Figure 1a:

Osteosarcoma of the right femur in a 15-year-old girl. (a) Sagittal T1-weighted MR image (370/10) shows complete replacement of normal fatty marrow signal intensity involving epiphysis and distal metadiaphysis of the right femur. Images obtained with nonenhanced T1-weighted sequence best depict contrast between marrow-replacing tumor and normal fatty marrow for accurately defining extent of the lesion. (b) Coronal fat-suppressed T2-weighted MR image (4000/66) shows perilesional bone marrow edema (short arrow), periosteal reaction (long arrows), and extension of tumor into adjacent soft tissues (arrowhead).