Harteela Markus, Hirvi Heidi, Mäkipää Anna, Teuho Jarmo, Koivumäki Tuomas, Mäkelä Marko M, Teräs Mika
Department of Mathematics and Statistics, University of Turku , Turku , Finland.
Acta Oncol. 2014 Aug;53(8):1079-85. doi: 10.3109/0284186X.2014.926028. Epub 2014 Jun 24.
Respiratory motion in positron emission tomography/computed tomography (PET/CT) causes underestimation of standardized uptake value (SUV) and variation of lesion volume, while PET and CT attenuation correction (CTAC) mismatch may introduce artefacts. The aim was to compare end-expiratory gating methods of PET and CTAC.
Three methods named the minimum-constant, slope-based and amplitude-median were developed and evaluated on gating efficiency. Method evaluation and optimization was performed on 23 simulated and 23 recorded signals from a mixed patient group. The optimized methods were applied in PET/CT imaging of seven patients, consisting of non-gated CTAC, whole-body PET and four-dimensional (4D) PET/CT. Gating efficiency was evaluated by preservation of the respiratory signal, PET-CTAC alignment, image noise and measurement of lesion SUV maximum (SUVmax), SUV mean (SUVmean) and volume. The methods were evaluated with non-gated PET and end-expiratory phase of five-bin phase-gated PET. End-expiratory gated 4D-CTAC and averaged CTAC were compared for attenuation correction of end-expiratory gated PET.
Mean fraction of data preserved was larger (23-34%) with end-expiratory gating compared to phase-gated PET. End-expiratory gating showed increased SUVmax (8.2-8.4 g/ml), SUVmean (5.7-5.8 g/ml) and decreased lesion volume (-11.3-16.8%) compared to non-gated PET (SUVmax 6.2 g/ml, SUVmean 4.7 g/ml) and phase-gated PET (SUVmax 8.0 g/ml, SUVmean 5.6 g/ml). Using averaged CTAC and end-expiratory 4D-CTAC produced similar results concerning SUVmax, with less than 5% difference. Additionally, CTAC-PET-mismatch was minimal when end-expiratory 4D-CTAC was used.
End-expiratory gating in PET/CT results in SUVmax and SUVmean increase and reduced lesion volume compared to non-gated PET and phase-gated PET. End-expiratory 4D-CTAC or averaged CTAC will offer similar accuracy for attenuation correction of end-expiratory gated PET.
正电子发射断层扫描/计算机断层扫描（PET/CT）中的呼吸运动会导致标准化摄取值（SUV）被低估以及病变体积发生变化，而PET与CT衰减校正（CTAC）不匹配可能会引入伪影。目的是比较PET和CTAC的呼气末门控方法。
开发了三种方法，即最小常数法、基于斜率法和幅度中位数法，并对门控效率进行了评估。对来自混合患者组的23个模拟信号和23个记录信号进行了方法评估和优化。将优化后的方法应用于7例患者的PET/CT成像，包括非门控CTAC、全身PET和四维（4D）PET/CT。通过呼吸信号的保留、PET-CTAC对齐、图像噪声以及病变SUV最大值（SUVmax）、SUV平均值（SUVmean）和体积的测量来评估门控效率。使用非门控PET和五分区相位门控PET的呼气末相位对这些方法进行评估。比较呼气末门控4D-CTAC和平均CTAC对呼气末门控PET的衰减校正效果。
与相位门控PET相比，呼气末门控保留的数据平均比例更大（23-34%）。与非门控PET（SUVmax 6.2 g/ml，SUVmean 4.7 g/ml）和相位门控PET（SUVmax 8.0 g/ml，SUVmean 5.6 g/ml）相比，呼气末门控显示SUVmax（8.2-8.4 g/ml）、SUVmean（5.7-5.8 g/ml）增加，病变体积减小（-11.3-16.8%）。使用平均CTAC和呼气末4D-CTAC在SUVmax方面产生的结果相似，差异小于5%。此外，使用呼气末4D-CTAC时，CTAC-PET不匹配最小。
与非门控PET和相位门控PET相比，PET/CT中的呼气末门控可使SUVmax和SUVmean增加，病变体积减小。呼气末4D-CTAC或平均CTAC对呼气末门控PET的衰减校正将提供相似的准确性。
