1) To understand the elastic properties of normal and pathologic breast tissues. 2) To get an overview of the different ultrasound methods and technologies. 3) To learn about the clinical results obtained with the different methods. 4) To understand the role of elastography within the imaging protocol.
Real-time elastography (RTE) of the breast may easily and quickly integrate conventional breast imaging.
A mechanical force is applied to the tissue and sophisticated algorithms are used to estimate the tissue stiffness. Qualitative scores are usually derived from the estimate of the strain and help to differentiate soft benign lesions from malignancies. These are usually stiffer due to the secretion of collagen and fibronectin, and the surrounding edema. Fluid lesions almost always show a typical three-layered pattern. Strain scores may be integrated by semi-quantitative data (fat-to-lesion ratio);
unfortunately cut off values vary for different companies. Dedicated RTE technologies as an alternative track the shear wave propagation through tissues to obtain a true quantitative evaluation of the acoustic modulus and promise to be the gold standard for the future applications.
Clinical reports show a high diagnostic accuracy: increased specificity for atypical carcinomas and a very high specificity in benign lesions, including BI-RADS category 3 lesions. With the best cutoff point between elasticity scores 3 and 4, the true negative predictive value is over 90%. In invasive carcinomas RTE clearly shows the peripheral infiltration improving the volume measurement; 3D elastography and tomographic imaging may help in this respect. RTE works better with small lesions, less than 10 mm in diameter. RTE is almost insensitive to breast thickness and echogenicity. RTE scores are well reproducible. Indexes of intra-observer and inter-observer agreement are very good. Still RTE score is only a complementary descriptor that requires global experience in breast imaging and strict guidelines.
http://media.rsna.org/media/abstract/2011/11000750/epbn670_11000750_Rizzatto_MSVB31-12.pdf
Rizzatto, G,
Elastography. Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL.
http://archive.rsna.org/2011/11000750.html
