256层螺旋CT结合迭代重建及“三低”肺动脉成像的可行性研究

The feasibility study of 256 slice spiral CT with iterative reconstruction and "three-low" in pulmonary artery imaging

目的:探讨256层螺旋CT结合idose4迭代重建及"三低"(低辐射剂量、低浓度对比剂及低对比剂用量)肺动脉成像的可行性。方法:将进行肺动脉CTA检查且体质量指数(BMI)为18.5~25.0kg/m2的80例患者随机分成常规组与"三低"组,每组各40例。常规组扫描参数:管电压120kV,管电流250mAs,对比剂浓度370mg I/mL,对比剂剂量1.0mL/kg;"三低"组扫描参数:管电压100kV,管电流150mAs,对比剂浓度270mg I/mL,对比剂剂量0.5mL/kg。两组均采用idose4迭代重建算法,其余扫描参数一致。由2位高级职称的放射科医师以统一标准对图像质量进行主观评分;图像质量客观评价指标包括肺动脉CT值、信噪比(SNR)、对比噪声比(CNR);辐射剂量评价指标包括平均容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)和有效剂量(ED)。两组图像质量主、客观评价结果的比较及辐射剂量的比较采用SPSS 13.0软件进行统计学分析,P<0.05为差异具有统计学意义。结果:两组图像质量的主观评分无显著差异(P>0.05);两组各区域肺动脉CT值的差异均具有统计学意义(P均<0.05),SNR、CNR差异均无统计学意义(P均>0.05)。常规组和"三低"组的CTDIvol分别为16.9和6.12mGy;DLP分别为(456.84±72.96)和(160.43±27.06)mGy·cm;ED分别为(6.44±1.01)和(2.25±0.38)mSv,两组间上述指标的差异均具有统计学意义(P均<0.05)。结论:256层螺旋CT结合idose4迭代重建及"三低"肺动脉成像是可行的,在图像质量满足临床诊断要求前提下,可大幅度降低辐射剂量及对比剂用量。

Objective：To investigate the feasibility of 256 slice spiral CT with iDose4 iterative reconstruction and ＂three low＂（low dose,low iodinated concentration and low contrast agent volume）in CT pulmonary angiography.Methods：Eighty patients whose body mass indexes（BMI）from 18.5to 25.0kg/m^2 underwent pulmonary artery CTA.All patients were randomly divided into control group and ＂three low＂ group with 40 patients in each group respectively.The parameters of control group were as follow：tube voltage 120 kV,tube current 250 mAs,iodine concentration of contrast agent 370 mg I/mL,dose of contrast agent 1.0mL/kg.However,those of ＂three low＂ were as follow：tube voltage 100 kV,tube current150 mAs,iodine concentration of contrast agent 270 mg I/mL,dose of contrast agent 0.5mL/kg,iDose4 iterative reconstruction was adopted in both groups,moreover,the other parameters were same.The imaging qualities of both groups were subjectively and objectively assessed.The image quality was subjectively scored by 2senior radiologists with unified standard.Image quality objective evaluation index included pulmonary artery CT value,signal noise ratio（SNR）and contrast noise ratio;however,radiation dose evaluation index included volume CT radio index（CTDIvol）,radio dose length product（DLP）and effective dose.The subjective and objective evaluation of image quality in two groups as well as radiation dose were compared statistically by SPSS software,and the level of statistical significance was set at P〈0.05.Results：There was no significant difference in image quality subjective score between two groups（P〉0.05）.The difference of pulmonary artery CT value between the two groups was statistically significant（P〈0.05）,however,there was no statistical important difference in SNR and CNR between the two groups（P〉0.05）.The CTDIvol of the control group and the ＂three low＂ group was 16.9and 6.12 mGy respectively,DLP was（456.84±72.96）and（160.43±27.06）mGy·cm respectively,ED was（6.44±1.01）and（2.25±0.38）mSv respectively,the differences of the above index between the two groups were statistically significant（P〈0.05）.Conclusions：The way of 256 slice spiral CT combined with iDose4 iterative reconstruction and＂three low＂is feasible for pulmonary artery imaging;based on the premise of satisfying the clinical diagnostic requirements,the radiation dose and the volume of contrast agent can be greatly reduced.