Imaging of Soft Tissue Sarcomas

Role of Imaging Radiographs have a limited role in the evaluation of soft tissue sarcomas and are useful only to detect bony destruction, periosteal reaction, and secondary bone changes. CT, in addition to assessing the bony features seen on radiographs, can depict subtle areas of mineralization and erosions that may not be apparent on MRI. MRI, however, is the best imaging modality to characterize and stage soft tissue sarcomas. MRI has multiplanar capability and the ability to distinguish between tumor and adjacent normal tissue. Based on signal characteristics, MRI can detect hemorrhage, fat content, or necrosis within a tumor and thus predict tumor behavior. Imaging features on MRI also are useful in choosing the optimal site for biopsy, by avoiding necrotic areas and directing the biopsy to the enhancing areas in the tumor. MRI also can be useful to guide the route for biopsy and thus prevent tumor seeding along the biopsy tract. MRI helps to detect tumor size, compartmental and fascial plane involvement, and proximity of the tumor to a neurovascular bundle, all of which are important for preoperative planning. MRI also is useful for postoperative follow-up and detection of tumor recurrence. In this article, we will discuss the various soft tissue sarcomas on the basis of the World Health Organization classification system. Table 1 summarizes some of the differentiating characteristics of these tumors, and Figure 1 shows the common sites of occurrence of some of these tumors. With the knowledge gained from this activity, the diagnostic radiologist will be better able to provide pertinent information regarding the preand postoperative treatment of patients with soft tissue tumors.