自适应统计迭代重建技术算法在头颅CT扫描降低噪声中的对比分析

目的：分析不同的ASIR（自适应统计迭代重建技术）值在降低头部图像噪声中的价值。方法：采用型号为Discovery CT750 HD的宝石CT，对32例受检者进行头部扫描。扫描结束后在双侧侧脑室最大层面重建图像，FOV25cm、层厚5mm、间隔20mm，共5层，分别将ASIR值设定为0％、20％、40％、60％、80％、100％重建图像，窗宽为100HU、窗位为35HU。在一侧侧脑室内选取圆形感兴趣区，测量不同的ASIR值时侧脑室脑脊液的CT值与标准差，应用医学统计软件SPSS13对数据进行统计分析。结果：各组间侧脑室脑脊液的CT值标准差有明显的统计学差异，随ASIR百分比的增加，图像噪声水平明显降低。结论：提高ASIR值能够降低图像噪声。扫描时，采用较高ASIR值具有降低射线剂量的作用。

Noise reduction using adaptive statistical iterative reconstruction technique in head CT imaging

Objective To evaluate the image noise and image quality in head CT examination reconstructed with different weighted values of adaptive statistical iterative reconstruction （ASIR） algorithm. Methods All 32 patients underwent head examination on a 64-slice multidetector-row CT scanner （GE Discovery CT750 HD）. FOV of the scanning was 25 cm, the slice thickness was 5 mm, the interval was 20 mm, and there were 5 slices in the scanning. After scanning the images were reconstructed （window width was 100 HU, window leveling was 35 HU） retrospectively by altering the ASIR percentage, from 0% to 100% at a 20% interval. After that an ROI on anterior part of lateral ventricle was drawn and the CT value and the standard deviation were measured. The attenuation value and standard deviation （SD） were analyzed statisti- cally with SPSS 13. Results The SD reflecting the image noise showed statistical difference significantly. Increasing the ASIR weighted value rendered a decreased image noise. Conclusion Increasing ASIR value helps to reduce image noise, therefore, using a higher weighted ASIR in head CT scanning may promise a lower radiation dose exposure.