Quantitative assessment of bowel wall vascularisation in Crohn's disease with contrast-enhanced ultrasound and perfusion analysis

Patients with inflammatory bowel disease (IBD) often undergo several radiologic imaging studies, which - with the exception of magnetic resonance imaging (MRI) and B-scan ultrasound (US) - subject patients to ionizing radiation. With contrast enhanced ultrasound microvascular imaging of the bowel is possible. Hence, the aim of our study was to assess the perfusion pattern of inflamed bowel walls in Crohn's disease compared with healthy volunteers quantitatively using a specific quantification software. We evaluated 4 volunteers and 20 patients with proven Crohn's disease, who went through an active episode based on clinical symptoms and complementary imaging by MRI (19 patients) and computed tomography (1 patient), respectively, with dynamic contrast-enhanced ultrasound (CEUS) using a second generation contrast agent (SonoVue, Bracco, Germany). Retrospectively, we applied the quantification software Qontrast (Bracco, Italy) to obtain contrast-enhanced sonographic perfusion maps for each lesion. Patients had significant higher peak values (median 46.86, lower quartile 37.91, upper quartile 53.20) and significant higher regional blood volume (median 2133.65, lower quartile 1202.90, upper quartile 2820.44) than volunteers. Considering the very low peak value of the healthy, it is easy to understand that the time-to-peak was significantly shorter in the volunteers (median 4.45, lower quartile 1.82, upper quartile 6.88) than in the patients (median 12.15, lower quartile 9.18, upper quartile 15.74). Our study showed clear differences between inflamed and normal bowel wall vascularity regarding all perfusion parameters. These results show that a quantitative assessment of the bowel wall vascularisation and inflammation, respectively, is possible. The software used here enables us to collect data, not only in a semi-quantitative but also in a reproducible, quantitative manner which is comparable with the evaluation of CT or MRI generated data.