Published online Apr 14, 2014. doi: 10.3748/wjg.v20.i14.4050
Revised: November 6, 2013
Accepted: January 2, 2014
Published online: April 14, 2014
AIM: To verify the performance of a lesion size measurement system through a clinical study.
METHODS: Our proposed system, which consists of a conventional endoscope, an optical device, an optical probe, and a personal computer, generates a grid scale to measure the lesion size from an endoscopic image. The width of the grid scale is constantly adjusted according to the distance between the tip of the endoscope and lesion because the lesion size on an endoscopic image changes according to the distance. The shape of the grid scale was corrected to match the distortion of the endoscopic image. The distance was calculated using the amount of laser light reflected from the lesion through an optical probe inserted into the instrument channel of the endoscope. The endoscopist can thus measure the lesion size without contact by comparing the lesion with the size of the grid scale on the endoscopic image. (1) A basic test was performed to verify the relationship between the measurement error eM and the tilt angle of the endoscope; and (2) The sizes of three colon polyps were measured using our system during endoscopy. These sizes were immediately measured by scale after their removal.
RESULTS: There was no error at α = 0°. In addition, the values of eM (mean ± SD) were 0.24 ± 0.11 mm (α = 10°), 0.90 ± 0.58 mm (α = 20°) and 2.31 ± 1.41 mm (α = 30°). According to these results, our system has been confirmed to measure accurately when the tilt angle is less than 20°. The measurement error was approximately 1 mm in the clinical study. Therefore, it was concluded that our proposed measurement system was also effective in clinical examinations.
CONCLUSION: By combining simple optical equipment with a conventional endoscope, a quick and accurate system for measuring lesion size was established.
Core tip: Our suggested system, which combines a conventional endoscope, several optical devices and a personal computer, can measure a lesion size by superimposing a grid scale on an image of the lesion and adjusting the width adequately according to the distance between the tip of the endoscope and the target lesion. Endoscopists can measure lesions by comparing the size of the grid scale with the size of the lesion on the monitor. After a basic performance test, the first clinical study for 3 colon polyps was performed. In the clinical study, we confirmed that our measurement system obtained a measurement accuracy of ± 1 mm when the tilt angle of the endoscope was less than 20°.