Previous studies demonstrated that our aperture domain model image reconstruction (ADMIRE) beamforming algorithm mitigates some common ultrasound imaging artifacts, which may increase ultrasound's clinical utility and reliability. Specifically, ADMIRE can suppress clutter caused by reverberation, off-axis scattering and wavefront aberration. Along with this, we demonstrated that ADMIRE is robust to model-mismatch caused by gross sound speed deviation. These findings suggest that ADMIRE may be an effective tool to provide high quality images in real clinical applications. Many of our previous effort have occurred on research platforms, but it is thought that dedicated clinical systems have better front-end electronics and transducers compared to research oriented platforms. If this is true then it is important to perform in vivo evaluations using the highest quality data possible in order to appropriately characterize (and not overemphasize possible) algorithmic gains. To this end, we modified a Siemens ACUSON SC2000 ultrasound system to capture I/Q channel signals. We acquired channel data using a full synthetic receive sequence. We also acquired channel data in conjunction with pulse inversion sequencing to obtain harmonic images. In this study, we collected data from a tissue-mimicking phantom and a human subject's abdomen and liver. We reconstructed both fundamental and harmonic B-mode images before and after applying ADMIRE. We then measured contrast and contrast-to-noise ratio (CNR). When comparing in vivo images, ADMIRE using low and high degrees of freedom improves contrast by 12.2 ± 2.6 dB and 2.5 ± 0.5 dB, respectively, relative to fundamental delay-and-sum(DAS) B-mode, and boosts contrast by 8.7 ± 3.7 dB and 2.0 ± 0.7 dB, respectively, with harmonic B-mode images.