目的：探讨256层螺旋CT在头颈联合动脉CTA成像中，应用低kV、低注射速率及全模型迭代重组（IMR）技术对头颈部动脉疾病诊断中的应用价值。方法：拟行头颈动脉CTA检查患者60例按照同期随机原则分为2组，每组30例。A组（对照组）采用常规剂量扫描及高级混合迭代重组（iDose4），B组（双低组）采用低kV、低注射速率，并采用IMR技术重组。采用t检验分别比较颈总动脉起始部、颈总动脉远端及颅内动脉各组客观评价指标（噪声、对比噪声比）及辐射剂量（CT剂量指数、CT剂量长度乘积、有效辐射剂量）的差异。采用χ2检验比较主观图像质量评分（对比度、锐利度、主观噪声）。结果：B组噪声（17.4±1.8，8.3±0.8，10.0±0.8）低于A组（25.5±3.2，9.0±0.6，11.9±1.2），差异有统计学意义（t=12.08，3.83，3.80，P均＜0.01）。B组对比噪声比（30.7±4.7，67.6±8.0，37.7±5.8）高于A组（19.0±3.7，58.0±7.3，37.7±5.8），差异有统计学意义（t=10.71，4.86，7.37，P均＜0.01）。B组显示了很好的主观图像质量，各部分主观评分在对比度及主观噪声方面均优于A组，而在锐利度方面略差于A组，但差异无统计学意义（χ2=0.27，0.07，0.61，P=0.64，0.81.0.49，P均＞0.05）。B组有效辐射剂量值为（0.84±0.03） mSv，较A组剂量（1.43±0.06） mSv降低约41%。结论：新型全模型迭代重组算法（IMR）较高级混合迭代重组算法（iDose4）可以进一步降低噪声，而图像质量可满足诊断需求。
Abstract
Objective: To investigate the clinical use of 256-slice spiral CT in the diagnosis of head and neck artery disease in CTA combined with low-tube-voltage and low rate injection of contrast medium by IMR reconstruction. Methods: Sixty patients who would perform head-neck CTA were enrolled and divided into two groups randomly. CTA was performed in group A using normal tube voltage(120 kV) and normal injection rate of contrast medium(5 mL/s) by iDose4 reconstruction. Group B received CTA by low-tube-voltage(100 kV) and low injection rate of contrast medium(4 mL/s) with IMR reconstruction. Quantitative measurements of CT value, image noise and contrast-to-noise ratio(CNR) were measured in either group. The t-test was used to compare objective evaluation indices(noise, CNR) and radiation dosage between the two groups. χ2-test was used to compare subjective evaluation of image quality(contrast, sharpness and subjective noise) between the two groups. A level of P＜0.05 was considered statistically significant. Results: There were significant differences in objective noise and CNR between the two groups(P＜0.01). Group B showed better subjective image quality. Compared to group A, group B showed better subjective scores of contrast and noise, and slightly worse score of sharpness with no significence(P>0.05). The effective dose(ED) of group B((0.84±0.03) mSv) was 41% lower compared to group A((1.43±0.06) mSv). Conclusion: Compared with iDose4, iterative model reconstruction technique can provide 41% ED reduction in head-neck CTA by 256 MSCT with satisfactory image quality.
关键词
体层摄影术 /
螺旋计算机
中图分类号：
Ｒ816.1
Ｒ814.42
R814.43
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