Stockpiles of salt (left) and a mineral containing mountain (right), that provided
the inspiration to measure breast volume stereoscopically.
ADDITIONAL READING
This paper describes the conception of the volume measurement system and its evolution. We highlight the principle findings from studies using the CBM system, and explain how they relate to the understanding of breast physiology.
Stockpiles of salt (left) and a mineral containing mountain (right), that provided
the inspiration to measure breast volume stereoscopically.
This lead to the concept of measuring the volume of the breast stereoscopically. Working in collaboration with a local mining company (Associated Surveys International Pty, Ltd), the volume of volunteers' breasts were measured. Unfortunately the breast was smoother and had a more uniform colour than ore bodies, presenting problems for the stereoscopic measurement technique. Nevertheless, it was possible to calculate breast volume (albeit in metric tonnes!).
Moire fringe patterns projected onto a breast.
These patterns were formed by projecting light through a screen of closely spaced moving wires.
While Moire topography allowed accurate measurement of breast volume, slow data processing made this method impractical for the measurement of large sample numbers. Also, the method required the formation of uninterrupted fringe patterns on the breast and, hence, was limited to the study of smaller breasts (Figure 2), since large breasts exhibit sharp depth discontinuities at the base and sides and these discontinuities cause the fringe patterns to break up. Therefore, a topographic system that could rapidly determine breast volume, on a wide range of breast sizes, was required. These conditions have been satisfied by the development of the CBM system.
The CBM system is both a hardware and software development of the ShapeC Measurement System (Alexander & Ng, 1987), which utilises the apparent distortion of horizontal coded light stripes to make volume measurements. A sequence of structured light patterns is projected on to the woman's breast so that interrupted stripes can be tracked by the computer program.
The CBM system (inset panel), surrounded by images of a breast with each of the coded light striping patterns projected onto it. The final image that is captured and used for the topographic reconstruction contains no stripes.
The images are captured over a period of 0.3 second by a CCD camera linked to a frame grabber. We now have two projector-camera pairs coupled to the system so that the breast can be sequentially viewed from above and below (Figure 3). This improves the precision of measurements for women with larger breasts. When the breast is viewed by the CCD camera from a position offset (by 15o in our system) from the plane of the light stripes (Figure 4), the parallel pattern of stripes is distorted by the curvature of the breast and a topographic map is created.
Three-dimensional topographic maps of a breast viewed from two angles.
These surface maps were constructed as described by Cox et al. (1994).
From the apparent distortion of the light stripes, the x, y, and z co-ordinates of individual points which track the light stripes are calculated by active triangulation. The aggregate of these points describes the three dimensional surface of the breast. Relative breast volume is then simply calculated by integration of the region under the surface curve, and within the black painted circle that surrounds the breast
(Huynh et al., 1990) View of the breast from an angle offset from the plane of light.
Note the apparent distortion of the stripes as they fall on the breast. Also note the hand-applied black acrylic paint circle that delimits the tissue for volume determination.
Thus, the CBM system does not determine absolute breast volume, but rather measures a relative volume, that is, the volume of tissue enclosed within the black painted circle. It is assumed that when synthetic tissue is making and secreting milk, the volume of non-breast tissue remains the same.
Calculation of the rate of milk synthesis. The solid red lines represent the change in breast volume with breastfeeding, and the dashed blue line represents the change in breast volume with the synthesis of milk. The rate of milk synthesis was calculated as the change in breast volume over time.
(Cox et al., 1996) The variation in the rate of milk synthesis, both within and between the breasts, of an individual mother over a single day.
Daly et al. (1993b) used the CBM system to measure the changes in breast volume of seven breastfeeding mothers over each breastfeed during a 24 h period. From these measurements they could determine the maximum and minimum volume of the breast over the 24 h period, the storage capacity of each breast (maximum-minimum breast volume), the degree of emptying of the breast, before and after each breastfeed, and the short-term rates of milk synthesis. They found that the storage capacity of the breasts ranged from 80 to 600 mL. The breast was not necessarily completely emptied at each breastfeed (Mother A; Figure 8), indicating that the infants regulated their milk intake presumably according to their appetite. Daly et al. (1993b) suggested that the storage capacity of the breast influenced the frequency of breastfeeding. Compared to mother A, mother B had a much smaller storage capacity and her infant nursed more frequently. By more frequent breastfeeding this infant was able to obtain at least as much milk as the infant of mother A (956 vs 896 mL/24 h, respectively).
