Kaymakci B, Wark J D
University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Victoria, Australia.
Bone Miner. 1994 Jun;25(3):231-46. doi: 10.1016/s0169-6009(08)80241-3.
An Hologic QDR 1000-W dual energy X-ray absorptiometer (DXA) was used to make a densitometric evaluation and to optimize ex vivo scanning and analysis conditions for excised sheep bones. Articulated lumbar spines and femora, removed at autopsy from eight 1-2-year-old cross-bred merino ewes, were studied using standard lumbar spine and hip protocols (version 4.20). Spine data were analysed with the ultra-high resolution (UHR) protocol (version 4.25). Preliminary hip measurements also were made using the lumbar spine (version 4.20) and scoliosis protocols (version 4.25). Bone mineral density (BMD) precision for the total hip (n = 5) was 0.4% using version 4.20, and 0.8% using the scoliosis protocol (version 4.25) but was 1.2-3.4% for femoral sub-regions. Precision for the lumbar spine was 0.8% (version 4.20). There was considerable variation in BMD and bone mineral content (BMC) at the same site between animals. Right and left hip BMD were highly correlated (r = 0.98, P < 0.00001). Measurement variables evaluated to determine the optimal conditions included: Hologic scanning protocols, depth of water immersion of bone and dimensions of the region of interest. Accuracy was determined by ashing. Use of the scoliosis protocol (version 4.25) gave the best results for proximal femur measurement. Measured BMC decreased by 4.4% as the water depth increased from 0 to 22.5 cm. At 5 cm water, BMC accuracy was 99% for the total hip, and BMD precision values (n = 3) were 0.3% (total hip) and 0.4% (femoral neck, trochanteric region and femoral shaft). The much-improved precision was attributed to use of a positioning device and to optimizing of the depth of water immersion. Rib segments (length 2.5 cm) were measured using the ultra-high resolution protocol (version 4.25). BMC accuracy determined using 6 ribs was best (100 +/- 2%) at 5 cm water. BMD precision (n = 5) was best (0.3%) at 0 cm water depth and was 0.5% at 4.5 cm water depth. Rib sample BMC (n = 15, 4.5 cm water depth) and ash weight were highly correlated (r = 0.985, P < 0.001). It is concluded that highly precise, accurate densitometry can be performed on excised small and large sheep bones. This technique will support studies evaluating the sheep as an animal model of human osteoporosis.
使用Hologic QDR 1000-W双能X线骨密度仪（DXA）对切除的绵羊骨骼进行密度测定评估，并优化离体扫描和分析条件。从8只1 - 2岁的杂交美利奴母羊尸体解剖中取出的关节腰椎和股骨，使用标准腰椎和髋部检测方案（版本4.20）进行研究。脊柱数据采用超高分辨率（UHR）方案（版本4.25）进行分析。还使用腰椎（版本4.20）和脊柱侧弯检测方案（版本4.25）对髋部进行了初步测量。使用版本4.20时全髋部（n = 5）的骨密度（BMD）精密度为0.4%，使用脊柱侧弯检测方案（版本4.25）时为0.8%，但股骨亚区域的精密度为1.2 - 3.4%。腰椎的精密度为0.8%（版本4.20）。动物之间同一部位的骨密度和骨矿物质含量（BMC）存在相当大的差异。右髋和左髋的骨密度高度相关（r = 0.98，P < 0.00001）。为确定最佳条件而评估的测量变量包括：Hologic扫描方案、骨骼水浸深度和感兴趣区域的尺寸。通过灰化确定准确性。使用脊柱侧弯检测方案（版本4.25）对股骨近端测量的结果最佳。随着水深从0增加到22.5 cm，测量的BMC下降了4.4%。在5 cm水深时，全髋部的BMC准确性为9 .9%，BMD精密度值（n = 3）为0.3%（全髋部）和0.4%（股骨颈、转子区和股骨干）。精密度的大幅提高归因于使用了定位装置和优化了水浸深度。使用超高分辨率方案（版本4.25）测量肋骨段（长度2.5 cm）。在5 cm水深时，使用6根肋骨确定的BMC准确性最佳（100±2%）。在0 cm水深时BMD精密度（n = 5）最佳（0.3%），在4.5 cm水深时为0.5%。肋骨样本的BMC（n = 15，4.5 cm水深）和灰重高度相关（r = 0.985，P < 0.001）。得出结论，可以对切除的绵羊大小骨骼进行高精度、准确的密度测定。该技术将支持评估绵羊作为人类骨质疏松症动物模型的研究。
