Pulse-Echo Imaging of Breast Speed of Sound as a Potential Biomarker for Breast Cancer

Speed-of-sound (SoS) images, derived from minute misalignments between ultrasound images consecutively acquired using a motion-robust technique, were studied with multi-frame acquisitions to derive a lesion assessment metric for the differential diagnosis of breast cancer.

SoS elevation within inclusions was characterized as SoS contrast by comparing inclusions with their surrounding tissue. Malignancy was predicted as having larger SoS contrast compared with benign inclusions. In a study involving 100 patients with various breast lesion types, the findings were compared with gold standard diagnoses based on biopsy and expert consensus.

The proposed SoS contrast metric achieved an overall malignancy classification with an area under the curve of 69.70% (95% confidence interval [CI]: 57.4%-81.2%), with results varying depending on lesion type. Accounting for breast density or lesion size improved the area under the curve to 77.40% (95% CI: 59.2%-93.3%) and 78.09% (95% CI: 56.2%-95.8%), respectively. Focusing on Breast Imaging Reporting and Data System 4 lesions, where mammography and B-mode imaging are inconclusive, a sensitivity of 25% at 100% specificity or a specificity of 23% at 100% sensitivity was attained.

This study highlights the feasibility of SoS contrast as an imaging biomarker for the differential diagnosis of breast lesions. It also indicates the need for further technical advancements in SoS imaging to strengthen its ability to effectively classify lesions and enable interactive measurements during ultrasound examinations.