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

Table 11 Summary of studies comparing intestinal ultrasound and magnetic resonance enterography or computed tomography enterography

Ref.	Study type	Number of patients	Follow up	Comparator	IUS parameter	Gold standard	Result
Miao et al[135], 2002	Prospective, single center	30 CD	15 months (median)	Ultrasound and MRI	BWT and contrast enhancement	Clinical + endoscopy/barium/surgery	Sensitivity: MRI (100%)> IUS (87%). Specificity: IUS (87%)> MRI (71%)
Schmidt et al[136], 2003	Prospective	48 CD	Three investigations done within 16 months	MRE, CT enteroclysis	Length of inflamed bowel, wall thickness, stenosis, fistula, abscess		MRE and IUS could predict all the parameters accurately except fistula where CT Enteroclysis was highly sensitive
Maccioni et al[145], 2014	Prospective	50 known pediatric CD	MRE done within 15 days	MRE	High resolution ultrasound	Capsule endoscopy, barium study	MRE identified jejunal lesions not detected in high resolution ultrasound (n = 2). False positive MRE findings in proximal to mid ileum (n = 1). 100% sensitivity and specificity of MRE in terminal ileum
Allocca et al[141], 2018	Prospective	60 ileo-colonic CD	20 Months	CS + MRE and MRE alone	Localisation, bowel wall flow, active disease, structure, fistula and abscess	MRE and colonoscopy	IUS highly specific (> 85%), sensitive (> 85%), accurate (about 90%) with high negative predictive value (> 85%) except for stricture (75% sensitivity). Excellent positive predictive value except for CD complications Concordance in CD management in about 80%
Taylor et al[1], 2018	Prospective, multi center	284 (newly diagnosed and relapsed CD)	6 months	MRE + IUS	Presence and extent of small, bowel disease	MRE	Extent of SB disease. Sensitivity: MRE (80%) > IUS (70%). Specificity: MRE (95%) > IUS (81%). Presence of SB disease. Sensitivity: MRE (97%) > IUS (92%). Specificity: MRE (94%) > IUS (84%)
Yuksel et al[142], 2019	Prospective, observational	71 known CD	1 Month	MRE, ileocolonoscopy	BWT, CDS, BWS, mesenteric fat, stenosis, dilation, rigidity	Ileocolonoscopy	Sensitivity to identify loss of stratification and stenosis was better with MRE Specificity for BWT, BWS and stenosis better with IUS
Hakim et al[54], 2020	Retrospective	93 CD (pediatric) (known, suspected)	Cross-sectional	MRE	Presence of lesion, stricture and dilation	MRE	Substantial agreement for presence of lesions (κ = 0.63), stricture (κ = 0.77) and dilation (κ = 0.68)
Bhatnagar et al[147], 2020	Prospective	38 (11 new, 27 relapsing)	2 IUS examinations done within 7 days	IUS	Mural and extra-mural features	MRE	Agreement for presence of Small bowel disease (MRI): 82% (new diagnosis). 81% (relapsing cohort). Colonic disease 64% (new diagnosis) 78% (relapsing cohort)
Kamel et al[138], 2020	Prospective	40 (14 UC, 26 CD)	Cross-sectional	Bowel ultrasound and MRE	BWT, CDS, mesenteric fat and lymph nodes, complication	MRE and colonoscopy	Accuracy of IUS: 85% ileum, 70% large bowel, 95% for fistula, strictures and proximal dilatation and 100% for abscess
Livne et al[139], 2020	Retrospective	42 CD	< 3 months between IUS and MRE	MRE	BWT, CDS, BWS, mesenteric fat, complications	MRE	Terminal ileum thickness and mesenteric fat proliferation are useful to build a stepwise regression model which can predict MARIA score in terminal ileum on MRE
Calavrezos et al[137], 2022	Retrospective	54 IBD (44 CD)	< 3 months between IUS and MRE	MRE	BWT, CDS, BWS	MRE	MRE and IUS were comparable in detecting active inflammation and complications. There was concordance in therapeutic decisions
Xu et al[68], 2023	Retrospective	115 CD	Investigations done within 7 days of each other	CTE, MRE	IBUS-SAS	MRE, IBUS	Sensitivitysmall bowel: MRE > IUS. Terminal ileum: IUS > MRE. Colon: IUS, CTE, MRE similar. IBUS-SAS ≥ 46.7 predicted active disease with AUC of 0.86
Ahmad et al[143], 2022	Correlation study	376	Not specified	MRE	Bowel wall enhancement and thickness	Clinical evaluation	Strong positive correlation (r = 0.83) between IUS and MRE findings for disease activity
Castiglione et al[140], 2013	Prospective	234	Not specified	MRE	BWT, disease extension	Ileocolonoscopy	Comparable sensitivity for IUS (94%) and MRE (96%); MRE superior in defining disease extension
Dillman et al[144], 2015	Prospective	29 pediatric CD	Multiple assessments	MRE	Bowel wall thickness, strictures, abscesses	MRE	Moderate to substantial agreement for BWT and complications (κ = 0.61–0.96)
Hakim et al[54], 2020	Retrospective	93 pediatric CD	Cross-sectional	MRE	Lesions, strictures, dilatation	Ileocolonoscopy, MRE	Substantial agreement for strictures (κ = 0.77) and lesions (κ = 0.63)
Malagò et al[47], 2012	Prospective	30	Not specified	MRE	Vascularity, lesion length, wall thickness	Clinical and imaging correlation	High correlation between CEUS and MRE for bowel wall vascularity and thickness; CEUS is a low-cost alternative
Onali et al[57], 2012	Prospective	15	≤ 3 months pre-surgery	CT Enteroclysis	Strictures, fistulas, abscesses	Surgical findings	SICUS and CT enteroclysis had comparable sensitivity and specificity for lesions; SICUS is non-invasive and radiation-free
Pauls et al[46], 2006	Prospective	21	21 months	Dynamic MRI	Bowel wall vascularity, segment length	MRI and histology	Significant correlation between CEUS and MRI for disease activity; CEUS effective in differentiating inflammatory vs fibrostenotic processes
Statie et al[151], 2023	Prospective	44	27 months	MRE	BWT, Limberg score	Clinical severity (CDAI, HBI)	Limberg score sensitivity of 93.33% and specificity of 71.43% for active disease; MRE better correlated with fecal calprotectin
Xu et al[68], 2023	Retrospective	115	7 days (comparison)	MRE, CT enterography	IBUS-SAS	Endoscopy	IBUS-SAS cutoff ≥ 46.7 predicted active disease (AUC = 0.86); MRE more sensitive for small bowel disease, IUS better for terminal ileum lesions

IUS: Intestinal ultrasound; CD: Crohn’s disease; UC: Ulcerative colitis; MRE: Magnetic resonance enterography; CTE: Computed tomography enterography; BWT: Bowel wall thickness; BWS: Bowel wall stratification; AUC: Area under curve; IBUS-SAS: International bowel ultrasound segmental activity score; MRI: Magnetic resonance imaging; CS: Colonoscopy; CDS: Color doppler signal; MARIA: Magnetic resonance index of activity; CEUS: Contrast-enhanced ultrasound; SICUS: Small intestinal contrast ultrasound; CDAI: Crohn’s disease activity index; HBI: Harvey Bradshaw Index.