A new paradigm in high-speed photoacoustic small animal whole-body imaging

There is increasing recognition of the need to track whole-body dynamics to understand complex biological processes and disease progression in living organisms. Currently, various imaging techniques, including X-ray CT, MRI, PET, and optical imaging, are used with small animal models, each with its own advantages and limitations. This has led researchers to explore PACT as a tool for observing the structural, functional, and molecular characteristics of biological tissues.

PACT system combines the strengths of optical and ultrasound imaging, presenting a promising alternative to traditional imaging methods. Conventional whole-body PACT approaches, however, were constrained by lengthy whole-body imaging times and a one-sided view.

To address these challenges, the team developed the PACT system to quickly capture multiple biological parameters within the torso of small animals. The system uses a rapidly rotating array of hemispherical ultrasound transducers, allowing simultaneous collection of multiple data points at a significantly faster rate than conventional step-by-step scans. With this innovation, the researchers were able to acquire 360° anatomical images of a rat torso in just nine seconds, complete a full whole-body scan in 54 seconds, and achieve a spatial resolution of approximately 212 micrometers (µm).

This system enabled the team to visualize whole-body structures and monitor drug kinetics as well as changes in hemoglobin oxygen saturation in live animals. Notably, the ability to observe oxygen saturation across a wide range of tissues is expected to substantially enhance our understanding of oxygen transport and distribution within complex biological systems.

Professor Chulhong Kim of POSTECH expressed the significance of the research by saying, "This technology matches the performance of existing imaging techniques while also providing molecular and functional information." Dr. Seongwook Choi remarked, "This system offers valuable insights into the rapid dynamics of biological systems and oxygen kinetics in preclinical research."

The research was conducted with support from the Program for Key Research Institutes for Universities of the Ministry of Education, the Mid-Career Research Program and the BRIDGE from the Ministry of Science and ICT, the Governmental Medical Device R&D Program, and BK21.