High Signal-to-Noise Ratio Contrast-Enhanced Photoacoustic Imaging using Acoustic Sub-Aperture Processing and Spatiotemporal Filtering

Contrast-enhanced photoacoustic imaging has shown great potential in medical imaging applications. Despite the obvious advantages of contrast enhancement, contrast agent signals attenuate significantly during the propagation process and can be masked by noise and clutter signals generated by tissue, resulting in the reduction of imaging sensitivity. In this study, we demonstrate that acoustic sub-aperture processing (ASAP) may be adapted to process photoacoustic images to generate high signal-to-noise ratio (SNR) images compared to the conventional spatiotemporal filtered images. Experiments were performed in vitro on a 0.6-mm diameter tube in a tissue-mimicking phantom containing a previously demonstrated exogenous photoacoustic contrast agent, Cyanine 7.5-coated nanodroplets. Data were acquired using a preclinical multispectral optoacoustic tomography (MOST) system. The results suggested that ASAP-assisted spatiotemporal filtering can improve SNR by about 8 dB in vitro compared to that without using ASAP. Besides flow imaging, this technique can also potentially benefit other photoacoustic imaging applications such as molecular imaging and super-resolution imaging.