双能CT物质分离技术对腰椎骨密度的定量研究

Dual-energy CT Material Separation Technique on Lumbar Spine Bone Mineral Density Assessment

目的以定量CT(QCT)测量的骨密度(BMD)为金标准,探讨以256排双能CT(DECT)羟基磷灰石(HAP)(脂)分离技术定量测量腰椎BMD的可行性。方法采用DECT物质分离技术测定腰椎椎体HAP(脂)含量,同时用QCT测定腰椎的BMD值。分别采用直接比较法及回归分析法对DECT测量的腰椎HAP(脂)含量与BMDQCT值进行配对t检验,计算并比较直接比较法及回归分析法测量相对误差(RE),并计算调整后的R2对线性模型进行定量评价。结果直接法中腰椎椎体HAP(脂)含量与BMDQCT差异有统计学意义(P<0.05),RE直接=29.76%;腰椎HAP(脂)含量与BMDQCT呈显著线性正相关,回归方程为Y(BMDDECT预测值)=1.226×HAP(脂)-58.228(R^2=0.980,RE回归=1.50%,P<0.05),通过回归方程所得BMDDECT预测值与BMDQCT差异无统计学意义(P>0.05)。结论通过DECT物质分离技术测量腰椎HAP(脂)含量,可定量测量成人腰椎BMD。

Objective To explore the feasibility of assessment of lumbar bone mineral density(BMD)by 256-row dual-energy CT(DECT)hydroxyapatite(HAP)-fat separation technique with quantitative CT(QCT)as the gold standard.Methods The HAP(fat)content of lumbar spine was measured by DECT material separation technique,and the BMD value of lumbar spine was measured by QCT.The HAP(fat)content of lumbar spine and BMDQCT were analyzed by paired t test in direct method and linear regression method respectively.The relative error(RE)measured by direct method and linear regression method was calculated and compared,and the adjusted R2 was calculated to evaluate the linear model.Results There was significant difference between the HAP(fat)density of lumbar spine and BMDQCT(P<0.05),RE=29.76%.There was a significant linear positive correlation between the HAP(fat)content of lumbar spine and BMDQCT.The linear regression equation was Y(BMD)=1.226×HAP(fat)-58.228(R^2=0.980,P<0.05).There was no significant difference between the predicted value of HAP(fat)content and BMDQCT(P>0.05).Conclusion The HAP(fat)content of lumbar spine can be measured quantitatively by DECT material separation technique.