  The quantification of liver fat as a diagnostic assessment of steatosis
remains an important priority for noninvasive imaging systems. We derive a
framework in which the unknown fat volume percentage can be estimated from a
pair of ultrasound measurements. The precise estimation of ultrasound speed of
sound and attenuation within the liver are shown to be sufficient for
estimating fat volume assuming a classical model of the properties of a
composite elastic material. In this model, steatosis is represented as a random
dispersion of spherical fat vacuoles with acoustic properties similar to those
of edible oils. Using values of speed of sound and attenuation from the
literature where normal and steatotic livers were studied near 3.5 MHz, we
demonstrate agreement of the new estimation method with independent measures of
fat. This framework holds the potential for translation to clinical scanners
where the two ultrasound measurements can be made and utilized for improved
quantitative assessment of steatosis.
