The researchers, from the Wellman Center for Photomedicine, at Massachusetts General Hospital (MGH) and Harvard Medical School, report the study in the 13 January online issue of Nature Medicine.
Screening Tool for Barrett's EsophagusFor their study, the researchers tested the device as a potential screening tool for Barrett's esophagus, a precancerous condition usually caused by repeated exposure to stomach acid.
Barrett's esophagus is uncommon in women, and current recommendations call for endoscopic screening of men with chronic, frequent heartburn and other symptoms of gastroesophageal reflux disease (GERD).
The hope is that the capsule camera will offer a much quicker, easier, and more comfortable way of screening for the condition. A way that does not require an endoscope specialist and equipment, thereby making it more affordable as a mass screening tool.
Co-author Norman Nishioka, a Gastroenterology, Internal Medicine doctor at MGH, says in a statement:
"An inexpensive, low-risk device could be used to screen larger groups of patients, with the hope that close surveillance of patients found to have Barrett's could allow us to prevent esophageal cancer or to discover it at an earlier, potentially curable stage."
"But we need more studies to see if that hope would be fulfilled," he adds.
Tethered Camera Uses Laser TechnologyThe camera, which is about the size of a large vitamin pill, uses optical lasers to take detailed, microscopic images of the esophageal wall.
It "doesn't require patient sedation, a specialized setting and equipment, or a physician who has been trained in endoscopy," says corresponding author Gary Tearney, a professor of Pathology at Harvard Medical School and a Research Scholar at MGH.
"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," he adds.
The camera contains OFDI (optical frequency domain imaging) technology comprising a rapidly rotating tip that emits a laser beam of near-infrared light. Sensors on the camera then record the light that is reflected back from the esophageal lining.
The camera is not stand-alone: it is attached via a string-like tether to an imaging console from which the health professional controls the system.
When the patient swallows the camera, attached to its tethering "string", the muscles of the esophagus help it travel down to the stomach, like a lump of food.
When it reaches the entrance to the stomach, the doctor pulls it back up again. This gives the system a chance to take images on the way down and also on the way up.
Detailed Microscopic Images of Entire Wall of EsophagusFor their study, Tearney and colleagues recruited 13 participants: six had already been diagnosed with Barrett's esophagus and the other seven were healthy volunteers.
The detailed images taken by the OFDI also showed structures just below the surface of the gullet lining that are not normally visible with an endoscope, clearly showing the telltale signs of Barrett's esophagus in the cells.
Tearney says the OFDI images were "some of the best we have seen of the esophagus".
He said at first they were worried that the OFDI system would miss a lot of data because the capsule is so small. But they were surprised to find that once the pill was swallowed, it was "firmly grasped" by the esophagus, allowing the camera to take complete microscopic images 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," says Tearney.
Four Passes of the Gullet in Six MinutesDuring the study, doctors were able to image the entire esophagus in under a minute. And they were able to carry out four passes with the camera (two down and two up the gullet), in around six minutes.
This is considerably less time than it takes to do an endoscopic exam of the gullet: typically this can take about an hour and a half altogether.
The participants who had experience of endoscopy also said they preferred the new camera system.
Grants from the National Institutes of Health helped finance the study.
Written by Catharine Paddock PhD