心率及重建时相对64层CT冠状动脉成像图像质量的影响

Coronary Angiography with 64-slice Spiral CT:Influence of Reconstruction Interval and Heart Rate on Image Quality

目的探讨不同重建时相对64层CT冠状动脉成像质量的影响。方法64例患者采用64层CT回顾性心电门控冠状动脉成像,扫描原始数据不同时相重建,用横断面、曲面重建、容积再现等方法对图像质量综合评分。患者心率<65次/min为Ⅰ组(n=36),65～79次/min为Ⅱ组(n=18),≥80次/min为Ⅲ组(n=10),患者冠状动脉血管分为12段,4条冠状动脉分支(左冠状动脉主干、左前降支、左回旋支、右冠状动脉)用于图像质量分析。结果Ⅰ和Ⅱ组60%、65%相位图像质量最优,Ⅲ组右冠状动脉(right coronary artery,RCA)最优的相位窗为40%相位,左回旋支(left circumflex coronary artery,LCX)、左前降支(left anterior descending coronary artery,LAD)、左主干(left main,LM)最优的相位窗为60%。结论心率低于80次/min的患者冠状动脉重建时相首选舒张中期60%或65%时相;心率高于80次/min患者,按左、右冠状动脉分支分别进行重建有利于提高冠状动脉的成像质量。

Objective The reconstructive intervals providing best image quality for non-invasive coronary angiography with 64- slice computed tomography（CT） were evaluated. Methods Contrast enhanced, retrospectively electrocardiography（ECG）-gated 64-slice CT coronary angiography was performed in 64 patients. Depending on the average heart rate during scanning, patients were grouped as 〈65 bpm（n =36）, 65 -79 bpm（n = 18） and I〉80 bpm（n = 10）. Two blinded and independent readers assessed the image quality of each coronary segment with a diameter ≥ 1.5 mm using the following scores ： 5, no motion artifacts ; 4, minor artifacts ; 3, moderate artifacts; 2, severe artifacts ; and 1, not evaluative. Results Best image quality was obtained in all coronary segments at 60% or 65% for group Ⅰ and Ⅱ. In group Ⅲ. The left main artery, the left anterior descending artery and the left circumflex artery were clearly visualized at 60% of R-R phases, while the right coronary artery was seen at 40% of R-R phases. Conclusion When heart rate is 〈 80bpm, 64-slice CT coronary angiography provides best image quality in mid-diastole, diagnostic image quality of all coronary segments can be obtained at reconstruction interval of 60% or 65%. When heart rate is ≥80 bpm, the right and left coronary artery should be reconstructed respectively to improve the image quality of coronary.