The purpose of this study was to evaluate the usefulness of three-phase bone scintigraphy in the diagnosis of rheumatoid arthritis.
Thirty-nine patients presenting with arthralgia were examined clinically: physical examination, laboratory tests, radiographs and three-phase bone scintigraphy with 99m-technetium were performed. The joints were evaluated as presenting scintigraphic features of inflammation when the tracer uptake was increased in all phases.
Early rheumatoid arthritis was diagnosed in 13 patients, rheumatoid arthritis in 4 patients, and 1 case was classified as undifferentiated arthritis. Scintigraphy showed inflammatory joint changes in 13 patients (72.2%). Scintigraphic abnormalities only in the skeletal phase were seen in 4 patients (22.2%), and the result was negative in 1 patient (5.6%).
Inflammatory joint disease was excluded in 21 patients.
A diagnosis of osteoarthritis was established in 2 of them, whereas 19 patients were considered as having fibromyalgia. In this group 14 patients (66.6%) had no increased tracer uptake in scintigraphy, 6 patients (28.6%) had abnormalities only on delayed images and the scan of 1 patient (4.8%) showed scintigraphic features of inflammation.
In this study the sensitivity of three-phase bone scintigraphy for detection of arthritis was 72.2% (95% CI: 57.5–76.8), and the specificity was 95.2% (95% CI: 82.8–99.1). Positive dynamic bone scintigraphy indicated the presence of inflammatory joint disease (PPV 92.9% [95% CI: 74.2–98.7]). Negative scintigraphy was less reliable (NPV 80% [95% CI: 69.5–83.3]).
Three-phase bone scintigraphy may be useful in the diagnosis of rheumatoid arthritis.