High-Frame-Rate Tri-Plane Echocardiography With Spiral Arrays: From Simulation to Real-Time Implementation

Abstract

Major cardiovascular diseases are associated with (regional) dysfunction of the left ventricle. Despite the 3D nature of the heart and its dynamics, the assessment of myocardial function is still largely based on 2D ultrasound imaging thereby making diagnosis heavily susceptible to the operator's expertise. Unfortunately, to date, 3D echocardiography cannot provide an adequate spatio-temporal resolution in real-time. Hence, triplane imaging has been introduced as a compromise between 2D and true volumetric ultrasound imaging. However, tri-plane imaging typically requires high-end ultrasound systems equipped with fully populated matrix array probes embedded with expensive and little flexible electronics for two-stage beamforming. This paper presents an advanced ultrasound system for real-time, high frame rate, tri-plane echocardiography based on low element count sparse arrays, i.e. the so-called spiral arrays. The system was simulated, experimentally validated, and implemented for real-time operation on the ULA-OP 256 system. Five different array configurations were tested together with four different scan sequences, including multi-line and planar diverging wave transmission. In particular, the former can be exploited to achieve, in tri-plane imaging, the same temporal resolution currently used in clinical 2D echocardiography, at the expenses of contrast (−3.5dB) and signal-to-noise ratio (−8.7dB). On the other hand, the transmission of planar diverging waves boosts the frame rate up to 250 Hz, but further compromises contrast (−10.5dB), signal-to-noise ratio (−9.7dB), and lateral resolution (+46%). In conclusion, despite an unavoidable loss in image quality and sensitivity due to the limited number of elements, high frame rate tri-plane imaging with spiral arrays is shown to be feasible in real-time and may enable real-time functional analysis of all left ventricular segments of the heart. Index Terms-Cardiac imaging, high frame rate imaging, 3D imaging, tri-plane echocardiography, multiline transmission, diverging waves, spiral arrays, sparse arrays, real-time.

Real-Time 3-D Spectral Doppler Analysis With a Sparse Spiral Array

“…For clinical examinations of shallow vessels, wider apertures, linear scans, and higher frequencies would be preferable. The presented configuration might be suitable for the investigation of the carotid artery or the jugular vein as well as for echocardiography [43] and abdominal vascular applications. Nevertheless, to make the system suitable for clinical tests, the following features should be included:…”

“…The total number of addressable elements is thus 1024. Although not easily recognizable, the selection matches, as much as possible, the layout of a 2-D spiral whose density is tapered with a Tukey window [43], [44]. Each selected element was paired to one channel of the ULA-OP 256 scanner so that it could be individually controlled both in transmission (TX) and in reception (RX).…”

High-Frame-Rate 3-D Vector Flow Imaging in the Frequency Domain

“…This could be partially compensated by using coded imaging techniques [43] or in-probe preamplifiers. Likewise, doubling the number of active elements by exploiting two synchronized ULA-OP 256 systems [34,35] could improve the system sensitivity and, at the same time, counteract the unavoidable grating lobes in the transmitted ultrasound beams associated with spiral arrays [42]. By taking these aspects into considerations, the results of this paper appear extremely encouraging and confirm that sparse arrays may be a relatively cheap solution for the implementation of 3-D imaging on systems based on a limited number of channels.…”

“…The proposed method was validated through simulation and experiments. In both cases, the tests were based on a 256-element gridded spiral array probe built by Vermon (Vermon S.A.,Tours, France) according to our design [34,35], at 3.7 MHz central frequency. The position of the array elements matched that of a spiral pattern of 256 seeds, the density of which was modulated according to a 50% Tukey (tapered cosine) window.…”

In Vivo Comparison of Multiline Transmission and Diverging Wave Imaging for High-Frame-Rate Speckle-Tracking Echocardiography

“…Since DW and MLT approaches have different advantages and disadvantages in terms of system requirements, computational load, energy transfer to the body, achievable frame rate, motion artifacts and not least, image quality, they were compared in different applications, e.g. in HFR color Doppler [38] and HFR tri-plane echocardiography [39]. Specifically for HFR STE, MLT and DW imaging were compared in [40] in terms of image quality, motion artifacts, and their effects on motion estimation when using a STE algorithm based on normalized cross correlation [41].…”