title: Diffusion tensor magnetic resonance imaging of the normal breast: reproducibility of DTI-derived fractional anisotropy and apparent diffusion coefficient at 3.0 T.
abstract: OBJECTIVE
  Diffusion-weighted imaging (DWI) may improve the diagnostic performance of conventional breast magnetic resonance imaging (MRI). Diffusion tensor imaging (DTI) is an extension of DWI. If DTI-derived measurements are to be clinically useful, particularly for predicting and/or monitoring therapeutic effects, they must be robust and reliable. The purpose of this study was to assess intra- and interobserver reproducibility of DTI-derived fractional anisotropy (FA) and apparent diffusion coefficient (ADC) at 3.0 T.
  
  
  METHODS
  This prospective study was approved by the Institutional Review Board, and participants provided written informed consent. Sixty normal contralateral breasts of 60 patients (28-85 years, median 57) were analysed with a DWI sequence following a standard MRI protocol. Four authors performed all postprocessing and analyses independently and in different sessions. The same authors, blinded to the initial results, repeated the image postprocessing and analysis 4 weeks after the initial session.
  
  
  RESULTS
  Mean ADC and FA for DTI sequences were, respectively, 1.92±0.30 and 0.32±0.09. Intra- and interobserver agreement of the four radiologists for ADC and FA were good (acceptable). Kappa values for ADC were intra-R1=0.82; intra-R2=0.84; intra-R3=0.89; intra-R4=0.88; inter-R1-R2=0.73; inter-R1-R3=0.74; inter-R1-R4=0.81; inter-R2-R3=0.76; inter-R2-R4=0.77; inter-R3-R4=0.83. Kappa values for FA were intra-R1=0.60; intra-R2=0.72; intra-R3=0.84; intra-R4 = 0.66; inter-R1-R2=0.64; inter-R1-R3=0.69; inter-R1-R4=0.72; inter-R2-R3=0.80; inter-R2-R4=0.71; inter-R3-R4=0.73. Within-subject coefficient of variation was 15% for ADC and 30% for FA. Repeatability with α=0.05 was 0.37×10-3 mm(2)/s for ADC and 0.112 for FA.
  
  
  CONCLUSIONS
  ADC and FA measurements obtained with DTI are reproducible and may be valid, reliable and sensitive to change. ADC values obtained with DTI are more reproducible than FA.
authors.affiliation: Department of Experimental Medicine, Institute of Anatomy, Università di Genova, Largo Rosanna Benzi 8, Genoa, Italy. alberto.tagliafico@unige.it
authors.forename: A
authors.initials: A
authors.lastname: Tagliafico
authors.forename: G
authors.initials: G
authors.lastname: Rescinito
authors.forename: F
authors.initials: F
authors.lastname: Monetti
authors.forename: A
authors.initials: A
authors.lastname: Villa
authors.forename: F
authors.initials: F
authors.lastname: Chiesa
authors.forename: E
authors.initials: E
authors.lastname: Fisci
authors.forename: D
authors.initials: D
authors.lastname: Pace
authors.forename: M
authors.initials: M
authors.lastname: Calabrese
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016880:Anisotropy; D001940:Breast / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values