Chen Keren, Massie Christine, Berger Andrew J
The Institute of Optics, University of Rochester, New York, New York, USA.
Department of Biomedical Engineering, University of Rochester, New York, New York, USA.
J Biophotonics. 2020 Nov;13(11):e202000256. doi: 10.1002/jbio.202000256. Epub 2020 Aug 31.
Transcutaneous determination of a bone's Raman spectrum is challenging because the type I collagen in the overlying soft tissue is spectroscopically identical to that in bone. In a previous transcutaneous study of murine tibiae, we developed a library-based model called SOLD to unmix spatially offset Raman measurements into three spectra: a bone estimate, a soft tissue estimate, and a residual. Here, we demonstrate the value of combining the bone estimate and the residual to produce a "top layer subtracted" (tls) spectrum. We report superior prediction of two standard bone metrics (volumetric bone mineralization density and maximum torque) using partial least squares regression models based upon tls spectra rather than SOLD bone estimates, implying that the spectral residuals contain useful information. Simulations reinforce experimental in vivo findings. This chemometric approach, which we denote as SOLD/TLS, could have broad applicability in situations where comprehensive spectral libraries are difficult to acquire.
经皮测定骨骼的拉曼光谱具有挑战性，因为覆盖其上的软组织中的I型胶原蛋白在光谱上与骨骼中的I型胶原蛋白相同。在之前一项对小鼠胫骨的经皮研究中，我们开发了一种基于库的模型，称为SOLD，用于将空间偏移拉曼测量结果分解为三个光谱：骨骼估计光谱、软组织估计光谱和残差光谱。在此，我们展示了将骨骼估计光谱和残差光谱相结合以生成“顶层扣除”（tls）光谱的价值。我们报告称，使用基于tls光谱而非SOLD骨骼估计光谱的偏最小二乘回归模型，对两个标准骨骼指标（体积骨矿化密度和最大扭矩）的预测效果更佳，这意味着光谱残差包含有用信息。模拟结果强化了体内实验结果。这种化学计量学方法，我们称为SOLD/TLS，在难以获取全面光谱库的情况下可能具有广泛的适用性。
