Multielement synthetic transmit aperture imaging using temporal encoding

A new method to increase the signal-to-noise ratio (SNR) of synthetic transmit aperture imaging is investigated. The approach utilizes multiple elements to emulate a spherical wave, and the conventional short excitation pulse is replaced by a linear frequency-modulated (FM) signal. The approach is evaluated in terms of image quality parameters in comparison to linear array imaging. Field II simulations using an 8.5-MHz linear array transducer with 128 elements show an improvement in lateral resolution of up to 30% and up to 10.75% improvement in contrast resolution for the new approach. Measurements are performed using our experimental multichannel ultrasound scanning system, RASMUS. The designed linear FM signal obtains temporal sidelobes below -55 dB, and SNR investigations show improvements of 4-12 dB. A 30 mm (/spl ap/45%) increase in penetration depth is obtained on a multitarget phantom with 0.5 dB/[cm MHz] attenuation. Furthermore, in vivo images of the abdomen are presented, which demonstrate the clinical application of the new approach.

[1]  J. Arendt.  Paper presented at the 10th Nordic-Baltic Conference on Biomedical Imaging: Field: A Program for Simulating Ultrasound Systems , 1996 .

[2]  M. O'Donnell,et al.  Coded excitation system for improving the penetration of real-time phased-array imaging systems , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[3]  K. Kristoffersen,et al.  Analysis of worst-case phase quantization sidelobes in focused beamforming , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[4]  Mustafa Karaman,et al.  Beam space processing for low-cost scanners , 1996, 1996 IEEE Ultrasonics Symposium. Proceedings.

[5]  J A Jensen,et al.  Potential of coded excitation in medical ultrasound imaging. , 2000, Ultrasonics.

[6]  J. G. Abbott,et al.  Rationale and derivation of MI and TI--a review. , 1999, Ultrasound in medicine & biology.

[7]  Jørgen Arendt Jensen,et al.  Clinical use and evaluation of coded excitation in B-mode images , 2000, 2000 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.00CH37121).

[8]  W.E. Engeler,et al.  Real-time phased array imaging using digital beam forming and autonomous channel control , 1990, IEEE Symposium on Ultrasonics.

[9]  J. Jensen,et al.  An effective coded excitation scheme based on a predistorted FM signal and an optimized digital filter , 1999, 1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027).

[10]  Jørgen Arendt Jensen,et al.  Experimental ultrasound system for real-time synthetic imaging , 1999, 1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027).

[11]  M. Schlaikjer,et al.  Tissue motion in blood velocity estimation and its simulation , 1998, 1998 IEEE Ultrasonics Symposium. Proceedings (Cat. No. 98CH36102).

[12]  Y. Takeuchi,et al.  Chirped excitation for <-100 dB time sidelobe echo sounding , 1995, 1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium.

[13]  J. A. Jensen,et al.  Multielement synthetic transmit aperture imaging using temporal encoding , 2002, IEEE Transactions on Medical Imaging.

[14]  E.S. Ebbini,et al.  A new coded-excitation ultrasound imaging system. I. Basic principles , 1996, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[15]  M. O'Donnell,et al.  A new filter design technique for coded excitation systems , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[16]  Jørgen Arendt Jensen,et al.  Ultrasound imaging using coded signals , 2001 .

[17]  G. Trahey,et al.  Synthetic receive aperture imaging with phase correction for motion and for tissue inhomogeneities. II. Effects of and correction for motion , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[18]  H. Blinchikoff,et al.  Filtering in the time and frequency domains , 1976 .

[19]  G.R. Lockwood,et al.  Real-time 3-D ultrasound imaging using sparse synthetic aperture beamforming , 1998, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[20]  J. Jensen,et al.  Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[21]  M. O'Donnell,et al.  Synthetic aperture imaging for small scale systems , 1995, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[22]  Y Takeuchi,et al.  An investigation of a spread energy method for medical ultrasound systems. Part one: theory and investigation. , 1979, Ultrasonics.

[23]  J. A. Jensen,et al.  Recursive ultrasound imaging , 1999, 1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027).