头颅CTA部分骨减影技术在降低剂量中的应用研究

Partial bone-subtraction CT angiography for the application of skull of low radiation dose

目的探讨部分骨减影技术在降低头颅CTA辐射剂量中的应用价值。方法河南省人民医院院临床怀疑脑血管疾患需行64排头颅CTA检查的患者,按时间顺序分两组,每组随机抽取50例病例。A组50例为完全减影组,平扫与增强扫描范围均为颅底至颅顶,B组50例为部分减影组,除平扫范围不同之外(颅底至前床突上方1cm),其他均与A组相同。两组扫描条件相同。以颅内血管树的清晰度、完整性(有无骨性伪影)将图像质量分为优、良、差三个等级,并对两组病例的辐射剂量及图像质量分别用t检验和χ2检验进行统计分析。结果两组辐射剂量比较,A组平均DLP为609.67 mGy.cm,B组平均DLP为429.4 mGy.cm,B组比A组辐射剂量降低29.5%,有统计学差异(t=15.807,P<0.05)。两组图像均满足临床诊断需要,两组图像质量没有统计学差异(χ2=2.130,P>0.05)。结论部分减影技术在保证图像质量的基础上还能明显降低辐射剂量。

Objective To investigate the value of partial bone-subtraction CT angiography（CTA） of skull for the application of low radiation dose.Methods The patients suspected cerebral vessels disease underwent 64 slice CT intracranial angiography in our hospital,and divided into two group according to chronological order,each group with 50 cases.The scanning range of group A with wholly bone-subtraction CTA were from base to roof of skull in both nonenhanced and enhanced scan,and group B with partial bone-subtraction CTA were from base to 1 cm above anterior clinoid process of skull in nonenhanced scan.The scanning parameters were same in two groups.The evaluation of image quality scores（excellent,good,and not good） were according to sharpness and integrality（bony artifact） of intracranial artery tree.The radiation dose and image quality score in two groups were compared by t test and χ^2 test.Results The radiation dose was reduced by 29.5% for group B with average DLP 429.4 mGy·cm（group A with average DLP 609.67 mGy·cm）,and was statistically significant（t=15.807,P〈0.05）.All images of both groups had clinically acceptable quality,and there was no significant difference in image quality scores（χ^2=2.130,P〈0.05）.Conclusion The method of partial bone-subtraction CTA of skull could decrease radiation dose significantly without affecting the image quality.