Colorectal polyp size is important for determining surveillance intervals, how to resect the polyp and whether to resect-and-discard the polyp. However, currently used polyp size measurement techniques are inaccurate and difficult to perform, highlighting the need for novel techniques. This international multicenter study evaluated the precision of visual assessment (VA) and biopsy forceps (BF)-assisted measurement compared to a novel laser-based measurement system during real-time colonoscopy. 

AccuMeasure (VTM Technologies, Haifa, Israel) is a novel laser-based measurement system to sub-mm–accurately perform 3D measurements during real-time colonoscopy. A previous ex vivo animal study showed this system to be more precise compared to VA with and without use of a BF. The system consists of a reusable through-the-scope (TTS) probe and a medical grade personal computer. The TTS probe inserted through the endoscope working channel projects a laser line across the polyp, enabling size measurement.

A total of 137 polyps was successfully measured in 110 patients (56.4% male; median age 68 years (interquartile range (IQR): 18)). Colonoscopy indications were screening in 47 patients (42.7%), surveillance in 34 (30.9%), and diagnostic in 29 patients (26.4%). Most polyps were adenomas (n=91) or hyperplastic (n=23) and were equally distributed through the colon. The polyps were measured with the laser measurement system, VA, and BF in randomized order. The laser-based system achieved successful measurements in 68.8% of polyps, with a mean measurement time of 120 seconds (standard deviation (SD): 109.9). As shown in Table 1, failed measurements were due to technical malfunctions or difficulty aligning the laser with the polyp surface. Moderate agreement (Cohen kappa (k)=0.514) was observed between the laser-based system and VA, with VA wrongly assigning a polyp size to >5 mm (instead of ≤5 mm) in 10 polyps (7.3%) and ≥10 mm (instead of <10 mm) in 2 polyps (1.5%). Moderate agreement (k=0.534) was also observed between the laser system and BF, with BF wrongly assigning a polyp size to >5 mm (instead of ≤5 mm) in 11 polyps (8.0%) and ≥10 mm (instead of <10 mm) in 1 polyp (0.7%). Based on VA, two patients were assigned a 3- and 5-year surveillance interval, respectively, whereas based on the laser-based measurements these patients should have returned to screening at 10 years, in accordance with ESGE recommendations. Bland-Altman plots indicated that VA resulted on average in an underestimation compared to laser measurement, specifically in polyps of around 5 mm (-0.11 mm, 95% confidence interval (CI) [-0.39 to 0.17]). In contrast, for polyps over 6 mm, VA showed an average overestimation of 0.29 mm (P=0.012). BF also resulted in an average underestimation compared to laser measurement (-0.16 mm, 95% CI [-0.38 to 0.06]) but showed no significant overestimation for polyps over 6 mm (P=0.118). During the study, no adverse events related to the laser measurement system were reported. 

Laser-based measurement system summary statistics on performance 

Although mechanical difficulties during colonoscopy limited successful measurement to only two-thirds of cases, the novel laser-based system demonstrated greater precision than VA and BF reducing size misclassification. Our findings indicate that laser-based measurement may offer a more reliable approach for determining polyp size, ensuring more appropriate surveillance intervals.