Elastic Moduli of Breast and Prostate Tissues under Compression

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.

The clinical viability of a method of acoustic remote palpation, capable of imaging local variations in the mechanical properties of soft tissue using acoustic radiation force impulse (ARFI) imaging, is investigated in vivo. In this method, focused ultrasound (US) is used to apply localized radiation force to small volumes of tissue (2 mm(3)) for short durations (less than 1 ms) and the resulting tissue displacements are mapped using ultrasonic correlation-based methods. The tissue displacements are inversely proportional to the stiffness of the tissue and, thus, a stiffer region of tissue exhibits smaller displacements than a more compliant region. Due to the short duration of the force application, this method provides information about the mechanical impulse response of the tissue, which reflects variations in tissue viscoelastic characteristics. In this paper, experimental results are presented demonstrating that displacements on the order of 10 microm can be generated and detected in soft tissues in vivo using a single transducer on a modified diagnostic US scanner. Differences in the magnitude of displacement and the transient response of tissue are correlated with tissue structures in matched B-mode images. The results comprise the first in vivo ARFI images, and support the clinical feasibility of a radiation force-based remote palpation imaging system.

Acoustic radiation force impulse imaging: in vivo demonstration of clinical feasibility.

Magnetic resonance elastography: Non-invasive mapping of tissue elasticity

The basic principles of using sonographic techniques for imaging the elastic properties of tissues are described, with particular emphasis on elastography. After some preliminaries that describe some basic tissue stiffness measurements and some contrast transfer limitations of strain images are presented, four types of elastograms are described, which include axial strain, lateral strain, modulus and Poisson's ratio elastograms. The strain filter formalism and its utility in understanding the noise performance of the elastographic process is then given, as well as its use for various image improvements. After discussing some main classes of elastographic artefacts, the paper concludes with recent results of tissue elastography in vitro and in vivo.

Elastography: ultrasonic estimation and imaging of the elastic properties of tissues.

PURPOSE: To determine the appearance of various breast lesions on elastograms and to explore the potential of elastography in the diagnosis of breast lesions. MATERIALS AND METHODS: A total of 46 breast lesions were examined with elastography. Patients underwent biopsy or aspiration of all lesions, revealing 15 fibroadenomas, 12 carcinomas, six fibrocystic nodules, and 13 other lesions. The elastogram was generated from radio-frequency data collected with use of a 5-MHz linear-array transducer. The elastogram and corresponding sonogram were evaluated by a single observer for lesion visualization, relative brightness, and margin definition and regularity. The sizes of the lesions at each imaging examination and at biopsy were recorded and compared. RESULTS: Softer tissues such as fat appear as bright areas on elastograms. Firm tissues, including parenchyma, cancers, and other masses, appear darker. The cancers were statistically significantly darker than fibroadenomas (P < .005) and substantially larger on...

M F Pennanen

Papers

Elastography of breast lesions: initial clinical results.