Ultrasound assessment of vascularization of the thickened terminal ileum wall in Crohn's disease patients using a low-mechanical index real-time scanning technique with a second generation ultrasound contrast agent

Abstract

Objective To prospectively evaluate the vascularization of the thickened terminal ileum in Crohn's disease patients using contrast enhanced ultrasound (CEUS) and to compare the clinical activity measured by the Crohn's disease activity index (CDAI) with the CEUS findings. Patients and methods Forty-eight of 104 consecutive patients (17 females and 31 males, aged 42.4 ± 13.8 years) with a thickened terminal ileum at sonography were recruited for the study. CEUS examinations were performed using a real-time low mechanical index harmonic ultrasound technique after intravenous injection of a second generation contrast agent. We used two parameters to assess the vascularization of the bowel wall: a semi-quantitative method, the pattern of enhancement (which is the description of the arrangement of the enhanced layer in the bowel wall) and a quantitative method, the E/ W ratio (which is the ratio between the major thickness of the enhanced layer, E, and the thickness of the entire wall section, W). In order to assess the accuracy of the CEUS findings in discriminating between active and inactive patients according to CDAI values (>150 and ≤ 150, respectively), the patterns of enhancement (four patterns) were dichotomized in two groups and an E/ W ratio cutoff value was calculated to differentiate between poor and abundant bowel wall enhancement. Results The CEUS findings, namely the pattern of enhancement and the E/ W ratio (best cutoff value ranging between 0.43 and 0.47), had a sensitivity of 81.0% and 81.0%, respectively, a specificity of 63.0% and 55.6%, respectively, a positive predictive value of 63.0% and 58.6%, respectively, and a negative predictive value of 81.0% and 78.9%, respectively, in distinguishing patients with active and inactive disease. Conclusions CEUS assessment of diseased bowel wall vascularization may be a sensitive tool for the detection of inflammatory activity.