Resolution, Sidelobe, and Contrast Analysis of Ultrasound Fourier Based High Frame Rate Imaging

Abstract

Recently, a variable frame rate imaging method based on Fourier transformation has been developed to increase resolution and reduce sidelobe. Experiments with the imaging methods including D&S, 1-angle HFR (HFR 1), 11-angle HFR (HFR 11), 19-angle HFR (HFR 19), and 91-angle HFR (HFR 91) have also been carried out. In the experiment, one linear array was used to construct 2D B-mode images for a tissue-equivalent phantom and pointer scatterer. The array had a center frequency of 2.5MHz, dimensions of 19.2mm×14mm, and 128 elements. The experiments on the resolution and sidelobe were done with pointer scatterer in the water tank. Results show that HFR 11, HFR 19, and HFR 91 have higher resolution than D&S at all depths. The sidelobe for HFR 1, HFR 11, HFR 19, D&S, and HFR 91 decreases in turn, and HFR 91 has the lowest sidelobe. The experiments on the contrast comparison between HFR and D&S method are made on one tissue-equivalent phantom, eight cones with different contrasts (−15dB, −10dB, −5dB, −2dB, 2dB, 4dB, 7.5dB and 12dB) over background. The contrast curves of eight cones for HFR 1, HFR 11, HFR 19, D&S, and HFR 91 shift downward in turn, which is compatible with their sidelobe property. The contrast recognition accuracy of HFR 91 is the best. All evaluation standards show that the high frame rate imaging method is better than the conventional delay and sum method if their frame rates are the same, so high resolution and low-sidelobe images can be constructed at a high frame rate with this Fourier method.