Ultrasonic backscatter imaging by shear-wave-induced echo phase encoding of target locations.
We present a novel method for ultrasound backscatter image formation wherein lateral resolution of the target is obtained by using traveling shear waves to encode the lateral position of targets in the phase of the received echo. We demonstrate that the phase modulation as a function of shear wavenumber can be expressed in terms of a Fourier transform of the lateral component of the target echogenicity. The inverse transform, obtained by measurements of the phase modulation over a range of shear wave spatial frequencies, yields the lateral scatterer distribution. Range data are recovered from time of flight as in conventional ultrasound, yielding a B-mode-like image. In contrast to conventional ultrasound imaging, where mechanical or electronic focusing is used and lateral resolution is determined by aperture size and wavelength, we demonstrate that lateral resolution using the proposed method is independent of the properties of the aperture. Lateral resolution of the target is achieved using a stationary, unfocused, single-element transducer. We present simulated images of targets of uniform and non-uniform shear modulus. Compounding for speckle reduction is demonstrated. Finally, we demonstrate image formation with an unfocused transducer in gelatin phantoms of uniform shear modulus.
Department of Biomedical Engineering University of Rochester, Rochester, NY, USA. stephenm@bme.rochester.edu
Stephen
S
McAleavey
D000465:Algorithms; D003198:Computer Simulation; D005583:Fourier Analysis; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods*
Ultrasonics. 1986 Jan;24(1):41-4
3510500
Ultrasound Med Biol. 1994;20(5):403-28
7941100
IEEE Trans Ultrason Ferroelectr Freq Control. 1988;35(6):768-74
18290214
IEEE Trans Ultrason Ferroelectr Freq Control. 2003 Jun;50(6):642-54
12839176
J Acoust Soc Am. 2001 Jul;110(1):625-34
11508987
IEEE Trans Ultrason Ferroelectr Freq Control. 2001 May;48(3):737-42
11381697
Phys Med Biol. 2000 Jun;45(6):1449-64
10870703
Ultrason Imaging. 2009 Apr;31(2):131-50
19630254
IEEE Trans Ultrason Ferroelectr Freq Control. 2003 Jun;50(6):631-41
12839175
IEEE Trans Ultrason Ferroelectr Freq Control. 2004 Apr;51(4):396-409
15139541
IEEE Trans Ultrason Ferroelectr Freq Control. 2002 Jan;49(1):39-46
11833890
Ultrasound Med Biol. 1990;16(3):231-9
1694603
IEEE Trans Ultrason Ferroelectr Freq Control. 1986;33(3):257-64
18291782
IEEE Trans Biomed Eng. 1983 Aug;30(8):438-52
6629379