Intestinal ultrasound in Crohn’s disease: A systematic review of its role in diagnosis, monitoring, and treatment response

Table 1 Summary of studies evaluating impact of intestinal ultrasound in the management of Crohn’s disease

Ref.	Study type	Number of patients	Impact on management
Novak et al[18], 2015	Prospective	49 CD	Clinical decisions changed in up to 60% of cases post-IUS compared to before IUS. Half of the patients with clinically asymptomatic disease had active disease on IUS
Wilkens et al[19], 2015	Retrospective	115 CD	70% with mild or no endoscopic inflammation on ileo-colonoscopy had moderate to severe disease on IUS. 75% of the above group had significant management changes
Kakkadasam Ramaswamy et al[27], 2020	Prospective	35 CD	IUS findings of BWT, BWS, and CDS activity correlate with endoscopic and clinical indices. Sensitivity (MRE gold standard): Transverse colon (100%) > ileum (93.7%) > left colon (89%) > right colon (80%). Specificity: 100% (all segments)
Freitas et al[39], 2022	Retrospective	50 CD	SUS-CD and IBUS-SAS scores in IUS were not different between active and inactive disease. Peak intensity in contrast-enhanced IUS correlated well with endoscopic activity (AUC: 0.80)
Bots et al[20], 2022	Retrospective	280 CD	60% had an impact on disease management and predicted preclinical relapse. Good correlation with MRI (86.3%) and endoscopy (80%). Use of MRI reduced after IUS
Allocca et al[64], 2022	Prospective	225 ileal and/or colonic disease	Bowel ultrasound score > 3.52, complications (stricture, fistula, abscess), fecal calprotectin ≥ 250 µg/g, and male sex predicted the 12-month course in CD
Esteban et al[23], 2001	Prospective	79	Color Doppler ultrasound showed increased vascularity in active CD. RI was lower in active vs inactive cases, correlating with clinical and histological activity
Goertz et al[26], 2021	Retrospective	221	Bowel wall thickening (> 3 mm) and hypervascularization strongly correlated with histological inflammation in Crohn’s ileitis. Limberg score had significant correlation with histopathology
Pedersen et al[22], 1986	Prospective	30 CD, 27 controls	Dynamic ultrasound detected bowel wall thickening (target lesions) in 67% of radiologically confirmed CD. Found useful for follow-up to reduce repeated radiographic exams

CD: Crohn’s disease; UC: Ulcerative colitis; IUS: Intestinal ultrasound; SUS-CD: Simple ultrasound activity score for Crohn’s disease; IBUS-SAS: International bowel ultrasound segmental activity score; AUC: Area under the curve; BWT: Bowel wall thickness; BWS: Bowel wall stratification; CDS: Colour doppler signal; MRI: Magnetic resonance imaging; MRE: Magnetic resonance enterography; RI: Resistive index.