title: Accuracy of magnetic resonance imaging for measuring maturing cartilage: A phantom study.
abstract: OBJECTIVE
  To evaluate the accuracy of magnetic resonance imaging measurements of cartilage tissue-mimicking phantoms and to determine a combination of magnetic resonance imaging parameters to optimize accuracy while minimizing scan time.
  
  
  METHODS
  Edge dimensions from 4 rectangular agar phantoms ranging from 10.5 to 14.5 mm in length and 1.25 to 5.5 mm in width were independently measured by two readers using a steel ruler. Coronal T1 spin echo (T1 SE), fast spoiled gradient-recalled echo (FSPGR) and multiplanar gradient-recalled echo (GRE MPGR) sequences were used to obtain phantom images on a 1.5-T scanner.
  
  
  RESULTS
  Inter- and intra-reader reliability were high for both direct measurements and for magnetic resonance imaging measurements of phantoms. Statistically significant differences were noted between the mean direct measurements and the mean magnetic resonance imaging measurements for phantom 1 when using a GRE MPGR sequence (512x512 pixels, 1.5-mm slice thickness, 5:49 min scan time), while borderline differences were noted for T1 SE sequences with the following parameters: 320x320 pixels, 1.5-mm slice thickness, 6:11 min scan time; 320x320 pixels, 4-mm slice thickness, 6:11 min scan time; and 512x512 pixels, 1.5-mm slice thickness, 9:48 min scan time. Borderline differences were also noted when using a FSPGR sequence with 512x512 pixels, a 1.5-mm slice thickness and a 3:36 min scan time.
  
  
  CONCLUSIONS
  FSPGR sequences, regardless of the magnetic resonance imaging parameter combination used, provided accurate measurements. The GRE MPGR sequence using 512x512 pixels, a 1.5-mm slice thickness and a 5:49 min scan time and, to a lesser degree, all tested T1 SE sequences produced suboptimal accuracy when measuring the widest phantom.
authors.affiliation: University of Toronto, The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto/ON, Canada.
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: McKinney
authors.affiliation: The University Health Network, Toronto General Hospital, Department of Medical Imaging, Toronto/ON, Canada.
authors.forename: Marshall S
authors.initials: MS
authors.lastname: Sussman
authors.affiliation: University of Toronto, Department of Family and Community Medicine, Toronto/ON, Canada.
authors.forename: Rahim
authors.initials: R
authors.lastname: Moineddin
authors.affiliation: University of Toronto, The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto/ON, Canada.
authors.forename: Afsaneh
authors.initials: A
authors.lastname: Amirabadi
authors.affiliation: University of Toronto, The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto/ON, Canada.
authors.forename: Tammy
authors.initials: T
authors.lastname: Rayner
authors.affiliation: University of Toronto, The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto/ON, Canada.|The University Health Network, Toronto General Hospital, Department of Medical Imaging, Toronto/ON, Canada.
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Doria
mesh_terms: D002356:Cartilage / Q000000981:diagnostic imaging*; D061827:Dimensional Measurement Accuracy; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015588:Observer Variation; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D012016:Reference Values; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D013997:Time Factors