The degree of fullness (1-degree of emptying (Cox et al., 1996)) of the left breast from before to the end of a breastfeed and the rate of milk synthesis in that breast for two of the women described by Daly et al. (1993b). Note that there is an inverse relationship between these two factors in the case of mother A, while for mother B both the rate of milk synthesis and the minimum degree of fullness after each breastfeed are relatively constant.
The rate of milk synthesis varied from breastfeed to breastfeed (Figs. 8 and 9). Taking the example of mother A, the rate of milk synthesis was lowest when the breasts were full and highest when they were near empty. In the case of mother B there was no major variation in the rate of milk synthesis throughout the day. Overall, Daly et al. (1993b) found that the rate of milk synthesis was related to the degree of emptying of the breast and concluded that the control of the rate of milk synthesis was localised within the breast. Furthermore, this control responded to changes in the degree of breast fullness (Daly et al., 1993b; Cox et al., 1996). The short-term rates of synthesis for mother B's right breast are consistent with this conclusion as it was emptied to a constant degree (Figure 9).
Since prolactin is a potent stimulator of the synthesis of milk components (Cowie et al., 1980), and the control of milk synthesis is localised within the breast (Daly et al., 1993b; Cox et al., 1996), we hypothesized that the control of milk synthesis may be related to a restriction on the binding and subsequent entry of prolactin into the mammary gland. Noilin (1979) found that the entry of prolactin into lactating rat lactocytes was restricted by the morphology of the lactating cell, that is, prolactin entered the cells only when they were tall and columnar and had minimal milk in the alveolus. We found that the amount of prolactin in the milk from a full gland was high at first and then declined as milk was removed from the breast. This is consistent with Noilin (1979) assuming that there is minimal mixing of milk within the breast, and that the fore-milk is synthesized during the periods when the lactocytes are in the columnar formation and the alveolus is close to empty (Cox et al., 1996).
Arthur, P. G., Jones, T. R., Spruce, J., and Hartmann, P. E., 1989, "Measuring short-term rates of milk synthesis in breast-feeding mothers", Quarterly Journal of Experimental Physiology, 74:419-428.
Cox, D. B., Kent, J. C., Owens, R. A. and Hartmann, P. E., 1994, "Mammary morphological and functional changes during pregnancy in women", Proceedings of the Australian Society for Reproductive Biology, 26:47.
Cox, D. B., Owens, R. A., and Hartmann, P. E., 1996, "Blood and milk prolactin and the rate of milk synthesis in women", Experimental Physiology, 81:1007-1020.
Cowie, A. T., Forsyth, I. A., and Hart, I. C., 1980, "Hormonal Control of Lactation", (Springer-Verlag; Berlin).
Daly, S. E. J., Di Rosso, A., Owens, R. A., and Hartmann, P. E., 1993a, "Degree of breast emptying explains changes in the fat content, but not fatty acid composition, of human milk", Experimental Physiology, 78:741-755.
Daly, S. E. J., and Hartmann, P. E., 1995, "Infant demand and milk supply. Part 2: The short-term control of milk synthesis in lactating women", Journal of Human Lactation, 11:27-37.
Daly, S. E. J., Kent, J. C., Huynh, D. Q., Owens, R. A., Alexander, B. F., Ng, K. C., and Hartmann, P.E., 1992, "The determination of short-term breast volume changes and the rate of synthesis of human milk using computerized breast measurement", Experimental Physiology, 77:79-87.
Daly, S. E. J., Owens, R. A., and Hartmann, P. E., 1993b, "The short-term synthesis and infant-regulated removal of milk in lactating women", Experimental Physiology, 78:209-220.
Dulbecco, R., 1987, "The Design of Life", (Yale University Press; New Haven) p. 161.
Huynh, D. Q., Owens, R. A., Daly, S. E. J., Kent, J. C., and Hartmann, P. E., 1990, "The rapid estimation of short term changes in breast volume", Proceedings of the 6th International Conference on Biomedical Engineering, Singapore, 93-96.
Noel, G. L., Suh, H. K., and Frantz, A. G., 1974, "Prolactin release during nursing and breast stimulation in post partum and non-post partum subjects", Journal of Clinical Endocrinology and Metabolism, 38; 413-423.
Noilin, J. M., 1979, "The prolactin incorporation cycle of the milk secretory cycle", Journal of Histochemistry and Cytochemistry, 27:1203-1204.
David B. Cox, Robyn Owens and Peter Hartmann
Department of Biochemistry
University of Western Australia
Nedlands, Perth
W.A. 6907 Perth, Australia
phone: +61 9 380 2303
fax : +61 9 380 1148
For additional information contact David Cox (e-mail: dbcox@uniwa.uwa.edu.au )
last update: June 1998
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