Crohn’s disease monitoring depends on assessing inflammatory activity while limiting invasive procedures. Ileocolonoscopy remains the reference standard, but non-invasive imaging can support repeated evaluation of bowel wall structure and perfusion. A 2026 prospective analysis published in Insights into Imaging evaluated super-resolution contrast-enhanced ultrasound (SR-CEUS) in patients who underwent B-mode ultrasound, colour Doppler flow imaging, contrast-enhanced ultrasound and ileocolonoscopy within one week. SR-CEUS generated microvascular maps of the bowel wall and distinguished active from inactive disease more effectively than colour Doppler and conventional contrast-enhanced ultrasound. Combining SR-CEUS with B-mode ultrasound produced the strongest diagnostic performance.
Non-Invasive Assessment Remains Central
Crohn’s disease activity is categorised as active or inactive using clinical, endoscopic and biochemical evidence. Active disease may be associated with complications such as fistulas, abscesses and ileus. Ileocolonoscopy with endoscopic scoring remains central for assessing mucosal activity, but it is invasive and limited in evaluating transmural and extraluminal disease. Cross-sectional imaging techniques, including computed tomography enterography and magnetic resonance enterography, support more complete assessment. Computed tomography enterography involves ionising radiation, while magnetic resonance enterography is costly and has long acquisition times.
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Intestinal ultrasound is promoted in the 2025 ECCO-ESGAR guidance because it is non-invasive, widely available and avoids ionising radiation. B-mode ultrasound assesses bowel wall thickness, wall structure and intra-abdominal complications, although thickening is not specific to Crohn’s disease activity. Colour Doppler flow imaging assesses blood flow in the bowel wall, but it has limited sensitivity for slow flow and small vessels. Conventional contrast-enhanced ultrasound allows real-time assessment of microvascular perfusion, although its spatial resolution remains constrained. SR-CEUS aims to overcome that constraint by localising and tracking individual microbubbles, allowing higher-resolution visualisation of microvascular structure and flow. Standardised ultrasound activity scores also support more objective assessment. Small intestinal contrast ultrasonography can improve lesion detection but adds time and logistical complexity.
Bowel Wall Findings Differed by Activity
The prospective cohort included 52 consecutive patients with Crohn’s disease confirmed through clinical assessment and ileocolonoscopy. Based on the endoscopic score, 30 patients had active disease and 22 had inactive disease. Patients with incomplete data, inadequate image quality or previous intestinal segment resection were excluded. Ileocolonic involvement was the most common location in both groups. All patients underwent the same set of ultrasound examinations within one week of ileocolonoscopy. B-mode ultrasound assessed bowel wall thickness, wall layering, mesenteric lymph nodes and surrounding mesenteric fat. Colour Doppler flow imaging graded bowel wall blood flow, while contrast-enhanced ultrasound assessed enhancement patterns.
B-mode ultrasound showed thicker bowel walls in active disease than in inactive disease. Disruption of the normal layered wall structure appeared more often in active disease, while preserved layers were more common in inactive disease. Mesenteric fat hypertrophy was also more frequent in active disease. Colour Doppler flow imaging more often showed longer blood flow signals connected to the mesentery in active disease, while inactive disease more often showed shorter or dot-like flow signals. On contrast-enhanced ultrasound, complete transmural enhancement appeared most often in active disease. Enhancement limited to the submucosal layer appeared more often in inactive disease.
Microvascular Mapping Added Functional Detail
SR-CEUS generated four types of parametric maps, covering vascular density, vascular directionality, flow velocity and flow direction. These maps enabled high-resolution visualisation of intestinal microvasculature and haemodynamics. In active Crohn’s disease, SR-CEUS showed disorganised and tortuous microvascular patterns, with enlarged vessels and abnormal branching in the inflamed bowel wall. Quantitative parameters related to vessel density and perfusion were higher in active disease than in inactive disease. Measurements were taken from a selected region of interest in the most vascularised section of the thickest inflamed bowel wall. Inter-operator reliability for the quantitative measurements was excellent, with all reported intraclass correlation coefficients above 0.900.
Diagnostic performance was assessed against the endoscopic score. SR-CEUS reached an area under the curve of 0.903 for active disease, with balanced sensitivity and specificity. It performed better than colour Doppler flow imaging and conventional contrast-enhanced ultrasound. B-mode ultrasound alone produced a very similar area under the curve, and direct comparison with SR-CEUS showed no statistically significant difference. The combined model using B-mode ultrasound and SR-CEUS reached an area under the curve of 0.967. This combined approach performed better than B-mode ultrasound alone, reflecting the value of bringing structural and microvascular information together. Larger multicentre prospective work is needed to validate the findings and standardise acquisition protocols.
SR-CEUS provides quantitative microvascular perfusion maps that show vascular density, flow velocity and flow direction in Crohn’s disease. The method distinguishes active from inactive disease more effectively than colour Doppler flow imaging and conventional contrast-enhanced ultrasound, while its standalone performance is similar to B-mode ultrasound. Combining SR-CEUS with B-mode ultrasound gives the strongest diagnostic performance. Important limitations remain, including the single-centre design, small sample size, selection of clearly visualised bowel segments and the effect of intestinal movement on image stability. Further validation and protocol standardisation remain necessary before broader integration into clinical decision-making.
Source: Insights into Imaging
Image Credit: iStock
References:
Wang Y, Ge W, Yu Y et al. (2026) A novel super-resolution contrast-enhanced ultrasound approach for evaluating inflammatory activity in Crohn’s disease. Insights Imaging; 17, 135.
