双源CT大螺距扫描技术在冠状动脉狭窄诊断中的应用

Dual-source CT coronary angiography using the high-pitch mode in diagnosing the coronary artery stenosis

目的:探讨128层双源CT大螺距扫描模式下冠状动脉成像的图像质量、准确性及辐射剂量。方法:123例怀疑或已知冠心病患者采用数字表法随机分为两组,分别行前瞻性心电触发序列扫描技术(序列扫描组,n=58)与前瞻性心电触发大螺距扫描技术(大螺距扫描组,n=65);2名有经验的放射医师,利用双盲法、以5分法评定系统对冠状动脉成像质量进行评分,计算2名医师评价图像质量的一致性,并对辐射剂量进行分析。以DSA为金标准,评价双源CT诊断冠状动脉狭窄(≥50%)的敏感性和特异性。结果:123例患者,1 920段(97.6%)冠状动脉节段可满足影像学评价;序列扫描组和大螺距扫描组满足影像学评价的冠状动脉节段分别为98.1%(910/928)和97.1%(1 010/1 040),两组间差异无统计学意义(χ2=0.030,P=0.867);123例患者冠状动脉成像质量均分为(4.7±0.8)分;其中序列扫描组冠状动脉均分(4.7±0.7)与大螺距扫描组冠状动脉均分(4.6±0.9)之间差异无统计学意义(t=0.603,P=0.548);2名评价者之间的Kappa值为0.799(P<0.01)。大螺距扫描组的有效剂量为(1.08±0.11)mSv,明显低于序列扫描组(2.26±0.49)mSv,两者间差异有统计学意义(t=11.642,P=0.000);双源CT诊断冠状动脉分支狭窄的敏感性、特异性分别为序列扫描组:97.6%、97.5%,大螺距扫描组:98.1%、96.5%。结论:在低心率及律齐人群中,双源CT前瞻性心电触发序列扫描及前瞻性心电触发大螺距扫描冠状动脉的图像质量及诊断冠状动脉狭窄的准确性均较高,但大螺距扫描技术能显著降低辐射剂量。

Objective： To evaluate the image quality,diagnostic accuracy and radiation doses for coronary artery imaging with second-generation 128-slice dual-source CT（DSCT） using the high-pitch mode.Methods： A total of 123 cases patients with suspected or known coronary artery disease were randomly divided into two groups.Group A（n = 58） underwent the adaptive prospective ECG-triggered sequence scan（CorAdpSeq） and group B（n =65） underwent the prospective high-pitch mode（pitch 3.4,Flash mode）.Two experienced radiologists assessed the image quality and significant coronary stenosis（≥50%） with a double blinded fashion in a five score scale.Interobserver agreement for image quality was calculated with Cohen kappa statistics.The radiation doses values were measured.The diagnostic performance presented by DSCT in detecting stenosis ≥50% were compared with the gold standard DSA.Results： There were 1 968 segments of coronary arteries in 123 patients included in this analysis.Diagnostic image quality（score≥3） was obtained in 1920 segments（97.6%） of the coronary artery segments,which was obtained in 98.1%（910/928） of segments in group A and 97.1%（1 010/1 040） in group B respectively with no significant difference（χ2 = 0.030,P = 0.867）.The mean image quality score for the whole coronary segments was（4.7 ± 0.8） in 123 patients.There was no statistical difference between mean image quality of group A（4.7 ±0.7） and group B（4.6 ±0.9）（t =0.603,P =0.548）.The kappa value between two radiologists was 0.799（P 0.01） on image quality.The effective radiation dose in group B（1.08 ± 0.11） mSv was significantly（t = 11.642,P = 0.000） lower than that in group A（2.26 ± 0.49） mSv.Sensitivity and specificity were 97.6% and 97.5% per-vessel in group A;98.1%,96.5% per-vessel in group B.Conclusion： Compared with DSA both the high-pitch and CorAdpSeq mode for CTCA provide high image quality and accuracy of significant coronary stenosis,but the high-pitch mode can significantly reduce the radiation dose in the lower heart rate and regular heart rhythm.