Esophageal squamous cell carcinoma (ESCC) is one of the most common causes of cancer death worldwide [
In recent years, image-enhanced endoscopy (IEE) has been reported to improve the detection and diagnosis of superficial ESCC. Narrow band imaging (NBI) has been particularly useful for the detection and diagnosis of superficial ESCC when compared with WLI [
We retrospectively enrolled patients with superficial ESCC who underwent endoscopic submucosal dissection (ESD) at Kyoto Prefectural University of Medicine from March 2012 to December 2014. We selected ESCCs that had endoscopic images obtained at the same angle and distance with NBI and BLI-bright before ESD. Finally, 25 ESCCs with both NBI and BLI-bright recorded images were selected and analyzed in this study. A typical ESCC was observed as a reddish area with the use of Olympus white light imaging (O-WLI) and Fujifilm white light imaging (F-WLI) or as a brownish area with the use of NBI and BLI-bright in a distant view. In all cases, squamous cell carcinoma was histopathologically diagnosed from a biopsy specimen obtained prior to ESD. All patients provided written informed consent for the endoscopic examinations, including the use of NBI and BLI-bright. This study was approved by the ethics committee of Kyoto Prefectural University of Medicine and was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) as number
Two different upper GI endoscopic systems manufactured by Olympus Medical Systems Co. and Fujifilm Co. were used in this study. A high-resolution endoscope (GIF-H260Z; Olympus Medical Systems Co., Tokyo, Japan) and a video processor with NBI function (EVIS LUCERA; Olympus Medical Systems Co., Tokyo, Japan) were used for white light imaging (O-WLI) observation and narrow band imaging (NBI) observation. The structure enhancement of the endoscopic video processor was set to B-mode level 3 for O-WLI and B-mode level 8 for NBI. The color mode was fixed at level 1 for NBI.
A high-resolution endoscope (EG-L590ZW; Fujifilm Co., Tokyo, Japan) and a video processor with BLI-bright function (LASEREO; Fujifilm Co., Tokyo, Japan) were used for white light imaging (F-WLI) observation and blue laser imaging-bright (BLI-bright) observation. The structure enhancement of the endoscopic video processor was set to A-mode level 6 for BLI-bright. The color mode was fixed at level C1. The depth of field for the GIF-H260Z and EG-L590ZW endoscope was 7 to 100
The endoscope was fixed at one angle for observing the lesions, and each lesion was recorded at that fixed angle using O-WLI, F-WLI, NBI, and BLI-bright imaging.
After ESD resection, the lesions were extended and fixed on boards with pins in 20% formalin, and a clinical pathologist histopathologically confirmed the diagnosis of ESCC according to the Japanese Classification of Esophageal Carcinomas.
For the subjective evaluation, the endoscopists provided a ranking score (RS) of the endoscopic images using the following 3-point ranking method based on ease of recognition of the cancerous area. Images with the easiest recognition were given 3 points; those with a comparatively lower degree of clarity were given 2 points, and obscure images scored only 1 point. Images obtained with each modality (O-WLI, F-WLI, NBI, and BLI-bright) were prepared for evaluation by placing them on a computer monitor and displaying them independently of the images obtained with the other endoscopic modality. A representative set of still images for the ESCC case is shown in Figure
Representative still images: superficial flat depressed lesion
The following methods were used to ensure that the endoscopic images were objectively evaluated. Each lesion and the surrounding mucosa were captured for image processing, and the region of interest (ROI) was highlighted. Representative still images illustrating the spots captured for the color difference score (CDS) calculation of the lesion and background mucosa are shown in Figure
Representative still images illustrating the spots captured for the color difference score (CDS) calculation of the lesion and background mucosa (Figure
In the
A post hoc power analysis was conducted to determine the power for the sample size
Inter- and intraobserver concordance was evaluated by calculating the
The clinicopathological features of the patients are shown in Table
Clinicopathological features of patients.
