Avascular Necrosis Diagnosis
Magnetic Resonance Imaging (MRI)
Avascular necrosis research studies have shown that magnetic resonance imaging, or MRI, is the most sensitive method for diagnosing avascular necrosis in the early stages. Unlike x-rays, bone scans, and CT (computed tomography) scans, MRI scans detect chemical changes in the bone marrow and can show avascular necrosis in its earliest stages. An MRI provides the doctor with a picture of the area affected and the bone rebuilding process. In addition, an MRI may show diseased areas that are not yet causing any avascular necrosis symptoms.
Also known as bone scintigraphy, bone scans are used most commonly in patients who have normal x-rays. A harmless radioactive dye is injected into the affected bone, and a picture of the bone is taken with a special camera. The picture shows how the dye travels through the bone and where normal bone formation is occurring. A single bone scan finds all areas in the body that are affected, thus reducing the need to expose the patient to more radiation. Bone scans do not detect avascular necrosis at the earliest stages.
A CT scan is an imaging technique that provides the doctor with a three-dimensional picture of the bone. It also shows "slices" of the bone, making the picture much clearer than x-rays and bone scans. Some doctors disagree about the usefulness of this test to diagnose avascular necrosis. Although an avascular necrosis diagnosis usually can be made without a CT scan, the technique may be useful in determining the extent of bone damage.
A biopsy is a surgical procedure in which tissue from the affected bone is removed and studied. Although a biopsy is a conclusive way to make an avascular necrosis diagnosis, it is rarely used because it requires surgery.