title: Evaluation of radial distribution of cartilage degeneration and necessity of pre-contrast measurements using radial dGEMRIC in adults with acetabular dysplasia.
abstract: BACKGROUND
  The purpose of the present study was to investigate the radial distribution patterns of cartilage degeneration in dysplastic hips at different stages of secondary osteoarthritis (OA) by using radial delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), and to assess whether pre-contrast measurements are necessary.
  
  
  METHODS
  Thirty-five hips in 21 subjects (mean age ± SD, 27.6 ± 10.8 years) with acetabular dysplasia (lateral CE angle < 25°) were studied. Severity of OA was assessed on radiographs using Tönnis grading. Pre- (T1pre) and post-contrast T1 (T1Gd) values were measured at 7 sub-regions on radial reformatted slices acquired from a 3-dimensional (3D) T1 mapping sequence using a 1.5 T MR scanner. Values of radial T1pre, T1Gd and ΔR1 (1/T1Gd - 1/T1pre) of subgroups with different severity of OA were compared to those of the subgroup without OA using nonparametric tests, and bivariate linear Pearson correlations between radial T1Gd and ΔR1 were analyzed for each subgroup.
  
  
  RESULTS
  Compared to the subgroup without OA, the subgroup with mild OA was observed with a significant decrease in T1Gd in the anterosuperior to superior sub-regions (mean, 476 ~ 507 ms, p = 0.026 ~ 0.042) and a significant increase in ΔR1 in the anterosuperior to superoposterior and posterior sub-regions (mean, 0.93 ~ 1.37 s-1, p = 0.012 ~ 0.042). The subgroup with moderate to severe OA was observed with a significant overall decrease in T1Gd (mean, 404 ~ 452 ms, p = 0.001 ~ 0.020) and an increase in ΔR1 (mean, 1.17 ~1.69 s-1, p = 0.001 ~ 0.020). High correlations were observed between radial T1Gd and ΔR1 for all subgroups (r = -0.869 ~ -0.944, p < 0.001).
  
  
  CONCLUSIONS
  Radial dGEMRIC without pre-contrast measurements is useful for evaluating different patterns of cartilage degeneration in the entire hip joint of patients with hip dysplasia, particularly for those in early stages of secondary OA.
authors.affiliation: Department of Radiology, 4th Medical College of Peking University (Beijing Jishuitan Hospital), 31 Xinjiekou East Street, Beijing, 100035, China.
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Su
authors.forename: Karl-Philipp
authors.initials: KP
authors.lastname: Kienle
authors.forename: Daichi
authors.initials: D
authors.lastname: Hayashi
authors.forename: Ali
authors.initials: A
authors.lastname: Guermazi
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Yongming
authors.initials: Y
authors.lastname: Dai
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Cheng
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D001848:Bone Diseases, Developmental / Q000000981:diagnostic imaging* / Q000453:epidemiology; D002357:Cartilage Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology; D015331:Cohort Studies; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging* / Q000453:epidemiology; D011859:Radiography
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA