DSCT大螺距扫描技术联合应用低浓度对比剂冠状动脉成像的初步研究

DSCT Using Large Pitch Scanning Technique Combined with Low Concentration Contrast Material for Coronary Angiography: Preliminary Study

目的探讨双源CT冠状动脉CT成像中应用前瞻性大螺距扫描技术与等渗低浓度对比剂时的图像质量及辐射剂量。方法将连续搜集的100例怀疑或已知冠心病患者分为两组,均采用前瞻性大螺距扫描技术,A组(对照组)采用常规浓度对比剂及滤波反投影(FBP)重建;B组(实验组)采用低浓度对比剂及迭代重建进行冠状动脉CT检查。入组标准:心率<70次/min,窦性心律且律齐,心率波动范围在±5次/min以内。由两位有经验的心血管系统诊断医师利用双盲法以5分法评定系统对冠状动脉16段分支血管成像质量进行评分,利用Kappa检验比较观察者间的差异;对两组有效辐射剂量、平均CT值、图像噪声、信噪比(SNR)、对比信噪比(CNR)、图像质量评分进行比较。Mann-Whitney检验比较计数资料组间差异,t检验比较计量资料组间差异。结果 100例受检者均成功完成检查。A组冠状动脉均分(4.7±0.8)与B组冠状动脉均分(4.6±0.9)之间差异无统计学意义(t=0.342,P=0.733);两位评价者之间的Kappa值为0.882(P<0.01)。A组图像平均CT值[(379.5±54.8)HU]略高于B组[(367.1±66.9)HU],但两组差异无统计学意义(t=0.435,P=0.664);两组间噪声、SNR、CNR差异无统计学意义(P>0.05),但B组略低于A组。B组的有效辐射剂量为(0.47±0.08)mSv,较A组剂量[(1.19±0.13)mSv]降低约60.2%,两者间差异有统计学意义(t=32.087,P<0.001)。结论 DSCT使用大螺距扫描技术和低浓度对比剂进行冠状动脉检查时,在不影响图像质量的前提下,可以将辐射剂量降至0.5 mSv以下。

Objective To investigate the image quality and radiation doses of dual-source CT（DSCT） large pitch scanning technique combined with isotonic low concentration contrast material for coronary angiography.Methods A total of100 consecutive patients with suspected or known coronary artery disease were collected,and the patients were randomly and equally divided into the study group（n=50） and the control group（n=50）.DSCT large pitch scanning technique with ECG-gated FLASH protocol for coronary angiography was performed in the patients of both groups.Routine concentration contrast material and filtered back projection（FBP） were used in the control group,while isotonic low concentration contrast material and iterative reconstruction technique were adopted in the study group.The image qualities of 16 segments of the coronary artery were evaluated by two experienced radiologists using double-blind method with a five scoring scale.The effective radiation dose,mean CT value,image noise,signal-to-noise ratio（SNR）,contrast-to-noise ratio（CNR） and image quality were measured,and the results were compared between the two groups using Cohen kappa statistical method.The enumeration data,including radiation doses and image quality scores,were compared between the two groups with Mann-Whitney test,while measurement data were compared between the two groups with t test.Results The examination was successfully completed in all patients.No statistical difference in mean image quality existed between the control group A（4.7 ± 0.8） and the study group（4.6 ± 0.9）（t=0.342,P=0.733）.The kappa value between two radiologists was0.882（P 0.01） for image quality.The mean attenuation of coronary artery segments was above 300 HU,especially in the control group [（379.5 ± 54.8） HU],which was slightly higher than that in the study group [（367.1 ± 66.9） HU],although the difference was not statistically significant（t=0.435,P=0.664）.The differences in image noise,SNR and CNR between the two groups were not statistically significant（P 0.05）,but the image noise of the study group was slightly higher than that of the control group.The effective radiation dose in the study group was（0.47 ± 0.08） mSv,which was significantly lower than that in the control group（1.19 ± 0.13） mSv（t=32.087,P 0.001）.Conclusion Combination use of DSCT with large pitch scanning technique and isotonic low concentration contrast material to perform coronary angiography can significantly reduce the radiation dose to below 0.5mSv with no loss of image quality.