成人颅骨表面遮盖重建理想阈值设定的探讨

目的 探讨成年人颅骨表面遮盖重建（SSD）的理想阈值设定，为利用SSD进行的头部CT血管成像（CTA）去骨成像提供阈值设定的依据。 方法 选取2012年8月，在成都市第一人民医院体检的、同一单位工作的86位体检对象，进行颅骨平均CT值、腰椎骨质密度、性别及年龄的两两对照及多重线性回归拟合，建立起预估颅骨平均CT值的多重线性回归方程，计算出18～80岁人群的理论平均颅骨CT值作为SSD的理想阈值。同时收集2012年10月－2013年2月在该院进行头部CTA检查的12例患者的相关资料以验证其可行性。 结果 18～80岁人群的理论平均颅骨CT值约为640 Hu。以该值作为SSD的阈值进行去骨成像，所有患者图像质量评分均为5分，可视为去骨成功。 结论 在利用理论颅骨平均CT值作为重建阈值的基础之上，通过简单的SSD图像质量再判断及修正，即可简便地完成后处理工作，具有可行性。

Study on Threshold Setting Surface Shaded Display Technique on Adult Skull

Objective To investigate the ideal threshold setting of surface shaded display （SSD） technique on adult skull, and then provide the threshold setting basis for head CT angiography （CTA） bone imaging by using SSD. Methods Eighty-six people undergoing physical examination and working in the same unit were selected in our study in August 2012. Their average CT values of skulls and bone mineral density （BMD） of vertebras were measured. A multiple regression equation was established to estimate the average CT value of skull by pair-wise comparison and multiple regressions fitting of average CT value of skull, BMD, gender and age. The theoretical average CT value between 18 to 80 year-old people was calculated by such equations, as the ideal reconstruction threshold of SSD. Its feasibility was verified by collecting relevant information of 12 cases of CTA patients. Results The theoretical average CT value between 18 to 80 years was approximately 640 Hu. By using the value as the SSD reconstruction threshold boneless imaging, they could be regarded as being successfully boneless if all image quality scores were 5 points. Conclusion On the basis of utilizing theoretical average skull CT value as the reconstruction threshold, it is feasible by simply judging the qualities and making the corrections of the SSD image.