Cardiac Strain Imaging Using Multi-Perspective Ultrafast Ultrasound

Abstract

The heart is a complex organ with a high level of deformation occurring in different directions. Ultrasound imaging has proven to be a valuable tool to quantify these deformations. However, strain is not always measured accurately in vital parts of the heart when only using a single probe, even at a high frame rate, because of the anisotropic spatial resolution and contrast. Therefore, a multi-perspective ultrafast ultrasound (US) strain imaging method was developed, aiming at investigating improvements in strain while operating two probes at different relative angles. In an ex-vivo experiment of a beating porcine heart, parasternal short axis views of the left ventricle (LV) were acquired by two phased array probes with different relative angles (30°–75°) at a frame rate of 170 frames per second (FPS). A fully automatic registration algorithm was developed to register the image datasets for all cases. Next, radio frequency (RF) based strain imaging was performed. Axial displacements were compounded based on the unit axial vectors of the dual probes to improve motion tracking and strain estimation. After performing multi-perspective strain imaging, compounded radial and circumferential strain both improve compared to single probe strain imaging. While increasing the inter-probe angle from 30° to 75°, the mean tracking error (ME), mean drift error (MDE) and strain variability (SV) decreased, and signal-to-noise ratio (SNRe) increased for both strain components. For the largest angle (75°), large reductions in ME (−42%), MDE (−50%) and SV (−48%) were observed. The SNRe increased by 253 and 39% for radial and circumferential strain, respectively, and strain curves revealed less noise for each region. In summary, a multi-perspective ultrafast US strain imaging method was introduced to improve cardiac strain estimation in an ex-vivo beating porcine heart setup.

In vivo bistatic dual-aperture ultrasound imaging and elastography of the abdominal aorta

“…Multi-aperture ultrasound imaging cannot only improve ultrasound image quality, but it can also improve the assessment of tissue deformation and strain ( Van Hal et al, 2021 ; Liu et al, 2022b ). Conventional strain imaging techniques are limited by the lack of phase information and resolution in the lateral direction of the ultrasound beam ( Lopata et al, 2009b ; Hansen et al, 2010 ).…”

“…Phase information in the lateral direction can be added by the use of beam steering ( Techavipoo et al, 2004 ; Hansen et al, 2010 ), however, this technique cannot be applied to the abdominal aorta or deeper lying structures in general, considering the limited overlapping region in compounding at large depths ( Petterson et al, 2021 ). This insufficient overlap can be overcome by the use of multiple probes, as shown in ( Van Hal et al, 2021 ; Liu et al, 2022b ). The addition of the second transducer improved accuracy and precision of radial and circumferential strain estimates in aortic and cardiac applications.…”

Coherent Bistatic 3-D Ultrasound Imaging Using Two Sparse Matrix Arrays

“…By performing high frame rate interleaved transmissions in 2D with two or more transducers, multi-perspective images can be directly compounded after spatial registration [21][22][23]. Additionally, functional information such as high resolution axial displacements can be also combined with minimum decorrelation for enhanced precision of tissue motion [21,24].…”

High-speed measurement of two-dimensional displacement of myocardium using element RF data of ultrasonic probe

“…Echocardiography is useful for evaluating cardiac function owing to its repeatability, non-invasive diagnostic capability, and high temporal resolution. Consequently, various medical applications have been studied to evaluate cardiac function, including measuring heart wall strain rates [1][2][3][4][5][6][7] and propagation of response of the myocardium to contraction. [8][9][10] However, further enhancement of the accuracy of heart wall motion measurements is essential to realise better cardiac function evaluations.…”