Elastography is a medical imaging technique that displays or measures the stiffness of soft tissue. It involves application of a compression force and measurement of the internal tissue motion using ultrasound or MRI. Stiffer tissues generally exhibit lower strain compared to the compliant tissues. In the basic variation of ultrasound elastography, known as strain imaging, relative tissue stiffness is inferred from the strain images that are displayed on the screen. While strain imaging has been found to be effective in some applications, its lack of widespread acceptance in clinical radiology was mainly due to the presence of numerous artifacts resulting from improper assumptions about tissue mechanics. Additionally, the inability of strain imaging to provide absolute values of tissue elasticity makes it unsuitable for applications such as patient monitoring, disease staging and comparative analysis of a large cohort.
MR elastography (MRE) can be considered as the gold-standard elastography technique because it produces the most complete data set, i.e. image of the shear-wave propagation within a volume of the tissue. However, due to the very high cost of MRI examinations and the long image acquisition time, MRE may not be suitable for routine clinical use.
Vibroelastography is a novel technique to remotely measure the viscoelastic properties of soft tissue using a robust multi-frequency approach. Vibroelastography can be used in various clinical applications such as breast, prostate, liver, thyroid, etc. and can yield absolute and relative maps of the viscoelastic parameters in real-time.