title: Comparing average breast fat content results from two different protocols at 1.5T and 3T: can the data be pooled?
abstract: OBJECTIVE
  To compare the total breast fat content computed from two separate studies, performed on different scanners and with different protocols, with the goal of defining a relationship to allow pooling the data.
  
  
  METHODS
  Twelve healthy volunteer women were scanned with two different protocols on the same day. The protocols differed in four important aspects: vendors (GE vs. Philips), scanner main magnetic field strengths (1.5T vs. 3T), pulse sequences (2D fast spin-echo vs. 3D spoiled gradient-echo), and water/fat separation techniques. The resulting water and fat maps were processed with in-house software to extract breast tissue slice-wise. Percent fat content was calculated for each breast, per subject.
  
  
  RESULTS
  Total percent fat contents (averaged across both breasts) resulting from both protocols were plotted against each other, on a subject-by-subject basis, revealing a strong correlation (R(2)  > 0.99), with an overestimation of the fat content from Protocol 1 relative to Protocol 2. The proposed T2 TE-correction for Protocol 1 improves the correlation while decreasing the discrepancy between protocols.
  
  
  CONCLUSIONS
  Total breast fat content of healthy women resulting from the two protocols can be pooled using a linear relationship. The proposed T2 TE-corrected Protocol 1 is expected to yield accurate fat content.
authors.affiliation: Centre for Addiction and Mental Health, Research Imaging Centre, Toronto, ON, Canada; University of Toronto, Psychiatry, Toronto, ON, Canada.
authors.forename: Sofia
authors.initials: S
authors.lastname: Chavez
authors.forename: Greg
authors.initials: G
authors.lastname: Stanisz
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology* / Q000502:physiology*; D050154:Adiposity / Q000502:physiology*; D000328:Adult; D001940:Breast / Q000033:anatomy & histology* / Q000502:physiology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: breast; fat content; magnetic resonance imaging; water fat imaging