Contrast harmonic imaging for vascularization assessment of the small bowel in Crohn's disease: A feasibility study

Contrast harmonic imaging employing a multi-frequency linear transducer represents a new technique, which allows high resolution imaging of microcirculation in vivo. The aim of this study was the evaluation of this approach for assessing bowel wall vascularization in patients with active Crohn's disease.

We evaluated this technique in 12 patients with active Crohn's disease. All patients had a CE MR-enteroclysis (MRE) as a baseline examination.

Using a novel multi-frequency linear transducer (6–9MHz, Logig 9, GE) we examined the affected thickened small bowel applying power Doppler (PD) and coded duplex ultrasound. To assess the vascularization of the bowel wall, contrast-enhanced ultrasound with contrast harmonic imaging (CHI) was performed in pulse inversion mode (PIHI) utilizing the true detection mode (2.5ml Sonovue®). The MRE examinations as well as the digitally archived ultrasound examinations were assessed by 2 radiologists independently. Doppler ultrasound as well as PD visualized just vascularization of the outer layer of the affected small bowel wall, whereas CHI with PIHI impressively demonstrated a mural vascularization in all patients with active Crohn's disease. Especially in patients with severe symptoms the quantitative CHI showed transmural vascularization with a major signal increase up to 10 dB (4–10 dB, mean 7.5 dB). In this study we were able to visualize vascularization of different bowel wall layers in patients with active Crohn's disease. This innovative technique allows subtle bowel wall imaging most likely with a superior temporal and spatial resolution compared with MRI enriched by the option of dynamic quantitative contrast uptake analysis.