Development and clinical usefulness of a unique red dichromatic imaging technology in gastrointestinal endoscopy: A narrative review

Red dichromatic imaging and linked color imaging as reliable image-enhanced endoscopic procedures for detecting the distal end of the palisade vessels in the columnar metaplastic mucosa of the gastroesophageal junction zone

BACKGROUND

There is a consensus that identifying the distal end of the palisade vessels (DEPV) is important for diagnosing gastroesophageal junction (GEJ). However, optimum observation methods have not been established. This study investigated the use of effective image-enhanced endoscopy (IEE) for DEPV detection.

METHODS

One hundred endoscopic images in 20 cases of columnar metaplastic mucosa of the GEJ recorded with white-light imaging (Olympus-WLI and Fujifilm-WLI) and IEEs (narrow-band imaging; RDI1/2/3, red dichromatic imaging; texture and color enhancement imaging 1/2; blue-laser imaging; and LCI, linked color imaging) from two manufacturers were extracted and evaluated by 10 evaluators. Up to 24 radial straight lines from the center of the lumen were placed on the image, and the evaluators placed markings according to confidence level (high, low, and not detectable) at the DEPV locations. The detectability and reproducibility at the rate of the confidence level and coefficient of variance of markings among the evaluator were analyzed.

RESULTS

In total, 15,180 markings were obtained. In terms of detectability, RDI1 (49.4%), RDI2 (53.0%), RDI3 (54.1%), TXI2 (49.7%), and LCI (34.6%) had a significantly higher rate of high confidence among the IEEs in each manufacturer. By contrast, Olympus-WLI (40.6%), Fujifilm-WLI (17.6%), narrow-band imaging (15.9%), and blue laser imaging (9.8%) presented with a significantly lower rates of high confidence. Regarding reproducibility, RDI3 and LCI had the lowest coefficient of variance for each manufacturer.

CONCLUSIONS

RDI and LCI could be reliable modalities for detecting DEPVs in the columnar metaplastic mucosa of the GEJ zone.

A new grading assessment of eosinophilic esophagitis using red dichromatic imaging: a pilot study

BACKGROUND AND AIMS

The endoscopic reference score using white-light imaging (WLI) is utilized for objectively evaluating the severity of findings in patients with eosinophilic esophagitis. A novel image-enhanced endoscopy technique, red dichromatic imaging (RDI), can visualize deeper vessels in the GI tract, which may assess edema more precisely than WLI.

METHODS

A total of 21 consecutive patients with eosinophilic esophagitis were prospectively evaluated. Patients were categorized according to 3 grades based on the visibility of vessels with RDI. Clinical features, such as peak eosinophil counts and presence of symptoms, were reviewed.

RESULTS

There were 10 patients with RDI Grade 0/1 and 11 patients with RDI Grade 2. Peak eosinophil counts and the prevalence of heartburn were significantly higher in patients with RDI Grade 2 than in patients with RDI Grade 0/1.

CONCLUSIONS

The severity of eosinophilic infiltration could be predicted more precisely using RDI than by evaluations with WLI.

Comprehensive advancement in endoscopy: optical design, algorithm enhancement, and clinical validation for merged WLI and CBI imaging

As endoscopic imaging technology advances, there is a growing clinical demand for enhanced imaging capabilities. Although conventional white light imaging (WLI) endoscopy offers realistic images, it often cannot reveal detailed characteristics of the mucosa. On the other hand, optical staining endoscopy, such as Compound Band Imaging (CBI), can discern subtle structures, serving to some extent as an optical biopsy. However, its image brightness is low, and the colors can be abrupt. These two techniques, commonly used in clinical settings, have complementary advantages. Nonetheless, they require different lighting conditions, which makes it challenging to combine their imaging strengths on living tissues. In this study, we introduce a novel endoscopic imaging technique that effectively combines the advantages of both WLI and CBI. Doctors don't need to manually switch between these two observation modes, as they can obtain the image information of both modes in one image. We calibrated an appropriate proportion for simultaneous illumination with the light required for WLI and CBI. We designed a new illumination spectrum tailored for gastrointestinal examination, achieving their fusion at the optical level. Using a new algorithm that focuses on enhancing specific hemoglobin tissue features, we restored narrow-band image characteristics lost due to the introduction of white light. Our hardware and software innovations not only boost the illumination brightness of the endoscope but also ensure the narrow-band feature details of the image. To evaluate the reliability and safety of the new endoscopic system, we conducted a series of tests in line with relevant international standards and validated the design parameters. For clinical trials, we collected a total of 256 sets of images, each set comprising images of the same lesion location captured using WLI, CBI, and our proposed method. We recruited four experienced clinicians to conduct subjective evaluations of the collected images. The results affirmed the significant advantages of our method. We believe that the novel endoscopic system we introduced has vast potential for clinical application in the future.

