Skeletal Health and Bone Marrow Composition in Newly Diagnosed Adolescents With Crohn Disease

The investigators will be evaluating bone marrow composition via magnetic resonance imaging in newly diagnosed adolescents with Crohn disease (CD) compared to healthy, matched controls. The investigators will also be assessing their bone mineral density via other imaging modalities, including dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. This longitudinal project will focus on abnormalities in bone marrow composition, and specifically whether adolescents with newly diagnosed CD exhibit increased bone marrow fat, its association with bone mineral density (BMD) and the underlying pathophysiology, including bone turnover markers and immune cellular/molecular parameters.