Open AccessA Primer on the Physical Principles of Tissue Harmonic Imaging
Author(s) -
Arash Anvari,
Flemming Forsberg,
Anthony E. Samir
Publication year - 2015
Publication title -
radiographics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.866
H-Index - 172
eISSN - 1527-1323
pISSN - 0271-5333
DOI - 10.1148/rg.2015140338
Subject(s) - second harmonic imaging microscopy , image quality , harmonic , medicine , acoustics , harmonics , fundamental frequency , bandwidth (computing) , speckle pattern , optics , artificial intelligence , computer science , second harmonic generation , physics , telecommunications , image (mathematics) , laser , quantum mechanics , voltage
Tissue harmonic imaging (THI) is a routinely used component of diagnostic ultrasonography (US). In this method, higher-frequency harmonic waves produced by nonlinear fundamental US wave propagation are used to generate images that contain fewer artifacts than those seen on conventional fundamental wave US tissue imaging. Harmonic frequencies are integer multiples of the fundamental frequency. The majority of current clinical US systems use second harmonic echoes for THI image formation. Image processing techniques (ie, bandwidth receive filtering, pulse inversion, side-by-side phase cancellation, and pulse-coded harmonics) are used to eliminate the fundamental frequency echoes, and the remaining harmonic frequency data are used to generate the diagnostic image. Advantages of THI include improved signal-to-noise ratio and reduced artifacts produced by side lobes, grating lobes, and reverberation. THI has been accepted in US practice, and variations of the technology are available on most US systems typically used for diagnostic imaging in radiologic practice. Differential THI is a further improvement that combines the advantages of THI, including superior tissue definition and reduced speckle artifact, with the greater penetration of lower frequency US, which permits high-quality harmonic imaging at greater depth than could previously be performed with conventional THI.