Development and validation of an automated algorithm to evaluate the abundance of bubbles in small bowel capsule endoscopy

• Published in: Endoscopy International Open Vol. 6; no. 4; pp. E462 - E469
• Main Authors: Pietri, Olivia, Rezgui, Gada, Histace, Aymeric, Camus, Marine, Nion-Larmurier, Isabelle, Li, Cynthia, Becq, Aymeric, Abou Ali, Einas, Romain, Olivier, Chaput, Ulriikka, Marteau, Philippe, Florent, Christian, Dray, Xavier
• Format: Journal Article
• Language: English
• Published: Stuttgart · New York Georg Thieme Verlag KG 01.04.2018
• Subjects: Original article
• ISSN: 2364-3722; 2196-9736; 2196-9736
• DOI: 10.1055/a-0573-1044

Abstract Background and study aims  Bubbles can impair visualization of the small bowel (SB) mucosa during capsule endoscopy (CE). We aimed to develop and validate a computed algorithm that would allow evaluation of the abundance of bubbles in SB-CE still frames. Patients and methods  Two sets of 200 SB-CE normal still frames were created. Two experienced SB-CE readers analyzed both sets of images twice, in a random order. Each still frame was categorized as presenting with < 10 % or ≥ 10 % of bubbles. Reproducibility (κ), sensitivity (Se), specificity (Sp), receiver operating characteristic curve, and calculation time were measured for different algorithms (Grey-level of co-occurrence matrix [GLCM], fractal dimension, Hough transform, and speeded-up robust features [SURF]) using the experts’ analysis as reference. Algorithms with highest reproducibility, Se and Sp were then selected for a validation step on the second set of frames. Criteria for validation were κ = 1, Se ≥ 90 %, Sp ≥ 85 %, and a calculation time < 1 second. Results  Both SURF and GLCM algorithms had high operating points (Se and Sp over 90 %) and a perfect reproducibility (κ = 1). The validation step showed the GLCM detector strategy had the best diagnostic performances, with a Se of 95.79 %, a Sp of 95.19 %, and a calculation time of 0.037 seconds per frame. Conclusion  A computed algorithm based on a GLCM detector strategy had high diagnostic performance allowing assessment of the abundance of bubbles in SB-CE still frames. This algorithm could be of interest for clinical use (quality reporting) and for research purposes (objective comparison tool of different preparations).