Figure 11a. Giant cell tumor in a 54-year-old woman. (a) Sagittal T2-weighted (6,000/112) MR image of the ribs (R) shows a mass (M) with overall signal intensity higher than that of muscle but with small foci of low signal intensity in the periphery. (b) Photograph of a resected specimen shows extensive vascular channels (arrows) that correspond to areas of low signal intensity on MR images.