Spatial coherence and its relationship to human tissue: An analytical description of imaging methods

This paper describes the spatial coherence properties of the signal backscattered by human tissue and measured by an ultrasound transducer. Fourier acoustics are used to describe the propagation of ultrasound through a model of tissue that includes multiple reverberations and random scatterers in the imaging plane. The theoretical development describes the evolution of the spatial coherence as it propagates through the near-field tissue layers, is reflected at the focus, and is received at the transducer surface. Simulations are used to propagate the acoustic field through a histologically measured representation of the human abdomen and to validate the theoretical predictions. In vivo measurements performed with a diagnostic ultrasound scanner demonstrate show that simulations and theory closely match the measured spatial coherence characteristics in the human body. The theoretical framework and simulations are then used to describe the physics of spatial coherence imaging, a type of ultrasound imaging that measures tissue´s scattering properties with high resolution and contrast.