UCL Great Ormond Street Hospital Institute of Child Health, London, UK.
UCL Great Ormond Street Hospital Institute of Child Health, London, UK.
Bone. 2021 Feb;143:115713. doi: 10.1016/j.bone.2020.115713. Epub 2020 Oct 26.
Many chronic illnesses affect bone health, and commonly lead to mineralization abnormalities in young people. As cortical and trabecular bone may be differentially affected in certain diseases, an imaging technique that allows for detailed study of the bone structure is required. Peripheral quantitative computed tomography (pQCT) overcomes the limitations of dual energy X-ray absorptiometry (DXA) and is perhaps more widely available for use in research than bone biopsy. However, in contrast to DXA, where there are large reference datasets, this is not the case for pQCT.
Fifty-five children and young adults aged 7 to 30 years had the non-dominant tibia scanned at the 3% & 4% sites for trabecular bone mineral density and the 38% site for cortical bone mineral density and bone mineral content. Image acquisition and analysis was undertaken according to the protocols of two of the largest reference datasets for tibial pQCT. The Z-scores generated were compared to examine the differences between protocols and the differences from the expected median of zero in a healthy population.
The trabecular bone mineral density Z-scores generated by the two protocols were similar. The same was true for cortical mineral content Z-scores at the 38% site. Cortical bone mineral density was significantly different between protocols and likely affected by differences in the ethnicity of our cohort compared to the reference datasets. Only one reference dataset extended from childhood to young adulthood. Only trabecular bone mineral density, periosteal and endosteal circumference Z-scores from one methodology were not significantly biased when tested for deviation of the median from zero.
pQCT is a useful tool for studying trabecular and cortical compartments separately but, there are variations in pQCT scanning protocols, analysis methodology, and a paucity of reference data. Reference datasets may not be generalizable to local study populations, even when analysed using identical analysis protocols.
许多慢性疾病会影响骨骼健康，并常导致年轻人出现矿化异常。由于皮质骨和小梁骨在某些疾病中可能受到不同影响，因此需要一种能够详细研究骨骼结构的成像技术。外周定量计算机断层扫描（pQCT）克服了双能 X 射线吸收法（DXA）的局限性，并且在研究中比骨活检更广泛地可用。然而，与 DXA 相比，pQCT 没有大型参考数据集。
55 名 7 至 30 岁的儿童和年轻人，对非优势胫骨的 3%和 4%部位进行小梁骨矿物质密度扫描，38%部位进行皮质骨矿物质密度和骨矿物质含量扫描。根据两个最大的胫骨 pQCT 参考数据集之一的方案进行图像采集和分析。生成的 Z 分数用于比较不同方案之间的差异，以及与健康人群中零中位数的预期差异。
两个方案生成的小梁骨矿物质密度 Z 分数相似。38%部位的皮质骨矿物质含量 Z 分数也是如此。两个方案之间的皮质骨矿物质密度存在显著差异，这可能是由于我们的队列种族与参考数据集不同所致。只有一个参考数据集从儿童期扩展到成年早期。只有一种方法学的小梁骨矿物质密度、骨膜和骨内膜周长 Z 分数在测试中位数与零的偏差时没有显著偏差。
pQCT 是研究小梁骨和皮质骨的有用工具，但 pQCT 扫描方案、分析方法存在差异，参考数据也很少。参考数据集可能无法推广到当地研究人群，即使使用相同的分析方案进行分析。
