Title :
Ultrasound backscatter tensor imaging (BTI): analysis of the spatial coherence of ultrasonic speckle in anisotropic soft tissues
Author :
Papadacci, Clement ; Tanter, Mickael ; Pernot, Mathieu ; Fink, M.
Author_Institution :
Inst. Langevin, Ecole Super. de Phys. et Chim. Industrielles (ESPCI), Paris, France
Abstract :
The assessment of fiber architecture is of major interest in the progression of myocardial disease. Recent techniques such as magnetic resonance diffusion tensor imaging (MR-DTI) or ultrasound elastic tensor imaging (ETI) can derive the fiber directions by measuring the anisotropy of water diffusion or tissue elasticity, but these techniques present severe limitations in a clinical setting. In this study, we propose a new technique, backscatter tensor imaging (BTI), which enables determination of the fiber directions in skeletal muscles and myocardial tissues, by measuring the spatial coherence of ultrasonic speckle. We compare the results to ultrasound ETI. Acquisitions were performed using a linear transducer array connected to an ultrasonic scanner mounted on a motorized rotation device with angles from 0° to 355° by 5° increments to image ex vivo bovine skeletal muscle and porcine left ventricular myocardial samples. At each angle, multiple plane waves were transmitted and the backscattered echoes recorded. The coherence factor was measured as the ratio of coherent intensity over incoherent intensity of backscattered echoes. In skeletal muscle, maximal/minimal coherence factor was found for the probe parallel/perpendicular to the fibers. In myocardium, the coherence was assessed across the entire myocardial thickness, and the position of maxima and minima varied transmurally because of the complex fibers distribution. In ETI, the shear wave speed variation with the probe angle was found to follow the coherence variation. Spatial coherence can thus reveal the anisotropy of the ultrasonic speckle in skeletal muscle and myocardium. BTI could be used on any type of ultrasonic scanner with rotating phased-array probes or 2-D matrix probes for noninvasive evaluation of myocardial fibers.
Keywords :
biomedical transducers; biomedical ultrasonics; diseases; muscle; ultrasonic transducers; 2D matrix probes; BTI; ETI; MR-DTI; anisotropic soft tissues; backscattered echoes; coherence variation; complex fiber distribution; ex vivo bovine skeletal muscle; fiber architecture; incoherent intensity; linear transducer array; magnetic resonance diffusion tensor imaging; maximal-minimal coherence factor; motorized rotation device; myocardial disease; myocardial fibers; myocardial thickness; myocardial tissues; noninvasive evaluation; phased-array probes; porcine left ventricular myocardial samples; shear wave speed variation; skeletal muscle; spatial coherence analysis; tissue elasticity; transmitted echoes; ultrasonic scanner; ultrasonic speckle; ultrasound backscatter tensor imaging; ultrasound elastic tensor imaging; water diffusion; Acoustics; Coherence; Imaging; Myocardium; Probes; Spatial coherence; Ultrasonic imaging;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2014.2994