Ultrasound has long been an efficient and useful adjunct technique for breast imaging. It is the first modality to be proposed in some situations: if a young or pregnant woman has a palpable mass, for example, or immediately after surgery.
Ultrasound is usually performed during the diagnostic workup of masses, if architectural distortion is detected on mammograms, or following mammographic screening in individuals who are at high risk of breast cancer and have dense breast tissue.
Ultrasound's primary role when imaging masses is to determine if the mass is cystic, and hence benign, or solid and potentially malignant. This differentiation is not always easy to make in practice, especially for complicated echoic cysts and lesions that are less than 7 mm in diameter.
This all suggests that we need new tools to increase the specificity of B-mode ultrasound findings.
Elastography is emerging as a promising candidate for this role. The technique has been reported in the literature since the 1980s, but it has not become routine. Now elastography is more userfriendly, and real-time images can be generated.
ESSENTIAL TECHNIQUE
Elastography is currently offered by two vendors: Hitachi (EUB-8500 ultrasound scanner with integrated elastography software and a 6.5- to 13-MHz probe) and Siemens (Sonoline Elegra, 7.5L40 transducer at 7.2 MHz or VFX13-5 transducer at 10 MHz). The principle of the technique is essentially the same for both systems.
Tissue compression produces displacement that is mainly in the longitudinal direction, the direction of the ultrasound beam. This can be used to calculate the strain in the tissue being compressed. Strain tends to be smaller in harder tissue than softer tissue.
So working backwards, once the strain has been calculated, the tissue hardness can be evaluated as well. The influence of probe movement on the skin's surface in the lateral direction is minimized during measurement.
