The Biodistribution and Utility of ^99mTc-Ethylenedicysteine-Deoxyglucose (^99mTc-Glucosamine) in the Identification of Active Disease in Patients with Rheumatoid Arthritis-a Single Center Prospective Study

Purpose: Our objectives were to investigate the utility of ^99mTc-ethylenedicysteine-deoxyglucose (ECDG) in identifying active disease in the joints of patients with rheumatoid arthritis (RA), as well as to evaluate the biodistribution of this radiopharmaceutical.

Methods: A prospective study was conducted at the Department of Nuclear Medicine of the University of the Free State/Universitas Academic Hospital in Bloemfontein, South Africa. Twenty-two participants from the rheumatology department diagnosed with RA according to the ACR/EULAR classification criteria were enrolled. Participants were injected with 20-25 mCi of ^99mTc-ECDG. Flow, blood pool, whole body, delayed static, and SPECT/CT images were acquired. Known sites of disease were qualitatively assessed for intensity of uptake, and disease severity was graded (Grade 0-3).

Results: Twenty-two participants were studied. The median (interquartile range) age was 59 (49-68) years, and the majority (n = 21; 95.5%) were females. There was abnormal increased uptake of ^99mTc-ECDG noted in majority of the sites of known disease, including unknown sites. SPECT/CT imaging localized radiotracer uptake specifically to the synovial space. Similar biodistribution of radiotracer was noted in all patients, irrespective of disease severity or fasting status.

Conclusion: ^99mTc-ECDG can efficiently assess disease activity in the joints of patients with RA. It accumulates in sites of both clinical and subclinical disease and might be a very useful tool for the rheumatologist in the management of patients with RA.