Caltech’s recent strides in photoacoustic imaging technology, known as PACTER (Photoacoustic Computed Tomography Through an Ergodic Relay), mark a noteworthy advancement in medical imaging. In a collaborative effort by Professor Lihong Wang and postdoctoral scholar Yide Zhang, improvements have been made to the previously introduced PATER (Photoacoustic Topography Through an Ergodic Relay) technique.
Photoacoustic imaging involves pulsing laser light into tissue, causing molecules to vibrate and generate ultrasonic waves for internal structure imaging. The initial challenges of this technology, including complexity and expense, were addressed by Wang and Zhang through the incorporation of an ergodic relay, reducing the number of required transducers.
The PACTER technology takes these advancements further by operating with a single transducer that, through software, can collect data equivalent to 6,400 transducers. PACTER introduces two key improvements: the ability to create three-dimensional images and eliminating the need for calibration before each use, a limitation present in its predecessor, PATER.
The transition to 3D imaging posed a significant data challenge, but the team addressed it by expanding one transducer into thousands of virtual ones, simplifying the reconstruction process. Additionally, PACTER overcomes the calibration requirement by introducing a delay line, ensuring accurate ultrasound information is received before the echo from the laser pulse interferes.
Professor Wang acknowledges the challenges faced during this development but emphasizes the practicality achieved with PACTER, making it a substantial step forward in medical imaging. The research, titled “Ultrafast longitudinal imaging of haemodynamics via single-shot volumetric photoacoustic tomography with a single-element detector,” was published in the November 30 issue of Nature Biomedical Engineering. The collaborative effort includes contributions from researchers at Caltech and USC.