非线性融合技术在头颈部CTA中的价值:体模实验

目的 探讨双源双能量CT非线性融合（NLB）技术提高头颈部CTA图像质量、降低辐射剂量的应用价值。方法 分别以常规120 kV （螺距为1.0）及双能量80/Sn140 kV （螺距分别为0.5、0.8、1.0和1.2）对人体头颈部仿真体模进行扫描，并对双能量扫描数据进行线性融合（LB）和NLB处理。比较9组图像颈内动脉、大脑中动脉的CT值、CNR和图像质量主观评分的差异；比较不同扫描条件下辐射剂量的差异。结果 螺距为0.5、0.8、1.0、1.2的NLB图像中，大脑中动脉和颈内动脉的CT值大于螺距为0.5、0.8、1.0、1.2的LB图像和常规120 kV图像（P均<0.05）。螺距为0.5和0.8的NLB图像中，大脑中动脉和颈内动脉的CNR大于螺距为1.0、1.2的NLB图像，螺距为0.5、0.8、1.0、1.2的LB图像和常规120 kV图像（P均<0.05）。主观评价显示，双能量扫描螺距为0.5时，图像质量最佳；双能量扫描螺距为0.8时，LB、NLB图像与常规120 kV图像评分相当。与常规120 kV扫描方式比较，双能量扫描螺距为0.8、1.0和1.2时，有效剂量分别降低36.12%、46.28%和53.22%。结论 NLB技术可在保证头颈部CTA图像质量的同时降低辐射剂量。

Value of non-linear blending technique in head and neck CTA of phantom

Objective To explore the value of non-linear blending (NLB) technique in improving image quality and reducing radiation dose of head and neck CTA using phantom.Methods CT scanning with conventional single energy 120 kV (pitch 1.0) and dual-energy 80/Sn140 kV (pitch 0.5, 0.8, 1.0 and 1.2) were performed on the head and neck of a phantom, respectively. The dual energy images were reconstructed with both NLB method and linear blending (LB) method. CT value and CNR of the internal carotid artery (ICA) and middle cerebral artery (MCA) were measured and calculated. The image quality of each group were evaluated, and the radiation dose was compared.Results CT value of ICA and MCA in NLB imaging with pitch of 0.5, 0.8, 1.0, 1.2 was larger than that in LB images with pitch of 0.5, 0.8, 1.0, 1.2 and conventional 120 kV images (all P<0.05). CNR of ICA and MCA in NLB images with the pitch of 0.5 and 0.8 was larger than that in NLB images with the pitch of 1.0 and 1.2, LB images with pitch of 0.5, 0.8, 1.0, 1.2 and conventional 120 kV images (all P<0.05). The subjective evaluation showed that the image quality of dual-energy images with the pitch of 0.5 was the best. The image quality of dual-energy images with pitch of 0.8 was equal to that of the conventional 120 kV images. Compared with conventional 120 kV scanning, the effective dose of dual-energy scanning with the pitch of 0.8, 1.0 and 1.2 reduced by 36.12%, 46.28% and 53.22%, respectively.Conclusion NLB technology can reduce the radiation dose while ensuring the quality of CTA image of head and neck.