Goodsitt M M, Rosenthal D I
Department of Radiology, Massachusetts General Hospital, Boston.
Invest Radiol. 1987 Oct;22(10):799-810. doi: 10.1097/00004424-198710000-00006.
Quantitative CT (QCT) has become a popular method for estimating bone mineral content. In addition, QCT can be used to estimate the fat content of trabecular bone. Although the latter has received little attention, it may prove to be clinically significant. Using a set of custom-built, tissue-mimicking plastic inserts in an anthropomorphic phantom, we tested a variety of methods for estimating mineral and fat content. We also investigated the influence of patient size, reconstruction circle size, and reference phantom choice on the accuracy of the results. Best estimates were obtained when there was a match between patient and reconstruction circle size. Single-energy methods yielded the best estimates of mineral content for inserts that did not contain fat, and dual-energy methods yielded the best estimates for inserts that contained fat. A dual-energy method that we developed was best in estimating the mineral and fat content of the latter inserts. We found that an external calibration reference phantom containing aqueous solutions of K2HPO4 could be used satisfactorily to estimate the mineral content of trabecular bone mimicking inserts; however, more representative materials must be used for accurate estimates of fat content.
定量CT（QCT）已成为估算骨矿物质含量的常用方法。此外，QCT还可用于估算小梁骨的脂肪含量。尽管后者很少受到关注，但可能具有临床意义。我们在一个仿真人体模型中使用一组定制的、模仿组织的塑料插件，测试了多种估算矿物质和脂肪含量的方法。我们还研究了患者体型、重建视野大小和参考模型选择对结果准确性的影响。当患者体型与重建视野大小相匹配时，能获得最佳估算结果。单能方法对不含脂肪的插件能给出最佳的矿物质含量估算，双能方法对含脂肪的插件能给出最佳估算。我们开发的一种双能方法在估算后一种插件的矿物质和脂肪含量方面表现最佳。我们发现，含有磷酸氢二钾水溶液的外部校准参考模型可令人满意地用于估算模仿小梁骨的插件的矿物质含量；然而，要准确估算脂肪含量，必须使用更具代表性的材料。
