64层螺旋CT冠状动脉图像质量控制研究:最佳重组时相与心率关系

目的量化评估64层螺旋CT冠状动脉各分支不同重组时相图像质量,探讨冠状动脉CT成像最佳重组时相与心率关系。资料与方法102例患者均采用64层螺旋CT回顾性心电门控冠状动脉成像,男68例,女34例,平均年龄(58.1±9.7)岁,平均心率(66.4±11.5)次/min。心率<65次/min(n=43)为Ⅰ组,65～75次/min(n=34)为Ⅱ组,>75次/min(n=25)为Ⅲ组,每例患者的4支冠状动脉(左主干、左前降支、左回旋支、右冠状动脉)共分为12个节段用于图像质量分析。扫描原始数据以间隔5%在20%～80%时相分别回顾性重组冠状动脉图像,采用横断位、曲面重组、容积再现等方法对图像质量综合评分。结果Ⅰ组60%、65%和70%为最佳时相,Ⅱ组60%、65%时相为最佳时相,Ⅲ组右冠状动脉较优时相为35%、40%,左冠状动脉较优时相为60%、65%。结论心率和重组时相的选择是决定冠状动脉图像质量的重要因素。平均心率≤75次/min,冠状动脉各分支图像质量在心脏运动的舒张中期(60%、65%)最佳;>75次/min时,左右冠状动脉分别进行重组能明显提高冠状动脉的成像质量。

Correlation Between Reconstruction Interval and Heart Rate in Image Quality Control of 64-slice Spiral Computed Tomography Angiography for the Coronary Arteries

Objective To explore the optimal reconstruction interval that related to heart rate by analyzing quantitative parameters of image quality in consecutive patients undergoing 64-slice computed tomography coronary angingraphy. Mate-rials and Methods Electrocardiography (ECG)-gated 64-slice scanner( 64 mm × 0. 6 mm collimation,330 ms per rota-tion,870mAs,120 kV) CT coronary angingraphy was performed in 102 patients(68 males,34 females; mean age (58.1 ± 9.7 ) years old, mean heart rate ( 66.4 ± 11.5 ) bpm]. Data sets were reconstructed in 5 % increments from 20% to 80% of the R-R interval. Patients were divided into 3 groups:group Ⅰ ( <65 bpm,n =43) ,group Ⅱ (65 -75 bpm,n =34) and group Ⅲ ( >75 bpm ,n = 25 ). Three blinded and independent readers assessed the image quality of 12 coronary segments in left main,left anterior descending,left circumflex and fight coronary artery using the following scores:5, no motion arti-facts; 4, minor artifacts; 3, moderate artifacts; 2, severe artifacts; and 1, not valuable. Results Best image quality was found in coronary segnents at 60% ,65% or 70% for group Ⅰ and 60% or 65% for group Ⅱ. In group Ⅲ ,The left coro-nary artery were clearly visualized at 60% ,65% of R-R phases,while the right coronary artery was seen at 35% ,40% of R-R phases. Conclusion Image quality is influenced by heart rate and reconstruction interval, at heart rates ≤75 bpm,64-slice CT coronary angiography provides best image quality in mid-diastole (60% ,65% ), at heart rates >75 bpm,the right and left coronary artery should be reconstructed respectively to improve the image quality of coronary.