Elastography-based imaging techniques have received substantial attention in recent years for non-invasive assessment of tissue mechanical properties. These techniques take advantage of changed soft tissue elasticity in various pathologies to yield qualitative and quantitative information that can be used for diagnostic purposes. Measurements are acquired in specialized imaging modes that can detect tissue stiffness in response to an applied mechanical force (compression or shear wave). Ultrasound-based methods are of particular interest due to its many inherent advantages, such as wide availability including at the bedside and relatively low cost. Several ultrasound elastography techniques using different excitation methods have been developed. In general, these can be classified into strain imaging methods that use internal or external compression stimuli, and shear wave imaging that use ultrasound-generated traveling shear wave stimuli. While ultrasound elastography has shown promising results for non-invasive assessment of liver fibrosis, new applications in breast, thyroid, prostate, kidney and lymph node imaging are emerging. Here, we review the basic principles, foundation physics, and limitations of ultrasound elastography and summarize its current clinical use and ongoing developments in various clinical applications.

Ultrasound Elastography: Review of Techniques and Clinical Applications

The clinical part of these Guidelines and Recommendations produced under the auspices of the European Federation of Societies for Ultrasound in Medicine and Biology EFSUMB assesses the clinically used applications of all forms of elastography, stressing the evidence from meta-analyses and giving practical advice for their uses and interpretation. Diffuse liver disease forms the largest section, reflecting the wide experience with transient and shear wave elastography . Then follow the breast, thyroid, gastro-intestinal tract, endoscopic elastography, the prostate and the musculo-skeletal system using strain and shear wave elastography as appropriate. The document is intended to form a reference and to guide clinical users in a practical way.

/pdf/efsumb-guidelines-and-recommendations-on-the-clinical-use-of-ic9tylpvfd.pdf

EFSUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography.Part 2: Clinical Applications

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.

Ultrasound elastography: Principles and techniques

The breast section of these Guidelines and Recommendations for Elastography produced under the auspices of the World Federation of Ultrasound in Medicine and Biology (WFUMB) assesses the clinically used applications of all forms of elastography used in breast imaging. The literature on various breast elastography techniques is reviewed, and recommendations are made on evidence-based results. Practical advice is given on how to perform and interpret breast elastography for optimal results, with emphasis placed on avoiding pitfalls. Artifacts are reviewed, and the clinical utility of some artifacts is discussed. Both strain and shear wave techniques have been shown to be highly accurate in characterizing breast lesions as benign or malignant. The relationship between the various techniques is discussed, and recommended interpretation based on a BI-RADS-like malignancy probability scale is provided. This document is intended to be used as a reference and to guide clinical users in a practical way.

WFUMB Guidelines and Recommendations for Clinical Use of Ultrasound Elastography: Part 2: Breast

Conventional diagnostic ultrasound images of the anatomy (as opposed to blood flow) reveal differences in the acoustic properties of soft tissues (mainly echogenicity but also, to some extent, attenuation), whereas ultrasound-based elasticity images are able to reveal the differences in the elastic properties of soft tissues (e.g., elasticity and viscosity). The benefit of elasticity imaging lies in the fact that many soft tissues can share similar ultrasonic echogenicities but may have different mechanical properties that can be used to clearly visualize normal anatomy and delineate pathologic lesions. Typically, all elasticity measurement and imaging methods introduce a mechanical excitation and monitor the resulting tissue response. Some of the most widely available commercial elasticity imaging methods are 'quasi-static' and use external tissue compression to generate images of the resulting tissue strain (or deformation). In addition, many manufacturers now provide shear wave imaging and measurement methods, which deliver stiffness images based upon the shear wave propagation speed. The goal of this review is to describe the fundamental physics and the associated terminology underlying these technologies. We have included a questions and answers section, an extensive appendix, and a glossary of terms in this manuscript. We have also endeavored to ensure that the terminology and descriptions, although not identical, are broadly compatible across the WFUMB and EFSUMB sets of guidelines on elastography (Bamber et al. 2013; Cosgrove et al. 2013).

WFUMB guidelines and recommendations for clinical use of ultrasound elastography: Part 1: basic principles and terminology.

