title: MR Parametric Mapping as a Biomarker of Early Joint Degeneration.
abstract: BACKGROUND
  Osteoarthritis (OA) is a common, worldwide disorder. Magnetic resonance (MR) imaging can directly and noninvasively evaluate articular cartilage and has emerged as an essential tool in the study of OA.
  
  
  METHODS
  A PubMed search was performed using the keywords quantitative MRI and cartilage. No limits were set on the range of years searched. Articles were reviewed for relevance with an emphasis on in vivo studies performed at 3 tesla.
  
  
  METHODS
  Clinical review.
  
  
  METHODS
  Level 4.
  
  
  RESULTS
  T2, T2*, T1 (particularly when measured after exogenous contrast administration, such as with the delayed gadolinium-enhanced MR imaging of cartilage [dGEMRIC] technique), and T1ρ are among the most widely utilized quantitative MR imaging techniques to evaluate cartilage and have been implemented in various patient cohorts. Existing challenges include reproducibility of results, insufficient consensus regarding optimal sequences and parameters, and interpretation of values.
  
  
  CONCLUSIONS
  Quantitative assessment of cartilage using MR imaging techniques likely represents the best opportunity to identify early cartilage degeneration and to follow patients after treatment. Despite existing challenges, ongoing work and unique approaches have shown exciting and promising results.
authors.affiliation: Radiology Service, VA San Diego Healthcare System, San Diego, California Department of Radiology, University of California, San Diego Medical Center, San Diego, California ericchangmd@gmail.com.
authors.forename: Eric Y
authors.initials: EY
authors.lastname: Chang
authors.affiliation: Department of Radiology, University of California, San Diego Medical Center, San Diego, California.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Radiology, University of California, San Diego Medical Center, San Diego, California.
authors.forename: Jiang
authors.initials: J
authors.lastname: Du
mesh_terms: D002358:Cartilage, Articular / Q000737:chemistry / Q000000981:diagnostic imaging*; D003094:Collagen / Q000737:chemistry; D006801:Humans; D008279:Magnetic Resonance Imaging; D010003:Osteoarthritis / Q000000981:diagnostic imaging*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging; D011509:Proteoglycans / Q000737:chemistry; D015203:Reproducibility of Results
chemical_list: D011509:Proteoglycans; D003094:Collagen
keywords: cartilage; osteoarthritis; parametric mapping; quantitative MRI