FIGURE 3. (A) Radiograph of 15-y-old girl with extension-based low-back pain shows sclerosis along left-sided transverse-sacral articulation (arrows). (B) Posterior (left) and anterior (middle) planar images and SPECT (axial [top right] and coronal [bottom right] images) show high uptake (arrows) along articulation. (C) Coronal T1-weighted MRI after gadolinium shows enhancement (arrows) indicating marrow edema on each side of articulation.