A magnet makes "travel" through stomach and intestines possible via capsule endoscopy

It is really a very "fine" thing: Instead of a relatively thick endoscope, patients now only need to swallow a very small capsule containing two tiny cameras that provide clear images of the interior of the stomach and intestines. Capsule endoscopy is not new. However, technical advances now even make it possible to move the capsule where it is supposed to go - controlled and manipulated by magnetic force. A particularly sophisticated model is a capsule that moves on its own "two feet". Today's state-of-the-art diagnostics in digestive tract imaging and what could be routine in the future is once again the topic at MEDICA 211, the world's largest medical trade fair to be held in Düsseldorf, Germany (November 16 -19, 2011) with over 4,500 exhibitors from 60 countries.

Capsule endoscopy can be used in all diseases of the small intestine in which conventional methods are unable or insufficient to shed any light. Private lecturer Dr. Jutta Keller of the medical clinic at the Israeli Hospital in Hamburg says that evidence of the sources of bleeding in the small intestine remains the most important indication for the method. Based on a resolution of the Joint Federal Commission of 2010, with this indication capsule endoscopy is now paid for by the German health care system. The method is recommended and applied, amongst others, in cases of suspected Crohn's disease in the small intestine, complicated sprue and when other tumours of the small intestine are suspected. In addition, says Dr. Keller, there are systems for examining the oesophagus and colon, the limits of whose clinical uses are not yet clear. Capsule diagnostics is not indicated for passage disorders of the gastrointestinal tract. Nor should it be used on patients with pacemakers, those with a history of multiple abdominal operations, and pregnant women. Obviously the method cannot yet completely replace conventional endoscopy of the stomach and colon. One reason: Biopsies are not possible. According to the gastroenterologist, one of the greatest disadvantages of capsule endoscopy to date has been the lack of controllability of the capsules. For that reason, new and different systems have been developed or are currently in the development phase.

Guiding hand-held magnets: relatively simple but nevertheless effective

The most advanced systems are controlled by means of magnetic forces. This requires a capsule made of magnetic material and an exterior magnetic field. One option, for example, is control by means of a hand-held magnet. Such a system was developed in a European research project (NEMO: nano based capsule-endoscopy with molecular imaging and optical biopsy). According to Dr. Keller, the system is based on a hand-held magnet developed by the Fraunhofer Institute in St. Ingbert and a modified capsule endoscope developed by the Israeli company Given Imaging Ltd., a leading producer of capsule endoscopes. Initial clinical trials with the hand-held magnet system were quite successful, says Keller. A targeted and comprehensive examination of specific structures was successful in most subjects, most of the mucosal lining of the stomach could be displayed.

Electromagnetic manoeuvring: as reliable as conventional endoscopy

Siemens and Olympus, both exhibitors at MEDICA 2011, have jointly developed a further system: MGCE - magnetically guided capsule endoscopy. The magnetic capsule (length 31 mm, diameter 11 mm) can be remotely navigated through the stomach by means of a joystick. The capsule with two cameras and a permanent magnet takes four pictures per second; they are then transferred wirelessly to an image processing system and can be viewed immediately. The results of a first study were presented and verify that this method works. Of the more than 50 people who were examined, a total of 30 showed pathological changes in the stomach. Of those, 14 were discovered using the capsule as well as a conventional gastroscope, ten with the capsule only, and six with the gastroscope only. "In gastrointestinal examinations, the magnetically controlled capsule produces results that are as reliable as those obtained by conventional endoscopy. However, stomach examinations using the capsule are more comfortable," concludes Studies Director Dr. Jean-Francois Rey. Since the procedure requires practise, Siemens Healthcare has developed a so-called stomach simulator. It contains an anatomically accurate model of the stomach. Every possible capsule manoeuvre is simulated. The simulator reproduces the video image of the capsule and displays the same navigation information available to doctors doing a real examination.

According to Dr. Keller, the results of current studies but, most of all, the technical advances, are "impressive" and promise that clinical capsule endoscopy examination of the stomach will be possible in the future. For this and, presumably, for examinations of the oesophagus and the retroperitoneally (= behind the peritoneum) fixed duodenum, the simple hand-held magnet system could be a "pragmatic, effective and inexpensive solution". It appears to be less suitable for examination of intraperitoneal sections of the intestine because the one-sided magnetic field that is generated will tend to move the mobile loops of the small intestine instead of manoeuvring the capsule longitudinally through the loops of the small intestine. By comparison, a precisely controlled electromagnetic system could manoeuvre a capsule to "float" through the entire gastrointestinal tract. However, the currently available system is "still a long way from achieving these requirements," explains the gastroenterologist from Hamburg.

On eight "feet" through the porcine intestine

Other developments are not yet ready for day-to-day use, says Dr. Keller, for instance VECTOR (Versatile endoscopic capsule for gastrointestinal tumour recognition and therapy), the "video capsule with feet", developed in a further European research project. The aim was a capsule that allows targeted movement through the stomach and intestines. Preliminary data show that an eight-legged capsule can "move through a phantom model of an ex vivo colon". In an in vivo porcine intestine, the capsule "automatically moved a limited distance (15 cm)". However, this model did not have any control mechanisms. In addition, attempts are being made to manoeuvre capsule endoscopes through the gastrointestinal tract by means of electrical stimulation. Electric pulses emitted from the capsule to the gastrointestinal wall trigger a contraction of the muscles in front of or behind the capsule. In this way, the capsule is moved in an oral or aboral direction. Systems such as this could be especially suitable for examinations of the oesophagus and small intestine.

The further technical development of capsule endoscopy is, of course, not limited to capsule navigation, emphasizes the Hamburg gastroenterologist Dr. Ingo Steinbrück. Battery power, visual range and image quality, amongst other things, were and are still being developed further. These developments aim to "enhance diagnostic sensitivity, optimize energy consumption, shorten the waiting time for findings and increase acceptance by patients". One of the most important objectives for gastroenterologists remains intestinal cancer screening at home.

Not only is MEDICA 2011 showcasing state of the art gastrointestinal diagnostics and therapy in terms of imaging systems such as the respective endoscopes, but the MEDICA Congress will include the event "Detection of early-stage lesions in the gastrointestinal tract" (no. 227) headed by Prof. Dr. Dieter Häussinger on November 17 at the Congress Center Düsseldorf (CCD.South).

Exhibitors of technologies for gastrointestinal diagnostics and endoscopic procedures are listed online under "Companies & Products" at http://www.medica-tradefair.com. A program overview of the MEDICA Congress is also posted on this website.

Author: Dr. Thomas Kron, Freelance Medical Journalist