Virtual scale endoscope-assisted wide-field resection of large sessile serrated lesions

Large sessile serrated lesions (SSLs) are associated with a very high risk of incomplete resection. The CARE study found almost 50 % incomplete resections among 10 to 20-mm SSLs [1]. Wide-field cold snare resection with submucosal injection (cap-assisted endoscopic mucosal resection, C-EMR) has been proposed as an effective method to prevent incomplete resection since distinguishing SSL margins during resection is difficult [2] [3] [4]. In contrast to a hot snare, a more extended resection field is recommended for a cold snare [5]. However, quantification of the resection field extent in comparison to polyp size has been challenging in the past. The novel virtual scale endoscope (VSE; SCALE EYE, Fujifilm, Tokyo, Japan) can be used as dedicated technology to measure polyp size before resection and to ensure adequate post-resection defect size. The VSE allows polyp size measurement during live colonoscopies by emitting a laser beam onto the mucosa to measure distance. This permits superimposition of a linear/circular ruler that changes in size depending on distance of the endoscope to the laser point ([Fig. 1]).

Fig. 1 Virtual scale endoscope with laser point on polyp from which a scale is projected on the endoscopy screen.

We present VSE-assisted C-EMR for two large SSLs ([Video 1]). The polyps were assessed with the VSE before and after submucosal injection and resection to ensure adequate wide-field resection. SSLs were initially measured using the VSE and assessed using computer-aided diagnosis (CADx) to determine their size (> 10 mm) and ensure that C-EMR was the adequate approach. Then the extent of wide-field resection was planned and controlled using the VSE. For resection, submucosal injection was used to allow better exposure of the entire polyp and obtain a pre-resection measurement using the VSE ([Fig. 2]). The polyps were then resected, and an artificial-intelligence system (CADx) was used to detect polyp remnants at the margins during C-EMR ([Fig. 3]). The resection extent was adjusted based on CADx and VSE information to ensure adequate and complete wide-field resection. The final resection defect size was measured to ensure that it was significantly larger than the pre-resection polyp size after submucosal injection ([Fig. 4]).

Video 1 Virtual scale endoscope-assisted resection of two large sessile serrated polyps with pre-resection measurement of the polyps and post-resection measurement of the resulting defect for wide field margins.

Fig. 2 Post-submucosal injection size measurement with virtual scale endoscope for polyp 1.

Fig. 3 Computer-aided diagnosis of polyp remnant.

Fig. 4 Resection defect size measurement for polyp 1.

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Publication History

Article published online:
13 December 2022

• References

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