Author: van Neer PL, Danilouchkine MG, Verweij MD, Demi L, Voormolen MM, van der Steen AF, de Jong N.
Affiliation: Department of Biomedical Engineering, Erasmus MC, P.O. Box 2040, 3000 CA, Rotterdam, The NetherlandsLaboratory of Electromagnetic Research, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, Mekelweg 4, 2628 CD, Delft, The NetherlandsLab of Acoustical Imaging and Sound Control, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The NetherlandsDepartment of Circulation and Imaging (ISB), Norwegian University of Science and Technology (NTNU), Prinsesse Kristinas gate 3, Trondheim, Norway.
Conference/Journal: J Acoust Soc Am.
Date published: 2011 Nov
Other:
Volume ID: 130 , Issue ID: 5 , Pages: 3148 , Word Count: 223
In medical ultrasound, fundamental imaging (FI) uses the reflected echoes from the same spectral band as that of the emitted pulse. The transmission frequency determines the trade-off between penetration depth and spatial resolution. Tissue harmonic imaging (THI) employs the second harmonic of the emitted frequency band to construct images. Recently, superharmonic imaging (SHI) has been introduced, which uses the third to the fifth (super) harmonics. The harmonic level is determined by two competing phenomena: nonlinear propagation and frequency dependent attenuation. Thus, the transmission frequency yielding the optimal trade-off between the spatial resolution and the penetration depth differs for THI and SHI. This paper quantitatively compares the concepts of fundamental, second harmonic, and superharmonic echocardiography at their optimal transmission frequencies. Forward propagation is modeled using a 3D-KZK implementation and the iterative nonlinear contrast source (INCS) method. Backpropagation is assumed to be linear. Results show that the fundamental lateral beamwidth is the narrowest at focus, while the superharmonic one is narrower outside the focus. The lateral superharmonic roll-off exceeds the fundamental and second harmonic roll-off. Also, the axial resolution of SHI exceeds that of FI and THI. The far-field pulse-echo superharmonic pressure is lower than that of the fundamental and second harmonic. SHI appears suited for echocardiography and is expected to improve its image quality at the cost of a slight reduction in depth-of-field.
PMID: 22087943