Ultrasound Evaluation of Crohn's Disease

The purpose of this study is to assess the effectiveness of a new ultrasound technology for evaluating Crohn's disease.

The investigators will study the efficacy of ultrasound shear wave elastography and vascularity imaging for Crohn's Disease (CD) evaluation. Literature evidences demonstrate that bowel stiffness is correlated with fibrosis, while bowel vascularity and perfusion is correlated with inflammation. Therefore, the investigators expect the combination of shear wave elastography and vascularity imaging can increase the sensitivity and specificity of CD evaluation. Ultrasound is safe, cost-effective, and widely accessible, thus provides an attractive alternative to the clinical standard Computed Tomography (CT), risks of radiation)) and Magnetic Resonance Imaging (MRI), more expensive and limited accessibility)). Because ultrasound may not be able to image bowel loops deep in the body, its main role is for follow-up after initial screening by CT or MRI, especially for terminal ileum, which is easily accessible by ultrasound and the most frequently affected bowel segment for CD.

Subjects will receive ultrasound exams of the bowel with 2 different machines (Ultrasound Elastography and Ultrasound Vascularity) at three time points: baseline, 4 weeks, and 6 months. The ultrasound exams will be performed at first with no contrast agent, and then ultrasound measurements will be repeated with 1-2 ml of Sulfur Hexafluoride, a contract agent. Subjects also will receive Magnetic Resonance Enterography (MRE) exams at baseline and 6 months as part of their clinical care.

Subjects will receive ultrasound (US) imaging of the terminal ileum without and with sulfur hexafluoride contrast at baseline, 4 week and 6 months. Subjects will receive one to two milliliters of the contrast agent.

Subjects will receive US Imaging with the GE Logiq E9 Ultrasound Scanner at baseline, 4 week and 6 months without and with contrast.

Subjects will receive US Imaging with the Verasonics Ultrasound Scanner at baseline, 4 week and 6 months without and with contrast.

Shear wave speed is a measure of small bowel stiffness; this will be measured on the General Electric (GE) Logiq E9 Ultrasound Scanner.

Vessel density is a measure of the vascularity of the bowel. It is the percentage of pixels in the bowel lesion with blood flow compared to the total area of the lesion. This will be measured with the Verasonics Ultrasound Scanner.

Inclusion Criteria: - Crohn's disease patients with involvement of terminal ileum (thickness > 3mm). Exclusion Criteria: Patients with change of medicine or going to surgery over the 6-months follow-up period. Patients with unreliable ultrasound images due to conditions such as large body habitus or poor ultrasound imaging window. Adults lacking capacity to consent. Vulnerable subjects such as prisoners. Pregnant women and nursing mothers. Patients with known or suspected right-to-left, bi-directional, or transient right-to-left cardiac shunts. Patients with history of hypersensitivity allergic reactions to ultrasound contrast agents.