Comparative analysis of incoherent and coherent backscattering approaches to quantitative ultrasound in complex biological media

This study compares two methods for characterizing complex tissues, with or without an overlying tissue layer. In heterogeneous tissues such as lung or bone, conventional ultrasound is inadequate. Quantitative ultrasound, particularly through the measurement of D, provides valuable insights into the “randomness” of such media. Variations in D reflect multiple scattering, typically manifesting as an increased intensity of incoherent backscattering (IBS) and a reduced intensity of coherent backscattering (CBS) over time. These variations reflect the porosity of the medium. To address aberrations caused by propagation through a fatty layer, we evaluate two approaches: (1) Estimating D from the increase of IBS within the random medium using virtual source beamforming at the medium’s surface. (2) Using plane wave insonication at multiple angles to calculate D from the decay of CBS, leveraging the phase coherence between backscattered waves in different directions. Numerical simulations demonstrate that phase-enhanced CBS (eCBS) provides more reliable measurements than IBS. Experimental results in phantoms further confirm this result. These methods shows promise for improved characterization of complex media, particularly in cases where conventional imaging techniques fall short like the lung or the bone. [Work supported by the National Heart Lung and Blood Institute, R01HL175513.]