Serrated polyps <10 mm cannot reliably be characterized by i-Scan without magnification at routine colonoscopy

Area of Science:

• Gastroenterology
• Endoscopic diagnostics
• Colorectal cancer prevention

Background:

• Colorectal lesions (CRLs) <10 mm often undergo "diagnose-and-leave" or "resect-and-discard" strategies based on Kudo pit-pattern assessment using i-Scan.
• i-Scan's validation for Kudo pit-pattern classification in routine colonoscopy is lacking.
• Accurate differentiation of hyperplastic polyps (HPs) from other serrated lesions (SLs) and conventional adenomas (CAs) is crucial for appropriate management.

Purpose of the Study:

• To evaluate the reliability of i-Scan, without magnification and optical enhancement (M-OE), in differentiating HPs from SLs and CAs in Kudo type II CRLs <10 mm.
• To assess i-Scan's ability to distinguish HPs from sessile serrated lesions (SSLs) and traditional/unknown serrated adenomas (TSAs/USAs) within the SL category.
• To determine if i-Scan meets the ASGE PIVI negative predictive value (NPV) threshold for adenomas.

Main Methods:

• Prospective recording of CRLs over 12 months.
• Classification of CRLs using i-Scan based on Kudo pit-pattern.
• Retrospective comparison of i-Scan classifications with histological findings.
• Analysis of lesion size (≤5 mm and 6-9 mm) and location (right vs. left colon).

Main Results:

• Type II pit-pattern was significantly associated with HPs and SLs/CAs (P<0.000001).
• Among SLs, i-Scan showed similar Type II pit-pattern prevalence in HPs (81.9%) and SSLs-TSAs (86.6%).
• The PIVI ≥90% NPV threshold for adenomas was met for 6-9 mm CRLs (92.1%) but not for ≤5 mm CRLs (88.2%) or SLs.

Conclusions:

• A "diagnose-and-leave" or "resect-and-discard" strategy is not recommended for SLs <10 mm with Kudo type II pit-pattern using i-Scan, especially in the right colon, when M-OE is unavailable.
• The reliability of i-Scan for differentiating specific serrated lesion subtypes is limited.
• Further validation of endoscopic imaging techniques is needed for accurate in-vivo diagnosis of colorectal lesions.