不同浓度泛影葡胺及不同CT扫描条件对PET/CT图像质量和标准摄取值的影响

目的 探讨不同浓度泛影葡胺及不同CT扫描条件对PET/CT图像质量和标准摄取值的影响.材料与方法 分别将2％、5％、10％、15％、30％的泛影葡胺溶液置入一圆桶模型中进行PET/CT显像,同时采用CT及37Cs两种衰减方法进行校正.比较不同管电压(90kV、120kV、140kV) CT扫描条件下各浓度泛影葡胺充盈区CT衰减校正(CTAC)和137Cs衰减校正(CsAC)的标准摄取值差异及图像差异.结果 不同管电压CT扫描条件下的CT衰减校正的标准摄取值均随泛影葡胺浓度增加而增加(r=0.977、0.979、0.985,P＜0.01),而137Cs衰减校正的标准摄取值则与泛影葡胺浓度无明显相关性(r=0.386,P＞ 0.05);在本底区、清水充盈区及浓度为2％的泛影葡胺充盈区,各CT衰减校正和137Cs衰减校正的标准摄取值间差异无统计学意义(F=1.222、0.912、0.721,P＞0.05);在浓度为5％、10％、15％、30％的泛影葡胺充盈区,CT衰减校正的标准摄取值明显高于137Cs衰减校正值(F=82.571、348.211、569.630、992.746,P＜0.01),管电压越高CT衰减校正的标准摄取值越小.在浓度为15％、30％的泛影葡胺充盈区,不同管电压CT扫描条件下的图像均出现18F-FDG高摄取伪影,以140kV下的图像“热区”范围及强度最小,而相同区域的137Cs衰减校正及无衰减校正图像均表现为圆形“冷区”.结论 高浓度(≥5％)的泛影葡胺可使PET图像出现高摄取伪影或标准摄取值的高估,增加CT扫描管电压值可以减轻图像伪影并减小标准摄取值的误差.

Influence of Different Meglumine Concentrations and CT Protocols on PET/CT Image Quality and Standard Uptake Value

Purpose To evaluate the influence of different meglumine concentrations and CT protocols on PET image quality and standard uptake value(SUV).Materials and Methods Different concentrations of meglumine(2%,5%,10%,15%,30%) were inserted into a cylindrical phantom to perform PET/CT,then images were reconstructed using CT attenuation correction(CTAC) and 137 Cs attenuation correction(CsAC).The image quality and SUV with different meglumine concentrations and different CT protocols(90kV,120kV,140kV) from the CTAC images were compared with those of the CsAC images were compared.Results The average SUVs were increased when the concentration increased in all CTAC images from 90kV,120kV and 140kV(r = 0.977,0.979,0.985,P < 0.01),while there was no significant difference on CsAC images(r = 0.386,P > 0.05).The average SUV of CTAC image from 90kV,120kV and 140kV was objectively higher than that on CsAC images in 5%,10%,15% and 30% meglumine regions(F = 82.571,348.211,569.630,992.746,P < 0.01),while there was no statistical difference in the background regions,rinsing regions and 2% meglumine regions(F = 1.222,0.912,0.721,P > 0.05).Artifacts were found in all CTAC images at meglumine concentration of 15% and 30%,while there was no artifact in the same regions between CsAC and NOAC images.The difference of average SUV and artifacts from 90kV was objectively higher than that from 120kV and 140kV.Conclusion High-concentration(≥ 5%) meglumine may cause SUV over-estimation and image artifacts.The image artifacts and SUV errors can be decreased with increased tube voltage.