title: High-resolution MRI assessment of dactylitis in psoriatic arthritis shows flexor tendon pulley and sheath-related enthesitis.
abstract: OBJECTIVE
  Dactylitis is a hallmark of psoriatic arthritis (PsA) where flexor tenosynovitis is common. This study explored the microanatomical basis of dactylitis using high-resolution MRI (hrMRI) to visualise the small entheses around the digits.
  
  
  METHODS
  Twelve patients with psoriatic dactylitis (4 fingers, 8 toes), and 10 healthy volunteers (6 fingers, 4 toes) had hrMRI of the digits using a 'microscopy' coil and contrast enhancement. All structures were evaluated including the tendons and ligaments, related enthesis organs, pulleys, volar/plantar plates and tendon sheaths.
  
  
  RESULTS
  In dactylitis, collateral ligament enthesitis was seen in nine digits (75%), extensor tendon enthesitis in six digits (50%), functional enthesitis (5 digits, 42%), abnormal enhancement at the volar plates (2/5 joints, 40%) and the plantar plate (1/5 joints, 20%). Nine cases (75%) demonstrated flexor tenosynovitis, with flexor tendon pulley/flexor sheath microenthesopathy observed in 50% of all cases. Less abnormalities which were milder was observed in the normal controls, none of whom had any signal changes in the tendon pulleys or fibrous sheaths.
  
  
  CONCLUSIONS
  This study provides proof of concept for a link between dactylitis and 'digital polyenthesitis' including disease of the miniature enthesis pulleys of the flexor tendons, further affirming the concept of enthesitis in PsA.
authors.affiliation: NIHR Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds, UK Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK Faculty of Medicine, Department of Radiology, Shimane University, Japan Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
authors.forename: Ai Lyn
authors.initials: AL
authors.lastname: Tan
authors.affiliation: NIHR Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds, UK Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK Faculty of Medicine, Department of Radiology, Shimane University, Japan Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
authors.forename: Eiji
authors.initials: E
authors.lastname: Fukuba
authors.affiliation: NIHR Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds, UK Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK Faculty of Medicine, Department of Radiology, Shimane University, Japan Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
authors.forename: Nicola Ann
authors.initials: NA
authors.lastname: Halliday
authors.affiliation: NIHR Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds, UK Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK Faculty of Medicine, Department of Radiology, Shimane University, Japan Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
authors.forename: Steven F
authors.initials: SF
authors.lastname: Tanner
authors.affiliation: NIHR Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds, UK Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK Faculty of Medicine, Department of Radiology, Shimane University, Japan Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Emery
authors.affiliation: NIHR Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds, UK Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK Faculty of Medicine, Department of Radiology, Shimane University, Japan Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
authors.forename: Dennis
authors.initials: D
authors.lastname: McGonagle
mesh_terms: D000328:Adult; D015535:Arthritis, Psoriatic / Q000473:pathology*; D016022:Case-Control Studies; D017885:Collateral Ligaments / Q000473:pathology*; D005260:Female; D005384:Finger Joint / Q000473:pathology*; D006801:Humans; D008023:Ligaments, Articular / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013710:Tendons / Q000473:pathology*; D013717:Tenosynovitis / Q000473:pathology*; D014033:Toe Joint / Q000473:pathology*; D055815:Young Adult