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

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(P0.05)。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P0.05)。A组DLP、ED和碘总量均低于B、C组(P0.05),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。

Preliminary study of low kV and low concentration contrast agents with iterative reconstruction of CT coronary angiography

Objective To evaluation the image quality and radiation dose of CT coronary angiography (CTCA) with low kV, low concentration contrast agents and with iterative reconstruction. Material and Methods 90 cases were randomly divided into groups of A, B and C, 30 cases in each group. The three groups of the contrast agent concentration were: group A 270 mg/ml, group B 350mg/ml, group C 370mg/ml. Group A scan parameters: tube voltage 100kV group, group B and group C tube voltage 120 kV, tube current are 200~250 mAs. Three groups were treated with 128 * 0.6mm collimator width and rotation speed is 0.27s. 4 points method was used to evaluate the quality of the images. The CT value of the left and right coronary arteries and the ascending aortic root was measured, and the SNR and CNR of the images were calculated to evaluate the image quality objectively. At the same time, the CTDI, DLP and contrast injection were recorded, and the radiation dose and dosage of the subjects were calculated respectively. The variance analysis was adopted in three groups of subjects, including age, DLP, effective dose, signal intensity, noise, CNR and SNR, and the difference between the two groups was compared. Gender, image quality of the images were using kappa test. Results There were no significant differences in sex, age, weight, height, and BMI between the three groups of subjects in each group. Left and right coronary artery and ascending aortic root CT value, background noise and SNR, CNR difference was not statistically significant. Compared with B and C, the ED group in the A group decreased by about 27.58% and 28.21% respectively. The total amount of iodine in the A group was decreased by about 21.27% and 24.83% respectively compared with the B and C groups. Conclusions Low kV and low concentration contrast agent combined with iterative reconstruction for CTCA imaging can obtain the image quality consistent with the conventional CTCA, while significantly reducing the radiation dose and the total amount of iodine injected.