title: Effect of the menstrual cycle on background parenchymal enhancement in breast MR imaging.
abstract: OBJECTIVE
  We assessed the influence of the menstrual cycle on background parenchymal enhancement (BPE) of the breast in the early and delayed phases of dynamic magnetic resonance (MR) imaging and the optimal timing of MR imaging of the breast in Japanese women.
  
  
  METHODS
  We reviewed dynamic MR images of 165 consecutive women with regular menstrual cycles and divided the women into 4 groups by week of the menstrual cycle: 32 in Week One (Days 1 through 4 of the menstrual cycle); 46 in Week 2 (Days 5 through 12); 49 in Week 3 (Days 13 through 20); and 38 in Week 4 (Days 21 through 30). We qualitatively evaluated BPE of the whole breast in the early and delayed phases of MR imaging; categorized enhancement as minimal, mild, moderate, or marked; and calculated the rate at which signal intensity increased (=SI post-SI pre/SI pre) in regions of interest in from the early and delayed phase to the before contrast administration phase to assess BPE quantitatively.
  
  
  RESULTS
  In both the early and delayed dynamic MR phases, BPE was significantly more extensive and stronger in Week 4 than Week 2 (P<0.01). Throughout the menstrual cycle, BPE was significantly stronger in the delayed phase than in the early phase in both qualitative (Week One, P=0.0002; Weeks 2 through 4, P<0.0001) and quantitative (Weeks One through 4, P<0.0001) assessments.
  
  
  CONCLUSIONS
  The optimal time to perform dynamic breast MR imaging in premenopausal Japanese women was during Days 5 through 12 of the menstrual cycle.
authors.affiliation: Department of Radiology, Kyoto Breast Center, Sawai Memorial Clinic, Kyoto, Japan. kajihara@nyusen.com
authors.forename: Mariko
authors.initials: M
authors.lastname: Kajihara
authors.forename: Mariko
authors.initials: M
authors.lastname: Goto
authors.forename: Yukari
authors.initials: Y
authors.lastname: Hirayama
authors.forename: Shoko
authors.initials: S
authors.lastname: Okunishi
authors.forename: Setsuko
authors.initials: S
authors.lastname: Kaoku
authors.forename: Eiichi
authors.initials: E
authors.lastname: Konishi
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Shinkura
mesh_terms: D000328:Adult; D001940:Breast / Q000378:metabolism* / Q000502:physiology*; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007564:Japan / Q000453:epidemiology; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008597:Menstrual Cycle / Q000502:physiology*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA