MRI: Use of Contrast
In the absence of reliable evidence, it is the opinion of the work group that IV contrast does not offer any advantages for detecting tumor presence over a non-contrast study.

Rationale
Although it is clear from the available literature and meta-analysis (2 high quality and 5 moderate quality studies) that the use of IV contrast assists in the differentiation between benign and malignant entities, a substantial amount of discussion was dedicated to the issue of how MRIs should be used as an initial imaging modality by referring practitioners. In most circumstances, a non-contrast study will provide adequate information to determine the underlying identity of a mass, specifically if the lesion is clearly consistent with a common benign entity, such as a lipoma or synovial cyst, or if there are abnormal characteristics consistent with a possible sarcoma, in which case referral to a specialty center is warranted and strongly recommended. The work group did not feel that a universal recommendation to perform contrast enhanced MRI in every patient was a judicious use of resources, but rather if contrast was deemed necessary by the treating cancer specialists, a limited contrast enhanced study could be performed at the discretion of the treating team on an individualized basis. Meta-analysis of 1 high quality and 4 moderate quality studies also showed that heterogeneous signal on contrast MRI has some value in determining whether a soft tissue tumor is malignant or benign.