Guidelines needed to advance diagnostic accuracy

Tiny mechanical microscopes – those that can see inside single living cells – increasingly are being used to diagnose illness in hard-to-reach areas of the body, but specialists say that improved, standardized guidelines are needed to advance diagnostic accuracy.

The little probes often are threaded into the narrow bile duct that connects the liver to the small intestine to search for cancer or are used to minutely explore the pancreatic duct, said Dr. Michel Kahaleh of New York-Presbyterian Hospital/Weill Cornell Medical Center.

But because the groundbreaking technology is comparatively new, Kahaleh suspects that specialists using the probes may be interpreting what they see in different ways.

This was precisely what he found when he and his research team sent six gastroenterologists at five medical institutions some videos taken by probe-based confocal laser endomicroscopy (pCLE). The specialists were asked to analyze seven variables in the approximately 1-min videos recorded deep inside 25 patients with abnormally narrowed bile ducts. Bile, secreted by the liver to aid digestion, is transported to the small intestine by the bile duct. Inflammatory disease, the passing of gallstones or tumors, however, can cause the duct to constrict, resulting in a blockage that can lead to cirrhosis, jaundice or other serious conditions.

Tiny microscopes that can see inside single living cells could help gastroenterologists diagnose conditions – as long as guidelines are developed, according to a recent study.

In the study, diagnostic agreement was poor to fair, depending on the variable, as was the final diagnosis.

“Physicians need to come up with a standard way of interpreting what the videos reveal in order to properly use this ‘amazing technology,’ ” said Kahaleh, who is chief of endoscopy at the Center for Advanced Digestive Care at the hospital and medical director of the Pancreas Program at Weill Cornell. “We can see detail that was just unimaginable a decade ago – this breakthrough is born for the bile duct and those tiny tubes and complicated organ structures that no one has ever been able to visualize before.

“And when physicians are certain of what they are seeing, we will be able to greatly improve patient treatment, avoiding unnecessary surgery whenever possible.”

The pCLE diagnostic system was approved by the FDA two years ago for use in the bile duct and pancreas. The device is a tiny microscopic probe that is threaded inside a larger “spyglass” probe to image blood vessels, mucosal structures and epithelial tissue in real time, broadcasting the images on a large monitor for physicians to examine.

Most institutions, however, still use hit-or-miss techniques to determine whether a bile duct is cancerous. In the traditional technique, a probe is threaded inside the duct to where it is abnormally narrowed, and then tiny forceps or a small brush is used to gather a cell sample that can be biopsied in the lab.

“We still miss 20 to 30 percent of bile duct cancer or other tumors in this way, and that is unacceptable,” Kahaleh said.

“It is clear physicians need a standard by which to understand what they see, which will also need to involve more training,” he noted. “This is increasingly important, as these minimally invasive systems are proposed for use in diagnosing other health issues in the gastrointestinal tract, including ulcerative colitis and Barrett’s esophagus.

“We can now see inside these tiny organs, but we just need to know exactly what we are looking at.”

The study was published in Digestive Diseases and Sciences (doi: 10.1007/s10620-012-2338-6).