Myocardial Strain Imaging Based on Two-Dimensional Displacement Vector Measurement

Abstract

In order to study total dose radiation effects of PbZr x Ti 1−x O 3 (PZT) film made with the pulsed excimer laser deposition (PLD) technique, hysteresis loops and capacitance-voltage (C-V ) curves of PZT film capacitors have been measured before and after γ -ray irradiation. The results show that, in a range of 0-2 × 10 5 Gy (Si), with increasing total dose, the remanent polarization 2P r increased while dielectric constant ε decreased. This can be explained by charges trapped by some defects during irradiation.

Minute Mechanical-Excitation Wave-Front Propagation in Human Myocardial Tissue

“…Alternatively, the measurement has been expanded into the two-dimensional (2D) space recently. [38][39][40][41] It is, however, still difficult to measure the rapid and minute velocity components in the heart wall by these methods. For thorough analysis of the propagation of the minute mechanical-excitation wave-front, the heart wall velocity distribution should be measured in the 2D space with high temporal and spatial resolutions.…”

Myocardial Strain Imaging with High-Performance Adaptive Dynamic Grid Interpolation Method

“…The moving-averagefilter window is W a ¼ 3:5 mm, the same size as that used in our previous studies. [27][28][29] The numbers of elements in the radial and circumferential directions are 80 and 256, respectively. The optimized pseudo elasticity parameters are set in the range of 20 to 2800 in the radial direction and 20 to 800 in the shear direction from the results of preliminary experiments as mentioned in §2.1.…”

3D Myocardial Contraction Imaging Based on Dynamic Grid Interpolation: Theory and Simulation Analysis

“…In these simulations, the RF signals with a signal-to-noise ratio (SNR) of 20 dB are digitized at a rate of 20 MHz. The median filter's window size and averaging filter's window size are the same as our pervious researches (16)- (18) , and their values are W m = 3.5 mm and W a = 3.5 mm, respectively. The element numbers in the radial direction are 80, and 256 in the circumferential direction.…”

“…Hence, it is not convenient and the processing speed is not fast. In order to solve the above problems, a myocardial strain imaging system based on the combined autocorrelation method (CAM) (13) and the 3-D weighted phase gradient method (WPGM) (14) (15) , which can detect all directions' true displacement vectors, has been proposed previously (16)- (18) . In this research, in order to obtain a more accurate phase-shift, a new method which incorporates an extended combined autocorrelation method (ECAM) (19) (20) into the WPGM is proposed.…”