Experimental validation of plane wave imaging using k-space beamforming for spectral characterization of isotropic media

The central concept of spectral tissue characterization is the backscatter coefficient (BSC). Due to its stochastic characteristic, it is often necessary to employ temporal averaging to obtain a coherent estimate. Thus, the acquisition rate plays a role in the characterization of fast moving tissues, such as arterial blood and cardiac walls. Plane wave imaging (PWI) presents a means to reduce BSC variability as it allows the acquisition of thousands of frames per second with sustained image quality over the entire field of view. However, the steering needed to increase the image quality of PWI can modify the spectral content of anisotropic tissues. Therefore, during the compounding process, different spectra are combined producing a biased BSC. Nonetheless, we hypothesized that in isotropic media, this drawback can be cancelled using the instrumentation compensation method (e.g., the reference phantom technique). We experimentally evaluated this hypothesis by estimating the BSC of a tissue mimicking phantom using PWI and compared it to data obtained with a single-element transducer. Our results suggest that PWI can produce accurate estimates of the BSC under isotropic conditions with percentage errors below 10%. These results indicate that the reference phantom technique effectively compensates for the effects of the compounding process in PWI for isotropic tissues.