title: Assessment of disease activity in rheumatoid arthritis using a novel folate targeted radiopharmaceutical Folatescan.
abstract: OBJECTIVE
  Development of a simple and accurate technique for detecting active inflammation in the joints and other tissues of patients with inflammatory disorders is an unmet need in rheumatic diseases. This study is a preliminary assessment of the safety and usage of a radiopharmaceutical, FolateScan (Technetium-99m EC20; 99mTc-EC20), for detecting disease activity in patients with rheumatoid arthritis.
  
  
  METHODS
  EC20 is a folate-targeted diagnostic radiopharmaceutical which binds to the folate receptor and is preferentially taken up by activated macrophages. In this open-label, cross-sectional study, a total of 40 patients with RA (26 with one or more swollen joints, 14 with clinically quiescent joint disease; 0/66 joint count) as well as 6 patients with osteoarthritis, 12 patients with other inflammatory conditions and 5 healthy subjects received 0.1 mg of EC20 labeled with 20-25mCi of technetium-99m. Disease activity was scored in each joint and other target tissues by a radiologist blinded to the clinical assessment, and results were compared to the rheumatologist's physical examination, which served as the test standard.
  
  
  RESULTS
  The 40 patients (78% female) with RA had a mean age of 56.9 years. Assessment of uptake of 99mTc-EC20 in joints of patients with RA based on image analysis was compared to the clinical examination. FolateScan detected more actively involved joints in 27 patients (68%) than joints recorded as "swollen", and more actively involved joints in 25 patients (63%) than joints recorded as "painful and/or swollen". The number of swollen joints by clinical exam was correlated with ESR (r=0.43; p=0.006) and C-rp (r=0.35; p=0.03). The number of actively involved joints by FolateScan was also correlated with ESR (r=0.47; p=0.002) and C-rp (r=0.36; p=0.02). Joint uptake was also seen in patients with osteoarthritis.
  
  
  CONCLUSIONS
  FolateScan is a potentially useful tool for detection of disease activity in patients with RA and may be more sensitive than the physical examination.
authors.affiliation: Division of Rheumatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Matteson
authors.forename: V J
authors.initials: VJ
authors.lastname: Lowe
authors.forename: F G
authors.initials: FG
authors.lastname: Prendergast
authors.forename: C S
authors.initials: CS
authors.lastname: Crowson
authors.forename: K G
authors.initials: KG
authors.lastname: Moder
authors.forename: D E
authors.initials: DE
authors.lastname: Morgenstern
authors.forename: R A
authors.initials: RA
authors.lastname: Messmann
authors.forename: P S
authors.initials: PS
authors.lastname: Low
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D005492:Folic Acid / Q000031:analogs & derivatives*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000473:pathology; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012720:Severity of Illness Index; D013670:Sodium Pertechnetate Tc 99m
chemical_list: C473829:EC20 folate peptide; D009842:Oligopeptides; D019275:Radiopharmaceuticals; D005492:Folic Acid; D013670:Sodium Pertechnetate Tc 99m