Remember Isaac Asimov’s “Fantastic Journey,” in which a medical team traveling in a microscopic submarine was injected into a man’s body, broke up a blood clot and was discharged inside a teardrop? A GI exam that sounds remarkably similar could be coming your way soon.
Capsule imaging, as its developers term it, begins when a patient swallows a small capsule — one half of an inch wide by 1 1/2 inches long — that’s packed with microelectronics, including a minuscule color video camera, transmitter and antenna. The capsule goes to work snapping two photographs a second of everything it encounters in the digestive tract until its revolutionary mini-battery runs out about five hours later. During that time, the patient wears an array of sensors on her body and a recorder the size of a Walkman on her hip as she goes about her normal activities.
So what happens to the capsule? It runs its course and is expelled naturally in about six to 10 hours. The capsule (which has yet to be submitted to the FDA) is “easily swallowed” and excreted from the body “without difficulty” says it’s maker, Given Imaging, which believes single-use will be the application of choice for the intimate machine.
Once the study is complete, the recorder’s contents are downloaded to a computer workstation and processed using software that condenses eight hours of filming into a 30-minute video clip. The software also creates a diagram that maps the position of the capsule as it passes through the small intestine, allowing a physician to correlate the image he sees with the location of the capsule.
This rival to endoscopy, enteroscopy and GI X-ray studies may be better than its counterparts when it comes to imaging the evasive small intestine — researchers say it can even spot polyps smaller than one-tenth of a millimeter in size. Future-generation capsules will be designed to image the rest of the upper GI tract and the large intestine; and further down the line, capsules under investigation today may deliver chemotherapy or laser treatments.
Of course, looking from the inside out is not a unique imaging method. Amazing images can be obtained with intraluminal catheters, endovaginal ultrasound probes and the like. What is unique to capsule imaging is that the patient does not feel the exam, in great contrast to endoscopy and colonoscopy, and that hard-to-reach nooks and crannies of the small intestine can be revealed with ease. Also, images are taped, downloaded and condensed automatically, without the need for technologist, in an easy-to-view video clip. Yet for now, the capsule is strictly for diagnostic use and can’t be used for intervention, a crucial element of endoscopy and angiography.
My gut feeling? We’ll see more of capsule endoscopy. Depending on its real-life resolution and diagnostic value, it may perhaps rival such purely diagnostic imaging procedures as virtual colonoscopy for patients at low risk of colon cancer, particularly for patients who desire a less invasive alternative.
If nothing else, it breathes life into the old saw, “Take two aspirins and call me in the morning.” The new twist? “Take one capsule and we’ll download the images in the morning!”
Mary C. Tierney, Editor
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