能谱单能量结合低剂量对比剂与常规CT增强扫描在门静脉成像中的对比研究

Clinical value of using lower contrast medium dose with spectral imaging in portal venography:comparison with the conventional 120kVp imaging protocol

目的:探讨能谱单能量(60keV)结合低剂量对比剂方案在门静脉成像中的应用价值。方法:将50例行腹部CT增强的患者随机分为A、B两组(每组各25例),均采用非离子型对比剂优维显370(370mg I/mL)。A组行宝石能谱成像(GSI)扫描(60keV),对比剂用量为0.9mL/kg;B组行常规CT增强扫描(120kVp),对比剂用量1.3mL/kg。采用独立样本t检验对A、B两组的门静脉CT值、噪声、肝内、外门静脉对比噪声比(CNR)、主观质量评分、容积CT剂量指数(CTDIvol)及有效辐射量(ED)进行统计学分析。结果:A组的门静脉主干、左支及右支的CT值均高于B组(P均<0.05);A组的门静脉主干、左支及右支的噪声均低于B组(P均<0.05);A组的肝内门静脉CNR高于B组(P=0.03<0.05);A、B组肝外门静脉CNR无统计学差异(P=0.90>0.05)。A组的主观评分(4.49±0.64)稍高于B组(4.35±0.65),但两组间差异无统计学意义(P=0.41)。A、B组的CTDIvol及ED均无统计学差异(P=0.12,P=0.58),A组的对比剂碘摄入量[(23.06±3.18)g]较B组[(30.49±4.99)g]约较少25%(P<0.001)。结论:在辐射量相当的条件下,单能量GSI结合低剂量对比剂在门静脉成像中优于常规CT增强扫描,且对比剂碘摄入量减少约25%。

Objective：To evaluate the clinical value of combining 60 keV in spectral CT with lower contrast medium dose protocol of 0.9mL/kg in portal venography.Methods：50abdominal CT patients were divided randomly into 2groups：Group A（n=25）using 60 keV spectral CT with 0.9mL/kg contrast injection protocol;Group B（n=25）using 120 kVp with 1.3mL/kg.CT number and noice of the portal vein,left and right branches,liver parenchyma and erector spinae on the120 kVp and 60 keV spectral CT images were measured.Contrast to noise-ratio（CNR）for intra-hepatic and extra-hepatic portal veins was calculated by t check.Image quality was evaluated using 5-point scores.Results：CT value of the portal vein,left and right branches with 60 keV spectral images was higher than that with 120 kVp images（P〈0.05）.Noice of the portal vein,left and right branches with 60 keV spectral images was lower than that with 120 kVp images（P〈0.05）.CNR value for the intrahepatic portal vein with 60 keV spectral images was higher than that with 120 kVp images（P=0.03〈0.05）.CNR values for the extrahepatic portal veins were the same（P=0.90〉0.05）.Subjectively evaluated image quality,CTDIvol and effective dose（mSv）of both groups had no statistical differences（P=0.41、P=0.12、P=0.58）.Conclusion：The60keV spectral images provide better or equal image quality as the 120 kVp images in portal venography with similar radiation dose but 25%lower contrast medium dose.