title: Background parenchymal enhancement at breast MR imaging and breast cancer risk.
abstract: OBJECTIVE
  To examine the relationships between breast cancer and both amount of fibroglandular tissue (FGT) and level of background parenchymal enhancement (BPE) at magnetic resonance (MR) imaging.
  
  
  METHODS
  A waiver of authorization was granted by the institutional review board for this retrospective HIPAA-compliant study. Among 1275 women who underwent breast MR imaging screening between December 2002 and February 2008, 39 breast carcinoma cases were identified. Two comparisons were performed: In one comparison, two normal controls--those of the women with negative (benign) findings at breast MR imaging--were matched to each breast cancer case on the basis of age and date of MR imaging. In the second comparison, one false-positive control--that of a woman with suspicious but nonmalignant findings at MR imaging--was similarly matched to each breast cancer case. Two readers independently rated the level of MR imaging-depicted BPE and the amount of MR imaging-depicted FGT by using a categorical scale: BPE was categorized as minimal, mild, moderate, or marked, and FGT was categorized as fatty, scattered, heterogeneously dense, or dense.
  
  
  RESULTS
  Compared with the odds ratio (OR) for a normal control, the OR for breast cancer increased significantly with increasing BPE: The ORs for moderate or marked BPE versus minimal or mild BPE were 10.1 (95% confidence interval [CI]: 2.9, 35.3; P < .001) and 3.3 (95% CI: 1.3, 8.3; P = .006) for readers 1 and 2, respectively. Similar odds were seen when the false-positive controls were compared with the breast cancer cases: The ORs for moderate or marked BPE versus minimal or mild BPE were 5.1 (95% CI: 1.4, 19.1; P = .005) and 3.7 (95% CI: 1.2, 11.2; P = .013) for readers 1 and 2, respectively. The breast cancer odds also increased with increasing FGT, but the BPE findings remained significant after adjustment for FGT.
  
  
  CONCLUSIONS
  Increased BPE is strongly predictive of breast cancer odds.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, Evelyn H. Lauder Breast Center, 300 E 66th St, Room 715, New York, NY 10065, USA.
authors.forename: Valencia
authors.initials: V
authors.lastname: King
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Brooks
authors.forename: Jonine L
authors.initials: JL
authors.lastname: Bernstein
authors.forename: Anne S
authors.initials: AS
authors.lastname: Reiner
authors.forename: Malcolm C
authors.initials: MC
authors.lastname: Pike
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Morris
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D009518:New York / Q000453:epidemiology; D015995:Prevalence; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors