title: Feasibility of Dual Flip Angle-Based Fast 3-Dimensional T1 Mapping for Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage of the Knee: A Histologically Controlled Study.
abstract: OBJECTIVE
  The aim of the study was to validate dual-flip angle-based fast 3-dimensional (3D) T1 mapping for delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) by means of histological analyses in the assessment of the cartilage of the knee in a porcine model.
  
  
  METHODS
  A total of 15 mini pigs were included in this study. The left knee anterior cruciate ligaments of all mini pigs were transected. The mini pigs were divided into 3 groups postoperatively, with 5 pigs randomly assigned to 1 group. Dual-flip angle-based fast T1 mapping for dGEMRIC was obtained in the sagittal planes at 0 week (group 1), 3 weeks (group 2), and 6 weeks (group 3) after operation, using an 8-channel knee coil. Magnetic resonance imaging was performed at 3T with dual-flip angle-based fast 3D T1 mapping sequence for morphological cartilage assessment of dGEMRIC T1 values. After MRI analysis, histological and biochemical composition (water, collagen, and glycosaminoglycan [GAG]) of the knee cartilage in the medial femoral condyle was quantified ex vivo.
  
  
  RESULTS
  The T1 values obtained by the dual-flip angle-based fast 3D T1 mapping were positively correlated with the glycosaminoglycan content (r = 0.85; P < 0.05). The values had no significant correlation with the collagen content. The dGEMRIC-T1 values obtained by this method showed the medial femoral condyle cartilage in the anterior cruciate ligament-transected knee after transection decreased with time (P < 0.05). Histological sections of cartilage damage were correlated with MRI data.
  
  
  CONCLUSIONS
  This study demonstrated the reliability of using dual-flip angle-based fast T1 mapping for dGEMRIC for the biochemical assessment of early cartilage degeneration. This technique is a powerful tool for researchers and clinicians to acquire sufficient resolution data within a reasonable scan time.
authors.affiliation: From the *Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China; †Department of Radiology, Columbia University Medical Center, New York, NY; ‡Department of Orthopedics Surgery, Nanjing First Hospital Affiliated to Nanjing Medical University; and §Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zong
authors.forename: Chao
authors.initials: C
authors.lastname: Yan
authors.forename: Lin
authors.initials: L
authors.lastname: Lu
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Shi
authors.forename: Rong-Bin
authors.initials: RB
authors.lastname: Yu
mesh_terms: D000465:Algorithms; D000818:Animals; D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D003287:Contrast Media / Q000008:administration & dosage; D005240:Feasibility Studies; D005682:Gadolinium / Q000008:administration & dosage*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine
chemical_list: D003287:Contrast Media; D005682:Gadolinium