Colon to Rectum

Gut. 2022;71(5):889–98

Gui X, Bazarova A, del Amor R, Vieth M, de Hertogh G, Villanacci V, Zardo D, Parigi TL, Røyset ES, Shivaji UN, Monica MAT, Mandelli G, Bhandari P, Danese S, Ferraz JG, Hayee B, Lazarev M, Parra-Blanco A, Pastorelli L, Panaccione R, Rath T, Tontini GE, Kiesslich R, Bisschops R, Grisan E, Naranjo V, Ghosh S, Iacucci M

PICaSSO Histologic Remission Index (PHRI) in ulcerative colitis: Development of a novel simplified histological score for monitoring mucosal healing and predicting clinical outcomes and its applicability in an artificial intelligence system

Histological remission is evolving as an important treatment target in ulcerative colitis (UC). The authors aimed to develop a simple histological index, aligned to endoscopy, correlated with clinical outcomes, and suited to apply to an artificial intelligence (AI) system to evaluate inflammatory activity.
Methods: Using a set of 614 biopsies from 307 patients with UC enrolled into a prospective multicenter study, they developed the Paddington International virtual ChromoendoScopy ScOre (PICaSSO) Histologic Remission Index (PHRI). Agreement with multiple other histological indices and validation for inter-reader reproducibility were assessed. Finally, to implement PHRI into a computer-aided diagnosis system, a novel deep learning strategy based on a convolutional neural network (CNN) architecture was trained and tested to detect neutrophils, calculate PHRI and identify active from quiescent UC using a subset of 138 biopsies.
Results: PHRI is strongly correlated with endoscopic scores (Mayo Endoscopic Score and UC Endoscopic Index of Severity and PICaSSO) and with clinical outcomes (hospitalization, colectomy and initiation or changes in medical therapy due to UC flare-up). A PHRI score of 1 could accurately stratify patients’ risk of adverse outcomes (hospitalization, colectomy and treatment optimization due to flare-up) within 12 months. The authors’ inter-reader agreement was high (intraclass correlation 0.84). Their preliminary AI algorithm differentiated active from quiescent UC with 78% sensitivity, 91.7% specificity and 86% accuracy.

Conclusions: PICaSSO Histologic Remission Index (PHRI) is a simple histological index in ulcerative colitis, and it exhibits the highest correlation with endoscopic activity and clinical outcomes. A PHRI-based artificial intelligence system was accurate in predicting histological remission.

DOI:  DOI: 10.1136/gutjnl-2021-326376