The Role of Tc 99m MDP SPECT/CT in Osteoarthritis

Osteoarthritis (OA) is a slowly developing chronic degenerative joint disease that progresses over years. After the classification and reporting of OA were established by American College of Rheumatology in 1986, the diagnosis has depended on the patients' symptoms and supported by plain radiographic findings.

Since X-ray image has a discrepancy with clinical findings, the therapeutic modalities tend to depend on the clinical symptoms, rather than the objective imaging findings.

MRI is a non-invasive and a very sensitive tool in detecting the early bony change such as bone marrow oedema, but it has some limitation in that it may have false positive or false negative results in the detection of the patella-femoral (PF) lesions. Bone scintigraphy is relatively sensitive because it reflects the early physiological changes of joints. But its image is planar that it cannot give enough information for the anatomic localization, and the image is overlapped.

To compensate for the defects of these imaging methods, bone single photon emission computed tomography (SPECT) has emerged as useful imaging tools in the diagnosis of OA.

Based upon the fact that subchondral bony changes precede joint space narrowing in OA, bone SPECT seems to be a very useful tool in early OA, reflecting the early bony changes.