IEEE Trans Med Imaging. 2022 Oct;41(10):2848-2855. doi: 10.1109/TMI.2022.3174561. Epub 2022 Sep 30.
Positron emission tomography is widely used in clinical and preclinical applications. Positronium lifetime carries information about the tissue microenvironment where positrons are emitted, but such information has not been captured because of two technical challenges. One challenge is the low sensitivity in detecting triple coincidence events. This problem has been mitigated by the recent developments of PET scanners with long (1-2 m) axial field of view. The other challenge is the low spatial resolution of the positronium lifetime images formed by existing methods that is determined by the time-of-flight (TOF) resolution (200-500 ps) of existing PET scanners. This paper solves the second challenge by developing a new image reconstruction method to generate high-resolution positronium lifetime images using existing TOF PET. Simulation studies demonstrate that the proposed method can reconstruct positronium lifetime images at much better spatial resolution than the limit set by the TOF resolution of the PET scanner. The proposed method opens up the possibility of performing positronium lifetime imaging using existing TOF PET scanners. The lifetime information can be used to understand the tissue microenvironment in vivo which could facilitate the study of disease mechanism and selection of proper treatments.
正电子发射断层扫描（Positron Emission Tomography，PET）广泛应用于临床和临床前研究。正电子素寿命携带了正电子发射所在组织微环境的信息，但由于两个技术挑战，这些信息尚未被捕获。第一个挑战是三重符合事件的检测灵敏度较低。最近，具有长（1-2 米）轴向视野的 PET 扫描仪的发展缓解了这一问题。第二个挑战是现有方法形成的正电子素寿命图像的空间分辨率较低，这取决于现有 PET 扫描仪的飞行时间（Time-of-Flight，TOF）分辨率（200-500 ps）。本文通过开发一种新的图像重建方法，利用现有的 TOF PET 生成高分辨率的正电子素寿命图像，解决了第二个挑战。模拟研究表明，与 PET 扫描仪的 TOF 分辨率限制相比，该方法可以在更高的空间分辨率下重建正电子素寿命图像。该方法为使用现有的 TOF PET 扫描仪进行正电子素寿命成像开辟了可能性。寿命信息可用于了解体内组织微环境，从而有助于研究疾病机制和选择合适的治疗方法。
