Endoscopy 2018; 50(03): 211-220
DOI: 10.1055/s-0043-121570
Original article
© Georg Thieme Verlag KG Stuttgart · New York

BASIC (BLI Adenoma Serrated International Classification) classification for colorectal polyp characterization with blue light imaging

Raf Bisschops
1  Department of Gastroenterology and Hepatology, Catholic University of Leuven (KUL), TARGID, University Hospitals Leuven, Leuven, Belgium
,
Cesare Hassan
2  Gastroenterology, Nuovo Regina Margherita Hospital, Rome, Italy
3  Digestive Endoscopy Unit, Humanitas University, Milan, Italy
,
Pradeep Bhandari
4  Solent Centre for Digestive Diseases, Portsmouth Hospital, Portsmouth, United Kingdom
,
Emmanuel Coron
5  Hepatogastroenterology, Centre Hospitalier Universitaire Hotel Dieu, Nantes, France
,
Helmut Neumann
6  First Medical Department, University Medical Center Mainz, Mainz, Germany
,
Oliver Pech
7  Department of Gastroenterology and Interventional Endoscopy, Krankenhaus Barmherzige Brüder Regensburg, Regensburg, Germany
,
Loredana Correale
2  Gastroenterology, Nuovo Regina Margherita Hospital, Rome, Italy
,
Alessandro Repici
3  Digestive Endoscopy Unit, Humanitas University, Milan, Italy
› Author Affiliations
Further Information

Publication History

submitted 06 June 2017

accepted after revision 12 October 2017

Publication Date:
24 October 2017 (eFirst)

Abstract

Background and study aim Advanced endoscopic imaging has revolutionized the characterization of lesions during colonoscopy. The aim of this study was to create a new classification for differentiating subcentimetric hyperplastic and adenomatous polyps, and deeply invasive malignant lesions using blue-light imaging (BLI) with high definition, with and without optical magnification, as well as to assess its interobserver concordance.

Methods A video library consisting of 48 videos/still images (with/without optical magnification) from 24 histologically verified polyps/cancer with BLI was prospectively created. In the first step, seven endoscopists with experience in electronic chromoendoscopy reviewed 12 BLI videos/still images with/without magnification representative of the different histotypes, and individually identified possible descriptors. In the second step, these descriptors were categorized and summarized with a modified Delphi methodology. In the third step, the seven endoscopists independently reviewed the remaining 36 videos/still images with/without optical magnification, and the interobserver agreement for the new descriptors was assessed. The interobserver agreement between endoscopists was assessed using Gwet’s AC1.

Results By reviewing the initial 12 videos/still images, 43 descriptors were proposed. By a modified Delphi process, the endoscopists eventually agreed on summarizing 12 descriptors into three main domains. The main domains identified were: polyp surface (mucus, yes/no; regular/irregular; [pseudo]depressed, yes/no), pit appearance (featureless, yes/no; round/nonround with/without dark spots; homogeneous/heterogeneous distribution with/without focal loss), and vessels (present/absent, lacy, pericryptal, irregular). Interobserver agreement for the polyp surface domain appeared to be almost perfect for mucus (AC1 0.92 with and 0.88 without optical magnification), substantial for the regular/irregular surface (AC1 0.67 with and 0.66 without optical magnification). For the pit appearance domain, interobserver agreement was good for featureless (AC1 0.9 with and 0.8 without optical magnification), and round/nonround (AC1 0.77 with and 0.69 without optical magnification) descriptors, but less consistent for the homogeneity of distribution (AC1 with/without optical magnification 0.58). Agreement was almost perfect for the vessel domain (AC1 0.81 – 0.85).

Conclusions The new BASIC classification takes into account both morphological features of the polyp, as well as crypt and vessel characteristics. A high concordance among the observers was shown for most of the summarized descriptors. Optical magnification had a beneficial effect in terms of interobserver agreement for most of the descriptors.

Appendix Tables e1 – e7