title: Detection of rheumatoid arthritis using non-specific contrast enhanced fluorescence imaging.
abstract: OBJECTIVE
  The aim of this study was to develop a new tool for the early detection of inflammatory joint diseases using fluorescence imaging in the near-infrared (NIR) spectral range following the intravenous administration of an unspecific contrast agent.
  
  
  METHODS
  A laser-supported system for fluorescence imaging of finger joints was designed and constructed. Five patients and a corresponding number of volunteers were examined using 0.1 mg/kg by weight of indocyanine green as an unspecific contrast agent. Fluorescence images were acquired continuously over a period of 15 minutes. As a control, 1 day before optical imaging, all patients and volunteers underwent contrast-enhanced magnetic resonance imaging (MRI) at 0.2 T. On the basis of MRI findings, all examined joints were divided into four groups: no change and mild, moderate, and severe synovitis. The emitted fluorescence photons were quantified in different regions of interest covering the finger joints and finger tips. The normalized fluorescence intensity of contrast agents was compared with MRI findings as a proven standard.
  
  
  RESULTS
  NIR dyes of the cyanine class are enriched in inflammatory joints and show a different kinetic behavior compared to normal joints after bolus injection. These findings demonstrate clearly the capability of contrast-enhanced fluorescence imaging to detect early changes caused by rheumatoid arthritis in finger joints. The NIR results were correlated with MRI findings (r = 0.84).
  
  
  CONCLUSIONS
  Contrast-enhanced fluorescence imaging provides adequate information for the evaluation of inflammatory involvement of finger joints comparable to low-field MRI.
authors.affiliation: Institut für Radiologie, Charité - University Berlin, Campus Charité Mitte, Charitéplatz 1, 10117 Berlin, Germany. thom.fischer@charite.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Fischer
authors.forename: Bernd
authors.initials: B
authors.lastname: Ebert
authors.forename: Jan
authors.initials: J
authors.lastname: Voigt
authors.forename: Rainer
authors.initials: R
authors.lastname: Macdonald
authors.forename: Udo
authors.initials: U
authors.lastname: Schneider
authors.forename: Anke
authors.initials: A
authors.lastname: Thomas
authors.forename: Bernd
authors.initials: B
authors.lastname: Hamm
authors.forename: Kay-Geert A
authors.initials: KG
authors.lastname: Hermann
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D005384:Finger Joint / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007208:Indocyanine Green; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods*; D008875:Middle Aged
chemical_list: D003287:Contrast Media; D007208:Indocyanine Green