Imaging studies commonly included in the evaluation of patients with ESFT are plain radiographs of primary and metastatic sites, bone scintigraphy, plain radiographs and computed tomography of the chest, and magnetic resonance imaging (MRI) of the primary site. MRI is the most sensitive imaging modality for delineating the extent of tumor in the medullary cavity and in soft tissue. Imaging features favoring ESFT include diaphyseal location and permeation into soft tissue without frank cortical destruction (Figure 20.2). The major differential diagnostic considerations on diagnostic imaging are usually osteosarcoma and osteomyelitis.