# A Hybrid Diffusion Model Enhances Multiparametric 3D Photoacoustic Computed Tomography

## TL;DR

A new imaging system improves 3D photoacoustic tomography using fewer sensors, enabling detailed biological and functional imaging at lower costs.

## Contribution

A hybrid diffusion model (HD-PACT) enables high-quality 3D imaging with fewer ultrasound elements, overcoming limitations of traditional systems.

## Key findings

- HD-PACT improves structural and functional imaging using only 256 ultrasound elements instead of 1024.
- The model captures dynamic biological processes like hypoxia and angiogenesis in tumors.
- HD-PACT works effectively even with as few as 128 ultrasound elements in live animals.

## Abstract

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.

The hybrid diffusion PACT (HD‐PACT) system enhances dynamic multiparametric information using only 128–256 ultrasound elements. By overcoming limited‐view artifacts, HD‐PACT refines structural and functional information such as oxygen saturation observed in 3D premium PACT with > 1000 elements. Through cost‐effective and faster multiparametric imaging, the system tracks tumor‐progression and captures dynamic contrast‐enhanced perfusion for oncology, cardiology, and pharmacology.