Contrast-enhanced ultrasound of Crohn's disease in children and young adults: quantitative metric correlations and MRI disease severity associations

Abstract

Background: There is a paucity of data comparing contrast-enhanced ultrasound (CEUS) to MR enterography in children and young adults with Crohn's disease.

Objective: To measure correlations across CEUS quantitative metrics in children and young adults with Crohn's disease, and to evaluate if these metrics are associated with MRI features of disease activity.

Materials and methods: Patients <21 years old with Crohn's disease affecting the terminal ileum who underwent clinically-indicated MR enterography were recruited between 2021 and 2024. Research CEUS of the terminal ileum was performed using sulfur hexafluoride lipid-type A microspheres, and images were analyzed using VueBox (Bracco Group). MRI exams were independently reviewed by three radiologists to document features of disease activity. Pearson's correlation (r) was used to measure associations across nine CEUS quantitative metrics and between CEUS metrics and mean or consensus MRI features.

Results: Twenty-five participants, 13 (52%) male, with a mean age of 16.5 years (range, 13-20 years) were included. The mean terminal ileal maximum bowel wall thickness at MRI was 7.5 mm±1.8 mm. The mean sMaRIA score was 3.4±0.8, consistent with severely active disease. CEUS quantitative measurements were highly variable across participants. The mean rise time was 7.0±2.7 s, while the mean peak enhancement was 3,282±3,754 a.u. Twelve of 36 (36%) CEUS quantitative metric bivariate comparisons were highly collinear with r>0.8 (P<0.0001). There were significant positive correlations between CEUS rise time and MRI maximum bowel wall thickness (r=0.40; P=0.046), visual analog scale assessment of overall inflammation (r=0.43; P=0.032), and postcontrast enhancement ratio (r=0.47; P=0.018); there were no other significant correlations between CEUS metrics and MRI measures of inflammation.

Conclusion: CEUS quantitative measurements are highly variable across patients with Crohn's disease, with multiple metrics being highly correlated with one another. CEUS rise time correlates with MRI features of disease activity.

Keywords: Children; Contrast-enhanced ultrasound; Crohn’s disease; Inflammation; Inflammatory bowel disease; Magnetic resonance imaging; Quantitative; Ultrasound.