Takahashi Naoki, Bae Kyongtae T
Mallinckrodt Institute of Radiology, Washington University, School of Medicine, 510 S Kingshighway Blvd, St Louis, MO 63110, USA.
Radiology. 2003 Jul;228(1):101-6. doi: 10.1148/radiol.2281012035.
To assess the interscan variability of coronary artery calcium as measured with different tube currents and quantification methods in prospective electrocardiography (ECG)-gated multi-detector row CT.
Thirty-three subjects who were asymptomatic for coronary heart disease underwent prospective ECG-gated, subsecond multi-detector row CT of the heart. Each subject underwent two consecutive CT examinations, the first with a dose of either 40 mAs (n = 18) or 80 mAs (n = 15) and the second with a dose of 150 mAs. Calcium volume and calcium score were calculated. Pearson correlation coefficient was computed between the calcium scores of high- and low-dose examinations. Interscan variability in these measurements (ie, the absolute percentage difference) was compared between the examinations with 40-150 mAs and those with 80-150 mAs by using an independent sample t test. In addition, the interscan variabilities of calcium scores between vessels were evaluated with repeated measures of analysis of variance. The interscan variabilities between calcium score and volume measurement were also compared with paired t tests.
Twenty-seven of 33 subjects had coronary artery calcium deposits on both CT scans. Five subjects had no calcium deposit on either scan. One subject had calcium deposits on only one scan. The total calcium score between the high- and low-dose scans was highly correlated (r = 0.98) and was not significantly different (P =.58). The interscan variability of calcium score showed no significant difference with respect to subject (P =.25) or vessel (P =.84). The interscan variability of the calcium volume measurement was significantly lower than that of the calcium score with respect to both the subject (P <.01) and the vessel (P <.01).
A dose of 40 mAs appears adequate for quantifying coronary artery calcium at multi-detector row CT. Interscan variability of multi-detector row CT is substantially reduced by using the calcium volume method.
评估在前瞻性心电图（ECG）门控的多排螺旋CT中，不同管电流和定量方法测量冠状动脉钙化的扫描间变异性。
33例无冠心病症状的受试者接受了前瞻性ECG门控的心脏亚秒级多排螺旋CT检查。每位受试者连续进行两次CT检查，第一次剂量为40 mAs（n = 18）或80 mAs（n = 15），第二次剂量为150 mAs。计算钙化体积和钙化积分。计算高剂量和低剂量检查的钙化积分之间的Pearson相关系数。使用独立样本t检验比较40 - 150 mAs检查与80 - 150 mAs检查之间这些测量值的扫描间变异性（即绝对百分比差异）。此外，采用重复测量方差分析评估血管间钙化积分的扫描间变异性。还通过配对t检验比较钙化积分与体积测量之间的扫描间变异性。
33例受试者中有27例在两次CT扫描中均有冠状动脉钙化沉积。5例受试者在两次扫描中均无钙化沉积。1例受试者仅在一次扫描中有钙化沉积。高剂量和低剂量扫描之间的总钙化积分高度相关（r = 0.98），且无显著差异（P = 0.58）。钙化积分的扫描间变异性在受试者方面（P = 0.25）或血管方面（P = 0.84）均无显著差异。钙化体积测量的扫描间变异性在受试者方面（P < 0.01）和血管方面（P < 0.01）均显著低于钙化积分的扫描间变异性。
40 mAs的剂量似乎足以在多排螺旋CT上定量冠状动脉钙化。使用钙化体积法可大幅降低多排螺旋CT的扫描间变异性。
