title: Evaluation of knee cartilage thickness: A comparison between ultrasound and magnetic resonance imaging methods.
abstract: BACKGROUND
  Establishing clinically accessible measures of cartilage health is critical for assessing effectiveness of protocols to reduce risk of osteoarthritis (OA) development and progression. Cartilage thickness is one important measure in describing both OA development and progression. The objective was to determine the relationship between ultrasound and MRI measures of cartilage thickness in the medial femoral condyle.
  
  
  METHODS
  Mean cartilage thicknesses of the left medial femoral cartilage were measured via T1 weighted MRI and ultrasound imaging from transverse, anterior, middle, and posterior medial femoral regions in 10 healthy females (Mean±Std Dev) (1.66±0.08m, 59.5±8.3kg, 21.6±1.4years) and nine healthy males (1.80±0.08m, 79.1±6.2kg, 21.7±1.5years). Pearson correlations examined relationships between MRI and ultrasound measures. Bland-Altman plots evaluated agreement between the imaging modalities.
  
  
  RESULTS
  Transverse ultrasound thickness measures were significantly positively correlated with MRI middle (r=.67, P≤.05) and posterior thicknesses (r=.49, P≤.05) while the middle and posterior longitudinal ultrasound measures were significantly correlated to their respective MRI regions (r=.67, P≤.05 & r=.59 P≤.05, respectively). There was poor absolute agreement between correlated measures with ultrasound thickness measures being between 1.9 and 2.8mm smaller than MRI measures.
  
  
  CONCLUSIONS
  These results suggest that ultrasound may be a viable clinical tool to assess relative cartilage thickness in the middle and posterior medial femoral regions. However, the absolute validity of the ultrasound measure is called into question due to the larger MRI-based thickness measures.
  
  
  METHODS
  Level IV.
authors.affiliation: The University of North Carolina at Greensboro, Greensboro, NC, United States. Electronic address: rjschmit@uncg.edu.
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Schmitz
authors.affiliation: China Medical University, Taiwan.
authors.forename: Hsin-Min
authors.initials: HM
authors.lastname: Wang
authors.affiliation: The University of North Carolina at Greensboro, Greensboro, NC, United States.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Polprasert
authors.affiliation: Wake Forest University, Winston-Salem, NC, United States.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kraft
authors.affiliation: The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Pietrosimone
mesh_terms: D001837:Body Weights and Measures; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000473:pathology; D064368:Healthy Volunteers; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D014463:Ultrasonography; D055815:Young Adult
keywords: Clinical assessment; Medial femur; Osteoarthritis