RADIOLABELED LYMPHOCYTE MIGRATION IN RHEUMATOID SYNOVITIS

Objectives-To study the ability of technetium-99m hexamethyl propylene amineoxime (HMPAO) labelled lymphocyte scintigraphy to quantify synov ial inflammation, and to analyse the kinetics of lymphocyte retention in the joints of patients with rheumatoid arthritis (RA). Methods-Afte r isolation of the lymphocytes, the cells were radiolabelled in vitro with 250 MBq Tc-99m-HMPAO. The scans were performed 30 minutes, three hours and 20 hours after injection. Results-An increase of the scintig ram signal obtained at 20 hours was associated with a high joint swell ing and joint pain score (F test = 3.07, p < 0.002), but not with the radiological score. A positive joint scintigram was predictive of acti ve synovitis. Although the scintigram variation over time did not reac h statistical significance, the kinetics of the scintigram signal tend ed to differ according to the disease duration: in early RA, active ar thritis could be clearly imaged as early as 30 minutes, increased at t hree hours and the signal intensity persisted at 20 hours. In contrast , in long standing disease, the affected joints were imaged at 30 minu tes, persisted unchanged at three hours, and the scintigram score decr eased significantly at 20 hours. Conclusions-The study shows that Tc-9 9m-HMPAO joint scintigraphy may be used to detect and to localise acti ve rheumatoid arthritis.