New guide could help scientists see deeper into the human body using light and sound

Scientists have unveiled the most detailed analysis yet of ultrasound detectors that power photoacoustic tomography (PAT), a cutting-edge medical imaging method capable of visualizing blood vessels, tumors, and tissue function deep within the body. The groundbreaking study, published in Nature Reviews Methods Primers, reveals that large ceramic detectors are currently the most effective for deep imaging, while optical ultrasound sensors hold promise for high-resolution imaging of minute structures.

Researchers from the University of Birmingham and UCL meticulously reviewed data on 82 ultrasound detectors employed in PAT, creating the first standardized noise-equivalent pressure (NEP) landscape—a performance map demonstrating which detectors can pick up the weakest biological signals across four primary detector types. PAT functions by emitting brief pulses of laser light into tissue; when the tissue absorbs the light, it generates minute ultrasound waves that researchers can detect to construct images of blood vessels, tumors, and other structures inside the body.

However, ultrasound waves emanating from deeper tissues are exceedingly weak, with signal strength diminishing as depth increases. Lead author Dr. James Guggenheim from the University of Birmingham noted, "There is no single best ultrasound detector for all photoacoustic imaging applications. Deep tissue imaging, such as breast cancer detection, currently benefits from highly sensitive ceramic detectors.

Yet, optical ultrasound sensors, which are already unparalleled in their ability to image tiny blood vessels with high resolution, may eventually become the dominant technology even for deep tissue imaging as their sensitivity continues to improve." The study aims to serve as a practical guide for researchers and manufacturers in selecting the appropriate detector technology for specific clinical challenges and outlines the areas where future innovation is required.

For instance, developing dense, small-element detector arrays that can perform both deep-tissue and high-resolution imaging is a priority. The study emphasizes that future advancements in PAT will hinge on creating more sensitive detectors, refining detector arrays, standardizing performance measurement, and developing practical high-channel-count systems suitable for clinical use.