title: Detection of articular pathology of the distal aspect of the third metacarpal bone in thoroughbred racehorses: comparison of radiography, computed tomography and magnetic resonance imaging.
abstract: OBJECTIVE
  To compare digital radiography (DR), computed tomography (CT), and magnetic resonance imaging (MRI) for detection of pathology of the distal aspect of the third metacarpal bone (MC3) and to assess whether arthrography would improve detection of articular cartilage or subchondral bone cracking.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Limb specimens from 17 Thoroughbred horses after catastrophic injury and 4 age-matched control horses.
  
  
  METHODS
  Standard DR, CT, and MRI images of the metacarpophalangeal joint were acquired before and after iohexol injection. Pathologic features detected with imaging and on visual inspection of cartilage and subchondral bone of the distal aspect of MC3 were graded. Imaging observations were compared with pathologic abnormalities.
  
  
  RESULTS
  Inspection revealed obvious changes in the cartilage and subchondral bone surfaces in Thoroughbreds. Both CT and MRI were superior to DR for detection of subchondral bone pathology. Cracking of cartilage was not detected by any imaging modality. Signal changes associated with cartilage loss and development of repair tissue were evident on MRI in 9/19 cases. There was significant correlation (P < .05) between subchondral bone pathology detected on both CT and MRI, and cartilage pathology on gross examination. Contrast arthrography did not improve the detection of articular cartilage or subchondral plate cracking.
  
  
  CONCLUSIONS
  Both CT and MRI are superior to DR for detection of subchondral bone pathology, but underestimate the extent of joint adaptation and pathologic damage. MRI was able to detect cartilage degeneration.
authors.affiliation: Comparative Orthopaedic Research Laboratory and Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: O'Brien
authors.forename: Theresa A
authors.initials: TA
authors.lastname: Baker
authors.forename: Sabrina H
authors.initials: SH
authors.lastname: Brounts
authors.forename: Susannah J
authors.initials: SJ
authors.lastname: Sample
authors.forename: Mark D
authors.initials: MD
authors.lastname: Markel
authors.forename: Mary C
authors.initials: MC
authors.lastname: Scollay
authors.forename: Patricia
authors.initials: P
authors.lastname: Marquis
authors.forename: Peter
authors.initials: P
authors.lastname: Muir
mesh_terms: D000818:Animals; D001175:Arthrography / Q000662:veterinary*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D006734:Horse Diseases / Q000175:diagnosis*; D006736:Horses; D007592:Joint Diseases / Q000175:diagnosis / Q000662:veterinary*; D008279:Magnetic Resonance Imaging / Q000662:veterinary*; D050279:Metacarpal Bones / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000662:veterinary*