Imaging of Low Back Pain in Adolescents and Young Adults: Looking Beyond the Usual Suspects

Low back pain is one of the most common causes of primary care visits in the United States and can begin early in life. When imaging is performed, MRI is the diagnostic test of choice after radiographs, but MRI findings can be subtle, and CT may also play a diagnostic role. This article reviews clinical and imaging findings of some less common causes of low back pain in young people: ring apophysis fractures; stress fractures of the pars interarticularis, pedicle, and sacrum; atypical Scheuermann disease; and nonradiographic axial spondyloarthritis. The most difficult of these entities to detect on MRI is the fracture of the ring apophysis, which mimics disc herniation. MRI detection of stress fractures is improved using spoiled gradient-echo thin-slice 3D T1 volumetric interpolated breath-hold examination and 2D Dixon techniques. Atypical Scheuermann disease can be distinguished from compression fractures, infection, and spondyloepiphyseal dysplasia tarda by the presence of undulating endplates without erosions and the absence of platyspondyly. Fat-suppressed fluid-sensitive axial MRI images are helpful in the detection of nonradiographic axial spondyloarthritis.

Learning Objective: To identify less common etiologies of low back pain that may present in adolescents and young adults using various radiologic modalities and techniques.