We present a detailed experimental study to evaluate our finite element based nonlinear reconstruction algorithm for recovery of acoustic properties in heterogeneous scattering media. Using a circularly scanning ultrasound system at 500 KHz, tissue phantom experiments were performed to study spatial resolution and contrast issues in model-based ultrasound tomography. Our results show that both acoustic attenuation and speed images can be quantitatively reconstructed in terms of the location, size, shape, and acoustic property value of the target when different contrast levels between the target and background were used. We also demonstrate that a high contrast target as small as 3 mm in diameter can be quantitatively resolved with our acoustic speed and attenuation images.