Friday, January 25, 2013

Pill-sized device provides rapid screening results

Physicians may soon have a new way to screen patients for Barrett’s esophagus, a precancerous condition usually caused by chronic exposure to stomach acid. Researchers at the Wellman Center for Photomedicine at the MGH have developed an imaging system enclosed in a capsule about the size of a multivitamin pill that creates detailed, microscopic images of the esophageal wall. The system has several advantages over traditional endoscopy.


IMAGING SYSTEM: The inch-long capsule

“This system gives us a convenient way to screen for Barrett’s that doesn’t require patient sedation, a specialized setting and equipment, or a physician who has been trained in endoscopy,” says Gary Tearney, MD, PhD, of the Wellman Center and the MGH Pathology Department, corresponding author of the report published online this month in Nature Medicine. “By showing the three-dimensional, microscopic structure of the esophageal lining, it reveals much more detail than can be seen with even high-resolution endoscopy.”

The new system developed by Tearney and his colleagues calls for a patient to swallow the capsule, which contains optical frequency domain imaging (OFDI) technology – a rapidly rotating laser tip emitting a beam of near-infrared light and sensors to record reflected light. The physicians operating the system, which includes a string-like tether, were able to image the entire esophagus in less than a minute. The study showed a procedure involving four passes – two down the esophagus and two up – could be completed in about six minutes.
A traditional endoscopic examination requires patients to stay in the endoscopy unit for about 90 minutes.


 FLEXIBLE TETHER By manipulating the device, physicians can control the position of the capsule in a patient’s esophagus. 

The detailed microscopic images produced by the OFDI system revealed subsurface structures not easily seen with endoscopy and clearly distinguished the cellular changes that signify Barrett’s esophagus. Study participants who had previously undergone endoscopy indicated they preferred the new procedure.

“The images produced have been some of the best we have seen of the esophagus,” says Tearney. “We originally were concerned that we might miss a lot of data because of the small size of the capsule; but we were surprised to find that, once the pill has been swallowed, it is firmly ‘grasped’ by the esophagus, allowing complete microscopic imaging of the entire wall. Other methods we have tried can compress the esophageal lining, making it difficult to obtain accurate, three-dimensional pictures. The capsule device provides additional key diagnostic information by making it possible to see the surface structure in greater detail.” 

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