DMN: Do all breast density measurement systems use the same methodology?

JP: No, one approach, which is most often used, measures the physical absorption of X-rays (given by the pixel values in the mammogram) to estimate the percent volume covered by fibroglandular tissue. The percent volume is then mapped to a score from a to d, analogous to the BI-RADS category. Such volumetric methods have inherent limitations. First, pixel values in the mammographic images may not reflect the actual absorption of X-rays, decreasing the accuracy of -- or completely invalidating -- the volumetric assessments. For example, volumetric measurements from mammograms imaged using a Lorad Selenia are less accurate than those from the GE Senographe; the Selenia compression paddle can tilt during compression, whereas the Senographe paddle remains rigid. Furthermore, the pixel values of both standard for-presentation images and synthetic C-view images are not directly related to the X-ray attenuation. Second, since BI-RADS categories are defined not only by the percentage of the breast covered by dense tissue, but also by the dispersion of this tissue throughout the breast, volumetric methods are inherently limited in their ability to accurately reproduce BI-RADS scores.


DMN: You mentioned the BI-RADS categories — to what extent does the appearance-based approach agree with the category descriptors?

JP: For automated breast density systems to be efficacious in a clinical setting, they must yield accurate and consistent results. Initial studies support such efficacy. Gweon, et al.11, reported a weighted kappa statistic of 0.54 -- indicating moderate agreement -- between the Volpara density grade (Matakina Technology) and a consensus of three radiologists' BI-RADS categories. A similar analysis of M-Vu Breast Density (reported in an FDA clinical study) yielded a weighted kappa statistic of 0.64 -- indicating substantial agreement between the VuCOMP density grade and a consensus of 13 expert radiologists' BI-RADS categories. In a different study of 490 patients, the density estimates produced by M-Vu had less than half the variability of those produced by 10 radiologists.

DMN: What are you seeing out there in terms of interest and adoption?

JP: We have seen significant adoption from practices and clinics large and small who want to remove the subjectivity out of their breast density assessment. Sites are searching for an automated tool that provides consistent results from physician to physician and year over year. Radiologists are saying that VuCOMP's approach to analyzing structure, texture, and dispersion of fibroglandular tissue provides useful adjunctive information. There are now 17 states which have passed breast density notification laws and federal legislation is being developed now, so this has and certainly will continue to drive adoption.

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