摘要目的 探讨多层螺旋CT(MSCT)低kV门静脉成像的可行性以及相关图像质量评价.方法 连续31例门静脉成像患者纳入研究,以3.0 mL/s速率经肘正中静脉注射欧乃派克(350 mgI/ml)90 ml,使用256层CT(Philips Brilliance iCT)机型分别完成动脉期(120 kV,150 mAs)和门脉期(80 kV,120 mAs)扫描,记录两次扫描时的平均容积CT剂量指数(CTDIvol)和辐射剂量长度乘积(DLP),并计算有效辐射剂量(E).对门脉期数据采用4组不同滤波函数进行回顾性重建:A组,滤过反投影(FBP)+平滑函数;B组,FBP+标准函数;C组,迭代4(iDose4)+标准函数;D组,迭代6(iDose4)+标准函数.在工作站上分别完成门脉血管重建的最大密度投影(MIP)、容积重建(VR)和多平面投影重建(MPR)显示,并在门脉分支中心层面分别测量腹主动脉、门脉、肝右叶实质3个结构的CT值和图像噪声(SD)值.由2位资深放射科医生和1位CT技师共同评价门脉图像质量.结果 门脉期扫描(低剂量)的DLP与E分别是(81.23±7.46)mGy·cm和(1.22±0.11)mSv,均明显低于动脉期(常规剂量)的(353.45±31.46)mGy·cm和(5.30±0.47)mSv(F=2197.23,P＜0.05);各组间SD值有明显差异(F=54.364,P＜0.05),以D组(57.09±13.59)最小,B组(115.55±31.12)最大.所有4组门脉图像均符合诊断图像质量要求,C和D两组门脉显示优于A和B两组.结论 80 kV结合迭代算法的低剂量MSCT门脉成像是可行的.

abstractsObjective To explore the feasibility and image quality of MSCT portal vein(PV)imaging with low-voltage.Methods The consecutive 31 patients were enrolled in the study.Ninety milliliter omnipaque(350 mg I/ml)with the rate of 3 ml/s was administrated through the median cubital vein.The arterial(120 kV,150 mAs)and PV(80 kV,120 mAs)phase scans were undertaken with a Philips Brilliance iCT scanner.The CTDIvol and DLP were stored and the effective dose(E)was calculated.Four PV image series were reconstructed with(A)FBP+smooth,(B)FBP+standard,(C)iDose4-4+standard,and(D)iDose4-6+standard algorithm.The maximum intensity projection,volume rendering and multiplanar reformation of portal vein were conducted on a workstation.The CT values of ROI of the aorta,PV,and liver parenchyma were measured,and the SD was considered as the noise.Two experienced radiologists and one technician together reviewed the images.Resnlts The DLP and E was significantly smaller in PV phases than that in arterial phases[low-dose:(81.23 ±7.46)mGy· cm,(1.22 ±0.11)mSv;routine dose:(353.45 ±31.46)mGy·cm,(5.30 ±0.47)mSv,F=2197.23,P＜0.05).The noises were different among the groups with that smallest in group D and largest in group B.All PV images were sufficient for diagnosis but those in the group C and D were better.Conclusions The hybrid low-dose MSCT PV imaging with 80 kV combined iterative method would be feasible.