title: Multielement synthetic transmit aperture imaging using temporal encoding.
abstract: 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 (approximately 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.
authors.affiliation: Center for Fast Ultrasound Imaging, Orsted, DTU, Building 348, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark. klg@oersted.dtu.dk
authors.forename: Kim Løkke
authors.initials: KL
authors.lastname: Gammelmark
authors.forename: Jorgen Arendt
authors.initials: JA
authors.lastname: Jensen
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging; D000328:Adult; D000465:Algorithms; D016477:Artifacts; D003198:Computer Simulation; D003560:Cysts / Q000000981:diagnostic imaging; D004867:Equipment Design; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods*; D008297:Male; D008954:Models, Biological; D009038:Motion; D019047:Phantoms, Imaging; D011786:Quality Control; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods*