title: Ultrashort echo time bi-component analysis of cortical bone--a field dependence study.
abstract: OBJECTIVE
  The purpose of this study is to investigate the effect of differing field strength on the T2* of cortical bone at 1.5 T and 3 T.
  
  
  METHODS
  Ultrashort echo time pulse sequences were used to study six bovine and nine human bone samples at 1.5 T and 3 T using single- and bi-component T2* analysis.
  
  
  RESULTS
  On average, the bound water T2* of bovine bone decreased by 16% (from 0.32 ms at 1.5 T to 0.27 ms at 3 T, P < 0.01) and the bound water T2* of human bone decreased by 21% (from 0.42 ms at 1.5 T to 0.33 ms at 3 T, P < 0.01) at the higher field strength. The free water T2* of bovine bone decreased by 50% (from 4.23 ms at 1.5 T to 2.12 ms at 3 T, P < 0.001) and the free water T2* of human bone decreased by 68% (from 7.65 ms at 1.5 T to 2.46 ms at 3 T, P < 0.001) at the higher field strength. Bound and free water fractions showed only minor change with field strength in bovine (< 2%, P > 0.05) and human bone (< 4%, P > 0.05).
  
  
  CONCLUSIONS
  Ultrashort echo time bi-component analysis provides consistent bound and free water fractions at 1.5 T and 3 T, thereby allowing field-independent comparisons.
authors: Department of Radiology, University of California, San Diego, California, USA; Department of Radiology, Hua Dong Hospital, Fudan University, Shanghai, People's Republic of China; Yancheng Medical College, Jiangsu, People's Republic of China.
authors: Shihong
authors: S
authors: Li
authors: Eric Y
authors: EY
authors: Chang
authors: Won C
authors: WC
authors: Bae
authors: Christine B
authors: CB
authors: Chung
authors: Song
authors: S
authors: Gao
authors: Shanglian
authors: S
authors: Bao
authors: Graeme M
authors: GM
authors: Bydder
authors: Yanqing
authors: Y
authors: Hua
authors: Jiang
authors: J
authors: Du
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism*; D002417:Cattle; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013977:Tibia / Q000033:anatomy & histology* / Q000737:chemistry*; D014018:Tissue Distribution