title: Pilot study of quantitative analysis of background enhancement on breast MR images: association with menstrual cycle and mammographic breast density.
abstract: OBJECTIVE
  To perform semiautomated quantitative analysis of the background enhancement (BE) in a cohort of patients with newly diagnosed breast cancer and to correlate it with mammographic breast density and menstrual cycle.
  
  
  METHODS
  Informed consent was waived after the research ethics board approved this study. Results of 177 consecutive preoperative breast magnetic resonance (MR) examinations performed from February to December 2009 were reviewed; 147 female patients (median age, 48 years; range, 26-86 years) were included. Ordinal values of BE and breast density were described by two independent readers by using the Breast Imaging Reporting and Data System lexicon. The BE coefficient (BEC) was calculated thus: (SI2 · 100/SI1) - 100, where SI is signal intensity, SI2 is the SI enhancement measured in the largest anteroposterior dimension in the axial plane 1 minute after the contrast agent injection, and SI1is the SI before contrast agent injection. BEC was used for the quantitative analysis of BE. Menstrual cycle status was based on the last menstrual period. The Wilcoxon rank-sum or Kruskal-Wallis test was used to compare quantitative assessment groups. Cohen weighted κ was used to evaluate agreement.
  
  
  RESULTS
  Of 147 patients, 68 (46%) were premenopausal and 79 (54%) were postmenopausal. The quantitative BEC was associated with the menstrual status (BEC in premenopausal women, 31.48 ± 20.68 [standard deviation]; BEC in postmenopausal women, 25.65 ± 16.74; P = .02). The percentage of overall BE was higher when the MR imaging was performed in women in the inadequate phase of the cycle (<35 days, not 7-14 days; mean BEC, 35.7) compared with women in the postmenopausal group (P = .001). Premenopausal women had significantly higher BEC when compared with postmenopausal women (P = .03). There was no significant difference in the percentage of BE between breast density groups.
  
  
  CONCLUSIONS
  Premenopausal women with breast cancer, and specifically women in the inadequate phase of the cycle, presented with higher quantitative BE than postmenopausal women. No association was found between BE and breast density.
authors: Department of Medical Imaging and Department of Biostatistics/Joint Department of Medical Imaging, Princess Margaret Cancer Centre, University Health Network, 610 University Ave, Room 3-922, Toronto, ON, Canada. anabel.scaranelo@uhn.on.ca
authors: Anabel M
authors: AM
authors: Scaranelo
authors: Maria Claudia
authors: MC
authors: Carrillo
authors: Rachel
authors: R
authors: Fleming
authors: Lindsay M
authors: LM
authors: Jacks
authors: Supriya R
authors: SR
authors: Kulkarni
authors: Pavel
authors: P
authors: Crystal
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008327:Mammography; D008597:Menstrual Cycle; D008875:Middle Aged; D009942:Organometallic Compounds; D010865:Pilot Projects; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol