Multi-element synthetic transmit aperture imaging using temporal encoding

Kim Gammelmark, Joergen A. Jensen, Michael F. Insana, William F. Walker
2002 Medical Imaging 2002: Ultrasonic Imaging and Signal Processing  
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
more » ... ment 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 ( 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. Index Terms-Experimental ultrasound scanning system, Field II, linear FM signals, multielement defocusing, synthetic transmit aperture ultrasound imaging.
doi:10.1117/12.462168 fatcat:53qemwyxejetrmfsj5w3d7uufy