Pulse Inversion Harmonic Imaging (ATL HDI 5000)
When ultrasonic waves are applied to a contrast medium, there is a given limit to the shrinkage of pressurized microbubbles, as shown in Fig. 12–1, but when microbubbles decompress, they freely become large. Accordingly, while transmitted waves are sine waves, reflected signals are, in comparison, greatly distorted. Waveform distortion means the generation of harmonic signals, which are several integral times larger than those of the transmitted frequency (Fig. 12–2). Those signals at the double transmitted frequency are known as second harmonics.
KeywordsHarmonic Signal Mechanical Index Pulse Inversion Harmonic Image Fundamental Wave
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