FIRST EXPERIMENTAL IMPLEMENTATION OF A BANDWIDTH ENHANCEMENT PULSE COMPRESSION TECHNIQUE ON AN ULTRASOUND ARRAY IMAGING SYSTEM

Laboratorio de Im ´agenes M edicas, Departamento de Ingenier´ ´a,Pontic ia Universidad Cat olica del Per´ ´u, San Miguel, Lima 32, Per u´ABSTRACTExtending the effective bandwidth of an ultrasonic imagingtransducer is advantageous for both qualitative and quanti ta-tive imaging methods. The resolution enhancement compres-sion (REC) technique allows to accomplish this task by com-bining frequency and amplitude modulated excitation withmodie d Wiener l ter compression. Although promising re-sults have been reported, the experimental implementation ofthe REC technique has been so far limited to single-elementtransducer systems. With the advent of array-based imag-ing systems with arbitrary waveform generation capabiliti es,the implementation of REC with multi-element transducers i snow feasible. In this work, experimental results of the r stimplementation of the REC technique on an ultrasound arraysystem are presented. Data were obtained from both wire andspeckle-based targets using an excitation signal designed toprovide a 33% increase in bandwidth over the one obtainedwith a broadband pulse excitation. The bandwidth was ex-perimentally determined to improve by 23% and 34% for thewire and speckle-based phantoms, respectively, when usingthe bandwidth enhancement compression technique. Further ,the axial resolution as derived from the modulation transfe rfunctionoftheenvelopeofthewiretargetsimprovedby29%.The results of this proof-of-concept study suggest that theREC technique can be successfully implemented in an array-based ultrasonic imaging system.1. MOTIVATIONIn conventional ultrasonography, i.e., B-mode imaging,shorter transmitted pulses result in shorter echoes and the re-fore, better axial spatial resolution. To this end, Oelze pr o-posed a coded excitation technique termed resolution en-hancement compression (REC) [1]. The REC techniqueemploys amplitude and frequency modulation excitation in