Mercolli Lorenzo, Steinberger William M, Rathod Narendra, Conti Maurizio, Moskal Paweł, Rominger Axel, Seifert Robert, Shi Kuangyu, Stępień Ewa Ł, Sari Hasan
Department of Nuclear Medicine, Inselspital, Bern University Hostpital, University of Bern, Bern, Switzerland.
ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
EJNMMI Phys. 2025 Aug 26;12(1):80. doi: 10.1186/s40658-025-00790-z.
Measuring the ortho-positronium (oPs) lifetime in human tissue bears the potential of adding clinically relevant information about the tissue microenvironment to conventional positron emission tomography (PET). Through phantom measurements, we investigate the voxel-wise measurement of oPs lifetime using a commercial long-axial field-of-view (LAFOV) PET scanner.
We prepared four samples with mixtures of Amberlite XAD4, a porous polymeric adsorbent, and water and added between 1.12 and 1.44 MBq of I. The samples were scanned in two different setups: once with a couple of centimeters between each sample (15 min scan time) and once with all samples taped together (40 min scan time). For each scan, we determine the oPs lifetime for the full samples and at the voxel level. The voxel sizes under consideration are 10.0 mm, 7.1 mm and 4.0 mm.
Amberlite XAD4 allows the preparation of samples with distinct oPs lifetime. Using a Bayesian fitting procedure, the oPs lifetimes in the whole samples are 2.52 ± 0.03 ns, 2.37 ± 0.03 ns, 2.27 ± 0.04 ns and 1.82 ± 0.02 ns, respectively. The voxel-wise oPs lifetime fits showed that even with 4.0 mm voxels the samples are clearly distinguishable and a central voxels have good count statistics. However, the situation with the samples close together remains challenging with respect to the spatial distinction of regions with different oPs lifetimes.
Our study shows that positronium lifetime imaging on a commercial LAFOV PET/CT is feasible using I.
测量人体组织中正电子素（oPs）的寿命，有望为传统正电子发射断层扫描（PET）增添有关组织微环境的临床相关信息。通过体模测量，我们使用商用长轴视野（LAFOV）PET扫描仪研究了oPs寿命的体素级测量。
我们制备了四个含有多孔聚合物吸附剂Amberlite XAD4和水的混合物的样品，并添加了1.12至1.44MBq的碘。样品在两种不同设置下进行扫描：一次是每个样品之间相隔几厘米（扫描时间15分钟），另一次是将所有样品粘在一起（扫描时间40分钟）。对于每次扫描，我们确定整个样品以及体素水平的oPs寿命。所考虑的体素大小为10.0毫米、7.1毫米和4.0毫米。
Amberlite XAD4可制备具有不同oPs寿命的样品。使用贝叶斯拟合程序，整个样品中的oPs寿命分别为2.52±0.03纳秒、2.37±0.03纳秒、2.27±0.04纳秒和1.82±0.02纳秒。体素级oPs寿命拟合表明，即使使用4.0毫米的体素，样品也能清晰区分，且中心体素具有良好的计数统计。然而，样品靠得很近的情况下，区分具有不同oPs寿命的区域在空间上仍然具有挑战性。
我们的研究表明，使用碘在商用LAFOV PET/CT上进行正电子素寿命成像是可行的。
