Hypothesis The study aims to demonstrate at least equivalence, or non-significant difference between TS and US in women with dense breast screened negative at 2D Mammography.

If the equivalence between TS and US will be demonstrated, US may be substituted by TS with great benefits for the patients and for the healthcare resources.

Aims

1. Assess if TS may detect additional cancers in dense breast that approximate US detection capability but with less false positive findings than US.
2. If TS detects new cancers in dense breast similarly to US (approximate rate or marginally lower rate), evaluate the the true positive/false positive ratio.
3. Cost-analysis. In case of less false positives detected by TS, the true-positive / false positive trade-off might be strongly in favour of TS with a great potential of costs reduction.

Inclusion Criteria:

• Asymptomatic subjects <50 years of age presenting for mammography, with the exception of those that, on previous mammograms are found to have breast density 1-2 according to the Breast Imaging Reporting and Data System (BIRADS D1-2). - Asymptomatic subjects ≥ 50 years of age who request mammography and have breast density BIRADS 3-4.
• No history of breast cancer - Written informed consent

Exclusion Criteria:

• Pregnant and breast feeding women
• Unable to tolerate breast compression
• Breast implants
• Unable to understand or execute written informed consent
• Unable or unwilling to agree to follow-up during observation period