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

Table 5 Summary of studies evaluating role of intestinal ultrasound elastography in characterizing strictures in Crohn’s disease

Ref.	Study type	Number of patients	IUS parameter	Follow up	Results
Maconi et al[72], 2003	Retrospective	43 (with single ileal stenosis undergoing surgery)	Echo pattern at stenosis site	Cross sectional	Stratified echo pattern: Fibrotic stricture; Hypoechoic pattern: Inflammatory stricture; Mixed echo pattern: Mixed stricture
Fraquelli et al[76], 2015	Prospective	23 ileal or ileocolonic CD for surgery (20 inflammatory CD as controls)	Quantitative strain ratio in ileum	Cross sectional	Higher strain ratio indicated higher ileal fibrosis based on semiquantitative and quantitative analysis (Masson’s trichrome staining). Excellent inter-rater agreement for assessing strain ratio
Serra et al[77], 2017	Prospective	26 symptomatic stricturing CD	MSR	Cross sectional	No significant correlation was found between MSR and fibrosis score (P = 0.877). MSR could not distinguish fibrotic from inflammatory stricture
Chen et al[73], 2018	Prospective	35 with ileal/ileocolonic stricture enrolled	SWE, Vascularization	Cross sectional	22.55 KPa was the cut-off in discriminating mild-moderate vs severe fibrosis (AUC 0.822). Vascularization (Limberg III/IV) predicted severe inflammation vs mild-moderate inflammation (AUC 0.811)
Orlando et al[78], 2018	Prospective	30 ileal/ileocolonic CD	Strain ratio	20 months (median)	Inverse correlation between strain ratio at baseline and thickness variations on anti-TNF therapy at 12 and 52 weeks. Baseline strain ratio lower in patients with transmural healing
Ding et al[85], 2018	Prospective	25 strictures	Strain elastography, ARFI, and SWE	Cross sectional	Shear wave velocity > 2.73 m/s had the highest accuracy (96%) compared to ARFI (accuracy 76%) and strain elastography (accuracy 68%)
Wilkens et al[87], 2018	Prospective	25 CD	Contrast enhancement	Cross sectional	No correlation between inflammation and fibrosis on histology with contrast-enhanced ultrasound (r = 0.16, P = 0.45 for inflammation and r = -0.28, P = 0.19 for fibrosis)
Ueno et al[84], 2022	Retrospective	36 CD	ARFI	30 months	Strong correlation noted between fibrocyte numbers and ARFI on IUS (R = 0.8383). High fibrocyte number associated with escalation of medical therapy and endoscopic/surgical treatment at 30 months follow-up
Zhang et al[81], 2022	Retrospective	37 CD	Shear wave elastography and CT enterography	30 months	The cut-off value for fibrotic lesions stiffness > 21.30 KPa (AUC: 0.877, sensitivity: 88.90%, specificity: 89.50%, 95%CI: 0.755–0.999, P < 0.001)
Sidhu et al[50], 2023	Retrospective	25 Pediatric	Shear wave elastography	Cross-sectional	SWE differentiated fibrotic from inflammatory strictures with good accuracy
Chen et al[73], 2024	Retrospective	130	SWE and stiffness thresholds	33 months	SWE (> 12.75 kPa) predicted progression to stricturing/penetrating disease with AUC: 0.792
Zhao et al[82], 2021	Retrospective	19	Histologic correlation with stiffness	Cross-sectional	Bowel stiffness correlated strongly with histopathology, including fibrosis and chronic inflammation (r > 0.69, P < 0.001)

IUS: Intestinal ultrasound; CD: Crohn's disease; AUC: Area under the curve; ARFI: Acoustic radiation force impulse; TNF: Tumor necrosis factor; SWE: Shear wave elastography; MSR: Mean strain ratio; CT: Computed tomography.