低碘浓度等渗对比剂联合低电压扫描在经导管主动脉瓣置换术前CT检查中的应用

Application of low tube voltage combined with low iodine load iso-osmolar contrast in CT angiography for thanscatheter aortic valve replacement planning

目的探讨应用低碘浓度等渗对比剂联合低管电压扫描模式,在经导管主动脉瓣置换术(TAVR)术前评估应用的可行性及安全性。方法前瞻性纳入2015年10月至2017年2月于中国医学科学院阜外医院行TAVR术前CT检查的98例患者,采用随机数字表法等分为两组,各49例,均采用西门子二代双源CT,应用前瞻性心电门控扫描模式采集主动脉根窦部图像,大螺距扫描模式采集主动脉图像。试验组应用含碘浓度270 mg/ml对比剂(碘克沙醇)联合100 kV管电压,对照组应用含碘浓度370 mg/ml对比剂(碘海醇)联合120 kV管电压进行扫描。对上述图像进行主观评分,以及主动脉根窦部和主动脉不同部位CT值及各部位的图像噪声、信号图像噪声比、对比图像噪声比的测量,在两组间进行独立t检验。所有患者于检查24~48 h内行肾功能检查,应用独立t检验比较两组患者CT检查前后肌酐水平、肾小球滤过率及肌酐变化幅度的差异。结果所有患者CT检查均获得成功。试验组主动脉根窦部、主动脉图像质量评分分别为(4.2±0.7)、(4.3±0.4)分,对照组图像质量评分分别为(4.3±0.6)、(4.3±0.3)分,两者间差异均无统计学意义(t值分别为-0.130、-0.155,P值分别为0.694、0.822)。试验组主动脉根窦部及主动脉噪声高于对照组(P均<0.05),余客观指标差异均无统计学意义。试验组患者总的有效辐射剂量为(6.1±0.4)mSv,明显低于对照组(8.0±0.4)mSv,差异具有统计学意义(t=-9.253,P=0.001)。两组患者CT检查前后肌酐变化差异无统计学意义。结论TAVR术前CT检查应用一次性注射低碘浓度等渗对比剂联合低管电压连续行心脏联合主动脉扫描是可行的,有效降低了患者的辐射剂量和对比剂用量,提高了高龄高危患者检查的安全性。

Objective To investigate the feasibility, image quality, and safety of low-tube-voltage, low iodine load iso-osmolar contrast comprehensive cardiac and aortoiliac CT angiography (CTA) for transcatheter aortic valve replacement (TAVR) planning. Methods Ninety-eight consecutive TAVR candidates prospectively underwent combined contrast-enhanced CTA of the aortic root complex and vascular access route. Patients were assigned to group A (2nd generation dual-source CT, 100 kV, contrast 270 mgI/ml iodixanol) or group B (2nd generation dual-source CT, 120 kV, contrast 370 mgI/ml). Mean vascular attenuation, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of aorta including aortic root, aortic arch, descending aorta at level of diaphragm, abdominal aorta at level of renal artery and femoral artery were compared. Patient creatinine levels before the examination of CTA and during follow-up (24-48 h) were measured. Results The image quality score of aortic root and whole aorta was (4.2±0.7) and (4.3±0.4) respectively in experimental group,(4.3±0.6) and (4.3±0.3) in control group. No significant difference in subjective image quality score between two groups including aortic root image and whole aorta image (t=-0.130,-0.155,P=0.694, 0.822). The image noise of aortic root and femoral artery were higher in experimental group than that in control group (P<0.05). Radiation dose in experimental group was higher than that in control group [(6.1±0.4) vs.(8.0±0.4) mSv, t=-9.253, P=0.001]. There were no significant changes in creatinine levels among groups during the follow-up. Conclusion TAVR candidates can be safely and effectively evaluated by a comprehensive CTA protocol with low iodine load iso-osmolar contrast using low-tube-voltage acquisition.