Next-Generation Endoscopy in Inflammatory Bowel Disease

Endoscopic healing is recognized as a primary treatment goal in Inflammatory Bowel Disease (IBD). However, endoscopic remission may not reflect histological remission, which is crucial to achieving favorable long-term outcomes. The development of new advanced techniques has revolutionized the field of IBD assessment and management. These tools can accurately assess vascular and mucosal features, drawing endoscopy closer to histology. Moreover, they can enhance the detection and characterization of IBD-related dysplasia. Given the persistent challenge of interobserver variability, a more standardized approach to endoscopy is warranted, and the integration of artificial intelligence (AI) holds promise for addressing this limitation. Additionally, although molecular endoscopy is still in its infancy, it is a promising tool to forecast response to therapy. This review provides an overview of advanced endoscopic techniques, including dye-based and dye-less chromoendoscopy, and in vivo histological examinations with probe-based confocal laser endomicroscopy and endocytoscopy. The remarkable contribution of these tools to IBD management, especially when integrated with AI, is discussed. Specific attention is given to their role in improving disease assessment, detection, and characterization of IBD-associated lesions, and predicting disease-related outcomes.

Difficult colorectal polypectomy: Technical tips and recent advances

Colonoscopy has been shown to be an effective modality to prevent colorectal cancer (CRC) development. CRC reduction is achieved by detecting and removing adenomas, which are precursors of CRC. Most colorectal polyps are small and do not pose a significant challenge for trained and skilled endoscopists. However, up to 15% of polyps are considered “difficult”, potentially causing life-threatening complications. A difficult polyp is defined as any polyp that is challenging for the endoscopist to remove owing to its size, shape, or location. Advanced polypectomy techniques and skills are required to resect difficult colorectal polyps. There were various polypectomy techniques for difficult polyps such as endoscopic mucosal resection (EMR), underwater EMR, Tip-in EMR, endoscopic submucosal dissection (ESD), or endoscopic full-thickness resection. The selection of the appropriate modality depends on the morphology and endoscopic diagnosis. Several technologies have been developed to aid endoscopists in performing safe and effective polypectomies, especially complex procedures such as ESD. These advances include video endoscopy system, equipment assisting in advanced polypectomy, and closure devices/techniques for complication management. Endoscopists should know how to use these devices and their availability in practice to enhance polypectomy performance. This review describes several useful strategies and tips for managing difficult colorectal polyps. We also propose the stepwise approach for difficult colorectal polyps.

Validation of red dichromatic imaging score (RDI score) to evaluate the severity of ulcerative colitis

BACKGROUND

Red dichromatic imaging (RDI) is a new imaging technology that has been closely correlated with the activity index of ulcerative colitis (UC). Although the RDI score has been developed no study has validated a correlation between the RDI score and the activity index of UC. Therefore, this study aims to validate the RDI score prospectively.

METHODS

A total of 34 patients with UC in whom colonoscopy was scheduled between May 2019 and October 2021 at our hospital were enrolled prospectively. MES, UCEIS, RDI scores, and Nancy index were evaluated in a blinded fashion. We evaluated the correlation between RDI and WLI scores using still images with histology.

RESULTS

We analyzed 191 sites of colorectum. RDI score showed the positive correlation with UCEIS (r = 0.74 P < 0.0001) and MES (r = 0.78 P < 0.0001). RDI score also showed the positive correlation with Nancy index (r = 0.63 P < 0.0001). RDI score was more strongly correlated with Nancy index than UCEIS (r = 0.51) and MES (r = 0.48).

CONCLUSIONS

When comparing still images of RDI and WLI scores, we showed RDI had a higher correlation to histology than WLI.

CLINICAL TRIAL ID

The University Hospital Medical Information Network (UMIN000041750).