JudyC Nov 26, 2021:

meaning... parvi- (up to 6-7 mm) is bigger than micro- (up to 3 mm)

For teaching purposes it may be useful to
classify mammographic structures into six main groups
reflecting the most frequently encountered breast tissue
patterns.
[...]
3) Micronodular structure - Less adipose tissue is seen.
The fibro-glandular component is abundant, most of it
forming a "cobblestone" effect made of small
radiopaque nodular opacities measuring up to 3mm
diameter. (Fig-3)
4) Parvinodular structure - similar to micronodular
structure, but the elementary radiopaque nodules are
larger, some reaching 6-7mm in diameter(Fig-4)
[...]