Table 1 Overview of the data-acquisition and -analysis settings for the natural and active SWE sequences.
From: A direct comparison of natural and acoustic-radiation-force-induced cardiac mechanical waves
Natural SWE | Active SWE | |
|---|---|---|
Data acquisition | ||
Wave excitation | ||
Push frequency | – | 2.0 MHz or 2.8 MHz |
Push duration | 400 µs | |
Wave imaging | ||
Virtual focus | − 34 mm or − 288 mm | |
DW imaging scheme | Progressive pulse-inversion (f0 of 2 MHz) or 3-angle compounding (f0 of 3 MHz) | |
Duration | 1.2 s | 20 ms or 28 ms, at a rate of 34 Hz during 1.2 s |
Frame rate | Minimum of 2.2 kHz | Minimum of 3.5 kHz |
RF filter | ||
Pulse-inversion | Butterworth 10th order BPF 3–4.5 MHz | |
Compounding | – | |
Data analysis | ||
IQ filter (removal of blood motion and noise) | Butterworth 6th order LPF 250 Hz | – |
Tissue motion estimator | One-lag autocorrelation algorithm | |
Autocorrelated IQ filter (smoothing) | Gaussian 5.6° by 3.0 mm | Gaussian 1.9° by 1.0 mm |
TDI filter (removal of gross motion and noise) | Butterworth 6th order BPF 15–100 Hz | Butterworth 6th order BPF 75–750 Hz |
Wave speed estimator | Radon | Manual |
