The innumerable divisions of the bronchi in the lungs can baffle researchers in search of tumors, but soon, lung specialists may be able to navigate accurately inside the airways using GPS-type technology say researchers with SINTEF, the largest independent research organization in Scandinavia. A team of physicians and engineers using a set of CAT scans linked with a new diagnostic tool can enable the medical team to locate a tumor with greater precision. They say that the technique could increase the possibility of a more accurate and rapid diagnosis, offering the patient appropriate treatment sooner.
The navigation system developed by SINTEF researchers and engineers and pulmonologists at St. Olav’s Hospital provides 3D images of the route into the patient’s lungs and airways, to allow surgeons to locate a within a few millimeters range.
Using a specialized bronchoscope, a pencil-thin flexible tube equipped with a camera and a small forceps to take tissue samples, as well as a position sensor at the tool-tip, allows the surgeons to identify the location of the bronchoscope tip in the tissue and bronchi. At the same time, the screen shows them a 3D pre-recorded image of the total “lungscape,” so that they always know exactly where they are.
One of the things that makes this a difficult task is that the lungs are constantly moving through the respiratory cycle; the movements caused by the patient breathing in and out, and those of the bronchoscope itself, mean that the tissue is changing shape and location during the examination. This means that the equipment not only has to take pictures under way but also has to relate these to the CAT images that have already been made.
In practice, the GPS system operates in such a way that the CAT scan is first adapted to the patient, via a registration procedure in which the computer is told that the CAT images of the internal organs must match those of the actual physical patient. The position sensor then registers the movements and position of the sensor that sits at the tip of the bronchoscope. The system can then show where the bronchoscope is located on the CAT images. The sensor is less than 1 mm in diameter, and a weak magnetic field that envelops the patient registers the location of the sensor in three dimensions in real-time. Both its direction and position inside the patient are displayed on a screen, so that the doctor always knows where the equipment is.