Which imaging mode is more effective in detecting gastric neoplasms?

The third-generation narrow-band imaging (3G-NBI) appears better for gastric neoplasm (GN) detection than texture and colour enhancement imaging (TXI) and high-definition white-light imaging (WLI), suggest the results of a phase II study.

“The early detection of GNs leads to favourable treatment outcomes,” the researchers said. “The latest endoscopic system, EVIS X1, includes 3G-NBI, TXI, and WLI.”

In this trial, patients with scheduled surveillance endoscopy after a history of oesophageal cancer or GN or preoperative endoscopy for known oesophageal cancer or GN were randomly allocated to undergo 3G-NBI, TXI, or WLI. The investigators detected new GN lesions via endoscopic observations and biopsied all suspected lesions.

A total of 901 patients were enrolled and assigned to 3G-NBI (n=300), TXI (n=300), and WLI (n=301). The detection rate was highest with 3G-NBI (7.3 percent), followed by WLI (5.6 percent), and TXI (5.0 percent). [Am J Gastroenterol 2024;119;2020-2028]

On the other hand, the rates of missed GNs were 1.0 percent with 3G-NBI, 1.0 percent with WLI, and 0.7 percent with TXI. Additionally, detection of early gastric cancer was higher with 3G-NBI (5.7 percent), followed by WLI (5.6 percent) and TXI (4.0 percent), while the positive predictive values for GN diagnosis were 36.5 percent, 36.8 percent, and 21.3 percent, respectively.

“[T]he detection rate of GN during the primary observation was higher in the 3G-NBI group than in the TXI and WLI groups,” the researchers said. “Thus, 3G-NBI is a promising candidate for subsequent phase III trials. A phase III trial comparing 3G-NBI with WLI is currently in progress.”

New instruments

New endoscopic instruments feature major improvements, such as brighter and lower-noise image quality. This was made possible by changing the image sensor attached to the tip of the scope from a charge-coupled device to a complementary metal-oxide semiconductor, which then lowers image noise mainly in distant views, according to the researchers.

In a previous study on colonic polyps, 3G-NBI demonstrated a significantly greater colour difference compared with 2G-NBI. [Tech Innov Gastrointest Endosc 2022;24:309-311]

“Although the target and scope are not directly applicable to our study, improvements in colour differences may have had an important impact on our findings,” the researchers said. “Thus, the development of NBI has made it possible to produce a brightness and resolution suitable for early gastric cancer screening.”

More time

The observation time for the stomach, however, tended to be longer in the 3G-NBI than in the WLI group, which may be driven by the unfamiliarity of endoscopists with cleaning and inspecting the stomach during 3G-NBI observation since mucus on the gastric mucosa can be more visible with NBI versus WLI-based imaging.

“Consequently, this process may have taken more time during the lavage. In addition, the actual observation of the stomach itself may have taken longer compared with WLI observation,” the researchers said.

“However, it is anticipated that this issue may improve over time with increasing familiarity and experience with 3G-NBI, particularly if it becomes a standardized imaging modality,” they added.