Shear wave Dispersion Ultrasound Vibrometry (SDUV), is an acousticradiation force based technique that measures tissue shear viscoelasticity bycharacterizing shear wave speed dispersion. One of the potential applications ofthis technique is the non-invasive measurement of liver viscoelasticity tostage liver fibrosis. In this study, a Philips' iU22 ultrasound system wasmodified to allow for the same transducer to generate and track propagatingshear waves. The pulse sequence was implemented on a C5-1 curvilineartransducer, with RF data acquisition and off-line processing. Liver scans ofthree healthy pigs were conducted under in vivo and ex vivo conditions. In vivodata were captured during inspiration or expiration of the breathing cycle withbreath hold. Shear modulus and viscosity were estimated in a 4 x 4 mm2 area close to the pushing focus. For pig #3, the in vivomeasurement revealed a shear modulus μ1 = 2.64 ± 0.48 kPa and a shearviscosity μ2 = 1.09 ± 0.30 Pa•s. The ex vivomeasurement made directly on the exposed liver after euthanasia resulted inμ1 = 2.63 ± 0.39 kPa and μ2 = 0.98 ±0.18 Pa•s. For pigs #1 and #2, the in vivo results are μ1 =2.41 ± 0.65 kPa, μ2 = 2.01 ± 1.00 Pa•s; andμ1 = 1.74 ± 0.56 kPa, μ2 = 1.25 ± 0.87Pa•s. Their corresponding ex vivo results are μ1 = 2.87± 0.32 kPa, μ2 = 1.06 ± 0.18 Pa•s; andμ1 = 1.84 ± 0.33 kPa, μ2 = 0.77 ± 0.15Pa•s, respectively. Higher variance in in vivo measurements of pigs #1 and2 may be attributed to phase aberration as these two animals had thickerabdominal fat and muscle layers than pig #3. To study phase aberration effects,SDUV measurements were made subsequently on the ex vivo liver under differentconditions: from intact to sequentially removing the overlying tissue layersuntil exposing liver. Results from this study demonstrate the feasibility ofconducting SDUV measurement using an ultrasound system and a single transducer.The reconstructed viscoelasticity for normal porcine liver agrees well with thevalues reported in the literature. Further in vivo evaluation in animals andhumans is required to validate these results.