Huang Hsin-Hsiung, Zhu Zheyuan, Booppasiri Slun, Chen Zhuo, Pang Shuo, Kao Chien-Min
Department of Statistics and Data Science, University of Central Florida, Orlando, FL 32816.
CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, FL 32816.
IEEE Trans Radiat Plasma Med Sci. 2025 Apr;9(4):478-486. doi: 10.1109/trpms.2025.3531225. Epub 2025 Jan 17.
Positron emission tomography (PET) is an important modality for diagnosing diseases such as cancer and Alzheimer's disease, capable of revealing the uptake of radiolabeled molecules that target specific pathological markers of the diseases. Recently, positronium lifetime imaging (PLI) that adds to traditional PET the ability to explore properties of the tissue microenvironment beyond tracer uptake has been demonstrated with time-of-flight (TOF) PET and the use of non-pure positron emitters. However, achieving accurate reconstruction of lifetime images from data acquired by systems having a finite TOF resolution still presents a challenge. This paper focuses on the two-dimensional PLI, introducing a maximum likelihood estimation (MLE) method that employs an exponentially modified Gaussian (EMG) probability distribution that describes the positronium lifetime data produced by TOF PET. We evaluate the performance of our EMG-based MLE method against approaches using exponential likelihood functions and penalized surrogate methods. Results from computer-simulated data reveal that the proposed EMG-MLE method can yield quantitatively accurate lifetime images. We also demonstrate that the proposed MLE formulation can be extended to handle PLI data containing multiple positron populations.
正电子发射断层扫描（PET）是诊断癌症和阿尔茨海默病等疾病的重要模态，能够揭示靶向疾病特定病理标志物的放射性标记分子的摄取情况。最近，通过飞行时间（TOF）PET以及使用非纯正电子发射体，已经证明了正电子素寿命成像（PLI）在传统PET的基础上增加了探索示踪剂摄取之外的组织微环境特性的能力。然而，从具有有限TOF分辨率的系统采集的数据中实现寿命图像的精确重建仍然是一个挑战。本文聚焦于二维PLI，介绍一种最大似然估计（MLE）方法，该方法采用指数修正高斯（EMG）概率分布来描述TOF PET产生的正电子素寿命数据。我们将基于EMG的MLE方法的性能与使用指数似然函数和惩罚替代方法的方法进行评估。计算机模拟数据的结果表明，所提出的基于EMG的MLE方法能够生成定量准确的寿命图像。我们还证明，所提出的MLE公式可以扩展以处理包含多个正电子群体的PLI数据。
