Small bowel ultrasound (SBUS) is emerging as a well tolerated, non-invasive, radiation free, low cost measure to assess inflammatory bowel disease (IBD), and is being used as first-line imaging in Europe. SBUS findings have been shown to correlate with endoscopic findings, and a small number of recent studies have looked at change in bowel wall thickness (BWT) in response to anti-tumor necrosis factor (anti-TNF) therapy. However, the use of SBUS to detect response to anti-TNF therapy has not been tested in pediatric patients. The purpose of this study is to apply the use of SBUS to pediatric patients with Crohn's disease and to assess response to treatment with infliximab. The investigators will also measure C-reactive protein and fecal calprotectin at baseline, and additionally measuring IFX levels and anti-infliximab antibodies (ATI) at week 14 to assess change in biochemical response to infliximab treatment, as well as correlation between these markers with changes in patient reported outcomes via a weighted pediatric Crohn's disease activity questionnaire (wPCDAI) and changes in BWT. This study is novel in that it will be the first study in pediatric patients to use SBUS to assess response to IFX therapy, and will also be the first study to correlate SBUS findings with therapeutic drug monitoring (TDM). This study has the potential to propagate the use of SBUS in the pediatric population, as the use of TDM in concert with small bowel imaging post-induction will allow the investigators to tailor therapy early in the treatment course.