Patent ID: 8100831

Claim:
An ultrasound system comprising: an ultrasound device configured to acquire a pair of ultrasound data sets from a biological tissue, the pair of ultrasound data sets comprising acquired ultrasound data of the biological tissue in a relaxed state and in a tensed state, respectively; a computer programmed to: (a) stretch the tensed state ultrasound data set; (b) calculate an imaginary part of a complex correlation function between the relaxed state ultrasound data set and the stretched tensed state ultrasound data set; (c) calculate a slope factor (SF) using one of a single set data method, a direct method, and an adaptive method, wherein: the single set data method is SF = ω 0 ⁢ R 0 = ω 0 ⁢ ∫ window ⁢  r ~ ⁡ ( t )  2 ⁢ t ⁢ ⁢ ⅆ t ; the direct method is SF=ω 0 ·∫ 0 T t·|{tilde over (r)}(t)|·|{tilde over (s)}*(t)|dt; and the adaptive method is SF = 𝔍 ⁢ { ∫ 0 T ⁢ r ~ ⁡ ( t ) · r ~ * ⁡ ( t ⁡ ( 1 - ɛ 0 ) ) ⁢ ⁢ ⅆ t } ɛ 0 , wherein: ω 0 corresponds to the center frequency of the relaxed state ultrasound data, R 0 = ∫ window ⁢   ⁢ r ~ ⁡ ( t )   2 ⁢ t ⁢ ⅆ t , T corresponds to a length of a correlation window used for strain estimation, {tilde over (r)}(t) corresponds to an analytic signal version of the relaxed state ultrasound data, {tilde over (s)}(t) corresponds to an analytic signal version of the tensed state ultrasound data, {tilde over (r)}* corresponds to a complex conjugate of the relaxed state ultrasound data, {tilde over (s)}* corresponds to a complex conjugate of the tensed state ultrasound data, ε 0 corresponds to a defined amount of stretching applied to the relaxed state ultrasound data; and (d) estimate a strain of the biological tissue from a relationship between the calculated imaginary part and the slope factor.