<unk>  can be done by two principally different methods. Tissue Doppler The Tissue Doppler method is based on the colour Doppler, giving a velocity field with velocity vectors along the ultrasound beam over the whole sector. It measures the velocity gradient between two points along the ultrasound beam with a set distance. It gives the same result as the velocity gradient. This method has been validated experimentally in a mechanical model, in an animal model, and in patients against echocardiography, coronary angiography and MR The method is limited to one direction; along the ultrasound beam, can thus mainly be used from the apical window, and for longitudinal<unk>  and<unk> <unk>  measurements only. It is sensitive to angle deviation between the velocity vector (direction of motion) and the ultrasound beam, and is sensitive to noise, especially clutter noise. It has a high temporal resolution, at the cost of a relatively low lateral spatial resolution. Speckle tracking Speckle tracking echocardiography is based on grey scale echocardiography (B-mode), and the fact that the reflected echo from the myocardium shows a speckle pattern that is a mixture of small scatters and interference patterns. The pattern being random, each region of the myocardium (called a "kernel"), has a unique speckle pattern, and that this speckle pattern is relatively stable, at least from one frame to next. By this, the movement of a kernel from one frame to the next, can be tracked by a "best match" search algorithm. The most commonly used is the "sum of absolute differences", shown to be similarly accurate as Cross-correlation. The method thus tracks a kernels motion from one frame to the next. From the frame<unk> , the velocity vector can be calculated, both in magnitude and direction. From this, a velocity field again can be generated over the whole sector, as with tissue Doppler, and<unk> <unk>  can be derived, and then<unk>  can be integrated. Alternatively<unk>  can be measured directly from the change in distance between speckles. (resulting in Lagrangian<unk>  directly), and<unk> <unk>  derived temporally (it then has to be converted to Eulerian<unk> <unk> . The speckle tracking methods varies with non-commercial and commercial systems. Speckle tracking has been shown to be comparable to tissue Doppler derived<unk> , and has been validated against MR The method tracks independently of the beam directions, and can thus track in two dimensions. It is also said to be independent of the angle error inherent in the Doppler algorithm. However, as the radial resolution (along the beam) is far better than the lateral resolution which also decreases with depth, both the angle independence and the tracking ability across the sector is lower. Also, instead of angle independency, the resulting<unk>  values are dependent on the ROI (Region Of Interest) size and shape. Finally, in order to achieve tracking quality, the values are in most commercial applications smoothed by a spline smoothing function along the ROI, so the regional measurements are not pure regional, but rather to a degree, spline functions of the global average. In addition, the method has a lower sampling<unk>  due to the limited frame<unk>  of B-mode, which reduces tracking validity, especially at high heart<unk> s. Colour-coded left atrial<unk>  assessed by speckle tracking during a representative cardiac cycle. Systemic sclerosis (SSc) patient: 2D longitudinal<unk>  of the right ventricle. The values of the basal, mid and apical segment of the free lateral wall were taken for further analysis.
Strain rate imaging
Multiscale motion mapping
Tissue Doppler echocardiography
Elastography
VistA Imaging
Doppler echocardiography
Ballistocardiography
Fractional flow reserve