PET-Adapter: Test-Time Domain Adaptation for Full and Limited-Angle PET Image Reconstruction

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Main Authors: Yilmaz, Rüveyda, Wu, Yuli, Stegmaier, Johannes, Schulz, Volkmar
Format: Preprint
Published: 2026
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author Yilmaz, Rüveyda
Wu, Yuli
Stegmaier, Johannes
Schulz, Volkmar
author_facet Yilmaz, Rüveyda
Wu, Yuli
Stegmaier, Johannes
Schulz, Volkmar
contents Positron Emission Tomography (PET) image reconstruction is inherently challenged by Poisson noise and physical degradation factors, which are further exacerbated in limited-angle acquisitions. While deep learning methods demonstrate promising performance, their generalization to unseen clinical data distributions remains limited without extensive retraining. We propose PET-Adapter, a test-time domain adaptation framework for generative PET reconstruction models pretrained solely on phantom data. Our method enables adaptation to clinical datasets with varying anatomies, tracers, and scanner configurations without requiring paired ground truth. PET-Adapter introduces layer-wise low-rank anatomical conditioning during adaptation and Ordered Subset Expectation Maximization-based warm-starting that initializes the generation from physics-informed reconstructions, reducing diffusion steps from 50 to 2 without compromising quality. Experiments across multiple clinical datasets demonstrate superior 3D reconstruction performance in both full-angle and limited-angle settings, highlighting the clinical feasibility and computational efficiency of the proposed approach.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08030
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle PET-Adapter: Test-Time Domain Adaptation for Full and Limited-Angle PET Image Reconstruction
Yilmaz, Rüveyda
Wu, Yuli
Stegmaier, Johannes
Schulz, Volkmar
Computer Vision and Pattern Recognition
Machine Learning
Positron Emission Tomography (PET) image reconstruction is inherently challenged by Poisson noise and physical degradation factors, which are further exacerbated in limited-angle acquisitions. While deep learning methods demonstrate promising performance, their generalization to unseen clinical data distributions remains limited without extensive retraining. We propose PET-Adapter, a test-time domain adaptation framework for generative PET reconstruction models pretrained solely on phantom data. Our method enables adaptation to clinical datasets with varying anatomies, tracers, and scanner configurations without requiring paired ground truth. PET-Adapter introduces layer-wise low-rank anatomical conditioning during adaptation and Ordered Subset Expectation Maximization-based warm-starting that initializes the generation from physics-informed reconstructions, reducing diffusion steps from 50 to 2 without compromising quality. Experiments across multiple clinical datasets demonstrate superior 3D reconstruction performance in both full-angle and limited-angle settings, highlighting the clinical feasibility and computational efficiency of the proposed approach.
title PET-Adapter: Test-Time Domain Adaptation for Full and Limited-Angle PET Image Reconstruction
topic Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2605.08030