Diagnostic Imaging
February 2003

OVERREAD

CT imaging loses to camera pill in small intestine

An ingestible camera that seemed like a novelty a couple of years ago has surpassed more established modalities in imaging the elusive anatomy of the small intestine.

A camera rig the size of a large vitamin pill appears to be more effective in finding small intestine abnormalities than barium studies or CT, according to a report presented at the RSNA meeting. Capsule endoscopy (CE) detected abnormalities in 57% of patients studied, while barium studies and CT found abnormalities in only 9%.

The CE pill contains a camera, light source, transmitter, and battery. It takes two pictures per second over eight hours as it tumbles through the digestive system.

Data are transmitted to external sensors, which record the information for further study. Patients wear the sensors on a belt. The capsule safely exits the body through normal digestion.

Previous work has documented the feasibility of such a modality, but this study is one of the first to compare the camera pill with traditional bowel imaging modalities.

CE has a number of advantages over traditional diagnostic methods, said Dr. Amy Hara, a diagnostic radiologist at the Mayo Clinic in Scottsdale, AZ. The technology is noninvasive, requires no medication, emits no radiation, and provides a better evaluation of problems.

In a study of 42 subjects who received both CE and barium studies, CE found small bowel disease in 23 patients, while barium detected disease in just one. Among another 23 patients, CE revealed disease in 15 patients, compared with just five patients with CT.

CE proved to be the most effective technology for detecting arteriovenous malformations, which can lead to bleeding in the bowels. Neither CT nor barium studies detected any incidences of AVM, while CE uncovered 16 cases.

CE also identified ulcers and tumors in the small intestine. The technique can be especially effective in people with Crohn's disease, a condition that most often affects the lower portion of the small intestine.

There are limits to CE's effectiveness, however. The camera cannot be aimed, so it may miss lesions if it is pointed the wrong way as it moves though the intestines. It is also ineffective at pinpointing the location or size of an abnormality, and it cannot gauge the effect of an abnormality on other organs.

These limitations can be addressed by combining CE and CT imaging, Hara said.

"CT provides a very good global view of the body, and specialized parameters can be employed to localize lesions," she said.