Goodsitt M M, Hoover P, Veldee M S, Hsueh S L
Department of Radiology, University of Washington, Seattle.
Invest Radiol. 1994 Jul;29(7):695-704. doi: 10.1097/00004424-199407000-00006.
The authors have been developing a dual-energy quantitative computed tomography (DE-QCT) technique that requires calibration standards that mimic the x-ray attenuation properties of bone, red marrow, and yellow marrow. To resolve questions regarding the compositions of red and yellow marrow that appear in the literature, the authors performed chemical analyses of bone marrow samples. The newly derived compositions were used in a simulation study to test the accuracy of the DEQCT technique.
Red marrow samples were extruded from the vertebrae of cadavers of young boys. Yellow marrow samples were removed directly from the femurs of cadavers of elderly women. The fat, protein, water, and mineral contents of these samples were determined. The compositions of 12 mixed marrow samples extruded from cadaver vertebrae also were measured. A computer simulation study was performed in which calibration standards with the new compositions were employed to estimate the fat and bone contents of spongiosas containing the 12 mixed marrows.
The red marrow samples contained 3% to 6% fat, 6% to 8% protein, 82% to 86% water, and 0.5% to 1% mineral. The yellow marrow samples contained 71% to 92% fat, 1% to 2% protein, 7% to 26% water, and 0.2% to 0.4% mineral. The simulation study yielded good results in three cases and mediocre to poor results in nine cases. An alternative approach was tried in which an average fat-free marrow was derived from the compositions of the 12 mixed marrows, and this substance, fat, and bone were used as the calibration standards. The DEQCT technique with these standards was applied to simulated spongiosas containing the 12 original mixed marrows plus nine additional mixed marrows. All of the estimates were in good agreement with the true compositions. The rms error of the mass fractions of fat was 0.03, and the rms error of the bone concentrations was 3.7 mg/mL.
作者一直在开发一种双能定量计算机断层扫描（DE-QCT）技术，该技术需要校准标准物来模拟骨骼、红骨髓和黄骨髓的X射线衰减特性。为了解决文献中出现的关于红骨髓和黄骨髓成分的问题，作者对骨髓样本进行了化学分析。新得出的成分被用于模拟研究，以测试DEQCT技术的准确性。
从年轻男孩尸体的椎骨中挤出红骨髓样本。直接从老年女性尸体的股骨中取出黄骨髓样本。测定这些样本的脂肪、蛋白质、水和矿物质含量。还测量了从尸体椎骨中挤出的12个混合骨髓样本的成分。进行了一项计算机模拟研究，其中采用具有新成分的校准标准物来估计含有这12种混合骨髓的海绵骨的脂肪和骨含量。
红骨髓样本含有3%至6%的脂肪、6%至8%的蛋白质、82%至86%的水和0.5%至1%的矿物质。黄骨髓样本含有71%至92%的脂肪、1%至2%的蛋白质、7%至26%的水和0.2%至0.4%的矿物质。模拟研究在3个案例中取得了良好结果，在9个案例中取得了中等至较差的结果。尝试了另一种方法，即从12个混合骨髓的成分中得出平均无脂肪骨髓，并将这种物质、脂肪和骨用作校准标准物。将具有这些标准物的DEQCT技术应用于含有12个原始混合骨髓以及另外9个混合骨髓的模拟海绵骨。所有估计值与真实成分高度一致。脂肪质量分数的均方根误差为0.03，骨浓度的均方根误差为3.7 mg/mL。
