Shibuya Kengo, Saito Haruo, Tashima Hideaki, Yamaya Taiga
Institute of Physics, Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan.
Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Anagawa 4-9-1, Inage-ku, Chiba 263-8555, Japan.
Phys Med Biol. 2022 Jan 25;67(2). doi: 10.1088/1361-6560/ac499b.
Positronium (Ps) lifetime imaging is gaining attention to bring out additional biomedical information from positron emission tomography (PET). The lifetime of Pscan change depending on the physical and chemical environments related to some diseases. Due to the limited sensitivity, Ps lifetime imaging may require merging some voxels for statistical accuracy. This paper presents a method for separating the lifetime components in the voxel to avoid information loss due to averaging. The mathematics for this separation is the inverse Laplace transform (ILT), and the authors examined an iterative numerical ILT algorithm using Tikhonov regularization, namely CONTIN, to discriminate a small lifetime difference due to oxygen saturation. The separability makes it possible to merge voxels without missing critical information on whether they contain abnormally long or short lifetime components. The authors conclude that ILT can compensate for the weaknesses of Ps lifetime imaging and extract the maximum amount of information.
正电子素（Ps）寿命成像正受到关注，以便从正电子发射断层扫描（PET）中获取更多生物医学信息。Ps的寿命会因与某些疾病相关的物理和化学环境而改变。由于灵敏度有限，Ps寿命成像可能需要合并一些体素以提高统计准确性。本文提出了一种在体素中分离寿命成分的方法，以避免因平均而导致信息丢失。这种分离的数学方法是拉普拉斯逆变换（ILT），作者研究了一种使用蒂霍诺夫正则化的迭代数值ILT算法，即CONTIN，以区分由于氧饱和度导致的微小寿命差异。这种可分离性使得在不丢失关于体素是否包含异常长或短寿命成分的关键信息的情况下合并体素成为可能。作者得出结论，ILT可以弥补Ps寿命成像的不足并提取最大量的信息。
