Speed of Sound Imaging

PURPOSE: The purpose of this study was to evaluate blindly breast ultrasound images corrected for the speed of sound in breast tissue compared with conventional images. MATERIALS AND METHODS: In this study, 409 images from 153 patients were obtained on an Antares Ultrasound system. The system was modified to process the radiofrequency data with the standard 1540 m/s as the speed of sound and at a corrected speed of sound for breast tissue. An offline MATLAB-developed program randomized the image pairs, and 3 blinded reviewers who were unaware of the new technique reviewed these. The reviewers were asked to rate the image quality of the pair on a 5-point scale (right++, right+, equal, left+, left++). Comments on differences in the images were also recorded. RESULTS: Conventional images were graded much better in 0.0% and better in 15.1% +/- 6.2%. Corrected speed of sound images were rated much better in 10.5% +/- 14.3%, better in 48.4% +/- 14.3%, and equal in 25.9% +/- 27.6%. Improvements in image quality with corrected speed of sound images included better margin characterization and improved resolution of calcifications. CONCLUSIONS: Correcting for the speed of sound in breast ultrasound improved the overall image quality in 59% of cases, whereas 26% were of similar quality. Specific improvements noted included better characterization of mass margins, tissue interfaces, and depiction of calcifications.