High-contrast ultrafast imaging of the heart

Clement Papadacci (1, 2) , Mathieu Pernot (1, 2) , Mathieu Couade (1, 2) , Mathias Fink (1) , Mickaël Tanter (1, 2)

1 IL - Institut Langevin - Ondes et Images (UMR7587)
2 Physique des ondes pour la médecine

Non-invasive ultrafast imaging of intrinsic waves such as electromechanical waves or remotely induced shear waves in elastography imaging techniques for human cardiac applications remains a big challenge. In this paper we propose to perform ultrafast imaging of the heart with adapted sector size by coherently compounding diverging waves emitted from a standard transthoracic cardiac phased-array probe. As in ultrafast imaging with plane wave coherent compounding, diverging waves can be summed coherently to obtain high-quality images of the entire heart at high frame rate in a full field-of-view. To image the propagation of shear waves with a large signal-to-noise ratio (SNR), the field-of-view can be adapted by changing the angular aperture of the transmitted wave. Backscattered echoes from successive circular wave acquisitions are coherently summed at every location in the image to improve the image quality while maintaining very high frame rates. The transmitted diverging waves, angular apertures and subapertures sizes were tested in simulation and ultrafast coherent compounding was implemented in a commercial scanner. The improvement of the imaging quality was quantified in phantoms and in one human heart, in vivo. Imaging shear wave propagation at 2500 frame/s using 5 diverging waves provided a large increase of the SNR of the tissue velocity estimates while maintaining a high frame rate. Finally, ultrafast imaging with 1 to 5 diverging waves was used to image the human heart at a frame rate of 4500-900 frames/s over an entire cardiac cycle. Spatial coherent compounding provided a strong improvement of the imaging quality, even with a small number of transmitted diverging waves and a high frame rate, which allows imaging the propagation of electromechanical and shear waves with good image quality.

Mots clés: Acoustics Apertures Gratings Heart Imaging Probes transducers

Domaines: Physique Médicale [physics.med-ph]

Clement Papadacci, Mathieu Pernot, Mathieu Couade, Mathias Fink, Mickaël Tanter. High-contrast ultrafast imaging of the heart. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2014, Volume:61 Issue: 2, pp.0885-3010. ⟨10.1109/TUFFC.2014.6722614⟩. ⟨hal-01057544⟩