Myocardial shear wave imaging(SWI)
SWI is a technique based on
ultrasonic mechanical effect, which can be used to evaluate the hardness
of soft tissue noninvasively and quantitatively. In the past ten years,
it has been used in breast, liver and other diseases, and has certain
clinical value. SWI uses the propagation characteristics of shear waves
and the speed of wave transmission to estimate the stiffness of the
tissue. Shear waves can be induced naturally in the heart when the
atrioventricular or ventricular artery valves are closed, but they can
also be induced mechanically using an external source. In fact, SWI has
been shown to be significantly positively correlated with age,
end-diastolic wall thickness, loading status (left atrial size, LVEDP),
and MRI cardiac-related fibrosis indicators in healthy volunteers and in
some patients with disease(59-63). However, the accuracy of the
technique is greatly challenged by the operator’s technique, the
particular geometry, viscosity, anisotropy, contraction and diastole of
the heart, haemodynamics and pathology that will affect the shear wave
generation and wave speed.(64) In addition to this, due to the
limitations of ultrasound views and sites, the shear waves assessed only
reflect local myocardial stiffness and do not reflect the overall level
of myocardial stiffness. With this in mind, there is an urgent need for
consistent data collection and reporting as the number of clinical
studies of cardiac SWI continues to increase. In a recent review, Caenen
A, et al.(64) made some constructive suggestions to improve the accuracy
of SWI and to facilitate the comparison of SWE results between studies.