title: Use of 3T MRI and an unspoiled 3D fast gradient echo sequence for porcine knee cartilage volumetry: preliminary findings.
abstract: OBJECTIVE
  To assess the utility of knee cartilage volumetry using an unspoiled fat-suppressed 3D fast gradient echo (FGRE) sequence at 3T.
  
  
  METHODS
  Sagittal magnetic resonance (MR) images were obtained with an unspoiled fat-suppressed 3D FGRE sequence in eight porcine knees. Manual segmentation was used to derive the cartilage volume. This volume was compared to a volume measurement of cartilage scraping specimens obtained by water displacement. Imaging was repeated five times in four of the knees to assess interscan volume measurement reproducibility and calculate precision error. A single 3D dataset was manually segmented five times at weekly intervals to assess intraobserver volume measurement reproducibility.
  
  
  RESULTS
  Total cartilage volume obtained from MRI and water displacement correlated well (r = 0.75). The interscan reproducibility of total volume measurements, expressed as the coefficient of variation (CV), was 4.2%, and the precision error (root mean square [RMS] CV) was 4.1%. The CV of intraobserver estimates of total cartilage volume by MRI was 3.6%.
  
  
  CONCLUSIONS
  Interscan reproducibility of quantification of total cartilage volume and reproducibility of the manual segmentation technique were both high (>95%). Accurate and reproducible cartilage volumetry can be obtained by using a clinical unspoiled fat-suppressed 3D FGRE acquired at 3T MRI.
authors.affiliation: Department of Radiology, Westmead Hospital, Sydney, Australia. megan.cromer@swahs.health.nsw.gov.au
authors.forename: Megan S
authors.initials: MS
authors.lastname: Cromer
authors.forename: Sheryl L
authors.initials: SL
authors.lastname: Foster
authors.forename: Roger M
authors.initials: RM
authors.lastname: Bourne
authors.forename: Marlene
authors.initials: M
authors.lastname: Fransen
authors.forename: Roger
authors.initials: R
authors.lastname: Fulton
authors.forename: Shih-Chang
authors.initials: SC
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D000818:Animals; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000502:physiology*; D006614:Hindlimb / Q000033:anatomy & histology / Q000502:physiology; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009929:Organ Size / Q000502:physiology; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine
keywords: 3T; cartilage quantification; magnetic resonance imaging; porcine knee