Imaging in sarcoma.

Imaging has contributed to diagnosis and treatment decision making for patients with sarcomas, a highly heterogeneous tumor group. Derived from mesenchymal tissues, sarcomas occur in all parts of the body and in all patient age groups, with a highly variable histologic appearance and behavior. They are commonly separated into soft-tissue-derived and bone-derived groups; however, many exceptions to these classifications are seen clinically. Tumor size, cellular type and differentiation, and presence of necrosis are tumor features that can be used clinically to predict the risk of aggressive behavior. At present for soft-tissue sarcomas, the 5-y survival is approximately 60%, with substantially better survival for patients with bone tumors, particularly pediatric patients. Imaging with nuclear medicine techniques plays an important role in diagnosis, treatment planning, and follow-up. Conventional (99m)Tc-methylene diphosphonate bone scans, (201)Tl tumor imaging, and PET techniques have contributed to the care of sarcoma patients. Newer PET techniques with biologically specific imaging agents have also been evaluated to characterize sarcomas and contribute to risk stratification for poor outcome.