A system and method are disclosed that facilitate characterizing vascular plaque tissue based upon spectral analysis of intravascular ultrasound echo signal segments. In particular, a power spectrum analysis of an integrated backscatter parameter renders a set of characterizing parameter values based on received intravascular ultrasound echo signal segments. The resulting parameter values are applied to plaque tissue characterization criteria to render a plaque tissue characterizations for regions of interest. The system and method include computer-executable instructions performed on a computing device to render an estimate of a system transfer function using a homomorphic deconvolution technique.