Keywords:
Cardiac, Computer applications, Molecular imaging, Echocardiography, Echocardiography (transoesophageal), Image manipulation / Reconstruction, Acceptance testing, Biopsy, Ablation procedures, Blood, Image verification, Pathology
Authors:
M. Karvandi, S. Ranjbar; Tehran/IR
Results
Assembled from data shown in (Figure 4),
we can illustrate a segment of the left ventricle with tracking results from all areas through the heart wall from endocardium to epicardium (Figure 5).
We have suggested a scalar quantity to measure the tangential shortening in a manner that is not sensitive to the deformations in the tangent plane. This quantity,
known as the shortening index (SI),
measures the change of the in-plane area based on the stretch tensor U,
in the radial,
longitudinal,
and circumferential (RLC) coordinate system.
With the consideration of the incompressibility of the myocardium,
the local thickening of the wall (T) is also calculated by elements of U.
Therefore,
T and SI can be measured at any point inside the heart muscle using stretch tensor in MATLAB software.
These two dependent quantities have been used in this study as surrogates for regional contraction level.
With the use of high resolution force field of the myocardium,
maps of T and SI with high spatial resolution were calculated based on the maximum deformation of the left ventricle,
i.e.,
from the end diastole to the end systole.
The macrostructure of the left ventricle was subsequently sought by calculation and comparison of the myofibers of these quantities for their relatively higher absolute values.
The myofibers were calculated for SI values above a certain threshold.
Starting from low values near zero,
we gradually increased the magnitude of the threshold and removed myocardium regions that were left out of myofibers corresponding to the threshold.
According to Moore et al.
the maximum mean SI magnitude in the left ventricle is -0.25 0.05 in healthy hearts.
(Figure 6) shows myofiber transactions of left ventricle wall thickening and tangential shortening,
corresponding to,
assembled from data shown in (Figure 4) that myofibres move on helical bands which begin from the Septal,
loop around the Apex and then go to the Anterior.
Finally,
we are able to define the whole LV myocardial model mathematically,
by MATLAB software in normal subjects (Figure 7).