"N1: the breast consists mainly of fat (N = normal)"
"P1: this pattern includes fat as well as linear densities (enlarged ducts) occupying no more than 25% of the breast"
"P2: linear densities (from enlarged ducts) occupying more than 25% of the breast. They are prominently in the upper outer quadrant but may be distributed throughout the breast (P=prominent ducts)"
"Dy: dense, radiopaque breast (Dy=dysplasia); these patterns are again subdivided into low-risk (N1 and P1) and high-risk (P2 and DY) patterns"
" A: 0%"
" B: >0-10%"
" C: >10-25%"
" D: >25-50%"
" E: >50-75%"
" F: >75%"
"I: balanced proportion of all components of breast tissue with a slight predominance of fibrous tissue"
"II: predominance of fat tissue (fat breast)"
"III: predominance of fat tissue with retroareolar residual fibrous tissue"
"IV: predominantly nodular densities"
"V: predominantly fibrous tissue (dense breast)"
"Boyd classification "
"Tabar classification "
"See the main article on breast density for the accepted BI-RADS descriptors."
"It is important to consider that some therapies may alter the pattern by increasing parenchymal density, as in hormone replacement therapy (HRT), or reducing it as in therapies with selective oestrogen-receptor modulators (SERM)."
"Prior version of BI-RADS classification of density"
"The prior, 4th edition of BI-RADS used a semi-quantitative method proposed by the American College of Radiology (2003) 30. It was a modification of Wolfe’s classification, defined using percentages of density divided into quartiles:"
"Qdy (quasi-dysplasia): this group consists of young women whose dense breast have a somewhat spongy texture due to fatty infiltration"
" A: 0%"
" B: >0-10%"
" E: >50-75%"
" F: >75%"
Expected headings
"Wolfe classification"
"Boyd classification "
"Tabar classification "
"Prior version of BI-RADS classification of density"
"Wolfe described the first qualitative classification of mammographic density patterns in 1976. Wolfe assigned the mammograms to four parenchymal patterns (N1, P1, P2 and Dy) according to the distribution of fat and the prominence of the ducts:"
"Patterns I, II and III are considered low-risk; patterns IV and V high-risk."
"Dy: dense, radiopaque breast (Dy=dysplasia); these patterns are again subdivided into low-risk (N1 and P1) and high-risk (P2 and DY) patterns"
"Patterns I, II and III are considered low-risk; patterns IV and V high-risk."
"Tabár (1997) classifies the mammograms in five patterns (I to V) based on an histologic-mammographic correlation with a three-dimensional, subgross (thick-slice) technique, and on the relative proportion of four “building blocks” (nodular densities, linear densities, homogeneous fibrous tissue, radiolucent fat tissue):"