目的：探讨全模型迭代重建（Iterative model reconstruction，IMR）技术在256层螺旋CT“双低”冠状动脉CTA成像中的应用价值。方法：100例拟行冠状动脉CTA检查者按照同期随机原则分为2组，每组50例。均采用前置门控扫描。A组（对照组）采用120 kV、管电流根据噪声指数自动调节DRI=15（Dose Right Index）及iDose4重建，B组（低剂量组），采用100 kV、DRI=11及IMR重建。A、B组对比剂注射方案分别为0.8 mL/kg体质量和0.6 mL/kg体质量，对比剂注射时间均为12 s。采用独立样本t检验比较两组客观评价指标（噪声、信噪比及对比噪声比）、辐射剂量（CT剂量指数、CT剂量长度乘积、有效辐射剂量）及碘负荷的差异。采用Mann-Whitney U秩和检验比较两组主观图像（管腔对比度、边缘锐利度、主观噪声及图像总体质量）质量评分的差异。结果：B组噪声为（23.4±2.8） HU，低于Ａ组（34.3±4.3） HU，差异有统计学意义（t=14.977，P=0.000）。Ｂ组信噪比为（16.3±2.2），高于A组（11.9±1.9），差异有统计学意义（t=-10.713，P=0.000）。B组对比噪声比为（21.1±2.7），高于A组（15.1±2.3），差异有统计学意义（t=-12.083，P=0.000）。B组主观噪声与整体质量优于A组，差异有统计学意义（U=951.000、934.000，P=0.008、0.005），两组对比度与锐利度差异无统计学意义（U=1 233.000、1 233.500，P=0.884、0.888）。B组有效辐射剂量为（0.94±0.23） mSv，较A组剂量（1.53±0.32） mSv降低约39%；B组碘负荷为（15.1±2.4） g，较A组（20.1±2.5） g降低约25%。结论：IMR较混合迭代重建（iDose4）可以进一步降低噪声，在剂量降低39%且碘负荷降低25%的条件下，图像质量仍可满足诊断需求。
Abstract
Objective: To investigate the clinical value of IMR technique in 256 slice prospective coronary CTA with low dose and low Iodine load. Methods: One hundred patients who would perform coronary CTA were enrolled and the patients were divided into two groups randomly. All the patients were performed prospective CTA. Patients in group A were performed CTA by using normal tube voltage(120 kV), dose right index(DRI)=15 was considered to be currents and iDose4 reconstruction. Patients in group B were performed CTA by using low tube voltage(100 kV), DRI=11 was considered to be currents and IMR reconstruction. The injection protocols of group A and group B were 0.8 mL/kg and 0.6 mL/kg, respectively. The injection time was 12 seconds. Quantitative measurements of CT value, image noise, signal-to-noise(SNR) and contrast-to-noise(CNR) were measured in each group. t-test was used for comparisons of objective evaluation, indices(noise, SNR, CNR), radiation dose(CTDIvol, DLP, ED) and Iodine load between the two groups. Mann-Whitney U test was used for comparisons of subjective evaluation of IQ between the two groups. A level of P＜0.05 was considered statistically significant. Results: There were significant differences in SD between group A(34.3±4.3) HU and group B(23.4±2.8) HU(t=14.977, P=0.000). There were significant differences in SNR between group A(11.9±1.9) and group B(16.3±2.2)(t=-10.713, P=0.000). There were significant differences in CNR between group A(15.1±2.3) and group B(21.1±2.7)(t=-12.083, P=0.000). Group B showed the better objective data. Compared with group A, there were significant differences in subjective noise and acceptability of images(U=951.000, 934.000, P=0.008, 0.005). There were no significant differences in image contrast and image sharpness(U=1 233.000, 1 233.500, P=0.884, 0.888). The effective dose(ED) of group B (0.94±0.23) mSv was 39% lower than that of group A (1.53±0.32) mSv. The Iodine load of group B (15.1±2.4) g was 25% lower than that of group A (20.1±2.5) g. Conclusion: Compared with iDose4, using 256 MDCT, iterative model reconstruction technique can provide 39% ED and 25% Iodine load reduction, while the images could still satisfy the requirement of diagnosis.
关键词
冠状动脉疾病 /
辐射剂量 /
体层摄影术 /
螺旋计算机 /
冠状血管造影术
Key words
Coronary disease /
Radiation dosage /
Tomography, spiral computed /
Coronary angiography
中图分类号：
Ｒ543.3
R814.42
Ｒ814.43
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基金
国家自然科学基金：81301221；辽宁省高等学校创新团队支持计划：LT2014017。