Purpose: To evaluate the diagnostic performance of real-time freehand elastography by using the extended combined autocorrelation method (CAM) to differentiate benign from malignant breast lesions, with pathologic diagnosis as the reference standard. Materials and Methods: This study was approved by the University of Tsukuba Human Subjects Institutional Review Board; all patients gave informed consent. Conventional ultrasonography (US) and real-time US elastography with CAM were performed in 111 women (mean age, 49.4 years; age range, 27–91 years) who had breast lesions (59 benign, 52 malignant). Elasticity images were assigned an elasticity score according to the degree and distribution of strain induced by light compression. The area under the curve and cutoff point, both of which were obtained by using a receiver operating characteristic curve analysis, were used to assess diagnostic performance. Mean scores were examined by using a Student t test. Sensitivity, specificity, and accuracy were compared b...

Breast disease: clinical application of US elastography for diagnosis.

Background
We evaluated the accuracy and feasibility of real-time elastography for detecting prostate cancer, using prostatectomy specimens

The impact of real-time tissue elasticity imaging (elastography) on the detection of prostate cancer: clinicopathological analysis

Objective: Elastography is a technique for detecting the stiffness of tissues. We applied elastography for the diagnosis of prostate cancer and evaluated the usefulness of elastography for prostate biopsy. Methods: The subjects of this study were 311 patients who underwent elastography during prostate needle biopsy at Hitachi General Hospital. Strain images obtained during compression of the prostate tissue were displayed on a monitor and recorded on the computer. The elastographic moving images (EMI) were evaluated retrospectively. The evaluable images and biopsy results were compared in terms of the feasibility and accuracy. Results: The median patient age was 67 years (range 50–85 years), the median serum level of prostate-specific antigen was 8.4 ng/ml (range 0.3 –8 2.5 ng/ml) and the median prostate volume was 42.6 ml (range 12 –1 50 ml). Among the 311 patients, prostate cancer was detected in 95 patients (30%) by biopsy. The diagnostic sensitivity was 37.9% for digital rectal examination (DRE) and 59.0% for transrectal ultrasonography (TRUS), whereas it was 72.6% for elastography and 89.5% for the combination of TRUS and elastography. Elastography-positive EMIs with negative biopsies were eventually determined to be due to benign prostatic hyperplasia. Conclusion: Elastography has a significantly higher sensitivity for the detection of prostate cancer than the conventionally used examinations including DRE and TRUS. It is a useful real-time diagnostic method because it is not invasive, and simultaneous evaluation is possible while performing TRUS.

/pdf/real-time-elastography-for-the-diagnosis-of-prostate-cancer-26nqrwlt0r.pdf

Real-time Elastography for the Diagnosis of Prostate Cancer: Evaluation of Elastographic Moving Images

To carry out objective or definitive diagnosis on the basis of an elastic image regardless of experience and proficiency, a method of displaying an elastic image includes the steps of measuring ultrasound cross-section data of a cross-section region of a subject by applying pressuring to the subject, determining a physical value correlating with the elasticity of tissue in the cross-section region on the basis of the ultrasound cross-section data, generating an elastic image of the cross-section region on the basis of the physical value and displaying the elastic image on a display device, determine compression state information relating to the compression state of the cross-section region on the basis of the pressure applied to the subject, and displaying the compression state information together with the elastic image on the display device.

Method of displaying elastic image and diagnostic ultrasound system

OBJECTIVE. The use of elastography is limited for prostate cancer detection because of the difficulty in obtaining stable and reproducible images. To overcome these limitations, we developed a new technique called real-time balloon inflation elastography (RBIE); with RBIE, balloon inflation and deflation are used in place of manual compression. We present the accuracy and feasibility of the RBIE technique for detecting prostate cancer.MATERIALS AND METHODS. The results of a pathologic analysis of 55 prostatectomy specimens were compared with elastographic moving images obtained at the time of biopsy of the prostate.RESULTS. The RBIE technique generated stable and repeatable elastographic moving images. The percentage of images affected by artifact due to slippage in the compression plane was reduced to 1% using the RBIE method compared with 32% using the manual compression method. With regard to tumor location, elastographic moving images obtained using the RBIE technique were in complete agreement with c...

https://www.ajronline.org/doi/pdf/10.2214/AJR.09.3301

Takeshi Matsumura

Papers

Breast disease: clinical application of US elastography for diagnosis.

The impact of real-time tissue elasticity imaging (elastography) on the detection of prostate cancer: clinicopathological analysis

Real-time Elastography for the Diagnosis of Prostate Cancer: Evaluation of Elastographic Moving Images

Method of displaying elastic image and diagnostic ultrasound system

Real-time balloon inflation elastography for prostate cancer detection and initial evaluation of clinicopathologic analysis.