Snap shot Freeze在CT冠状动脉成像中应用价值的研究

Initial study of snapshot freeze on the image quality of coronary CTA

目的探讨SSF在CT冠状动脉成像中的应用价值。方法收集在本院行冠状动脉CTA检查且在1周内行冠状动脉造影检查的20例患者资料,选取最佳重建期相,分别用常规重建方法及Snap shot Freeze(SSF)技术重建图像。由2名放射科医师用5分法对两种重建方法的图像质量进行主观评价,测量常规重建图像、SSF重建图像及DSA图像中各段冠状动脉的直径,对其差异行统计学分析;并记录患者的平均心率、心率变化、右冠状动脉的CT值,分析SSF技术重建图像的主观评分与RCA的CT值、患者平均心率及心率变化的相关性。结果常规重建图像的主观评分为3.83±0.62,SSF图像的主观评分为4.49±0.71,其差异有统计学意义且具有相关性(Z=-5.17、r=0.76,P=0.00)。252段血管的直径在常规重建图像、SSF图像及DSA图像上的直径分别为(2.59±0.79)mm、(2.57±0.81)mm、(2.48±0.82)mm,其差异没有统计学意义(F=0.27,P=0.77);常规重建图像及SSF重建图像的RCA的CT值分别为(284.57±106.76)HU、(296.15±101.89)HU,其差异没有统计学意义(t=-0.73,P=0.48);SSF重建图像主观评分与CT值、平均心率、心率变化的具有相关性(r=0.73、-0.52、-0.52,P<0.05)。结论 SSF能有效校正冠状动脉的运动伪影,提高冠状动脉CTA的图像质量,且不影响其测量结果的准确性,具有较好的应用价值。

Objective To assess the application value of snapshot freeze （SSF） in improving the image quality of coronary CTA. Methods Twenty patients were performed coronary computed tomographic arteriography （ CTA）, and all of them under- went coronary angiography in a week. The images with the optimal phase were reconstructed by conventional method and SSF re- spectively. The coronary artery was divided into 15 segments. Two radiolagists assessed the image quality using a 5 score scale. The diameter of coronary artery segments showed in the image of CTA and coronary angiography were measured. The measurement results were analyzed. The patients＇ average heart rate and the heart rate changes were recorded. CT value of the right coronary artery （RCA） was measured. The relationship between RCA CT value, average heart rate, heart rate changes and the subjective scoring of the image was rreconstructed with SSF. Results The subjective scoring of the image reconstructed by conventional method and SSF were 3.83 ± 0.62, 4.49± 0.71; the differences and relationship between the two methods were statistically sig- nificant （ Z = -5.17, r = 0. 76, P = 0.00）. The coronary artery segments diameter of conventional reconstructing method, SSF and coronary angiography were （2.59±0.79） mm, （2.57 ±0.81 ） mm and （2.48 ±0.82） mm respectively; the differences be- tween three groups were not statistically significant （ F = 0.27, P = 0.77 ）. The CT value of the coronary artery reconstructed by conventional method and SSF were （284.57 -±106.76） HU and （296.15 ±101.89） HU respectively, the differences between two groups were not statistically significant （ t = -0. 73, P = 0.48 ）. The relationship was different between the subjective sco- ring of the image reconstructed using SSF with CT value, verage heart rate and heart rate changes （ r = 0.73. - 0.52, - 0.52, P 〈 0.05 ）. Conclusion SSF can correct motion artifact of coronary artery, improve the image quality of CTA, and not affect the measurement result accuracy.