低浓度对比剂、低管电压结合迭代重建在CT冠状动脉成像检查中的临床价值

The clinical value of combining low concentration contrast agent, low tube voltage and iterative reconstruction in CT coronary angiography

目的评价低k V、低浓度对比剂结合使用迭代重建CT冠状动脉成像(CTCA)的影像质量和辐射剂量。方法符合纳入标准的CTCA受检者共90例,男52例,女38例;年龄30~85岁,平均年龄(56.72±14.51)岁。将其随机分为A、B、C共3组,每组各30例。分别给予不同碘浓度的对比剂:A组270 mg I/m L、B组350 mg I/m L、C组370 mg I/m L。A组管电压100 k V,B、C组管电压120 k V,3组管电流为200~250 m As。采用4分法主观评价影像质量;测量左、右冠状动脉开口、升主动脉根部的CT值,计算影像的信噪比(SNR)、对比噪声比(CNR)来客观评价影像质量。同时记录受检者的CT剂量指数、剂量长度乘积(DLP)、对比剂注射的容量和浓度,分别计算受检者辐射剂量和碘用量。3组受检者年龄、DLP、有效剂量(ED)、信号强度、噪声、SNR和CNR的差异采用方差分析进行比较,组间进一步两两比较采用LSD-t检验。性别、影像质量的主观评分采用χ~2检验。结果 3组受检者的性别、年龄、身高、体质量、BMI差异均无统计学意义(P>0.05)。3组受检者冠状动脉段显示质量达诊断需求者有1 210段(98.94%)。3组之间在冠状动脉各段显示质量上差异无统计学意义(χ~2=4.56,P=0.325)。3组中左、右冠状动脉及升主动脉根部的CT值、SNR、CNR差异均无统计学意义(均P>0.05)。A组DLP、ED和碘总量均低于B、C组(P<0.05),相对于B组分别降低了约27.58%、27.58%、21.27%,相对于C组分别降低了约28.21%、28.21%、24.83%。结论低k V、低浓度对比剂结合迭代重建进行CTCA成像,能获得与常规CTCA一致的影像质量,同时明显地降低受检者的辐射剂量和注射的碘总量。

Objective To evaluation the image quality and radiation dose of combining low k V, low concentration contrast agents and with iterative reconstruction in CT coronary angiography（CTCA）. Methods Ninety cases（52 males, 38 females; age 56.72±14.51 years） were randomly equally divided into groups of A, B and C（30 cases in each group）. The contrast agent concentrations of the three groups were： group A 270 mg I/m L, group B 350 mg I/m L, and group C 370 mg I/m L.Group A tube voltage 100 k V, group B and group C tube voltage 120 k V. Tube current were 200~250 m As. We used 4 points method to evaluate the quality of the images. The CT values at the entrances of left and right coronary arteries and the ascending aortic root were measured. The signal-to-noise ratio（SNR） and contrast-to-noise ratio（CNR） of the images were calculated to evaluate the image quality objectively. At the same time, the CT dose index, dose length product（DLP） and contrast injection were recorded. The radiation dose and iodine dose were calculated respectively. The analysis of variance with Fisher＇s Least Significant Difference（LSD） post hoc was used to test the differences in age, DLP, effective dose, signal intensity, noise, CNR, and SNR among the three groups. Gender, subjective scores of image quality were checked by χ^2. Results There was no significant difference in gender, age, height, body mass, body mass index among the 3 groups（P〉0.05）. Total of1210（98.94%） coronary artery segments fulfilled diagnostic requirements in 3 groups. Among the 3 groups, the images quality of the coronary arteries showed no significant difference（ χ^2=4.56, P=0.325）. There was no significant difference in CT value, SNR and CNR at entrances of left and right coronary arteries and ascending aorta roots among the 3 groups（ P〉0.05）. Thetotal DLP, effective dose and iodine dose in group A were significantly lower than those in group B and C（P〉0.05）, which decreased by 27.58%, 27.58% and 21.27% respectively compared with group B, and decreased by 28.21%, 28.21% and24.83% respectively compared with group C. Conclusions Low k V, low concentration contrast agent and iterative reconstruction in CTCA can obtain comparable image quality to conventional CTCA, while significantly reducing the radiation dose and the administration of iodine dose.