碘对比剂对定量CT测量骨密度的影响及其与年龄相关性的研究

The Influence of Iodine Contrast Medium on Bone Mineral Density Measurements from Quantitative CT and the Correlation with Age

目的:通过定量CT测量,评估受试者注射碘对比剂前后骨密度(BMD)的变化,分析碘对比剂对BMD测量的影响及其与年龄的关系。方法:回顾性分析2019年12月至2020年4月行腹部CT检查的138例患者影像资料,采用QCT测量腰1~腰3椎体平扫、动脉期、门脉期、延迟期的BMD值,计算3个椎体各期相平均BMD及增强前后BMD增加值(ΔBMD)。以平扫BMD作为标准QCT-BMD,采用单因素方差分析比较增强前后各期相BMD的差异,采用两独立样本非参数检验比较老年组与非老年组间各期相ΔBMD的差异,Pearson相关分析评价增强后各期相与平扫BMD以及ΔBMD与年龄的相关性。结果:QCT-BMD与增强各期BMD差异有统计学意义(P=0.026、0.000、0.012,均<0.05),门脉期与动脉期之间差异有统计学意义(P=0.034<0.05),其余各期相间无统计学差异;门脉期及延迟期老年组与非老年组各期相ΔBMD比较有统计学差异(门脉期P=0.003<0.05,延迟期P=0.009<0.05)。增强后动脉期、门脉期、延迟期与标准QCT-BMD均呈正相关(r=0.992、0.983、0.987,均P=0.000<0.05);门脉期及延迟期ΔBMD与年龄呈正相关,r值分别为0.307(P=0.001<0.05)和0.269(P=0.000<0.05)。结论:QCT测量增强扫描各期相与平扫之间BMD有较好的相关性,动脉期及延迟期较门脉期更好;门脉期及延迟期BMD增加值与年龄正相关;增强扫描各期相中,应以动脉期作为增强QCT-BMD测量的最佳期相。

Purpose: To evaluate the difference of bone mineral density(BMD) measured by quantitative computed tomography(QCT) before and after injection of contrast media and analyze the relationship between the changes of BMD and age. Methods: A retrospective data analysis was performed on 138 subjects who underwent both plain and three contrast-enhanced abdominal CT between December 2019 and April 2020.The BMD of lumbar1,2 and 3 vertebral bodies were measured, the mean BMD and ΔBMD in every contrast phase were calculated. BMD measured in the plain phase was regarded as the standard QCT-BMD, an ANOVA test was used to identify the differences in BMD between different phases before and after the enhancement. In addition, a non-parametric test was used to compare the differences in ΔBMD of each phase between the elderly and non-elderly groups. Pearson correlation analysis was used to evaluate the correlation not only between three phases of enhancement and the plain phase, but also between ΔBMD and age. Result: There was a significant difference in BMD between the standardQCT and all contrast phases(P=0.026, 0.000, 0.012<0.05);There was a significant difference in BMD between portal phase and arterial phase(P=0.034<0.05). In different age group, there was significant differences in ΔBMD between portal phase and delayed phase(P=0.003<0.05 in portal phase, P=0.009<0.05 in delayed phase). The BMD in the all contrast phases were positively correlated with standard QCT-BMD, with r values of 0.992, 0.983 and 0.987(all P=0.000<0.05). The ΔBMD in portal phase and delayed phase were positively correlated with age, with r values of 0.307 and 0.269(P=0.001<0.05 in portal phase, P=0.000<0.05 in delayed phase). Conclusion: There was a good correlation between each contrast phase and plain phase in BMD, and the arterial phase and the delayed phase were better. The ΔBMD of the portal phase and the delayed phase showed a weak, positive correlation with age. The arterial phase should be the best phase for BMD measurement with enhanced QCT.