Patients/lesions | 25/25 |
Median age, years (range) | 70 (55–87) |
Sex | |
Male | 20 |
Female | 5 |
Mean tumor size, mm (range) | 20.5 (4–42) |
Depth | |
Intramucosal | 24 |
Submucosal | 1 |
Macroscopic type | |
0-IIa type | 3 |
0-IIb type | 14 |
0-IIc type | 8 |
The total RS of the four methods by the endoscopists was as follows: O-WLI was 35/32/48 (NY/OD/RK) (mean, 35.3), F-WLI was 37/35/58 (mean, 43.3), NBI was 48/47/61 (mean, 52.0), and BLI-bright was 54/59/68 (mean, 60.3; Figure
Subjective evaluation. Statistical comparison of the ranking score of O-WLI, F-WLI, NBI, and BLI-bright images for quality of ESCC visualization (Wilcoxon signed-rank test). Numbers above each row denote the numbers of ESCCs.
The
Inter- and intraobserver agreement (
NY to OD | NY to RK | OD to RK | |
---|---|---|---|
Interobserver agreement | 0.613 | 0.382 | 0.317 |
| |||
NY | OD | RK | |
| |||
Intraobserver agreement | 0.673 | 0.873 | 0.599 |
The mean CDS of O-WLI, F-WLI, NBI, and BLI-bright were 15.92, 15.27, 18.43, and 26.72, respectively. There was no significant difference between the mean CDS of O-WLI and F-WLI. The mean CDS of NBI was significantly higher than that of O-WLI (
Objective evaluation. Statistical comparison of the mean CDS of O-WLI, F-WLI, NBI, and BLI-bright images for quality of ESCC visualization (Wilcoxon signed-rank test). n.s.: not significant.
In 25 study patients, post hoc power analysis demonstrated a statistical power value greater than 90% for FWL versus BLI (power = 0.99) and BLI versus NBI (power = 0.97) for both the subjective and objective evaluation.
These images are representative of a 0-IIc type early squamous cell carcinoma of the middle thoracic esophagus (Figure
This is the first report of the use of BLI-bright for the detection of superficial ESCC in comparison with WLI in a distant view. Previous studies have shown that the detection rate of NBI for superficial ESCC is higher than that of WLI [
BLI-bright facilitates the detection of ESCCs that show a well-demarcated brownish area. An important element for the detection of a brownish area in a distant view is the background coloration of the epithelium between each of the intraepithelial papillary capillary loops (IPCL). Recently, it has been reported that the presence of hemoglobin in the epithelium of ESCC is an important factor affecting background coloration [
We compared the endoscopic recognition of superficial ESCCs using four different methods (OWL, FWL, NBI, and BLI-bright). Our study showed the utility of IEE compared with WLI by both RS and CDS. Furthermore, we also showed the utility of BLI-bright compared with NBI by both RS and CDS. In this way, lesions detected with BLI-bright were significantly more visible than those detected with the other methods, both subjectively and objectively. Additionally, the differences between the Olympus and Fujifilm system specifications, such as field of view and depth of field, were negligible and did not influence the results of our study.
The
Our study has three major limitations. First, we evaluated NBI images with a first-generation NBI system in this study. Since BLI-bright provides a brighter image than the first generation of NBI, it is possible that this contributed to the higher detection ability in the distant view. Second, the number of cases was small, and the data were gathered from a single center. Third, we evaluated only still images. Therefore, further multi-institutional studies with a larger number of cases are required to compare real-time images for ESCC detection with WLI, BLI-bright, and NBI.
In conclusion, BLI-bright visualized superficial ESCC better than the other methods tested (O-WLI, F-WLI, and NBI), both subjectively and objectively. BLI-bright may be a useful tool for detecting superficial ESCCs during screening endoscopy.
Yoshito Itoh has an affiliation with a domination-funded department from Fujifilm Medical Co., Ltd. The other authors have no financial conflict of interests.
The authors would like to thank members in the Department of Molecular Gastroenterology and Hepatology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, who assisted them with clinical data collection and image evaluation.