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

Abstract

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.

Measurement of polyp size at colonoscopy: Addressing human and technology bias

“…In Shimoda et al . 's study, 8 one trainee did not achieve higher accuracy with virtual scale estimation, likely due to failure to adequately align the scale with the target lesion.…”

“…Measurement error using visual estimation is a systemic phenomenon at colonoscopy, and one of many facets of colonoscopy performance that vary between endoscopists. Integrated colonoscope measurement devices using virtual scales 8 or AI 9 will reduce bias and can only improve the awareness and performance of endoscopists for accurate sizing of colorectal lesions.…”

“…In this issue of Digestive Endoscopy is the first study of an integrated measurement device within a commercially available instrument platform. Shimoda et al 8 evaluate a promising advance in which a measurement scale or ruler for real-time polyp measurement is incorporated within a current generation colonoscope. On identification of a target lesion, the endoscopist can instantly switch on (and off) a virtual scale using a button on the colonoscope, and apply the scale to the mucosa without the need for any additional tools.…”

“…Compared with the use of existing noncalibrated devices, such as forceps and snare catheters, calibrated tools further improve measurement accuracy. These include graduated forceps and injection needles, ruler snares, calibrated hoods, and structured laser light probes, 8 which fundamentally provide a calibrated reference for more accurate visual estimation of polyp size. If combined with systematic photography of the lesion, 5 these devices could reduce both technology and endoscopist bias.…”

“…In this issue of Digestive Endoscopy is the first study of an integrated measurement device within a commercially available instrument platform. Shimoda et al 8 . evaluate a promising advance in which a measurement scale or ruler for real‐time polyp measurement is incorporated within a current generation colonoscope.…”