An MRI is a medical imaging technique using a magnet to take photos of your body’s soft tissues, bones, inner organs and other tissues and allows the doctor to examine them with great detail. MRI is useful for determining the size and extent of the tumor and the tissues involved. It is also useful for determining the involvement of adjacent structures including the important. MRI is rarely diagnostic as many different benign and malignant entities can have similar appearances. MRI also can show edema around tumors. Generally, soft tissue tumors that are greater than 5 cm, deep to the fascia and heterogeneous on an MRI (meaning shows hemorrhage and necrosis) are usually high grade sarcomas (high grade cancers). MRI does not expose the patient to radiation. Gadolinium is a contrast dye that can be used to highlight tumors better and monitor for recurrence after surgical removal where there may be other postoperative changes and scar tissue. The contrast may help differentiate a returning tumor from the scar tissue and artifacts created from the surgery.