Proton MR spectroscopy in normal breasts between pre- and postmenopausal women: a preliminary study

The purpose of our study was to assess the differences in the water and lipid fractions and lipid line widths in normal breasts between premenopausal and postmenopausal women using single-voxel proton MR spectroscopy (1H-MRS).

Thirty-two premenopausal and 25 postmenopausal women were enrolled in the study. Single-voxel proton MR spectroscopy of the breast was performed using point-resolved spectroscopy (PRESS) with water suppression and stimulated echo acquisition mode (STEAM). On STEAM, water fraction 1 was the ratio of the integration of water to the sum of the integration of water and methylene resonances, and the lipid fraction 1 was the ratio of the integration of methylene to water and methylene resonances. Lipid fraction 2 was the ratio of the integration of allylic methylene to water and allylic methylene resonances. Lipid line width was measured on PRESS.

The premenopausal group had a higher water fraction 1 and lower lipid fraction 1 than the postmenopausal group (p < 0.01, Student's t test). The breast density had a positive effect on water fraction 1 and a negative effect on lipid fraction 1 for premenopausal women (p = 0.018, multivariate regression) and for the total population (p = 0.019). The premenopausal women had a higher lipid fraction 2 than postmenopausal women without significance (Student's t test), but the premenopausal status had a positive effect on lipid fraction 2 (p = 0.024, multivariate regression). There was no significant correlation between all independent variables and lipid line width.

Breast 1H-MRS shows the differences of water and lipid compositions between pre- and postmenopausal women. Lipids containing methylene and allylic methylene protons had different implications in normal breasts.