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Abstract：
This study aimed to evaluate the impact of contrast media application on CT attenuation of the bone using a novel calcium-only imaging technique (VCa) from dual-layer spectral detector CT (DLCT), which enables CT-based bone mineral density measurement unimpeded by soft tissue components. For this, true non-contrast (TNC) and venous phase images (VP) of n = 97 patients were acquired. CT attenuation of the first lumbar vertebra (L1) was measured in TNC-VCa, VP-VCa, and in virtual non-contrast images (VNC). CT attenuation was significantly higher in VP-VCa than in TNC-VCa (p < 0.001), although regression analyses revealed a strong linear association between these measures (R2 = 0.84). A statistical model for the prediction of TNC-VCa CT attenuation was established (TNC-VCa[HU] = - 6.81 + 0.87 × VP-VCa[HU]-0.55 × body weight[kg]) and yielded good agreement between observed and predicted values. Furthermore, a L1 CT attenuation threshold of 293 HU in VP-VCa showed a sensitivity of 90% and a specificity of 96% for detecting osteoporosis. The application of contrast media leads to an overestimation of L1 CT attenuation in VCa. However, CT attenuation values from VP-VCa can be used within CT-based opportunistic osteoporosis screening eighter by applying a separate threshold of 293 HU or by converting measured data to TNC-VCa CT attenuation with the given regression equation.
摘要：
本研究旨在使用双层光谱探测器CT（DLCT）的新型钙成像技术（VCa）评估造影剂应用对骨骼CT衰减的影响。这使得基于CT的骨密度测量不受软组织成分的阻碍。为此，获得了n=97例患者的真实非对比（TNC）和静脉期图像（VP）。在TNC-VCa中测量第一腰椎（L1）的CT衰减，VP-VCa,和虚拟非造影图像（VNC）。VP-VCa的CT衰减明显高于TNC-VCa（p<0.001），尽管回归分析显示这些测量值之间存在强线性关联(R2=0.84).建立了预测TNC-VCaCT衰减的统计模型（TNC-VCa[HU]=-6.810.87×VP-VCa[HU]-0.55×体重[kg]），并在观测值和预测值之间取得了良好的一致性。此外，VP-VCa中293HU的L1CT衰减阈值显示检测骨质疏松的灵敏度为90%,特异性为96%.造影剂的应用导致VCa中L1CT衰减的高估。然而,通过应用293HU的单独阈值或通过使用给定的回归方程将测量数据转换为TNC-VCaCT衰减，可以在基于CT的机会性骨质疏松症筛查中使用VP-VCa的CT衰减值。
