低浓度对比剂与低管电压在后门控CT冠脉成像中的可行性研究

Feasibility of Low Concentration Contrast Medium Combined with Low kV in Retrospectively Gated CT Coronary Angiography

目的：比较低浓度对比剂与低管电压和常规高浓度对比剂与高管电压在后门控CT冠状动脉血管成像（CT coronary angiography,CTCA）中的图像质量.方法：2014年2月11日至2014年5月9日,对150名心率超过65次/min的患者行64排容积后门控CT冠状动脉血管成像扫描,根据他们的身体质量指数（BMI）分成3组（A组：n=50,BMI＜23kg/m2,对比剂浓度为300mgI/ml,管电压为80kV;B组：n=50,23kg/m2≤BMI＜28kg/m2,对比剂浓度为300mgI/ml,管电压为100kV;C组：n=50,BMI＜28kg/m2,对比剂浓度为370mgI/ml,管电压为120kV）,其中C组为常规剂量对照组.所有患者的对比剂的用量为70～80ml,注射速率为4.5～5ml/s.测量主动脉根部、左主干以及右主干的平均CT值,并根据下述的公式计算对比噪声比和信噪比.记录辐射剂量并且对图像质量进行评分.所有结果进行方差分析或者秩和检验.结果：三组患者主动脉根部、左主干以及右主干的对比噪声比和信噪比之间无统计学差异（P＞0.05）,三组患者所吸收的辐射剂量有显著统计学差异（P＜0.05）,低管电压组辐射剂量分别下降68％和44％,三组患者之间的图像质量无统计学差异（P＞0.05）.结论：采用低浓度对比剂与低管电压技术不会降低CTCA的图像质量,不影响诊断,可以运用于后门控CTCA.

Purpose：To compare the image quality of low concentration contrast medium combined with low kV and high concentration contrast medium combined with 120 kV in retrospectively gated CT coronary angiography （CTCA）.Methods：A total of 150 patients,each with a heart rate above 65bpm,underwent retrospectively gated CTCA on a 64-slice CT scanner.All the patients were divided into three groups according to （their） respective BMI（s） （group A：n=50,BMI〈23kg/m2,80kV,300mgI/ml; group B：n=50,23kg/m2≤BMI〈28 kg/m2,100kV,300mgI/ml; group C：n=50,BMI〈28kg/m2,120kV,370mgI/ml）.The total volume of contrast medium was 70-80ml,and injection rate was 4.5-5.0ml/s.The CT values of aortic root（AR）,left main artery（LMA）,right main artery（RMA） and subcutaneous fat tissue were measured.The contrast-to-noise ratio （CNR） of AR,LMA and RMA were calculated.The values of CTDI and DLP were recorded.Image quality was assessed on 5-point scale.The results were compared between groups with one-way ANOVA.Results：The mean CNR and SNR of vessels in group A and group B was with no significant difference from group C（P〉0.05）.The effective radiation dose in group A and group B was both lower than that in group C（P〈0.05）,group A and group B fell by 68% and 44% in terms of effective radiation dose comparing to group C.There was no significantly difference on image quality scores between group A,group B and group C （P〉0.05）.Conclusion：The use of the low concentration contrast medium and low tube voltage will not lower the image quality of CTCA and affect the diagnosis,which can be used in retrospectively gated CT coronary angiography.