Fig. 20

Ewing’s sarcoma. Axial CT image in the bone window (a) demonstrates an ill-defined lesion with destructive changes of the right vertebral body. The bone cortex has a “smudged” appearance (black arrow) due to perforation of tumor through the cortex. Sagittal proton-density image (b) demonstrates the ill-defined tumor as abnormal marrow signal with epidural extension (orange arrows). Sagittal T2-weighted (c) and T2 fat-saturated (d) images demonstrate variable signal within the lesion (orange arrows). This lesion demonstrates low to intermiediate T1 signal (e, orange arrows). On T1-weighted post-contrast imaging (f), there is heterogenous enhancement of the tumor (orange arrows), which is difficult to distinguish from the enhancing peritumoral edema (white arrow)