheter, which can be up to two meters long,” said Pätz. “Our algorithm only needs a fraction of the data to localize the catheter in a known vascular system.” As a result, the MEVIS approach promises cost-effective technology without special fibers and measurement systems and is less sensitive to measurement errors than other approaches, said MEVIS.
The next step in the project is to test the IntelliCath system on both a full-body model of the human vascular system and a pig’s lung. The researchers expect to have a prototype suitable for clinical trials ready by next year.
In addition, Pätz and his team are developing acoustic feedback so that doctors won’t have to constantly view the monitor during the procedure. Various audible alerts will signal how far the next vessel junction is and in which direction the catheter should be inserted, for example. “It is similar to a car’s parking assistance system,” explained Pätz, “where you also receive acoustic indications about the distance to the next obstacle.”
IntelliCath is a part of the SAFE project—Software support and assistance systems for minimally invasive neurovascular procedures—which has the goal of supporting physicians by facilitating X-ray navigation during catheter procedures. Project partners Automation in Medicine and Biotechnology at the Fraunhofer Institute for Manufacturing Engineering and Automation IPA are developing an intelligent assistance system to support catheter procedures involving manual as well as automated navigation.
SAFE is a €2.4 million Fraunhofer project that began in April 2017 and will end in September 2020.