Tissue harmonic imaging: why does it work? Thomas JD; Rubin DN J
Am Soc Echocardiogr 1998 Aug;11(8):803-8 The recent utilization
of harmonic frequencies in the imaging of both tissue and
contrast agents has dramatically improved echocardiographic
image quality. In contrast harmonics, the harmonic frequency
energy is generated on reflection from the microbubble contrast
agent. In tissue harmonics, the harmonic frequency energy is
generated gradually as the ultrasonic wave propagates through
the tissue. Critical to the utility of tissue-generated harmonic
frequencies is their origin beyond the chest wall and their
nonlinear relation to the fundamental frequency energy strength.
These two characteristics of tissue-generated harmonics ensure
that the echoes most likely to produce artifact are least likely
to produce harmonic waves. Armed with an understanding of how
these images are produced and with data emerging as to their
clinical utility, we anticipate that harmonic imaging will
become the standard for asses