Teuho Jarmo, Riehakainen Leon, Honkaniemi Aake, Moisio Olli, Han Chunlei, Tirri Marko, Liu Shihao, Grönroos Tove J, Liu Jie, Wan Lin, Liang Xiao, Ling Yiqing, Hua Yuexuan, Roivainen Anne, Knuuti Juhani, Xie Qingguo, Teräs Mika, D'Ascenzo Nicola, Klén Riku
Turku PET Centre, University of Turku, Turku, Finland.
Turku PET Centre, Turku University Hospital, Turku, Finland.
EJNMMI Res. 2020 Dec 10;10(1):155. doi: 10.1186/s13550-020-00724-z.
We investigated the image quality of C, Ga, F and Zr, which have different positron fractions, physical half-lifes and positron ranges. Three small animal positron emission tomography/computed tomography (PET/CT) systems were used in the evaluation, including the Siemens Inveon, RAYCAN X5 and Molecubes β-cube. The evaluation was performed on a single scanner level using the national electrical manufacturers association (NEMA) image quality phantom and analysis protocol. Acquisitions were performed with the standard NEMA protocol for F and using a radionuclide-specific acquisition time for C, Ga and Zr. Images were assessed using percent recovery coefficient (%RC), percentage standard deviation (%STD), image uniformity (%SD), spill-over ratio (SOR) and evaluation of image quantification.
Ga had the lowest %RC (< 62%) across all systems. F had the highest maximum %RC (> 85%) and lowest %STD for the 5 mm rod across all systems. For C and Zr, the maximum %RC was close (> 76%) to the %RC with F. A larger SOR were measured in water with C and Ga compared to F on all systems. SOR in air reflected image reconstruction and data correction performance. Large variation in image quantification was observed, with maximal errors of 22.73% (Zr, Inveon), 17.54% (Zr, RAYCAN) and - 14.87% (Ga, Molecubes).
The systems performed most optimal in terms of NEMA image quality parameters when using F, where C and Zr performed slightly worse than F. The performance was least optimal when using Ga, due to large positron range. The large quantification differences prompt optimization not only by terms of image quality but also quantification. Further investigation should be performed to find an appropriate calibration and harmonization protocol and the evaluation should be conducted on a multi-scanner and multi-center level.
我们研究了具有不同正电子分数、物理半衰期和正电子射程的碳（C）、镓（Ga）、氟（F）和锆（Zr）的图像质量。评估中使用了三台小动物正电子发射断层扫描/计算机断层扫描（PET/CT）系统，包括西门子Inveon、睿碳X5和Molecubesβ-cube。评估是在单个扫描仪层面上使用美国国家电气制造商协会（NEMA）图像质量体模和分析方案进行的。采用标准的NEMA方案对F进行采集，并针对C、Ga和Zr使用特定放射性核素的采集时间。使用百分恢复系数（%RC）、百分比标准差（%STD）、图像均匀性（%SD）、溢出率（SOR）和图像定量评估来评估图像。
在所有系统中，Ga的%RC最低（<62%）。F在所有系统中5毫米棒的最大%RC最高（>85%）且%STD最低。对于C和Zr，最大%RC与F的%RC接近（>76%）。在所有系统中，与F相比，在水中C和Ga的SOR更大。空气中的SOR反映了图像重建和数据校正性能。观察到图像定量存在较大差异，最大误差分别为22.73%（Zr，Inveon）、17.54%（Zr，睿碳）和-14.87%（Ga，Molecubes）。
使用F时，这些系统在NEMA图像质量参数方面表现最佳，C和Zr的表现略逊于F。使用Ga时性能最差，原因是正电子射程较大。较大的定量差异促使不仅要在图像质量方面进行优化，还要在定量方面进行优化。应进一步开展研究以找到合适的校准和协调方案，并且评估应在多扫描仪和多中心层面进行。
