EUROECHO and other imaging modalities 2012 location:Athens, Greece date:05-08 December 2012
Purpose: Ultra-fast cardiac imaging (frame rate (FR) ~500Hz for a 90° sector) can be achieved by transmitting a plane wave (PW) instead of a focused beam. This increased temporal resolution is at the expense of spatial resolution, reducing 2D image quality. However, for functional imaging, temporal resolution gain might outbalance reduced spatial resolution.
We aimed to, at an initial stage of development, test the feasibility of PW imaging for myocardial motion estimation in normals.
Methods: The septum was imaged in 10 healthy volunteers from the apex by PW and Colour Doppler Myocardial Imaging (CDMI), both with 2.5 MHz transducers. A PW transmit combined with 4 parallel receive beams was implemented on an Epsilon Ultra DCI5000, using B-mode imaging at FR of 212Hz. CDMI data were obtained with a GE Vivid E9. A similar FR was achieved by adjusting the opening angle. Mid-septal velocity profiles were extracted from both datasets. The Sum of Absolute Differences was used to obtain the velocity trace from the RF data from the PW system and a commercial software package (GE EchoPac) was used to extract it from the CDMI data. The peak systolic (S') and early (E')/late (A') diastolic velocities were extracted from the PW and CDMI traces.
Results: Peak velocity values were comparable between the two modalities: CDMI S' 5.4 ± 0.8, PW S' 5.7 ± 1.9, CDMI E' −8.5 ± 2.3, PW E' −7.6 ± 2.2, CDMI A' −5.11 ± 1.5 PW A' −4.4 ± 1.6, all cm/s, P>0.05. Figure 1 shows positive correlations between PW and CDMI values.
Conclusions: Our results demonstrate the feasibility of PW in functional cardiac imaging. The available hardware allowed for a 4x increase in acquisition rate which could be increased with multiple beamformers. PW imaging provides improved temporal resolution in myocardial velocity/deformation imaging.