title: Diffusion-tensor MR imaging of the breast: hormonal regulation.
abstract: OBJECTIVE
  To investigate the parameters obtained with magnetic resonance (MR) diffusion-tensor imaging (DTI) of the breast throughout the menstrual cycle phases, during lactation, and after menopause, with and without hormone replacement therapy (HRT).
  
  
  METHODS
  All protocols were approved by the internal review board, and signed informed consent was obtained from all participants. Forty-five healthy volunteers underwent imaging by using T2-weighted and DTI MR sequences at 3 T. Premenopausal volunteers (n = 16) underwent imaging weekly, four times during one menstrual cycle. Postmenopausal volunteers (n = 19) and lactating volunteers (n = 10) underwent imaging once. The principal diffusion coefficients (λ1, λ2, and λ3), apparent diffusion coefficient (ADC), fractional anisotropy (FA), and maximal anisotropy (λ1-λ3) were calculated pixel by pixel for the fibroglandular tissue in the entire breast.
  
  
  RESULTS
  In all premenopausal volunteers, the DTI parameters exhibited high repeatability, remaining almost equal along the menstrual cycle, with a low mean within-subject coefficient of variance of λ1, λ2, λ3, and ADC (1%-2% for all) and FA (5%), as well as a high intraclass correlation of 0.92-0.98. The diffusion coefficients were significantly lower (a) in the group without HRT use as compared with the group with HRT use (P < .01) and premenopausal volunteers (P < .01) and (b) in the lactating volunteers as compared with the premenopausal volunteers (P < .005). No significant differences in DTI parameters were found between premenopausal volunteers free of oral contraceptives and those who used oral contraceptives (P = .28-0.82) and between premenopausal volunteers and postmenopausal volunteers who used HRT (P = .31-0.93).
  
  
  CONCLUSIONS
  DTI parameters are not sensitive to menstrual cycle changes, while menopause, long-term HRT, and presence of milk in lactating women affected the DTI parameters. Therefore, the timing for performing breast DTI is not restricted throughout the menstrual cycle, whereas the modulations in diffusion parameters due to HRT and lactation should be taken into account in DTI evaluation.
authors.affiliation: From the Department of Biological Regulation (N.N., D.G., H.D.) and Unit of Biological Services (E.F.H.), Weizmann Institute of Science, PO Box 26, Rehovot 76100, Israel; and Department of Radiology, Meir Medical Center, Kfar Saba, Israel (M.S.F.).
authors.forename: Noam
authors.initials: N
authors.lastname: Nissan
authors.forename: Edna
authors.initials: E
authors.lastname: Furman-Haran
authors.forename: Myra
authors.initials: M
authors.lastname: Shapiro-Feinberg
authors.forename: Dov
authors.initials: D
authors.lastname: Grobgeld
authors.forename: Hadassa
authors.initials: H
authors.lastname: Degani
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D003276:Contraceptives, Oral; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007774:Lactation / Q000502:physiology; D008593:Menopause / Q000502:physiology; D008597:Menstrual Cycle / Q000502:physiology*; D008875:Middle Aged; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D003276:Contraceptives, Oral; D003287:Contrast Media