[6][7] The movement of the kernel across the image can thus be tracked, in principle independent of the beam angle, as opposed to tissue Doppler.
Also, the transverse resolution (and hence, tracking ability) decreases with depth, in a sector scan where ultrasound beams diverge.
Left ventricular shearing increases towards the subendocardium, resulting in a subepicardial to subendocardial thickening strain gradient.
Similar to MRI, STE utilizes "Lagrangian strain" which defines motion around a particular point in tissue as it revolves through time and space.
[14] Throughout the cardiac cycle, the end-diastolic tissue dimension represents the unstressed initial material length.
Twist or torsional deformation define the base-to-apex gradient and is the result of myocardial shearing in the circumferential-longitudinal planes such that, when viewed from the apex, the base rotates in a counterclockwise direction.
This stored energy is released with the onset of relaxation similar to a spring uncoiling and results in suction forces.
Its use has remained limited due to angle dependency, substantial intraobserver and interobserver variability and noise interference.
In order to achieve sufficient tracking quality when single markers are used, however commercial algorithms very often resort to varieties of spline smoothing using available information from the strongest echoes, very oft the mitral annulus, so the regional measurements are not pure regional, but rather to a degree, spline functions of the global average.
Increasing frame rate in B-mode is done by reducing line density, i.e. lateral resolution, and thus making the method more angle dependent.
The ROC analysis showed significantly higher AUC for speckle tracking for detecting dysfunctional segments.