Figure 2a. Fatigue fracture in a 25-year-old woman runner with low back pain. Coronal T1-weighted (a) and coronal T2-weighted fat-suppressed (b) MR images show edema in the left sacral ala as well as a linear band (arrow) that extends through the region of edema, a typical finding of stress fracture. MR images from nearly 2% of patients referred to the Orthopaedic Oncology Clinic showed features characteristic of stress fracture or stress reaction that were misinterpreted as a potential malignancy.