Microcalcifications and high-performance breast ultrasound

Abstract

Breast microcalcifications (MCs) are small crystals of calcium phosphate which are in some cases the only evidence of malignancy. Thus MCs serve as important diagnostic indicators, despite the fact that mammography has a low specificity in cases where MCs are the only suspicious feature. The overall sensitivity and specificity of mammography is also reduced in the radiographically dense breast. While the adjunctive use of breast ultrasound continues to expand with advances in the state of the art, ultrasound is currently not considered a reliable means to visualize MCs. Their improved visualization under ultrasound would be of significant clinical benefit, particularly in the dense breast. The findings to date of ongoing studies of the in vivo acoustic properties of MCs and breast tissues are reviewed. These include investigations of the scattering properties of MCs and breast tissue as well as direct measurements of in vivo phase aberrators and mean tissue sound speed using MCs as in vivo point scatterers. These studies suggest that MCs have elastic acoustic properties, and that gross sound speed error and tissue backscatter are the most significant factors limiting the visualization performance of ultrasound, among those studied. [This work is supported by NIH Grant Nos. RO1-CA43334-01 and R01-CA76059-01.]