Multiple-bandwidth photoacoustic tomography

TLDR

Photoacoustic tomography generates ultrasonic waves from short laser pulses, producing images that depend on the convolution of sample structure, laser pulse shape, and transducer impulse response, but a single transducer’s limited bandwidth restricts the usable spectral range. The study systematically investigates this bandwidth limitation by building a photoacoustic system that simultaneously employs multiple ultrasonic transducers tuned to different central frequencies. Images from each transducer were compared and analyzed after testing the system on mouse brains and phantom samples. All transducers visualized brain vasculature, with higher‑frequency detectors yielding finer resolution and lower‑frequency detectors offering superior signal‑to‑noise for major structural features.

Abstract

Photoacoustic tomography, also referred to as optoacoustic tomography, employs short laser pulses to generate ultrasonic waves in biological tissues. The reconstructed images can be characterized by the convolution of the structure of samples, the laser pulse and the impulse response of the ultrasonic transducer used for detection. Although the laser-induced ultrasonic waves cover a wide spectral range, a single transducer can receive only part of the spectrum because of its limited bandwidth. To systematically analyse this problem, we constructed a photoacoustic tomographic system that uses multiple ultrasonic transducers simultaneously, each at a different central frequency. The photoacoustic images associated with the different transducers were compared and analysed. The system was tested by imaging both mouse brains and phantom samples. The vascular vessels in the brain were revealed by all of the transducers, but the image resolutions differed. The higher frequency detectors provided better image resolution while the lower frequency detectors delineated the major structural traits with a higher signal–noise ratio.