Diffuse optical spectroscopy of lactating and non-lactating human mammary physiology.

Breastfeeding provides widely recognized advantages for infant and maternal health. Unfortunately, many women experience trouble with breastfeeding. Nevertheless, few suitable imaging modalities are available to study human lactation and determine the possible causes of breastfeeding problems. In this study, we apply broadband, quantitative diffuse optical spectroscopy (DOS) for this purpose. We present a study of fourteen lactating and eight similarly aged, premenopausal, non-lactating women to investigate the feasibility of DOS to study the optical and physiological differences between 1) lactating and non-lactating breasts, 2) the areolar and non-areolar region within the breast, and 3) lactating breasts before and after milk extraction. Our study shows that i) the median total hemoglobin concentration [tHb] of the lactating breast is 51% higher than for the non-lactating breast. ii) the median [tHb] of the lactating breast is 37% higher in the areolar region compared to the non-areolar region. iii) lactating breasts exhibit a positive median difference of 8% in [tHb] after milk extraction. Our findings are consistent with the expected physiological changes that occur during the lactation period. Importantly, we show that DOS provides unique insight into breast tissue composition and physiology, serving as a foundation for future application of the technique in lactation research.