title: Assessment of disease activity in patients with rheumatoid arthritis using optical spectral transmission measurements, a non-invasive imaging technique.
abstract: OBJECTIVE
  In rheumatoid arthritis (RA), treat-to-target strategies require instruments for valid detection of joint inflammation. Therefore, imaging modalities are increasingly used in clinical practice. Optical spectral transmission (OST) measurements are non-invasive and fast and may therefore have benefits over existing imaging modalities. We tested whether OST could measure disease activity validly in patients with RA.
  
  
  METHODS
  In 59 patients with RA and 10 patients with arthralgia, OST, joint counts, Disease Activity Score (DAS) 28 and ultrasonography (US) were performed. Additionally, MRI was performed in patients with DAS28<2.6. We developed and validated within the same cohort an algorithm for detection of joint inflammation by OST with US as reference.
  
  
  RESULTS
  At the joint level, OST and US performed similarly inproximal interphalangeal-joints (area under the receiver-operating curve (AUC) of 0.79, p<0.0001) andmetacarpophalangeal joints (AUC 0.78, p<0.0001). Performance was less similar in wrists (AUC 0.62, p=0.006). On the patient level, OST correlated moderately with clinical examination (DAS28 r=0.42, p=0.001), and US scores (r=0.64, p<0.0001). Furthermore, in patients with subclinical and low disease activity, there was a correlation between OST and MRI synovitis score (RAMRIS (Rheumatoid Arthritis MRI Scoring) synovitis), r=0.52, p=0.005.
  
  
  CONCLUSIONS
  In this pilot study, OST performed moderately in the detection of joint inflammation in patients with RA. Further studies are needed to determine the diagnostic performance in a new cohort of patients with RA.
authors.affiliation: Department of Clinical Immunology and Rheumatology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: van Onna
authors.affiliation: Department of Rheumatology, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: D F
authors.initials: DF
authors.lastname: Ten Cate
authors.affiliation: Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: K L
authors.initials: KL
authors.lastname: Tsoi
authors.affiliation: Department of Rheumatology, Regional Rheumatology Center, Eindhoven, The Netherlands.
authors.forename: A J L
authors.initials: AJ
authors.lastname: Meier
authors.affiliation: Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: J W G
authors.initials: JW
authors.lastname: Jacobs
authors.affiliation: Department of Rheumatology, Regional Rheumatology Center, Eindhoven, The Netherlands.
authors.forename: A A A
authors.initials: AA
authors.lastname: Westgeest
authors.affiliation: Hemics, Eindhoven, The Netherlands.
authors.forename: P B L
authors.initials: PB
authors.lastname: Meijer
authors.affiliation: Hemics, Eindhoven, The Netherlands.
authors.forename: M C
authors.initials: MC
authors.lastname: van Beek
authors.affiliation: Hemics, Eindhoven, The Netherlands.
authors.forename: W H J
authors.initials: WH
authors.lastname: Rensen
authors.affiliation: Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: J W J
authors.initials: JW
authors.lastname: Bijlsma
mesh_terms: D000328:Adult; D000368:Aged; D018771:Arthralgia / Q000175:diagnosis; D001172:Arthritis, Rheumatoid / Q000175:diagnosis*; D016022:Case-Control Studies; D005260:Female; D050823:Hand Joints / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D061848:Optical Imaging; D010865:Pilot Projects; D012720:Severity of Illness Index; D013057:Spectrum Analysis; D013585:Synovitis / Q000175:diagnosis*; D014463:Ultrasonography
keywords: Disease Activity; Magnetic Resonance Imaging; Rheumatoid Arthritis; Synovitis; Ultrasonography