The quantitative analysis of mammographic densities

Abstract

Quantitative classification of mammographic parenchyma based on radiological assessment has been shown to provide one of the strongest estimates of the risk of developing breast cancer. Existing classification schemes, however, are limited by coarse category scales. In addition, subjectivity can lead to sizeable interobserver and intraobserver variations. Here, we propose an interactive thresholding technique applied to digitized film-screen mammograms, which assesses the proportion of the mammographic image representing radiographically dense tissue. Observers viewed images on a CRT display and selected grey-level thresholds from which the breast and regions of dense tissue in the breast were identified. The proportion of radiographic density was then calculated from the image histogram. The technique was evaluated for the mammograms of 30 women and is well correlated (R > 0.91, Spearman coefficient) with a six-category subjective classification of radiographic density by radiologists. The technique was found to be very reliable with an intraclass correlation coefficient between observers typically R > 0.9. This technique may have a role in routine mammographic analysis for the purpose of assessing risk categories and as a tool in studies of the etiology of breast cancer, in particular for monitoring changes in breast parenchyma during potential preventive interventions.

The association of breast mitogens with mammographic densities

“…We determined the total area of the breast, and the area of dense tissue on mammography, using a previously described computer assisted method (Byng et al, 1994).…”

“…Images were analysed using a computer assisted method (Byng et al, 1994(Byng et al, , 1996a. Images from subjects in the pre and postmenopausal groups were randomly ordered, and thus measured without knowledge of menopausal status, or of any of the other characteristics of the subjects.…”

Mammographic density and the risk of breast cancer in Japanese women

“…To evaluate the validity, our mammogram measurements were compared with those assessed by researchers at the Cancer Research Center of Hawaii (Maskarinec et al, 2002). They adopted the validated method described by Byng et al (1994) and Ursin et al (1998). Based on mammograms from 131 women, the rank correlation coefficients between their method and our method were 0.95 for total breast area and 0.80 for percent density.…”

Dietary patterns and breast density in the Minnesota Breast Cancer Family Study

“…If no mammogram had been taken in the previous year (2 years if\50 years at time of interview), they were instructed to obtain a new one through their personal physician. Percent breast density was estimated using the semi-automated breast density method developed by Dr. Martin Yaffe and colleagues at the Uni versity of Toronto [20]. The method involves dividing the mammographic image into a distribution of gray values, then setting two thresholds: one that differentiates the edge of the breast from the rest of the mammogram, and the other that identifies the border of the region(s) in the pixel distri bution representing the radiographically dense tissue in the image.…”