不同密度口服阳性对比剂对PET/CT图像质量及标准摄取值的影响

Impact on the PET image quality and standard uptake value with positive oral contrast agents

目的探讨不同密度口服阳性对比剂对PET/CT图像质量和标准摄取值(SUV)的影响。方法60例PET/CT显像患者,显像前常规口服浓度为2%的泛影葡胺1000ml,其中14例患者肠道内发现多处高密度残留钡剂。所有患者均同时采用CT及137Cs两种衰减校正方法,分别重建CT衰减校正(CTAC)、137Cs衰减校正(CsAC)图像。选择所有患者胃肠道内泛影葡胺充盈区、无对比剂充盈区、臀部软组织区以及14例患者高密度钡剂充盈区勾划感兴趣区(ROI)。比较各感兴趣区CTAC和CsAC的平均SUV差异,以及CTAC、CsAC的图像差异。结果在所有正常软组织区、无对比剂充盈区以及泛影葡胺充盈区,CTAC和CsAC的平均SUV无显著性差异。在高密度残留钡剂充盈区,CTAC的平均SUV明显高于CsAC(t=3.451,P=0.018),其差异与CT值成正相关(r=0.445,P=0.021)。比较所有图像,正常软组织、无对比剂充盈区、泛影葡胺充盈区CTAC和CsAC图像质量无明显差异。在高密度残留钡剂充盈区,CTAC图像上可见FDG高摄取伪影,而CsAC图像为正常摄取。结论低密度口服泛影葡胺对PET/CT显像图像质量和标准摄取值无明显影响,高密度钡剂可使PET/CT的SUV明显高估,且可出现不同程度的FDG高摄取伪影。

Objective To evaluate the impact of orally take low-density meglumine and high-density barium on the PET image quality and standard uptake value（SUV）.Methods Sixty patients underwent PET/CT on the Gemini system.All orally took 2% meglumine 1000 ml before imaging,and high-density barium in abdomen was found in 14 patients.CT attenuation correction（CTAC）and ^137Cs attenuation correction（CsAC）images were reconstructed respectively.Regions of interest（ROI）of the bowel that full of meglumine and barium,no contrast region and the buttocks muscle region were drawn respectively in all patients.Then the image quality and SUV from the CTAC images were compared with those from the CsAC images.Results The values of SUV from the normal soft tissues,meglumine regions and no contrast regions were not statistically different between the CTAC and CsAC methods,while the average SUVs of CTAC images were objectively higher than that of the CsAC ones in barium regions（t=3.451,P=0.018）.Image quality of normal soft tissue,meglumine regions and no contrast regions from CTAC and CsAC respectively had no obviously difference.The image artifact was obvious in the barium region with CTAC method and no artifact in the same regions with CsAC method.Conclusion This study showed that low-density meglumine has no obvious impact to the image quality and SUV,but SUVs might be high-estimated and the image artifacts may develop in the high-density barium regions.