Soft-tissue masses: diagnosis using MR imaging.

The MR images of 112 soft-tissue masses of various causes were retrospectively reviewed. Pathologic diagnosis by biopsy was available in 96 cases. Diagnosis in the remaining 16 cases was established by characteristic radiographs, CT scans, and/or arteriograms, in conjunction with appropriate history and clinical follow-up. All masses were evaluated with both T1-weighted, 300-600/20-30 (TR/TE), and T2-weighted, 2000/80-100, images. They were reviewed to determine (1) if these images were sufficiently unique to allow a preoperative diagnosis based exclusively on the MR appearance and (2) if benignity vs malignancy could be predicted on the basis of the analysis of the MR image characteristics of the lesion. Concerning the latter, attention was directed to the margins of the lesions, to the impact of the lesion on the surrounding tissues (edema, infiltration, etc.), and to the intensity and homogeneity of the MR signal of the lesion. MR images were sufficiently characteristic to allow a specific diagnosis in 27 (24%) of the 112 cases (10 lipomas, eight hemangiomas, six pigmented villonodular synovitis, two hematomas, and one arteriovenous malformation). MR was incapable of reliably distinguishing between benign and malignant soft-tissue tumors.