Augat P, Gordon C L, Lang T F, Iida H, Genant H K
Department of Radiology, University of California-San Francisco, USA.
Phys Med Biol. 1998 Oct;43(10):2873-83. doi: 10.1088/0031-9155/43/10/015.
In order to assess the accuracy of peripheral QCT (Stratec XCT 960) we analysed scans of the European Forearm Phantom and another phantom consisting of K2HPO4 encased in aluminium tubes to simulate cortical walls. Additionally 14 cadaveric forearm specimen scans were compared to CT scans acquired on a GE9800Q. The accuracy for density assessment of the European Forearm Phantom was better than 3%. A small increase in density was observed with increasing thickness of the aluminium wall (10% for each mm). Density measurements within the wall were confounded by limited spatial resolution. For a thickness of less than 4 mm, the density within the wall was underestimated by up to 40%. The measurement of mineral content was not influenced by this effect and showed an accuracy error of less than 6%. The agreement of density measurements on the different CT systems was very strong (R2 > 0.96; RMSE < 6.2%). Our findings suggest that the Stratec pQCT scanner very accurately measures volumetric trabecular and total bone mineral densities at the distal radius while the assessment of cortical density is associated with considerable inaccuracies due to limited spatial resolution.
为评估外周定量CT（Stratec XCT 960）的准确性，我们分析了欧洲前臂模型以及另一个由包裹在铝管中的磷酸氢二钾组成以模拟皮质骨壁的模型的扫描结果。此外，还将14个尸体前臂标本的扫描结果与在GE9800Q上获取的CT扫描结果进行了比较。欧洲前臂模型密度评估的准确性优于3%。随着铝壁厚度增加，观察到密度有小幅增加（每毫米增加10%）。壁内密度测量因空间分辨率有限而受到干扰。对于厚度小于4毫米的情况，壁内密度被低估高达40%。矿物质含量的测量不受此影响，显示出的准确性误差小于6%。不同CT系统上密度测量的一致性非常强（R2 > 0.96；均方根误差 < 6.2%）。我们的研究结果表明，Stratec外周定量CT扫描仪能非常准确地测量桡骨远端的体积骨小梁和总骨矿物质密度，而由于空间分辨率有限，皮质骨密度评估存在相当大的不准确性。
