The goals of imaging of soft tissue tumors are threefold: (1) lesion detection, (2) identifying a specific diagnosis or reasonable differential diagnosis, and (3) lesion staging. The radiologic evaluation of soft tissue tumors to achieve these goals has markedly evolved, improved, and expanded with the advent of computerized tomography (CT) and particularly magnetic resonance imaging (MRI). CT and more recently MRI allow lesion detection and staging by delineating anatomic extent in essentially all cases and relatively specific diagnosis in approximately 25% to 50% of soft tissue tumors. We would suggest that evaluation of soft tissue tumors is now similar to that of bone tumors in that pathologic diagnosis should incorporate the imaging findings in most cases. This is particularly true in large tumors in which only a small amount of tissue might be available for histologic review initially and there is doubt about whether the tissue is a true representation of the entire lesion. As in bone tumors, close working relationship among three groups of physicians is needed: the pathologist, radiologist, and orthopedic oncologist. The purpose of this chapter is to provide a framework for the use of radiologic evaluation of soft tissue tumors. Although this approach reviews multiple imaging modalities, the authors emphasize MRI because it is generally considered the optimal radiologic tool in evaluation of soft tissue tumors.

The annual incidence of benign soft tissue tumors has been estimated at 300 per 100,000 people, leading to an estimated 750,000 to 800,000 lesions in the United States.