Role of intestinal ultrasound in ulcerative colitis: A systematic review

Table 3 Role of intestinal ultrasound in predicting response to therapy in ulcerative colitis

Ref.	Study type	Number of patients	Treatment agent(s)	IUS predictor(s)	Follow-up duration	Time points of IUS	Therapeutic outcomes
Dubbins[25]	Retrospective	9 UC (19 CD)	Steroid ± immunosuppressive therapy	BWT	2-4 mo	Baseline, 2-4 mo	No significant change in BWT in UC but there was significant response in CD
Maconi et al[38]	Prospective	30 active UC	Steroids	BWT	2 mo	Baseline and 2 mo	Significant reduction in BWT in clinical responders; IUS response significantly correlated with clinical biochemical and endoscopic activity
Yoshida et al[26]	Prospective	26 UC	Cytaphresis + conventional therapy	BWT	1 year	Baseline and 2-3 wk	Early IUS response (decrease in BWT by 2.5 mm at 2-3 wk) predicted 1 year response (91% vs 40%) lower relapse (9% vs 47%)
Goertz et al[27]	Prospective	7 UC	Vedolizumab	BWT, CDS, CEUS- amplitude and time derived parameters	14 wk	Baseline, 14 wk	Decrease in CDS intensity. Decrease in amplitude dependent CEUS parameters (peak enhancement and wash in rates)
Maaser et al[28]	Prospective, multi centre	224 UC	Steroid, anti-TNF, anti-integrin, AZA/6-MP	BWT, BWS, CDS, haustration, lymph nodes, inflammatory fat, ascites	16 wk	Baseline, 2, 6, and 12 wk	Significant improvement in IUS parameters was seen as early as 2 wk. Significant correlation of normalisation of BWT at 12 wk with clinical improvement and biomarkers
Les et al[29]	Prospective	28 UC (89 CD)	5-ASA, budesonide, AZA, anti-TNF	BWT, BWS, CDS, i-fat, lymph nodes	6 mo	Baseline	Predictors (overall IBD); immediate treatment escalation (31.7%) Score = 1/[1 + Exp (-XB)] where XB = 0.75 × [BWT (mm)] + 3.5 × (CDS = 1) – 7.31; AUC: 0.94, score > 0.5 100% sensitivity, 83% specificity; subsequent treatment escalation (17.9%), AUC: 0.92; Score = 1/[1 + Exp (-XB)] where XB = 0.8X [bowel wall thickness (mm)] - 1.3X (Presence of wall stratification =1) – 3.82 Score > 0.6 has 90% sensitivity, 86.4% specificity
Smith et al[30]	Retrospective	23 CD, 8 UC (22 CD and 7 UC on biologics)	Anti-TNF, ustekinumab, vedolizumab	BWT, CDS	46 wk	2, 6, and 14 wk	16% improvement in BWT at 6 wk and 10% improvement at wk 14 predicted treatment persistence/response at 46 wk
Vaughan et al[31]	Prospective	79 UC and 24 CD	Maintenance infliximab	BWT, CDS	Cross-sectional (median disease duration 8 years)	Cross-sectional data	Lower infliximab trough level was associated with higher CDS in both UC and CD
Helwig et al[32]	Post-hoc analysis of prospective, multi centre studies	131 UC (118 CD)	Standard of care	BWT, CDS, BWS, i-fat, transmural healing, transmural response	52 wk	0, 12, 52 wk	76.6% TR and 45%-61.4% TH at 12 wk after treatment intensification
de Voogd et al[33]	Longitudinal, prospective	30 UC on tofacinib	Tofacitinib	BWT	8 wk	Baseline and 8 wk	Most accurate BWT cut-off for endoscopic remission was 2.8 mm; for endoscopic response: 3.9 mm and > 32% decrease in BWT
Ilvemark et al[34]	Blinded, prospective multi centre, observational	56 acute severe UC	IV steroid	BWT	48 h and 6 d	Baseline, 48 ± 24 h and 6 ± 1 d	≤ 20% reduction in BWT has 84.2% sensitivity and 78.4% specificity for determining non-response (AUC: 0.85)
Allocca et al[19]	Prospective	49 UC	Infliximab, adalimumab, vedolizumab, ustekinumab	Milan ultrasound criteria based on BWT and CDS intensity	1 year	Baseline, week 12, and 1 year	MUC ≤ 6.2 at week 12 independent predictor of MES ≤ 1; A ≥ 2 reduction in MUC predicted MES = 0
de Voogd et al[33]	Prospective, single center	51 UC patients	Steroids, 5-ASA, thiopurines, biologics, tofacitinib, cyclosporin	BWT, CDS, haustrations, BWS, fat wrapping, lymph nodes	26 wk	Baseline, week 2, week 6, weeks 8-26	BWT and CDS at weeks 2 and 6 predicted endoscopic remission and response at 8-26 wk

CD: Crohn’s disease; TNF: Tumor necrosis factor; TH: Transmural healing; BWT: Bowel wall thickness; CDS: Color doppler signal; IUS: Intestinal ultrasound; CEUS: Contrast enhanced ultrasound; TI: Terminal ileum; RCT: Randomized controlled trial; IFX: Infliximab; SWE: Shear wave elastography; SUS-CD: Simple Ultrasound Activity Score for CD; IBUS-SAS: International Bowel Ultrasound Segmental Activity Score; BUSS: Bowel Ultra-Sound Score; SICUS: Sall Intestine Contrast Ultrasonography.