Fourier-Based Fast 3-D Ultrasound Imaging Using Row–Column-Addressed 2-D Arrays

A Fourier-based fast 3-D ultrasound imaging method using row–column-addressed (RCA) 2-D arrays is presented. The row elements in an RCA array are activated sequentially, and all the column elements are used to receive. The obtained dataset is adapted to approximate to that obtained using a fully sampled array after a plane wave at a given incident angle is transmitted. In this way, the fast algorithm in plane-wave Fourier imaging (PWFI) can be applied to the adapted dataset. In addition, synthesizing multiple datasets based on multiple incident angles enables angular compounding, which improves the image quality. The proposed method was validated using computer simulations and physical-phantom experiments. The results show that the spatial resolution and contrast of the proposed method are comparable with those of its PWFI counterpart without requiring a fully sampled (FS) array. Compared with the delay-and-sum (DAS) method using the RCA array, the proposed method provides comparable spatial resolution but lower contrast; however, the computational complexity is significantly reduced from
${O}({N}^{{{4}}}{N}_{z})$
to
${O}({W}{N}^{{{2}}}{N}_{z} \log _{{2}}({N}^{{{2}}}{N}_{z}))$
, where
${N}$
is the number of elements on each side of the RCA array,
${N}_{z}$
is the number of voxels in the axial direction in the output image, and
${W}$
is the number of compounding angles. For example, in the simulated results when the maximum compounding angle
${M}$
is 5°, at a given point the lateral – 6-dB width provided by the proposed method is 0.241 mm (0.267 mm for DAS), the contrast ratio of a hyperechoic cyst is 8.87 dB (9.10 dB for DAS), the number of real number operations is reduced by a factor of 20.62, and the number of memory accesses is reduced by a factor of 47.21, both compared with DAS. This novel fast algorithm could facilitate the development of compact real-time 3-D imaging systems, especially when the channel count is high and a large field of view (FOV) is required.