Researchers publish first standardized guide to ultrasound detectors for deep-body imaging

Researchers at the University of Birmingham and University College London have published the most comprehensive analysis to date of ultrasound detectors used in photoacoustic tomography (PAT), a medical imaging technique that combines laser light and ultrasound to visualize blood vessels, tumors, and tissue function deep inside the body. The study, published in Nature Reviews Methods Primers, reviewed published data on 82 detectors across four main types: ceramic piezoelectric, polymer piezoelectric, capacitive micromachined ultrasonic transducers (CMUTs), and optical ultrasound sensors.

The team established the first standardized "noise-equivalent pressure" (NEP) landscape, a performance map showing which detectors can detect the faintest biological signals. Because sound waves from deep tissues are extremely weak, detector sensitivity is a critical limiting factor for imaging depth. The analysis found that large ceramic detectors are currently the most sensitive to low-frequency ultrasound waves arriving head-on, making them best suited for deep-tissue applications such as breast cancer imaging.

Optical ultrasound sensors, which detect sound using light rather than electricity, excel when detectors must be extremely small — often under 100 micrometers across — while remaining highly sensitive. These sensors are already the best choice for high-resolution imaging of tiny structures such as microvasculature. Polymer detectors provide broader frequency coverage, which can capture more image detail, particularly for superficial structures. CMUT detectors showed sensitivity comparable to leading technologies, but the authors noted that published measurements lacked sufficient detail to fully assess their true performance.

Lead author Dr. James Guggenheim of the University of Birmingham emphasized that no single detector type is best for all applications. He said the study provides researchers and manufacturers with a practical guide for selecting the right detector technology for specific clinical challenges today, while also highlighting where future innovation is needed. Key gaps include the development of dense, small-element detector arrays capable of delivering both deep-tissue penetration and high resolution.

Until now, comparing detector technologies has been difficult because researchers used inconsistent definitions and measurement approaches. The study concludes that future improvements in photoacoustic imaging will depend on creating more sensitive detectors, standardizing performance measurements, and developing practical high-channel-count systems for clinical use.