In the not-so-distant past, endoscopists always sought the input of pathologists when diagnosing gastrointestinal cancers.

Now, thanks to the maturation of image-enhanced endoscopy, endoscopists are sometimes able to make a diagnosis on the spot.

"The time for endoscopic diagnosis

"This technology is now hand in hand with the much-improved optics of the endoscopes. This allows more things to be done during endoscopic assessment, such as cutting tumors at time of assessment rather than going back in, so it's increasing efficiency and reducing costs."

In an effort to assist clinicians in the appropriate use of such technology, Dr. Soetikno and his associates assembled the guidelines, "Technology Assessment on Image-Enhanced Endoscopy," based on a Medline search performed through June 2007. The guidelines are the first of their kind (Gastroenterology 2008;134:327-40).

One reason that the researchers assembled these guidelines is to promote the use of image-enhanced endoscopy (IEE) outside of specialized academic centers, where it has been used almost exclusively. For many clinicians, using dye for image enhancement was a cumbersome process, requiring preparation of the solution, spraying it on, and interpretation.

"It added more time," Dr. Soetikno explained. "It was not just 'turn the key,' so to speak. Today, though, by changing the properties of the lights that go through the endoscope, we can mimic what could have been achieved by the dye. Either the endoscopy lights have changed, or we're using some kind of computer software to process the image, so in the end you highlight the gland or the abnormality, and you get a better diagnosis."

According to the guidelines, available data support the use of IEE in the detection and treatment of early squamous cell carcinoma of the esophagus, early gastric cancer, and superficial colorectal lesions.

The guidelines also state that the use of Lugol's solution "may improve the endoscopic visualization of high-grade dysplasia and early squamous cell carcinoma of the esophagus, and thus may be considered [for use] in high-risk patient populations."

Diluted indigo carmine solution can be helpful in the diagnosis and treatment of early gastric cancer because it "pools at the border of the lesion and thus enhances visualization of these lesions, which are most often nonpolypoid. By pooling into the depression or ulceration of the lesion, the solution aids in the classification of the morphology, which in turn is important in the medical decision making of treatment strategy."

Equipment-based advances in endoscopic imaging continue to evolve and enhance visualization, including devices that use manipulations of the light source or captured light.

Other approaches being studied include narrow-band imaging, which uses a narrow light source to enhance visualization of the surface microvessels; spectral estimation technologies, which use computerized processing to convert standard RGB (red, green, blue) signals from the endoscope's charged-coupled device; and autofluorescence imaging, which uses changes in concentrations of endogenous fluorophores.

The researchers also noted that high-resolution or high-definition endoscopes provide "a more detailed image of gastrointestinal mucosa, and high-magnification endoscopy enlarges the image up to 100X," compared with 30x in standard endoscopy, which uses a 20-inch monitor. "At higher magnification with IEE, the visualized surface patterns of the gastrointestinal mucosa have been suggested to correlate well with the underlying histology.

"Proposed uses for high magnification used in conjunction with IEE include distinguishing neoplastic and nonneoplastic lesions, assessing depth of invasion in early colorectal carcinoma, and detecting minute tumor residue after endoscopic mucosal resection," the authors said.

Potential barriers to the dissemination of IEE "include perceptions of its inefficiency and [high] cost, inadequate mechanism for reimbursement, lack of standardized training in techniques, and deficiency of high-quality comparison studies," the researchers wrote.

Dr. Soetikno said that neither he nor his associates have any relevant financial relationships to disclose.

BY DOUG BRUNK

San Diego Bureau