Novel Endoscopic Findings as Visualized by Non-Magnification Endoscopy with Linked Color Imaging are Indicative of Gastric Intestinal Metaplasia
Gastric intestinal metaplasia (GIM) is widely recognized as a significant precursor to gastric adenocarcinoma, making its accurate endoscopic diagnosis crucial for early detection and intervention. Traditional methods for diagnosing GIM, such as histologic assessment of biopsy specimens, methylene blue chromoendoscopy, and narrow-band imaging with magnification (M-NBI), have limitations in terms of accuracy, cost, and time. This study explores the potential of linked color imaging (LCI), a novel endoscopic technique, in identifying GIM through a unique endoscopic finding termed “Purple in Mist” (PIM).
Background and Rationale
GIM is a condition where the normal gastric mucosa is replaced by intestinal-type epithelium, often considered a precursor to gastric cancer. Current diagnostic methods, while effective, have limitations. Histologic assessment requires multiple biopsies, which can be time-consuming and may miss up to 50% of GIM cases. Chromoendoscopy and M-NBI, though useful, are not universally available and can be costly. LCI, a recently developed endoscopic imaging technique, enhances color contrast, making it easier to identify mucosal lesions without the need for magnification.
The study aimed to investigate whether PIM, a specific color pattern observed under LCI, could serve as a reliable optical marker for GIM. The hypothesis was that PIM, characterized by a purple mixed with white color on the epithelium with signs of mist, could be a novel endoscopic sign for predicting GIM.
Methods
The study was conducted as a single-center, blinded, prospective investigation involving consecutive patients aged 40 years or older who underwent endoscopic examination for various indications. Exclusion criteria included recent use of nonsteroidal anti-inflammatory drugs, proton pump inhibitors, or antibiotics, severe uncontrolled coagulopathy, prior gastric surgery, and pregnancy or lactation.
All endoscopic procedures were performed using a high-definition GF-L590WR endoscope, part of the LASEREO endoscopic system. The LCI technique, based on blue-laser imaging (BLI) with additional image processing, enhances the color separation of red and white colors, allowing for more vivid visualization of mucosal lesions.
The endoscopist used LCI to carefully observe the gastric antrum, body, and angulus. When PIM was identified in the surface layer, targeted biopsies were taken from the area. If the suspected area had no PIM on the surface, targeted biopsies were also taken. All biopsy specimens were evaluated histologically by an experienced pathologist blinded to the endoscopic findings.
Results
The study included 63 consecutive patients, with a prevalence of intestinal metaplasia (IM) of 46% (29/63). In PIM-positive patients, the prevalence of IM was 89% (23/26). A total of 146 biopsy specimens were included, with 52 being PIM positive. Of these, 44 showed histological evidence of IM. Among the 94 biopsy samples taken from non-PIM mucosa in suspected IM patients, 89 showed no evidence of IM.
For the diagnosis of IM, LCI findings had an accuracy of 91.1%, a sensitivity of 89.8%, a specificity of 91.8%, a positive predictive value of 84.6%, and a negative predictive value of 94.7%. These results suggest that PIM observed under LCI is a highly reliable marker for GIM.
Discussion
The findings of this study demonstrate that PIM, observed under LCI, is a novel and effective optical marker for predicting GIM. The high accuracy, sensitivity, and specificity of PIM in identifying IM suggest that LCI can significantly enhance the diagnostic process for GIM. This is particularly important given the limitations of current diagnostic methods, which often miss a significant proportion of GIM cases and add to the cost and time of diagnosis.
One of the key advantages of LCI is its ability to enhance color contrast, making it easier to distinguish between normal and abnormal mucosa. This is particularly useful in identifying flat lesions, such as those seen in GIM, which often show few morphologic changes. The study found that LCI could reliably target areas for biopsy, reducing the need for random sampling and increasing the diagnostic yield.
The study also highlighted the importance of understanding the color patterns observed under LCI. The RGB pixel brightness analysis showed that the colors did not change significantly with distance, ensuring the fidelity of the LCI images. This is crucial for the accurate identification of PIM and other mucosal lesions.
Limitations
While the study provides promising results, it has some limitations. The single-center design may limit the generalizability of the findings. Additionally, the study involved only one experienced endoscopist, so interobserver reproducibility could not be evaluated. Further research involving larger, multicenter studies is needed to confirm the effectiveness of PIM as a marker for GIM.
Conclusion
In conclusion, this study demonstrates that LCI, particularly the observation of PIM, is a valid and reliable method for detecting GIM. The high accuracy, sensitivity, and specificity of PIM in identifying IM suggest that LCI can significantly enhance the diagnostic process for GIM. This technique can reliably target which patients should be biopsied to evaluate IM and those who do not need biopsies, potentially reducing the cost and time associated with the diagnostic process. More data should be accumulated to confirm whether PIM is associated with GIM and to further validate its use in clinical practice.
doi.org/10.1097/CM9.0000000000000172
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