Abstract-In fast pulse-echo diagnostic ultrasound imaging the acquisition time for a single image is crucial. This time depends significantly on the number of sequentially emitted sound waves. For fewer wave emissions the inverse scattering problem is increasingly ill-posed. In this contribution we establish and investigate a solution based on compressive sensing (CS). This approach accounts for the lack of measurement data by assuming sparsity of the material parameters in an arbitrary basis. Using measurements obtained from a wire and a multi-tissue phantom, we evaluate the performance of our CS solution in comparison to synthetic aperture focussing, delay-and-sum (DAS) beamforming and filtered backpropagation (FBP). Emitting only a single plane wave, the CS approach yields the best results for the sparse wire phantom in terms of sidelobe reduction and lateral -6 dB-widths. For the non-sparse multi-tissue phantom, we observe equivalent results for CS, DAS, and FBP when a single plane wave is emitted and a discrete cosine basis is employed as sparsifying transform.
We propose a concept for fast image acquisition in diagnostic ultrasound imaging using compressed sensing (CS). Our concept is based on the formulation of an inverse scattering problem (ISP) to recover deviations in compressibility in a specified region from measurements of the scattered sound. For its derivation, we utilize the Born approximation and assume the emission of a single broadband plane sound wave. We employ CS to regularize this ill-posed ISP, assuming the existence of a sparse representation of the deviations in compressibility in a suitable basis or tight frame. We validate our concept experimentally and compare the recovered images to those generated by synthetic aperture (SA; 128 wave emissions), filtered backpropagation (FBP; single plane wave emission), and delay-and-sum (DAS; single plane wave emission) algorithms. For a sparse wire phantom, our concept outperformed SA, FBP and DAS in terms of sidelobe reduction and lateral -6 dB-widths. Axial -6 dB-widths were comparable. Using wave atoms or curvelets for sparse representation, our concept recovered a commercial multi-tissue phantom with fewer image artifacts and smaller lateral -6 dB-widths than FBP and DAS. Moreover, the achieved contrast was comparable to SA.
We present a method to speed up the acquisition of multispectral photoacoustic data sets by using unipolar orthogonal Golay codes as excitation sequences for the irradiation system. Multispectral photoacoustic coded excitation (MS-PACE) allows acquiring photoacoustic data sets for two irradiation wavelengths simultaneously and separating them afterwards, thus improving the SNR or speeding up the measurement. We derive an analytical estimation of the SNR improvement using MS-PACE compared to time equivalent averaging. We demonstrate the feasibility of the method by successfully imaging a phantom composed of two dyes using unipolar orthogonal Golay codes as excitation sequence for two high power laser diodes operating at two different wavelengths. The experimental results show very good agreement with the theoretical predictions.
We extended our concept for fast image acquisition in pulse-echo ultrasound imaging based on sparse recovery (SR) to compensate for the combined effects of absorption and dispersion. Using measurement data obtained from a multi-tissue phantom (A) and a human thyroid (B, in vivo), we demonstrated that image quality can be significantly improved by this extension. Emitting only two steered plane waves, our extended SR-based concept outperformed synthetic aperture (SA) imaging (128 wave emissions), delay-and-sum beamforming (11 wave emissions), and minimum variance beamforming (11 wave emissions) in terms of contrast for object A. Lateral −6 dB-widths were similar to SA. For object B, SR improved the visibility of anatomical contours in contrast to the algorithms used for comparison.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.