Score-based generative models have demonstrated highly promising results for medical image reconstruction tasks in magnetic resonance imaging or computed tomography. However, their application to Positron Emission Tomography (PET) is still largely unexplored. PET image reconstruction involves a variety of challenges, including Poisson noise with high variance and a wide dynamic range. To address these challenges, we propose several PET-specific adaptations of score-based generative models. The proposed framework is developed for both 2D and 3D PET. In addition, we provide an extension to guided reconstruction using magnetic resonance images. We validate the approach through extensive 2D and 3D $\textit{in-silico}$ experiments with a model trained on patient-realistic data without lesions, and evaluate on data without lesions as well as out-of-distribution data with lesions. This demonstrates the proposed method's robustness and significant potential for improved PET reconstruction.

基于评分的生成模型在医学图像重建任务中，如磁共振成像或计算机断层扫描，已经展现出极具潜力的结果。然而，它们在正电子发射断层扫描（PET）中的应用尚未被广泛探索。为了应对PET图像重建中的多个挑战，包括具有高方差和广泛动态范围的泊松噪声，我们提出了几种针对PET的评分生成模型的适应性改进。该提出的框架适用于2D和3D PET，并通过使用磁共振图像进行引导重建的扩展。我们通过广泛的2D和3D$	extit{in-silico}$实验，利用在没有病变的患者现实数据上训练的模型进行验证，并对没有病变的数据以及含病变的离群数据进行评估。这证明了所提方法的稳健性和显著的PET重建改进潜力。

基于评分的PET图像重建的生成模型