64层螺旋CT冠状动脉成像时心率对成像质量的影响

Influence of heart rate on vessel visibility in CT coronary angiography using 64-slice spiral CT

目的 评价患者的心率对64层螺旋CT冠状动脉成像时图像质量的影响.方法 100名患者因怀疑有冠心病或冠心病治疗后复查进行了冠状动脉CTA检查.所有患者没有服用控制心率的药物.扫描用飞利浦64层CT进行,扫描后常规75%时相重建,有运动伪影时增加其他重建时相.冠状动脉的血管分段按AHA的15段分类法进行.对每例患者的2 mm以上的血管段进行分析.血管的成像质量按Ⅰ：无伪影;Ⅱ轻度伪影和Ⅲ严重伪影分类.用多元回归分析方法和Fisher＇s exact检验进行分析.结果 100例患者共有1353个血管段大于2 mm.冠状动脉CTA的质量主要受患者的心率影响（P=0.000）,当心率小于60次/min时,无任何伪影;心率为60～70次/min时,11.2%的患者图像在一些血管段有Ⅱ级伪影,但不影响诊断;心率大于70次/min时,58.6%的患者图像有Ⅱ级伪影,其中一个血管段为Ⅲ级伪影.并且随着患者心率的增加,重建的时相增多,后处理时间延长.结论 64层CT冠状动脉成像的质量有了明显的提高,但心率的快慢仍然是影响图像质量的主要因素,较快的心率出现伪影的机会增多,后处理的时间延长.

Objective To evaluate the influence of heart rate on the image quality of coronary angiography by 64-slice computed tomography （MSCT）. Methods In 100 patients with suspected coronary artery diseases or after treatment as coronary artery diseases, ECG-gated coronary CT angiography （CTA） was performed with a 64slice MSCT Scanner. No β-blocker was administrated in all patients. Fifteen coronary segments were analyzed in each patient according to American Heart Association classification. The segments with the diameter 92 mm were included in final analysis. The image quality was defined as type Ⅰ： no artifact; type Ⅱ ： mild artifact, but assessable; type Ⅲ ： severe artifact, unassessable for the vessel. Multiple regression and fisher＇s exact analysis was used to statistics study. Results One thousand three hundreds and fifty- three segments in 100 patients had the diameter ≥2 mm. The image quality of coronary artery CTA was mainly affected by patients＇ heart rate. When the heart rate was less than 60/min, no artifact was found in the image; when its range was from 60 to 70 beats per minute （bpm）, mild artifact was detected in 11.2% patients; when it was larger than 70 bmp, 58.6% patients had mild artifact, and one patient had severe artifact in one segment. Meanwhile, following the heart rate increased, the post-processing time for the patient augmented. Conclusion Although the image quality of coronary artery CTA with MSCT is improved, vessel visibility is still highly dependent on the patients heart rate. The higher HR means possibly more artifacts in the vessels, and longer post-processing time.