DISCOVER Vol. 21 No. 7 (July 2000)
Table of Contents
Lights, Camera, Swallow!
Open wide... and say cheese! A camera in a pill may be coming soon to an intestine near you.
By Eric Powell
Modern medicine may no longer need to slice people open to see what's going on inside, but it still has a ways to go. For decades doctors have used cumbersome and painful procedures to peer inside the gastrointestinal tract. Now the bowels may finally be ready for their close-up. Scientists at Given Imaging in Israel have developed a camera in a pill that promises to let us see the guts as they've never been seen before.
Snapshots from the voyage of the camera-in-a pill. From top to bottom, the esophagus, stomach, three spots in the small intestine and finally the large intestine.
The plastic capsule, equipped with a tiny solid-state camera, transmits video of the digestive system to the outside world, allowing gastroenterologists to examine ailing intestines before they decide to operate. All that's asked of patients is that they swallow the pill, roughly an inch long. "It went down easy, like an aspirin," says Dr. Paul Swain of the Royal London Hospital, one of the developers of the pill and also a volunteer in the human trials. "It wasn't a brave thing; it was actually one of the more enjoyable experiences in a patient trial that I've ever had. We didn't feel a thing."
The stomach and intestines take it from there. The contractions of the gastrointestinal tract propel the pill and also act as a natural squeegie, wiping the camera's transparent dome clean and ensuring clear images. Powered by a battery that emits a mere 3 milliwatts, the capsule transmits up to 6 hours of video, after which it exits the body in the usual digestive fashion. The strength of the signal from the pill is also recorded. This indicates its position in the body, and for the first time lets a doctor know precisely what part of the gut he's looking at.
The patients don't sense their examination-in-progress, in sharp contrast with current methods. There, long fiber optic cables called endoscopes are inserted through the mouth or nose, and can cause extreme discomfort. Other diagnosis techniques, such as X-rays, force the patient to swallow chemicals to provide contrast, and then only pick up major abnormalities in the intestines.
Once a staple of science fiction, the edible capsule became reality thanks to several advances. The pill's camera, a third of the size of a dime, was developed by Photobit, a California company that produces image sensors first pioneered by NASA's Jet Propulsion Laboratory. The camera is made by a process called CMOS, or complimentary metal oxide semiconductor, that has long been used to create computer chips. Because of its silicon origins, the camera combines a host of functions on one chip, explains Sabrina Kemeny, CEO of Photobit. The pill also contains white LEDs to ensure the camera has light to film by and a radio transmitter to send the video to an outside receiver. The patient wears an antenna and recorder on a belt as they go about their daily routine.
Preliminary human trials in England and Israel have shown that the "M2A" capsule, as Given Imaging has dubbed the pill, successfully navigates the intestine and takes high quality video images. Gastroenterologists are particularly excited by video of the hard-to-reach lower half of the small intestine, previously accessible only by X-ray. More human trials are slated to begin this summer at Mount Sinai Hospital in New York, and, pending FDA approval, the camera in a pill may soon be making stars of lower intestines everywhere.
RELATED WEB SITES:
Given Imaging's website discusses the camera in a pill in detail: http://www.givenimaging.com
Photobit developed the CMOS image sensors used in the capsule. Background on CMOS technology can be found at their website: http://www.photobit.com
"Wireless capsule endoscopy" by Gavriel Iddan, Gavriel Meron, Arkady Glukhovsky and Paul Swain. Nature, 25 May 2000, p 417. See www.nature.com.
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