In the classification of breast density, "Heterogeneously dense" indicates what?

In the classification of breast density, the term "Heterogeneously dense" refers to a breast that exhibits a mixing of both fatty and dense tissue. This classification implies that while there are significant areas of dense fibroglandular tissue present, there are also regions where fatty tissue predominates.

Breast density is determined using mammographic imaging, and it plays an important role in assessing cancer risk as well as interpreting mammography results. Heterogeneously dense breasts contain enough dense tissue that it may obscure small masses, which is why proper classification is crucial for appropriate screening.

In contrast, "almost entirely fatty tissue" would indicate a breast comprised mostly of non-dense tissue with little to no fibroglandular density. "Scattered areas of fibroglandular density" implies only occasional small areas of density within mostly fatty tissue, while "exclusively dense tissue" would indicate an absence of fatty tissue altogether. These classifications help radiologists make informed decisions on screening and follow-up care.