Ultrasound elastography: Principles and techniques

Abstract

Ultrasonography has been widely used for diagnosis since it was first introduced in clinical practice in the 1970's. Since then, new ultrasound modalities have been developed, such as Doppler imaging, which provides new information for diagnosis. Elastography was developed in the 1990's to map tissue stiffness, and reproduces/replaces the palpation performed by clinicians. In this paper, we introduce the principles of elastography and give a technical summary for the main elastography techniques: from quasi-static methods that require a static compression of the tissue to dynamic methods that uses the propagation of mechanical waves in the body. Several dynamic methods are discussed: vibro-acoustography, Acoustic Radiation Force Impulsion (ARFI), transient elastography, shear wave imaging, etc. This paper aims to help the reader at understanding the differences between the different methods of this promising imaging modality that may become a significant tool in medical imaging.

Value of Strain Elastography Ultrasound in Differentiation of Breast Masses and Histopathologic Correlation

“…There are 2 different types of techniques widely used for determination of the rigidity of the lesion with US; strain elastography and shear wave elastography techniques. In strain elastography, the observer or the patient produces the pressure either with the probe or by breathing whereas in the shear wave technique that pressure is formed by the US probe by a special sound wave, which is called shear wave (3). In this study, we aimed to evaluate the value of strain elastography technique in breast lesions by correlation of elastographic features with histopathological results.…”

Usefulness of percutaneous elastography by acoustic radiation force impulse for the non-invasive diagnosis of chronic pancreatitis

“…Reports on pancreatic elastography by ARFI technique have been increasing over the past 3 years (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22), having noted that currently it can only be used with a percutaneous ultrasound equipment and not by EUS. Yashima et al (19) presented the first study of diagnostic accuracy by ARFI between healthy volunteers and patients with chronic pancreatitis, taking standard magnetic resonance imaging (MRI), MR cholangiopancreatography (MRCP) and/or endoscopic retrograde cholangiopancreatography (ERCP) as a reference, and describing for SWV of 1.4 m/s sensitivity and specificity of 75% and 72%, respectively.…”

“…The literature on pancreatic elastography has been evaluated by three different approaches: percutaneous, endoscopic and magnetic resonance imaging (14 (17), is a dynamic method that produces a mechanical tissue excitation by acoustic pulses of short duration (< 1 ms) in a region of interest (ROI), which produce a tissue distortion and waves transverse cut to ROI (a defined area of 10 x 6 mm). SWV is expressed in meters per second (m/s) with a range of from 0.5 to 5.5 m/s (18).…”

The Evolution of Ultrasound Technologies; from Anatomic to Physiologic,Histologic, and Molecular Imaging

“…The force acting on unit area is known as the stress. Properties reflecting organ anatomy, physiology and pathology can be quantified with Elastography [15].…”