【摘要】 目的 探讨低剂量64层CT测定冠状动脉钙化积分的可重复性。方法 43例冠状动脉钙化的患者连续进行2次64层螺旋CT扫描,管电流分别为100 mAs和55 mAs,其余参数不变,由2名放射科医生测定钙化积分,计算前后2次扫描差值;同时测量升主动脉的CT值的均数及标准差。结果 2次扫描在观察者和观察者内部差值的绝对值多数在50以内(分别为81.4%和86.5%)。低剂量扫描对不同测量者无明显统计学差异(P=0.883和0.952);取平方根转换后均具有明显相关(r均为0.998)。采用管电流55 mAs,所测均数与2倍标准差之和低于130 HU,可将辐射剂量降低0.6 mSv。结论 低剂量前门控64层CT钙化积分扫描在降低辐射剂量的同时,图像满足测量需要,具有较高的可重复性。更多还原

【Abstract】 Objective To determine the reproducibility of coronary artery calcium(CAC) measurements with low-dose prospective ECG-gated 64-slice spiral CT.Methods Forty-three patients with CAC suspected of having coronary artery disease were scanned twice using a tube current setting of 100 mAs and 55 mAs,respectively.CAC scores(Agatston) of subjects and vessel were recorded by two radiologists and interscan variability were evaluated.The mean±SD of the CT attenuation values in regions of interest in the aorta were measured,and the value(mean+2 SD) were obtained.Results The absolute value of difference between the sequential scans among observers were smaller than fifty in most cases.There were no significantly different between observerl and observer2 in the low-dose calcium scan(P=0.883,0.952).A high correlation of Square root of Agatston score was observed between sequential spiral CT scans in subject and vessel(both r=0.998).With the tube current of 55 mAs,the value(mean+2SD) did not exceed a CT attenuation value of 130 HU.The low-dose protocol could reduce the radiation exposure more than 0.6mSv.Conclusion Low-dose prospective ECG-gated 64-slice spiral CT shows low interscan and interobserver variability in CAC scoring with great radiation exposure reduction while maintaining low image noise.更多还原