A new LED endoscopy system, the EP-8000 (Fujifilm, Tokyo, Japan), was launched in 2024, featuring Triple Noise Reduction (TNR) and Extended Dynamic Range Image Processing (EDRIP). We previously demonstrated that this system provides low-noise, bright images with minimal halation compared with the previous system (VP-7000) [1]. In addition, the EP-8000 includes a novel observational mode, amber-red color imaging (ACI), which enhances the visibility of blood vessels and active bleeding points in the mucosa and submucosa. Several case reports have shown that ACI improves visualization of vessels, the submucosal layer, and the muscle layer during endoscopic submucosal dissection (ESD), suggesting that safer dissection under ACI may be possible [2]. However, no studies have evaluated the efficacy of ACI specifically in colorectal ESD. This study assessed the visibility of vessels and the submucosal layer using ACI during colorectal ESD.

This international, multicenter study retrospectively reviewed consecutive patients who underwent colorectal ESD at a single institution between January 2021 and June 2025. Therapeutic outcomes of 72 cases performed using ACI were compared with those of 505 cases performed using white-light imaging (WLI). The primary outcome was the mean number of intraoperative bleeding (IB) events during ESD in the ACI and WLI groups. Secondary outcomes included additional therapeutic outcomes of ESD. Furthermore, fifteen endoscopists (seven experts and eight non-experts) from four countries (Japan, Malaysia, Singapore, and Chile) evaluated the visibility of vessels, submucosa, and muscle layer under ACI and WLI using a four-point scale (1 = poor, 4 = excellent).

Among 72 cases (mean age: 67.3 ± 11.9 years, male proportion: 48.6%), the en bloc resection rate was 98.6%. The ACI group showed fewer IB events than the WLI group (2.1±2.5 vs 2.8±3.4, p=0.040), significant only among non-experts (1.3±1.2 vs 2.7±3.2, p=0.032). Regarding image evaluations, ACI achieved higher visibility scores for vessels (3.54±0.67 vs 2.81±0.77, p<0.001), submucosa (3.60±0.60 vs 2.96±0.75, p<0.001), and muscle layer (2.99±0.78 vs 2.45±0.85, p<0.001). Significant differences in ACI scoring between Japanese and other international endoscopists were observed for vessels and submucosa among experts, and muscle layer visibility among both groups.

ACI facilitated safer colorectal ESD by reducing perioperative bleeding and improving visualization of vessels, submucosa, and the muscle layer. Further randomized controlled trials are warranted to confirm these findings.