MRI of soft tissue tumors.

Magnetic resonance imaging (MRI) is the only noninvasive method of defining a soft tissue tumor. The extent of the tumor and the question of involvement or noninvolvement of various adjacent tissues and structures can be determined. This information, determination of lymphatic and distant metastatic spread, is invaluable for staging and management of the disease. Whether or not the tumor type can be reliably determined, or even whether the malignant or benign nature of the tumor can be ascertained on MRI examination, is open to question. Review of the literature indicates proponents on both sides of the issue. This review illustrates the imaging features that are relevant to suggesting a histologic diagnosis, and the pitfalls that are encountered in trying to determine the malignancy or benignity of a lesion. The clinical significance of these determinations is also discussed.