Intestinal Ultrasound and Its Advanced Modalities in Characterizing Strictures in Crohn's Disease.

Background And Aims
Crohn's disease (CD) strictures exhibit varying levels of inflammation and chronicity. We evaluate whether intestinal ultrasound (IUS) is accurate in characterizing stricture composition.
Methods
This prospective, cross-sectional study included CD patients who underwent (IUS) prior to a small bowel segment resection. Histology in the resection specimen was assessed in location-matched tissue sections. Following a consensus session, two pathologists blindly assessed the predominant phenotype (inflammatory (IP), chronic (CP) or a mixed (MP)) in the strictures. The primary objective of the study was to find a parameter to identify strictures with IP.
Results
A total of 36 patients were included (IP:7 (20%), CP:16 (44%), MP:13 (36%)). Univariate analysis showed a positive association with an IP for loss of wall layer stratification (WLS) (OR:7.86, p=0.029) and higher contrast-enhanced ultrasound (CEUS) parameters. Bowel wall thickness (BWT) (5.74 vs 7.46 mm, p=0.002) was lower and colour Doppler signal (CDS) (OR:0.14, p=0.03) and loss of WLS (OR:0.14, p=0.027) were less present in CP. In multivariate analysis, loss of WLS and wash-in area under the curve at CEUS indicated an IP, whereas lower BWT and CDS≤2 indicated a CP. With these parameters, the Stricture Score Amsterdam (SSA) was constructed and demonstrated accuracy for IP (AUROC:0.88, p=0.002) and CP (AUROC:0.90, p<0.0001), respectively. Inter-observer agreement for the score was good (ICC:0.73, p<0.0001).
Conclusion
A combination of IUS and CEUS is accurate to differentiate between inflammatory and chronic strictures in CD. The SSA needs external validation and confirmation in its potential as a diagnostic decision aid when choosing between surgical and available medical treatments.