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Quasi-Static Ultrasound Elastography

2009; Elsevier BV; Volume: 4; Issue: 3 Linguagem: Inglês

10.1016/j.cult.2009.10.009

1879-9647

Tomy Varghese,

Photoacoustic and Ultrasonic Imaging

Elastography is a new imaging modality whereby elastic tissue parameters related to the structural organization of normal and pathologic tissues are imaged. Basic principles underlying the quasi-static elastography concept are addressed. The rationale for elastographic imaging is reinforced using data on elastic properties of normal and abnormal soft tissues. The several orders of magnitude difference between the elastic modulus of normal and abnormal tissues, the primary contrast mechanism in elastographic imaging, underlines the probability of success with this imaging modality. Recent advances enabling the clinical practice of elastographic imaging in real-time on clinical ultrasound systems is also discussed. In quasi-static elastography, radiofrequency echo signals acquired before and after a small amount (about 1%) of applied deformation are correlated to estimate tissue displacements. Local tissue displacement vector estimates between small 1D segments or 2D/3D kerners of the pre- and postdeformation signals are estimated and the corresponding strain distribution imaged. Elastographic imaging techniques are based on the hypothesis that soft tissues deform more than stiffer tissue, and these differences can be quantified in images of the tissue strain tensor or the Young modulus. Clinical applications of quasi-static elastography have mushroomed over the last decade, with the most commonly imaged situations involving the breast, prostate, thyroid, cardiac, treatment monitoring of ablation procedures , and vascular imaging applications.