Estimating colorectal polyp size with a virtual scale endoscope and visual estimation during colonoscopy: Prospective, preliminary comparison of accuracy.

The virtual scale endoscope (VSE) is a new endoscope that helps estimate the size of neoplasms in the gastrointestinal tract. We compared the accuracy of polyp size estimation by VSE with that of visual estimation. A dual center prospective study was conducted in two Japanese academic endoscopy units. Ten endoscopists (five trainees and five experts) estimated the size of 20 simulated polyps in four colon phantoms during colonoscopy by two methods: conventional visual estimation and estimation by VSE. The primary endpoint was the relative accuracy in relation to true polyp size according to visual estimation and VSE estimation during colonoscopy. The secondary endpoint was the required time (the time needed to measure in each procedure). The mean values of the primary end-point were 62.5% for visual estimation and 84.0% for VSE estimation; hence the result differed significantly (95% confidence interval 18.3-24.7; P < 0.001). The mean of required times was significantly longer for estimation by VSE (6.4 min) than that by visual estimation (2.9 min; P < 0.001). The accuracy of colorectal polyp size estimation was superior with VSE than with visual estimation during colonoscopy. In the future, VSE should be evaluated in actual clinical settings, including the time required for size estimation.

Virtual scale function of gastrointestinal endoscopy for accurate polyp size estimation in real-time: a preliminary study.

SIGNIFICANCE: Polyp size is important for selecting the surveillance interval or treatment policy. Nevertheless, it is challenging to accurately estimate the polyp size during endoscopy. An easy and cost-effective function to assist in polyp size estimation is required. AIM: To propose a virtual scale function for endoscopy and evaluate its performance and expected accuracy. APPROACH: An adaptive virtual scale behavior was demonstrated. The measurement error of the virtual scale along the distance between the tip of the endoscope and the object plane was evaluated using graph paper. The accuracy of polyp size estimation by an expert endoscopist was compared with the accuracy of the biopsy forceps method using phantom images. RESULTS: The measurement errors of the virtual scale were ≤ 0.7 mm when the distance to the graph paper, which faced the tip of the endoscope, varied from 4 to 30 mm. The accuracy with the virtual scale was significantly higher than that obtained with biopsy forceps (5.3 ± 5.5 % versus 11.9 ± 9.4 % , P < 0.001). CONCLUSIONS: The virtual scale function, which operates in real-time without any additional device, can be used to estimate polyp sizes easily and accurately with endoscopy.

A detailed comparison between the endoscopic images using blue laser imaging and three-dimensional reconstructed pathological images of colonic lesions.

Blue laser/light imaging (BLI) is an image-enhanced endoscopy (IEE) technique that can provide an accurate diagnosis by closely observing the surface structure of various colonic lesions. However, complete correspondence between endoscopic images and pathological images has not been demonstrated. The aim of this study was to accurately compare endoscopic images and the pathological images using a three-dimensionally (3D) reconstructed pathological model. Continuous thin layer sections were prepared from colonic tissue specimens and immunohistochemically stained for CD34 and CAM5.2. Three-dimensional reconstructed images were created by superimposing immunohistochemically stained pathological images. The endoscopic image with magnifying BLI was compared with the top view of the 3D reconstructed image to identify any one-to-one correspondence between the endoscopic images and histopathological images using the gland orifices and microvessels as a guide. Using 3D reconstructed pathological images, we were able to identify the location on the endoscope image in cases of colonic adenocarcinoma, adenoma and normal mucosa. As a result, the horizontal plane of the endoscopic image and the vertical plane of the 2D pathological specimen were able to be compared, and we successfully determined the visible blood vessel depth and performed a detailed evaluation on magnifying BLI. Examples are as follows: (1) The median vasculature depth from the mucosal surface that could be recognized as vasculature on magnifying BLI was 29.4 µm. The median depth of unrecognizable vessels on magnifying BLI was 218.8 µm, which was significantly deeper than recognizable vessels. (2) Some brownish structures were suggested to potentially be not only dense vessels, vessel expansions, corrupted vessels but also bleeding or extravasation of erythrocytes. Overall, we demonstrated a new approach to matching endoscopic images and pathological findings using a 3D-reconstructed pathological model immunohistochemically stained for CD34 and CAM5.2. This approach may increase the overall understanding of endoscopic images and positively contribute to making more accurate endoscopic diagnoses.