Contrast agent-free 3D ultrasound deep-depth vascular imaging with a 2D row column addressed Array: In vivo human clinical feasibility study.

Three-dimensional (3D) imaging of vascular networks is essential for accurately diagnosing deep organ diseases. However, current ultrasound imaging methods are primarily limited to visualizing 2D cross-sections, which restricts the ability to evaluate the full structure of vascular networks. Although several 3D ultrasound techniques have been proposed to overcome this limitation, most struggle to achieve deep penetration and a wide field of view due to their high resource requirements. Row-column addressed arrays (RCAs) have emerged as a promising solution, enabling 3D imaging with significantly reduced hardware complexity. Nevertheless, the limited image quality achievable with RCAs has hindered their broader application. In this study, we propose a coded plane-wave-based, contrast-free 3D imaging system using RCAs for in vivo imaging of deep human vasculature. To validate the method, we imaged the liver and spleen of two healthy adult volunteers and successfully visualized vascular structures without contrast agent injection. Flow dynamics were captured at a frame rate of 27  Hz. Additionally, we demonstrated contrast-to-noise ratio (CNR) improvements of approximately 9  dB and 10  dB in the z-y and z-x planes, respectively, compared to non-coded excitation. This approach offers strong potential for in vivo 3D visualization and assessment of complex, deeply located vascular networks.