Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
SA Pathology and University of Adelaide, Adelaide, Australia.
PLoS One. 2019 Feb 13;14(2):e0212280. doi: 10.1371/journal.pone.0212280. eCollection 2019.
In the clinical field of diagnosis and monitoring of bone diseases, high-resolution peripheral quantitative computed tomography (HR-pQCT) is an important imaging modality. It provides a resolution where quantitative bone morphometry can be extracted in vivo on patients. It is known that HR-pQCT provides slight differences in morphometric indices compared to the current standard approach micro-computed tomography (micro-CT). The most obvious reason for this is the restriction of the radiation dose and with this a lower image resolution. With advances in micro-CT evaluation techniques such as patient-specific remodeling simulations or dynamic bone morphometry, a higher image resolution would potentially also allow the application of such novel evaluation techniques to clinical HR-pQCT measurements. Virtual supersampling as post-processing step was considered to increase the image resolution of HR-pQCT scans. The hypothesis was that this technique preserves the structural bone morphometry. Supersampling from 82 μm to virtual 41 μm by trilinear interpolation of the grayscale values of 42 human cadaveric forearms resulted in strong correlations of structural parameters (R2: 0.96-1.00). BV/TV was slightly overestimated (4.3%, R2: 1.00) compared to the HR-pQCT resolution. Tb.N was overestimated (7.47%; R2: 0.99) and Tb.Th was slightly underestimated (-4.20%; R2: 0.98). The technique was reproducible with PE%CV between 1.96% (SMI) and 7.88% (Conn.D). In a clinical setting with 205 human forearms with or without fracture measured at 82 μm resolution HR-pQCT, the technique was sensitive to changes between groups in all parameters (p < 0.05) except trabecular thickness. In conclusion, we demonstrated that supersampling preserves the bone morphometry from HR-pQCT scans and is reproducible and sensitive to changes between groups. Supersampling can be used to investigate on the resolution dependency of HR-pQCT images and gain more insight into this imaging modality.
在骨疾病的诊断和监测的临床领域，高分辨率外周定量计算机断层扫描（HR-pQCT）是一种重要的成像方式。它提供了一种分辨率，可以在患者体内提取定量骨形态计量学。已知与当前的标准方法微计算机断层扫描（micro-CT）相比，HR-pQCT 在形态计量指数上存在细微差异。最明显的原因是辐射剂量的限制，因此图像分辨率较低。随着 micro-CT 评估技术的进步，例如患者特异性重塑模拟或动态骨形态计量学，更高的图像分辨率也有可能将这些新的评估技术应用于临床 HR-pQCT 测量。作为后处理步骤的虚拟过采样被认为可以提高 HR-pQCT 扫描的图像分辨率。该假设是该技术保留了结构骨形态计量学。通过对 42 个人体前臂的灰度值进行三次线性插值，将分辨率从 82μm 提高到虚拟 41μm，结果结构参数具有很强的相关性（R2：0.96-1.00）。与 HR-pQCT 分辨率相比，BV/TV 被略微高估（4.3%，R2：1.00）。Tb.N 被高估（7.47%，R2：0.99），Tb.Th 被略微低估（-4.20%，R2：0.98）。该技术具有可重复性，PE%CV 介于 1.96%（SMI）和 7.88%（Conn.D）之间。在以 82μm 分辨率进行 HR-pQCT 测量的 205 例前臂骨折或无骨折的临床研究中，该技术在所有参数上（除了小梁厚度）都能敏感地反映组间差异（p<0.05）。总之，我们证明了过采样能够保留 HR-pQCT 扫描的骨形态计量学，并且具有可重复性和对组间差异的敏感性。过采样可用于研究 HR-pQCT 图像的分辨率依赖性，并更深入地了解这种成像方式。
