不同心率对于640层螺旋CT冠状动脉成像质量及相关辐射剂量的影响

目的探讨不同心率在640层螺旋CT冠状动脉CTCA中对血管图像质量的影响以及辐射剂量变化。方法选取91例患者,男性51例,女性40例,平均年龄58岁。分成三组,A组30例,心率≤65次/分;B组30例,65次/分心率≤80次/分;C组31例,心率80次/分。扫描完成后选取最佳时相进行容积再现(VR)、最大密度投影(MIP)、多平面重建(MPR)及曲面重建(CPR)进行血管重建,根据4分法对血管图像质量分级并进行统计学分析,记录各组的辐射剂量程度乘积(DLP)。结果三组的血管图像质量在可评价比例及优良率无统计学意义,心率与血管图像质量等级呈负相关。A组DLP为(3.37±2.12)m Gy.cm,B组为(4.78±1.92)m Gy.cm,C组为(6.11±2.79)m Gy.cm,三组的辐射剂量有差异,经检验,有统计学意义,心率与辐射剂量呈正相关。结论 640层螺旋CT冠状动脉CTCA在高心率患者能较好的显示图像,同时辐射剂量也增加,应该在情况允许的条件下尽可能降低心率至65次/分以下,在获得优良血管图像质量的同时降低辐射剂量,有利于冠状动脉CTCA的可持续发展,以便让更多患者从中获益。

The Different Heart Rate Effect of 640 Slice Spiral CT Coronary Artery Imaging in the Image Quality and Radiation Dose related

Objective To investigate the influence of heart rate and blood vessel image quality and radiation dose changes in 640 slice spiral CT coronary artery imaging. Methods A total of 91 patients, male 51 cases, female 40 cases, average age is 58 years old. Divided into three groups, 30 cases in group A whose heart rate was equal or greater than 65 beats per minute; 30 cases in group B and the heart rate of them was greater than 65beats per minute but less than 80 beats per minute; 31 cases in group C whose heart rate was greater 80 beats per minute. After the scan completed, the most optimum phase was chosen for volume rendering (VR), maximum intensity projection (MIP), multi planar reconstruction (MPR) and curved planar reconstruction (CPR) to have vascular reconstruction, vascular image quality was classified according to the 4 points method and it was statistically analyzed. We recorded the radiation dose product of each group(DLP). Results The blood vessel image quality evaluation and the excellent and good rate in the proportion of the three groups had no statistical significance, the heart rate was negatively correlated with the quality grade of blood vessel image. A group DLP was (3.37±2.12) mGy.cm, B group was (4.78±1.92) mGy.cm, C group was (6.11±2.79) mGy.cm, radiation dose of three groups was statistically significant, the heart rate is positively correlated with the radiation dose.Conclusion 640 slice spiral CT coronary angiography can show the image better in patients with high heart rate, but also increase the radiation dose, we should reduced heart rate to 65 beats per minute below as far as possible with the condition permitted. To obtain excellent vascular image quality by lower radiation dose at the same time, is conducive to the sustainable development of coronary artery CT angiography imaging, so that more patients can be benefitted from it.