双能CT虚拟平扫定量评估骨质疏松的可行性研究

Study on the feasibility of quantitative evaluation of osteoporosis by dual-energy CT virtual non-contrast scan

目的:以QCT测量的骨密度(BMD)为金标准,探讨双能CT(DECT)虚拟平扫在无体模的状态下定量评估BMD与骨质疏松程度的可行性。方法:回顾性收集100例行腹部混合能量常规平扫(TNC)与能谱模式(GSI)三期增强扫描的病人,并随机分为训练集和验证集各50例。使用QCT Pro软件测量L1椎体BMD值。在训练集中比较常规模式平扫图像和GSI模式增强门静脉期虚拟平扫图像中L1椎体CT值差异,并确定虚拟平扫椎体CT值与BMD值的相关性,通过多元回归分析建立虚拟平扫椎体CT值预测其BMD值的回归模型。验证集用来评估该方程诊断骨质疏松的准确性以及虚拟平扫椎体CT值对骨质疏松的诊断效能。结果:虚拟平扫的L1椎体CT值低于常规平扫(P<0.01);在减去常规平扫后图像的总辐射剂量减少了21.94%;虚拟平扫CT值预测椎体BMD值的回归模型:BMD=102.375+1.349×CT值-0.321×年龄-0.433×身高(R^(2)=0.979);经ROC曲线分析发现基于门静脉期的虚拟平扫椎体CT值诊断骨质疏松和骨量减少的截断值分别为54.35 HU和64.51 HU。结论:在不依赖体模的情况下,DECT虚拟平扫的椎体CT值能够可靠测量BMD,通过建立的预测BMD模型,可定量诊断骨质疏松和骨量减少,是QCT技术的有益补充。

Objective:To investigate the feasibility of dual-energy CT(DECT)virtual non-contrast scan in the quantitative evaluation of bone mineral density(BMD)measured by QCT as the gold standard in the absence of a body mode.Methods:A retrospective study was performed on 100 patients with abdominal true non-contrast scan(TNC)and GSI three-phases enhanced scan,and the patients were randomly divided into the training set and validation set(50 cases in each set).The BMD value of L1 vertebral body in two sets was measured using QCT Pro software.In the training set,the difference of L1 vertebral CT value between conventional non-contrast scan image and GSI enhanced virtual non-contrast scan image in portal vein phase was compared,and the correlation between virtual non-contrast scan vertebral CT value and BMD value was determined.The regression model of virtual non-contrast scan vertebral CT value to predict BMD value was established through multiple regression analysis.The validation set was used to evaluate the accuracy of this equation in the diagnosis of osteoporosis and effectiveness of virtual non-contrast scan vertebral CT value in the diagnosis of osteoporosis.Results:The CT value of L1 vertebral body of VNC was lower than that of TNC(P<0.01).After subtracting the TNC,the total radiation dose of image was reduced by 21.94%,the multiple linear regression model of CT value of VNC to predict BMD of L1 vertebra was as follows:BMD=102.375+1.349×CT value-0.321×age-0.433×height(R^(2)=0.979).The ROC curve analysis showed that the cut-off value of virtual non-contrast scan vertebral body CT value based on portal vein phase in the diagnosis of osteoporosis and osteopenia were 54.35 HU and 64.51 HU,respectively.Conclusions:In the case of independent body model,the DECT virtual non-contrast scan vertebral CT value can reliably measure the BMD,and the established predictive BMD model can quantitatively diagnose the osteoporosis and osteopenia,which is a beneficial supplement to QCT technology.