A system and method include storage of an echo signal power spectrum of a reference phantom for a fundamental frequency band and an echo signal power spectrum of the reference phantom for a harmonic frequency band, acquisition of an echo signal power spectrum of a region of tissue for the fundamental frequency band and an echo signal power spectrum of the region of tissue for the harmonic frequency band, determination of a first backscatter coefficient based on the echo signal power spectrum of the region of tissue for the fundamental frequency band and the echo signal power spectrum of the reference phantom for the fundamental frequency band, determination of a second backscatter coefficient based on the echo signal power spectrum of the region of tissue for the harmonic frequency band and the echo signal power spectrum of the reference phantom for the harmonic frequency band, and determination of a non-linearity of the region of tissue based on the first backscatter coefficient and the second backscatter coefficient.
