Restoration of the velocity field of the heart from two-dimensional echocardiograms

Abstract

A method to quantify the motion of the heart from digitized sequences of two-dimensional echocardiograms (2-D) echos was recently proposed. This method computes on every point of the 2-D echoes, the 2-D apparent velocity vector (or optical flow) which characterizes its interframe motion. However, further analysis is required to determine what part of this motion is due to translation, rotation, contraction, and deformation of the myocardium. A method to locally obtain this information is presented. The proposed method assumes that the interframe velocity field U(xy), V(x,y) can be locally described by linear equations in the form U(x,y)=a+Ax+By; V(x,y)=b+Cx+Dy. The additional constraint was introduced in the computation of the local velocity field by the method of projections onto convex sets. Since this constraint is only valid locally, the myocardium must be first divided into sectors and the velocity fields computed independently for each sector.

Spatio-temporal nonrigid registration for ultrasound cardiac motion estimation

“…Specific designs for echocardiographic data consider the Rayleigh statistics of the signal in the process [29]. Both differential and block matching techniques add mechanical, spatial or temporal constraints to overcome the well-known aperture problem with solutions adapted for echocardiography [26], [27], [30], [31]. The third approach with promising results is to obtain myocardial motion and deformation using speckle tracking [32] and elastographic techniques [33]- [35].…”

“…An additional problem is that the borders are usually not well defined in echocardiographic data. Another approach is to use optical flow methods to compute local myocardial movements [26]- [31]. Specific designs for echocardiographic data consider the Rayleigh statistics of the signal in the process [29].…”

Strain Quantification In Ultrasound Sequences

“…This approach is very dependent upon the hardware of the imager and requires direct access to the RF signal. Hence current research has favoured towards intrinsic (image-based) methods over extrinsic (invasive) techniques to quantify displacements; more specifically traditional ultrasound motion analysis research has concentrated on analysing specific frame pairs using a variety of methods including optical flow [4], spectral integrals [2] and block differentials [5] [1].…”

Real-Time Multi-model Tracking of Myocardium in Echocardiography Using Robust Information Fusion

“…Model-based deformable templates [1,2], Markov random fields [3], optical flow methods [4,5,6], or combinations of above, have been applied for tracking left ventricle (LV) from 2-D image sequences. Jacob et al provided a brief recent review in [7].…”