Department of Nuclear Medicine, Maastricht University Medical Center, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Eur J Nucl Med Mol Imaging. 2011 May;38(5):940-8. doi: 10.1007/s00259-011-1732-1. Epub 2011 Feb 2.
The aim of this study was to investigate the effect of positron range on visualization and quantification in (18)F, (68)Ga and (124)I positron emission tomography (PET)/CT of lung-like tissue.
Different sources were measured in air, in lung-equivalent foams and in water, using a clinical PET/CT and a microPET system. Intensity profiles and curves with the cumulative number of annihilations were derived and numerically characterized.
(68)Ga and (124)I gave similar results. Their intensity profiles in lung-like foam had a peak similar to that for (18)F, and tails of very low intensity, but extending over distances of centimetres and containing a large fraction of all annihilations. For 90% recovery, volumes of interest with diameters up to 50 mm were required, and recovery within the 10% intensity isocontour was as low as 30%. In contrast, tailing was minor for (18)F.
Lung lesions containing (18)F, (68)Ga or (124)I will be visualized similarly, and at least as sharp as in soft tissue. Nevertheless, for quantification of (68)Ga and (124)I large volumes of interest are needed for complete activity recovery. For clinical studies containing noise and background, new quantification approaches may have to be developed.
本研究旨在探讨正电子射程对肺样组织中（18）F、（68）Ga 和（124）I 正电子发射断层扫描（PET）/CT 可视化和定量的影响。
在空气、肺等效泡沫和水中使用临床 PET/CT 和 microPET 系统测量了不同的源。得出了强度分布曲线和累积湮灭数曲线，并进行了数值特征描述。
（68）Ga 和（124）I 给出了相似的结果。它们在肺样泡沫中的强度分布曲线与（18）F 的峰值相似，尾部强度非常低，但延伸距离可达数厘米，包含了大部分湮灭。对于 90%的回收，需要直径达 50mm 的感兴趣区域，而 10%强度等浓度线内的回收率低至 30%。相比之下，（18）F 的尾部效应较小。
含有（18）F、（68）Ga 或（124）I 的肺病变将被类似地可视化，并且至少与软组织中的一样锐利。然而，对于（68）Ga 和（124）I 的定量，需要较大的感兴趣区域才能完全回收活性。对于含有噪声和背景的临床研究，可能需要开发新的定量方法。
