Improved microcalcification visualization using dual-energy digital mammography

Quantitative evaluation of breast density using a dual-energy technique on a digital breast tomosynthesis system

Purpose

Although breast density is considered a strong risk factor of breast cancer, its quantitative assessment is difficult. To investigate a quantitative method of measuring breast density using dual‐energy mammographic imaging with central digital breast tomosynthesis in physically uniform and nonuniform phantoms.

Material and methods

The dual‐energy imaging unit used a tungsten anode and silver filter with 30 kVp for high‐energy images and 20 kVp for low‐energy images. Uniform glandular‐equivalent phantoms were used to calibrate a dual‐energy based decomposition algorithm. The first study used uniform breast phantoms which ranged in thicknesses from 20 to 70 mm, in 10‐mm increments, and which provided 30%, 50%, and 70% of breast density. The second study used uniform phantoms ranging from 10% to 90% of breast density. The third study used non‐uniform phantoms (at an average density of 50%) with a thickness which ranged from 20 to 90 mm, in 10‐mm increments.

Results

The root mean square error of breast density measurements was 2.64–3.34% for the uniform, variable thickness phantoms, 4.17% for the uniform, variable density phantoms, and 4.49% for the nonuniform, variable thickness phantoms.

Conclusion

The dual‐energy technique could be used to measure breast density with a margin of error of < 10% using digital breast tomosynthesis.

Contrast-Enhanced X-ray Detection of Microcalcifications in Radiographically Dense Mammary Tissue Using Targeted Gold Nanoparticles

Breast density reduces the accuracy of mammography, motivating methods to improve sensitivity and specificity for detecting abnormalities within dense breast tissue, but preclinical animal models are lacking. Therefore, the objectives of this study were to investigate a murine model of radiographically dense mammary tissue and contrast-enhanced X-ray detection of microcalcifications in dense mammary tissue by targeted delivery of bisphosphonate-functionalized gold nanoparticles (BP-Au NPs). Mammary glands (MGs) in the mouse mammary tumor virus - polyomavirus middle T antigen (MMTV-PyMT or PyMT) model exhibited greater radiographic density with age and compared with strain- and age-matched wild-type (WT) controls at 6-10 weeks of age. The greater radiographic density of MGs in PyMT mice obscured radiographic detection of microcalcifications that were otherwise detectable in MGs of WT mice. However, BP-Au NPs provided enhanced contrast for the detection of microcalcifications in both radiographically dense (PyMT) and WT mammary tissues as measured by computed tomography after intramammary delivery. BP-Au NPs targeted microcalcifications to enhance X-ray contrast with surrounding mammary tissue, which resulted in improved sensitivity and specificity for detection in radiographically dense mammary tissues.