低管电压在经导管主动脉瓣置换术前CTA中的应用

目的:通过分析经导管主动脉瓣置换术(TAVR)患者术前CTA主观及客观图像质量,探讨320排CT低管电压可变螺距(VHP)技术在TAVR术前评估中的应用价值。方法:前瞻性纳入2016年1月至2020年12月拟行主动脉瓣膜置换的96例患者,所有患者术前采用320排螺旋CT VHP技术进行CTA检查。按随机数字法将患者分为80 kV组、100 kV组、120 kV组,各32例,对比剂用量分别为0.9、1.1、1.2 mL/kg,流速分别为3、3.5、4 mL/s。每组患者图像均采用迭代算法,图像质量评价采用主观(Likert 5法)和客观评估方法CT值、SD值、对比噪声比(contrast to noise ratio, CNR)]进行评估。比较3组间左、右颈总动脉,升主动脉根部,左、右股动脉层面的图像质量。结果:3组患者间性别、年龄、体质量指数(BMI)、扫描时间等差异无统计学意义。3组间主观评分差异仅在左、右股动脉层面有统计学意义(P0.01);3组间左、右颈总动脉及左、右股动脉层面CT值差异有统计学意义(P0.001),各层面SD值及CNR值差异均有统计学意义(P0.001)。80 kV组对比剂用量为(57.70±9.01)mL,低于100 kV组(71.80±10.37)mL]和120 kV组(75.20±11.08)mL],差异均有统计学意义(P0.01)。80 kV、100 kV、120 kV组患者的剂量长度乘积(DLP)分别为(1 096.88±155.2) mGy×cm、(963.02±137.9) mGy×cm、(1 048.53±168.2) mGy×cm,有效辐射剂量的均值分别为16.45、14.44、15.73 mSv,以100 kV组患者接受的剂量最低,与80 kV组和120 kV组之间差异有统计学差义(P0.05)。结论:320排CT VHP技术中采用80、100、120 kV管电压均能获得良好的图像质量,其中,采用80 kV时对比剂用量最少,采用100 kV时所接受的辐射剂量最低。

Application of low tube voltage in CTA before transcatheter aortic valve replacement

Objective:By analyzing the subjective and objective image quality of preoperative CTA in patients with TAVR, the application value of 320-slice CT low-kV VHP technique in preoperative evaluation of TAVR was explored. Materials and methods:Patients who planned to undergo aortic valve replacement in the cardiovascular surgery department of our hospital from January 2016 to December 2020 were prospectively included. All patients underwent preoperative CTA examination with 320-slice spiral CT variable pitch (VHP) technique.According to random number method, the patients were divided into group A: 80kV group;Group B: 100kV group;Group C: 120kV group.The dosage and flow rate of contrast agent for group A, B and C were 0.9 ml/kg body weight and 3 ml /s flow rate, respectively.1.1ml/kg body weight, flow rate 3.5ml /s;1.2ml/kg body weight, flow rate 4 ml/s.Images of each group were evaluated using an iterative algorithm (AIDR), and image quality was evaluated using both subjective (Likert 5-point scale independently scored by two doctors) and objective assessment methods (CT value, SD value, Contrast to Noise Ratio (CNR)).The image quality of left and right common carotid artery, ascending aortic root and left and right femoral artery were compared between group A, B and C.All data were analyzed using SPSS21.0 statistical software.P < 0.05 indicated statistical significance. Results:Ninety-six patients were enrolled in this study, including 32 in Group A, 32 in Group B, and 32 in Group C.There were no statistical differences in gender, age, body mass index (BMI), scanning time and other general information among the three groups.Comparison results of image quality among groups A, B and C: Subjective image quality: The difference of subjective scores between the three groups was statistically significant only in the left and right femoral artery (P =0.005).Objective image quality: CT values of the three groups were significantly different in left and right common carotid artery and left and right femoral artery (P <0.001).The differences of SD and CNR values among the three groups were statistically significant at all levels (P <0.05). Comparison of the dosage of contrast agents among groups A, B and C: the dosage of contrast agents in the three groups were 57.7±9.01ml, 71.8±10.37ml and 75.2±11.08ml, respectively.The amount of contrast agent in group A was the least, and there was A statistical difference between group B and group C (P <0.001). Comparison of radiation doses among groups A, B and C: the DLP of patients in the three groups were 1096.88± 155.2mGy *cm, 963.02± 137.9mGy *cm and 1048.53 ± 168.2mGy *cm respectively, and the mean effective radiation doses were 16.45mSv, 14.44mSv and 15.73mSv respectively.The 100kV group received the lowest dose, and the difference was statistically significant between the 80kV and 120kV groups (P =0.003). Conclusion: The 320-slice CT VHP technique can obtain good image quality at the tube voltages of 80kV, 100kV and 120kV, among which, the dosage of contrast agent is the least in the 80kV group, and the dose received by the 100kV group is the lowest.