title: Impact of fibroglandular tissue and background parenchymal enhancement on diffusion weighted imaging of breast lesions.
abstract: OBJECTIVE
  To evaluate the influence of the amount of fibroglandular breast tissue (FGT) and background-parenchymal enhancement (BPE) on lesion detection, quantitative analysis of normal breast tissue and of breast lesions on DWI.
  
  
  METHODS
  IRB approved this retrospective study on focal findings at contrast-enhanced (CE)breast MR and DWI performed during July-December 2011. Patients with cysts, previous irradiation,silicone implants and current chemotherapy were excluded. DWI with fat suppression was acquired before dynamic acquisition (b factors: 0.1000 s/mm2) using 1.5 and 3 T scanners. Using correlation with dynamic and T2 images, ROIs were drawn free-hand within the borders of any visible lesion and incontralateral normal breast. Fisher's exact test to evaluate visibility and Wilcoxon-rank-sum test for comparison of ADC values were used. The amount of FGT and BPE was visually assessed by concurrent MRI. Analysis was stratified by menopausal status.
  
  
  RESULTS
  25/127 (20%) lesions were excluded for technical reasons. 65/102 (64%) lesions were visible on DWI (median diameter: 1.85 cm). Mass lesions (M) were more visible (43/60 = 72%) than non-mass enhancement (NME) (22/42 = 52%) and malignant lesions were more visible (55/72 = 76%) than benign(10/30 = 33%). BPE and FGT did not influence visibility of M (p = 0.35 and p = 0.57 respectively) as well as of NME (p = 0.54 and p = 0.10). BPE and FGT did not influence visibility of malignant (p = 0.96 and p = 1.0)and benign lesions (p = 1.0 and p = 0.10). Results were confirmed adjusting for menopausal status. The ADC value of normal breast tissue was not influenced by BPE, while it was lower in predominantly fatty breasts compared to dense ones (p = 0.002).
  
  
  CONCLUSIONS
  FGT affects the quantitative evaluation of ADC in normal breast tissue whereas BPE does not.Furthermore, both BPE and FGT do not influence visibility of benign or malignant findings, including both mass lesions and non-mass enhancement, on DWI.
authors.affiliation: Breast Unit, USL1 Massa-Carrara, Piazza Monzoni 2, Carrara 54033, Italy. Electronic address: chiara.iacconi@tin.it.
authors.forename: Chiara
authors.initials: C
authors.lastname: Iacconi
authors.affiliation: Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, NY 1275 York Avenue, New York, NY 10065, USA. Electronic address: thakurs@mskcc.org.
authors.forename: Sunitha B
authors.initials: SB
authors.lastname: Thakur
authors.affiliation: Department of Radiology - Breast Imaging Center, Memorial Sloan-Kettering Cancer Center, NY 1275 York Avenue, New York, NY 10065, USA. Electronic address: dershawd@mskcc.org.
authors.forename: David D
authors.initials: DD
authors.lastname: Dershaw
authors.affiliation: Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, 307 East 63rd Street, New York, NY 10065, USA. Electronic address: brooksj@mskcc.org.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Brooks
authors.affiliation: Memorial Sloan-Kettering Cancer Center, NY 1275 York Avenue, New York, NY 10065, USA. Electronic address: charles_fry@nymc.edu.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Fry
authors.affiliation: Department of Radiology - Breast Imaging Center, Memorial Sloan-Kettering Cancer Center, NY 1275 York Avenue, New York, NY 10065, USA. Electronic address: morrise@mskcc.org.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Morris
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008875:Middle Aged; D012189:Retrospective Studies