Experimental investigation of finite amplitude distortion-based, second harmonic pulse echo ultrasonic imaging

Abstract

The computational predictions for the imaging potential of the second harmonic produced by finite amplitude distortion were investigated with a simple experiment. A focused transducer containing concentric 2.5 MHz and 5.0 MHz elements was used to obtain a sequence of radio-frequency (r-f) backscattered signals using a tissue equivalent phantom. The 2.5 MHz element was used as the transmitter and the 5.0 MHz element was used as the receiver. At 0.68 cm in front of the geometric focal point of the transducer, the phantom contained a 0.6 cm diameter cylindrical volume which contained no scatterers. Each of these r-f signals was then processed to produce the corresponding fundamental (2.5 MHz-centered) and second harmonic (5.0 MHz-centered) envelopes. The contrast resolution obtained for the scatterer-free or cyst region of the envelopes was compared against the computed prediction and good agreement was obtained. The results of this experiment also suggest that the simple one-pulse scheme may be adequate for second harmonic imaging.

Harmonic Imaging Using Multitone Nonlinear Coding

“…Because the images are formed with only the first harmonic components, which are usually at least 20 dB below the fundamental, the dynamic range is limited. The nonlinear effects, including contrast agents improving the imaging sensitivity, was intensively studied by many authors (e.g., Christopher et al 1997Christopher et al , 1998Gong et al1996;Wu and Tong 1998). …”

Supplementary Golay pair for range side lobe suppression in dual-frequency tissue harmonic imaging

“…Tissue harmonic imaging has become the essential diagnostic tool in clinical applications due to the reduced reverberation from the shallow tissue structures and the improved directivity of the acoustic beam [1][2][3]. Conventionally, tissue harmonic imaging is performed by transmitting at fundamental ( f 0 ) frequency band and receiving the second-order nonlinear signal from the imaged object at second harmonic (2f 0 ) frequency band.…”

Ultrasonic Piezoceramic Transducer Modeling With VHDL-AMS: Application to Ultrasound Nonlinear Parameter Simulations

“…in the spectral wave representation. The utilization of these harmonics in ultrasound imagery gives an improvement in image quality [5], [6]. The ultrasound nonlinear parameter B/A, which is a characteristic of each medium, could be measured using two different methods: the thermodynamic method [7], [8] and the finite amplitude method [9], [10].…”