心率及心律对320排容积CT冠状动脉血管成像及相关辐射剂量的影响

Influence of heart rate and heart rhythm on 320-detector CT coronary imaging and radiation dose

目的探讨320排容积CT(DVCT)冠状动脉血管成像心率(律)对图像质量、诊断准确性及辐射剂量的影响。方法回顾性分析济南军区总医院2009年11月至2010年7月行DVCT冠状动脉血管成像患者94例,男65例,女29例,年龄39～91岁,平均(65.6±10.3)岁。以图像质量1级(无运动伪影,优)至4级(严重伪影,差),按照美国心脏协会推荐的15分段法对冠状动脉图像质量进行评价。心率以扫描各心跳平均值表示,心律变化程度以扫描各心跳标准差(SD)表示。分析心率及心律变化对图像质量、辐射剂量的影响。对其中35例冠状动脉血管成像CT检查发现异常患者行冠状动脉导管造影(ICA),分析DVCT冠状动脉血管成像诊断管腔明显狭窄(狭窄率≥50%)的敏感度、特异度、阳性预测值(PPV)、阴性预测值(NPV)。对双变量非正态分布资料采用Spearman相关分析或直线回归分析;利用多元回归分析心率与心律变化的相互作用。结果 (1)图像质量随着心率增高而降低(P<0.001),主要集中于优-良的转变,心律变化对图像质量无明显影响(P=0.16),通过心电编辑,优、良图像质量占96.4%,可诊断节段达99.7%;(2)平均辐射剂量为(14.8±9.8)mSv,随着心率的增加,辐射剂量明显增加(F=64.6,P<0.001)。心律不齐程度对辐射剂量无明显影响(P=0.47);(3)35例行ICA患者中,DVCT诊断冠状动脉狭窄的敏感度97.4%,特异度99.4%,PPV94.9%,NPV99.7%。14例单扇区扫描患者,无假阳性(FP)及假阴性(FN);21例多扇区扫描患者中,出现2例FP,1例FN。经Logistic检验,平均心率与心律不齐程度均不影响诊断准确性(P=0.28,0.55)。结论 DVCT明显降低了心律不齐对CT冠状动脉成像、辐射剂量及诊断准确性的影响;但建议条件允许情况下尽可能降低心率,以减少辐射剂量。

Objective To investigate the impact of heart rate (HR) and heart rate variability(HRv)on image quality,diagnostic accuracy and radiation dose of 320-detector volume CT(DVCT).Methods 94 patients (65 men,29 women; mean age 65.6±10.3) who underwent DVCT coronary angiography from November 2009 to July 2010 were included.Data sets were evaluated according to 15 segments proposed by the American Heart Association.The motion score for each vessel was graded from 1 (no motion artifacts,excellent) to 4 (severe motion artifacts over entire vessel,bad).HR was defined as the mean HR during examination; the variability in HR during scanning was calculated as the standard deviation (SD) from the average HR.The sensitivity,specificity,positive predictive value (PPV),negative predictive value(NPV) index were analyzed in 35 patient who underwent invasive coronary angiography (ICA).Effects of HR,HRv on image quality and radiation dose were analyzed.Results (1)An inverse correlation between average HR and image quality was detected(P<0.001),while the effect of HRv was not significant (P=0.16).Image quality of excellent and good accounted for 96.4% of all segments and diagnostic image quality was obtained in 99.7% of segments.(2)The mean dose of 94 patients was (14.8 ± 9.8) mSv.Effective dose increased with higher HR (F=64.6,P<0.001).(3) HRv did not influence radiation dose significantly (P=0.47).The accuracy of DVCT was as followed:sensitivity:97.4%,specificity:99.4%,PPV:94.9%,NPV:99.7%.There was no false positive (FP) and false negative (FN) in cases scanned in one heart beat.2 FP and 1 FN were detected in 21 cases with multi-segment algorithms reconstruction.According to multivariate logistic regression analysis,HR and HRv showed no impact on accuracy of lesion detection (P=0.28 and 0.55,respectively).Conclusions Coronary angiography with DVCT provides good image quality,lower radiation dose and high diagnostic accuracy within a wide range of HRv.However,from a dosimetric point of view,it is recommended that HR should be controlled at a lower HR,if possible,to decrease radiation doses.