Doctors diagnose bone marrow edema in the foot by use of MRI imaging technology and by taking the patient's medical history, according to the American Roentgen Ray Society. The MRI can also find such conditions as fracture lines and erosion.
The MRI can also help the doctor with a diagnosis by finding the double line sign, says the American Roentgen Ray Society. This double line indicates bone death, or osteonecrosis, says the UW Medicine Department of Radiology. Bone spurs may also be found. All of these conditions can contribute to fluid in the bone.
MRI is the technology preferred over CT scan or X-ray because it uses protons to create images, specifically those found in water molecules, says Rheumatology. This makes it easier to find the water that causes bone edema in the foot and other places.
If the doctor is uncertain about the MRI findings, he can still turn to other technologies, such CT scans, X-rays and bone scans. Bone scans are done by injecting a radiotracer into the patient that travels to his bones, says MedlinePlus. Though their usefulness in finding bone edema is limited, bone scans can help the physician evaluate the patient's symptoms and rule out cancers that have spread to the bone from other sites, claims Rheumatology. CT scans can't find edema in the bone marrow, but can rule out other pathologies, such as bone tumors.