Question
How can a doctor tell if the MRI findings are bone marrow edema and not cancer?
Answer
Increasingly MRIs are used to evaluate joints of patients with arthritis. The MRI is a very sensitive technique that allows better visualization of the bones, cartilage, and joint tissue. An MRI picture is in black and white like an XRay but can provide cross sectional pictures from several different perspectives. “Bone marrow edema” can be seen in a number of different conditions. While the term “edema” implies fluid in the area, there are actually many different conditions that can cause this MRI finding. This can be seen in osteoarthritis in bone under areas where cartilage is damaged; in rheumatoid arthritis edema may precede an erosion developing; in ankylosing spondylitis edema may precede the development of tendon insertional calcification. In other circumstances, similar findings may be seen in microfractures of the bone, and many other conditions. The meaning of the “bone marrow edema” is thus based on the particular clinical context. While certain forms of tumors can also have edema on MRI, there are other characteristics that usually can help a radiologist to make this distinction.
