A Hybrid Diffusion Model Enhances Multiparametric 3D Photoacoustic Computed Tomography

Photoacoustic computed tomography (PACT) reveals biological structures, pharmacokinetics, and physiological functions. Although a premium PACT system with many ultrasound (US) transducers delivers high-quality volumetric imaging, it suffers from high system costs and slow temporal resolution. Here, using a limited number of US elements, a hybrid diffusion model (HD-PACT) is demonstrated that enhances dynamic multiparametric (structural, functional, and contrast-enhanced) 3D PACT. Using just 256 out of the 1024 elements in a premier hemispherical US array for PACT, HD-PACT improves structural images acquired in different planes, organisms, and wavelengths. In functional imaging, HD-PACT enables 256-element PACT to observe hypoxia, pharmacokinetics, and angiogenesis during tumor progression. Lastly, HD-PACT is transferable to low-end PACT (only 128 US elements), where it dynamically captures contrast-free/enhanced organs, oxygen-perturbed brains, and cardiac dynamics with high spatiotemporal resolution in live animals. It is believed that HD-PACT will be valuable in oncology, cardiology, pharmacology, and endocrinology.