  The current methods for characterization of frequency-dependent material
properties of human liver are very limited. In fact, there is almost no data
available in the literature showing the variation in dynamic elastic modulus of
healthy or diseased human liver as a function of excitation frequency. We show
that frequency-dependent dynamic material properties of a whole human liver can
be easily and efficiently characterized by an impact hammer. The procedure only
involves a light impact force applied to the tested liver by a hand-held
hammer. The results of our experiments conducted with 15 human livers harvested
from the patients having some form of liver disease show that the proposed
approach can successfully differentiate the level of fibrosis in human liver.
We found that the storage moduli of the livers having no fibrosis (F0) and that
of the cirrhotic livers (F4) varied from 10 to 20 kPa and 20 to 50 kPa for the
frequency range of 0 to 80 Hz, respectively.
