Comparison of Technetium-99m-Labelled Human Polyclonal Immunoglobulin Scintigraphy with Conventional Bone Scintigraphy in Patients with Rheumatoid Arthritis and Osteoarthritis
The ability of technetium 99m labelled polyclonal human immunoglobulin G (99mTc-IgG) scintigraphy and conventional bone scintigraphy with technetium 99m labelled hydroxymethylene diphosphonate (99mTc-HDP) to detect and to differentiate between the different degrees of arthritis activity was studied in 24 patients with rheumatoid arthritis (RA) and 10 patients with osteoarthritis (OA). The patients with RA were divided into 4 groups based upon clinical and radiological observations: 1: non-erosive, in remission (n=5); 2: non-erosive, active (n=5); 3: erosive, in remission (n=7); 4: erosive, active (n=7). The patients were scored for joint pain, swelling and uptake of the radiopharmaceutical on a 4-point scale. The mean joint scores of 99mTc-IgG scintigraphy in RA patients with active disease was significantly (p< 0.001) higher than of patients with inactive disease. The mean joint scores were also higher in patients with erosions compared to patients without erosions but the difference was less significant (p< 0.05). For 99mTc-HDP scintigraphy no significant differences were found between the mean scores of these patient groups. When 99mTc-IgG scintigraphy is regarded as a test to detect arthritis as defined by joint swelling, this test has a sensitivity that ranged between 64 and 100% for the different joints. Comparison of scintigraphic results between patients with RA and OA revealed that the mean joint score of 99mTc-IgG scintigraphy was significantly (p< 0.001) higher in the patients with RA than in patients with OA whereas for 99mTc-HDP scintigraphy this difference was not significant.
This study shows that 99mTc-IgG scintigraphy, in contrast to, 99mTc-HDP scintigraphy is a sensitive and specific method to detect synovitis and differentiates between the different degrees of disease activity in RA.
KeywordsArthritis Osteoarthritis Synovitis Hydroxy Methylene Technetium
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