Ambient Denoising Diffusion Generative Adversarial Networks for Establishing Stochastic Object Models from Noisy Image Data
Xichen Xu, Wentao Chen, Weimin Zhou
TL;DR
This work tackles objective image quality assessment in medical imaging by learning stochastic object models (SOMs) from noisy data. It introduces Ambient Denoising Diffusion GAN (ADDGAN), an augmentation of denoising diffusion GANs that trains directly on noisy measurements by integrating the imaging operator, enabling realistic SOMs from real clinical data. Across CT and DBT datasets, ADDGAN achieves superior fidelity (lower FID) and texture realism compared to DDPM, DDGAN trained on noise, and AmbientGAN-based methods, with task-based metrics like the Hotelling observer further supporting its efficacy. The approach offers a practical pathway to robust SOM-based IQ analysis in clinical imaging workflows.
Abstract
It is widely accepted that medical imaging systems should be objectively assessed via task-based image quality (IQ) measures that ideally account for all sources of randomness in the measured image data, including the variation in the ensemble of objects to be imaged. Stochastic object models (SOMs) that can randomly draw samples from the object distribution can be employed to characterize object variability. To establish realistic SOMs for task-based IQ analysis, it is desirable to employ experimental image data. However, experimental image data acquired from medical imaging systems are subject to measurement noise. Previous work investigated the ability of deep generative models (DGMs) that employ an augmented generative adversarial network (GAN), AmbientGAN, for establishing SOMs from noisy measured image data. Recently, denoising diffusion models (DDMs) have emerged as a leading DGM for image synthesis and can produce superior image quality than GANs. However, original DDMs possess a slow image-generation process because of the Gaussian assumption in the denoising steps. More recently, denoising diffusion GAN (DDGAN) was proposed to permit fast image generation while maintain high generated image quality that is comparable to the original DDMs. In this work, we propose an augmented DDGAN architecture, Ambient DDGAN (ADDGAN), for learning SOMs from noisy image data. Numerical studies that consider clinical computed tomography (CT) images and digital breast tomosynthesis (DBT) images are conducted. The ability of the proposed ADDGAN to learn realistic SOMs from noisy image data is demonstrated. It has been shown that the ADDGAN significantly outperforms the advanced AmbientGAN models for synthesizing high resolution medical images with complex textures.