3-D super-resolution ultrasound imaging of rabbit kidney compared with ex vivo micro CT

Super-resolution ultrasound (SRU) imaging has emerged as a promising technology for microvascular imaging in recent decades. However, current applications typically use 1-D arrays for 2-D cross-sectional images, which do not assess out-of-plane flow and provide a comprehensive 3-D visualization of the vascular network. Implementing 3-D SRU is challenging for both hardware and software due to the required large scale of high frame rate data. The row-column array (RCA) is a promising candidate for achieving 3-D imaging with fewer transducer elements. However, a sophisticated optimization of imaging parameters intertwined with the pulse sequences and signal processing is required for successful implementation. In this study, we present an optimized imaging sequence and algorithm for 3-D SRU using an RCA (6 MHz) to address these issues. A total of 10k volume frames from rabbit kidney were collected in vivo using orthogonal plane wave compounding with 42° at 250 Hz over and processed with 3-D super-resolution algorithm. The complete 3-D vascular network in the rabbit kidney was successfully reconstructed and compared with microCT image on the harvested kidney. This successful validation paves the way for advancing 3-D SRU imaging which allows more accurate in vivo vascular assessment in future preclinical and clinical applications.