Two research groups used Volpara software to examine breast cancer screening performance across density categories. One group looked at the influence of age and density on the cancer detection rate in a U.K. screening program. Researchers included 70,435 screening mammograms from 63,577 women with 557 cancers, for an overall detection rate of 0.8%. Breast density was assessed and categorized by Volpara Density Grades (VDG). The cohort was divided into nine age groups to compare detection rates in the lowest (VDG 1) and highest (VDG 4) density women, stratified by age.
Results demonstrated that extreme density (Volpara VDG4) appears to correspond to higher detection rates in younger women, while the opposite is true for older women. The results suggest the relationship between cancer detection rate and density may vary with age, and, thus, age should be taken into account when stratifying women into different screening strategies based on density, the firm said.
Also, results from the Comparison of Tomosynthesis with Digital Mammography in the U.K. National Health Service Breast Screening Programme (TOMMY) trial established that screening sensitivity appears to significantly increase for women with intermediate density (4.5% to 15.5% Volpara density) compared with those with very high or very low density. In the study, the addition of digital breast tomosynthesis (DBT) significantly increased the specificity of 2D for all breast density subgroups, but it only significantly increased sensitivity in patients with quantitative breast density in the middle ranges. The results suggest DBT may not improve cancer detection in women with very low or very high breast density, according to Volpara.
In the third study, VolparaDensity was used to measure personalized radiation dose across VDGs on 4,764 DBT and digital mammograms, obtained by the same acquisition system in the same breast compression. Results showed the mean glandular dose for the four breast density categories was higher with tomosynthesis than mammography. However, the results also show an inverse relationship between VDG and dose in the DBT exams, and the relative dose increase is higher for fatty breasts and lower for dense breasts.
The fourth study objectively measured contrast-to-noise ratio (CNR) on clinical images (as opposed to phantoms) and showed near-perfect correlation to the European Reference Organisation for Quality Assured Breast Screening and Diagnostic Services' current method of measuring CNR from phantom images. As a description of an objective CNR measure that can be made directly from mammographic images, the technique may enable real-time and patient-specific image quality evaluation, Volpara said.
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