中文摘要：

目的通过与3DPET／CT的采集方式进行对比，探讨4D采集对肺部结节呼吸伪影纠正的应用价值。方法选择在我科进行常规3DPET／CT显像并同意进行呼吸门控4D显像的患者14例，均伴有多个肺部结节。3DPET采集时间2rain／床位，4DPET采集时间6min／床位，分为6个呼吸时相，平均每时相1min。SUV值由AW系统全自动分析获得。每个结节在3DPET以及4DPET的6个时相中共测量7次。结果所有患者4D和3D胸部PET／CT图像清晰，PET信噪比分别为4．00±0．35和3．98±0．55，二者之间差异没有统计学意义（Z=-1．109，P=0．267）；而4DCT噪声水平较3DCT略增高，在肺结节特性显示中某些时相优于常规CT。14例患者37个肺部结节中，3DPET／CT发现呼吸伪影33个，4DPET／CT纠正伪影31个（93．9％）；4DPET显像可以提高病灶的SUV值，3D和4DPET所获得的SUVmax相关性非常好（r=0．971），但4DPET得到的SUVmax明显高于3DPET／CT（13．69±6．70 vs 12．76±6．74，t=3．475，P=0．001）。结论采用4DPET／CT显像图像质量清晰，呼吸伪影校正良好，能达到诊断的要求，且4DPET／CT所获得的肺部结节SUVmax比3D常规采集明显升高，可以为临床诊断提供更多的临床依据。

英文摘要：

Objective To explore the value of 4D PET/CT in correcting the respiration artifact of pulmonary nodules in comparison with 3D PET/CT. Methods Fourteen patients with multiple pulmonary nodules were performed PET/CT scan from May 2010 to March 2011 in department of nuclear medicine. All patients were performed with both respiratory gating and non-gating PET/CT scans. The acquisition time was set 2 min/bed for 3D PET and 6 min/bed for 4D PET. There was 6 respiratory phases with 1 min each phase for 4D PET. SUV was measured via AW workstation automatically. Every nodule was measured 7 times including 6 phases data and non- gating data. Results All 4D and 3D images in patients with chest PET/CT were clear,and the signal-to-noise ratios of those PET im- ages were 4.00 ± 0.35 and 3.98 ± 0.55, respectively. The noise level of 4D CT was slightly higher than that of 3 D CT, and the difference between 3D and 4D PET was not statistically significant （Z = - 1. 109 ,P = 0.267）. The pulmonary nodules characteristics of 4D CT images were better than those of 3D CT in some respiratory phases. A total of 33 pulmonary nodules were observed with respiratory artifacts in 3 D PET/CT, while 31 artifacts （93.9%） were corrected by 4D PET/CT. The SUVmax of 4D PET was obviously higher than that of non-gating PET（13. 69 ± 6. 70 vs 12.76±6.74,t=3.475,P=0.001） with good relativity （r=0.971）. Conclusion 4D PET/CT can correct respiratory artifact with clear images, and the SUVmax of 4D PET/CT is obviously higher than that of 3D PET/CT. 4D PET/CT scan would provide much more evidences for the clinical diagnosis.