Upper endoscopy – used to diagnose conditions of the upper gastrointestinal tract – is a time consuming, costly and uncomfortable procedure that typically requires patient sedation. A new alternative lies in rescreening with tethered capsule endomicroscopy (TCE), in which an imaging capsule is lowered down the throat on an optical fibre. The capsule uses optical coherence tomography to collect cross-sectional microscopic images of the entire oesophagus as it passes up and down the throat, images that are then algorithmically characterized (see Tethered capsule detects GI tract disease for more details of this technique).

With dimensions of only 2.48 cm in length and 1.1 cm in diameter, and a weight of 6 g to aid oesophageal transit via natural peristalsis, the capsule is intended to be minimally invasive and not require patient sedation.

Since demonstrating the potential of the tethered capsule device and their image characterization algorithm, lead author Guillermo Tearney reports that the team "has now developed a portable TCE system that should greatly increase usability of the device in the clinical setting."

To assess the feasibility and acceptability of the new tethered capsule setup device in a primary care setting, the researchers imaged the oesophagus of 20 patients in a standard outpatient examination room at the Internal Medical Associates clinic at Massachusetts General Hospital. Eight of the patients had a history of gastro-oesophageal reflux disease. Patients were instructed to fast for four hours prior to the examination – and afterward were asked a series of questions regarding their experience with the tethered capsule.

The examination was administered by a research nurse trained in the operation of the capsule, and accompanied during the trials by an experienced capsule operator and a reporting researcher. The average time taken for the examination was 4.8 minutes with an average number of 3.7 capsule passes through the oesophageal passage required for successful imaging.

The study also revealed that using a double-breath technique to assist with the withdrawal of the capsule was easier on both the patient and the capsule operator than relaxing the upper oesophageal sphincter by having the patient swallow.

"We did not encounter any particular challenges implementing TCE in the primary care setting," said Tearney. In fact, the examination of all patients yielded an image of sufficient quality, and tissue visualization improved with successive passes through the oesophagus; the last imaging run for each patient typically provided the best visualization, with the full circumference of the oesophagus clearly visible in around 97% of the frames.

While patients reported some anxiety prior to the examination, 16 of the 17 patients who were able to swallow the capsule reported that they would definitely recommend the procedure, with the remaining patient saying they would probably recommend it. The patients reported experiencing only minor discomfort during the examination procedure.

While three patients were unable to swallow the capsule with water, this might potentially be improved in the future, Tearney notes, by reducing the size of the tethered capsule, or by numbing the patients' throats with a topical anaesthetic. Other potential future improvements highlighted by the study include a single-user operating procedure and a smaller imaging system footprint.

Following this study, the researchers are now starting several larger clinical studies to test the device in a broader population of subjects, alongside investigating the natural history of Barrett's oesophagus.

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