Adaptable coded excitation for elasticity imaging

Previously, we found that coded excitation significantly lowers decorrelation errors for strain estimation under several conditions, particularly those involving low echo signal-to-noise ratios (eSNR). To expand the utility of coded excitation to a broader range of experimental conditions, we examined two types of phase modulated (PM) codes - optimal and m-sequence - and two types of receive processing - matched filter and inverse filter. Strain imaging quality is evaluated using a displacement SNR (SNR_d), local modulation transfer function (LMTF) and contrast-to-noise ratio for strain (CNR_strain). The performances of optimal and m-sequence codes with matched and inverse filters were compared using simulations and phantom measurements. A combination of optimal codes and inverse filter receivers was found to lower strain image noise significantly without reducing lesion contrast or spatial resolution.