THE ROLE OF MAGNETIC-RESONANCE-IMAGING IN THE EVALUATION OF THE SOFT-TISSUE MASS

Magnetic resonance imaging is used widely to investigate soft tissue m asses. The effectiveness of MRI derives from unrivaled soft tissue con trast and multiplanar imaging capability. Magnetic resonance spectrosc opy has been used to examine the phosphometabolites of normal and path ological soft tissues. We review the role of MRI and MRS in the detect ion and characterization of soft tissue masses and in staging soft tis sue malignancies. The detection of a soft tissue mass depends on image contrast between normal and pathological tissue. We review the salien t factors, both intrinsic properties of tissues and parameters of MR i maging, which influence soft tissue contrast on an MR image. Specific pulse sequences that have been compared for tumor detection are discus sed. One goal of a radiological test is to provide tissue-specific cha racterization. Alone or in combination, various MR imaging characteris tics of a soft tissue mass have been studied for an association with b enign or malignant tissue. MR imaging signs discussed in this review i nclude signal intensity, relaxation time, homogeneity of signal patter n, septation, size at presentation, shape, margin definition, peritumo ral edema, involvement of bone or neurovascular tissue, and contrast e nhancement. The MR imaging appearance of hemangioma, lipoma, pigmented villonodular synovitis, desmoid tumor, hematoma, arteriovenous malfor mation, and ganglion cyst is also reviewed. MR imaging is the quintess ential imaging method for staging a soft tissue malignancy. We review three staging systems in common use and the role of MR imaging for loc al staging of untreated and treated soft tissue malignancies.