双低MSCT技术对非肥胖患者门脉成像的临床研究

A clinical study of double low dose MSCT portography in non-obese patient

目的:探讨联合应用低管电压和低对比剂方案用于非肥胖患者门静脉成像(MSCTP)的可行性。方法:纳入接受MSCTP、体质量指数≤25kg/m2的患者160例,采用数字法随机分为2组,每组80例。常规组管电压为120kVp,对比剂用量为1.2mL/kg,双低组管电压为80kVp,对比剂用量为1.0mL/kg。采用独立样本t检验比较各组CT剂量容积指数(CTDIvol)、有效管电流(mAs)、剂量长度乘积(DLP)、有效辐射剂量(ED)和对比剂用量、肝实质CT值(CTH)、门静脉CT值(CTp)、图像噪声(SD)、肝实质SNR(SNRH)、门静脉与肝实质CNR(CNRp)的差异;采用秩和检验比较两组图像评分。采用Kappa检验两位医师评分结果一致性。结果:双低组CTDIvol[(4.59±1.03)mGy]低于常规组CTDIvol[(7.50±1.45)mGy(P<0.05)],均有统计学差异;双低组ED[(1.71±0.50)mSv]低于常规组[(2.75±0.67)mSv(P<0.05)];双低组平均辐射剂量比常规组减少了1.05mSv,减少38.09%;双低组图像质量评分(3.93±0.88)高于常规组[(3.33±0.81),有统计学差异(P<0.05)];双低组CTH和CTp分别为(126.74±30.59)和(223.78±45.85)HU均明显高于常规组(95.60±15.89)和(161.47±25.37)HU,差异有统计学意义(P<0.05);双低组SD(24.61±2.77)HU高于常规组(1.65±3.38)HU,P<0.05],双低组SNRH为(5.20±1.24)HU低于常规组SNRH(7.00±2.44)HU,差异有统计学差异(P<0.05),但是双低组门静脉与肝实质CNRp为(4.33±0.97)HU与常规组(4.67±1.44)HU比较差异无统计学意义(P>0.05);双低组平均对比剂用量为(66.56±2.48)mL显著低于常规组[(80.48±2.97)mL(P<0.05)],双低组平均造影剂用量较常规组减少17.30%。结论:采用80kVp低管电压结合低剂量和对比剂方案对非肥胖患者进行MSCTP能降低辐射剂量和对比剂用量并进一步提高图像质量。

Objective：To investigate the feasibility of low tube voltage protocol combined with low dose contrast media in MSCT portography（MSCTP）in non-obese patients.Methods：Totally 160 patients with body mass≤25kg/m2 underwent MSCTP.The patients were randomly divided into 2groups,80 cases in each group.The regular group was examed using tube voltage of 120 kVp with contrast media of 1.2mL/kg,while the study group using tube voltage of 80 kVp with contrast media of 1.0mL/kg.The image quality was assessed in both objective and subjective methods.Independent samples t-test was used to compare the average volume CT dose index（CTDIvol）,effective mAs,dose length product（DLP）,effective dose（ED）,CT value of hepatic parenchyma（CTH）and portal vein（CTP）,image noise（SD）,SNR of hepatic parenchyma（SNRH）and CNR of portal vein（CNRP）between two groups.Interobserver agreement with regard to image quality was assessed using kappa test.And the subjective image score was compared using Wilcoxon rank sum test.Results：The average CTDIvol in the study group [（4.59±1.03）mGy]was lower than that in regular group [（7.50±1.45）mGy（P〈0.05）].ED in the study group[（1.71±0.50）mSv]was significantly lower than that in regular group[（2.75±0.67）mSv（P〈0.05）].Compared with the regular group,the ED in study group was decreased 38.09%.The score of image quality in study group（3.93±0.88）was significantly higher than that in regular group（3.33±0.81,P〈0.05）.CTH（126.74±30.59）,CTP（223.78±45.85）and SD（24.61±2.77）HU in the study group were all higher than those in regular group[（CTH（95.60±15.89）Hu;CTP（161.47±25.37）HU,SD（1.65±3.38）HU,P〈0.05].SNRHin the study group[（5.20±1.24）HU]was lower than that in regular group[（7.00±2.44）HU,P〈0.05].There was no significant difference of CNRPbetween the two groups[（4.33±0.97）HU vs（4.67±1.44）HU].The contrast media dose in study group[（66.56±2.48）mL]was lower than that in regular group[（80.48±2.97）mL,P〈0.05].Compared with regular group,the contrast media dose in study group was decreased by 17.30%.Conclusion：In MSCTP of non-obese patients,the quality of image is improved,and the radiation dose is reduced by using low tube voltage of 80 kVp combined with low contrast media scan protocol.