Nagy Tim R, Johnson Maria S
Division of Physiology and Metabolism, Department of Nutrition Sciences, and the Clinical Nutrition Research Center, The University of Alabama at Birmingham, Birmingham, AL 35294-3360, USA.
Int J Body Compos Res. 2004 Jan 1;1(4):155-160.
Peripheral quantitative computed tomography (pQCT) was used to determine percent body fat in mice, and relative liver fat in lemmings fasted for 0, 6, 12 or 18 hours to induce a wide range of liver fat content. Accuracy of the pQCT was determined by comparing pQCT-derived fat to that from chemical extraction using 30 male mice (whole body) and 26 female lemmings (liver only). To determine whether pQCT could measure changes in liver fat (%) in live animals, two groups of lemmings were scanned on 4 consecutive days under anesthesia. Controls (n = 3) had ad libitum access to food, whereas the fasted group (n = 5) was deprived of food for 18 hr before being measured on day 2 and then refed. The coefficient of variation (CV) for determining percent body fat in mice using the pQCT was 3.9% (±1.8 SD). Percent body fat determined by pQCT significantly overestimated percent fat as measured by chemical extraction (14.5 ± 3.2 vs 12.3 ± 2.9% respectively, P < 0.01, mean ± SD). However, percent body fat by pQCT was highly related to chemical extraction percent fat (r = 0.95, P < 0.001). The liver attenuation values from pQCT were highly related to percent liver fat (r=0.98, P<0.001) in lemmings. The technique showed excellent precision with a CV of 0.3 ± 0.1%. The two groups (control vs fasted) did not differ in their percent liver fat on day 1 (5.4% vs 5.8%). On day 2 the fasted group had a significantly higher percent liver fat than controls (5.9% vs 17.3%; p<0.05). Following refeeding, there were no significant group differences in percent liver fat on days 3 and 4. Our data indicate that pQCT has good accuracy and precision for determining percent body fat, and liver fat in small animals and can be used to track changes in liver fat over time.
采用外周定量计算机断层扫描（pQCT）测定小鼠体脂百分比，并测定禁食0、6、12或18小时的旅鼠的相对肝脏脂肪含量，以诱导出广泛的肝脏脂肪含量范围。通过比较30只雄性小鼠（全身）和26只雌性旅鼠（仅肝脏）的pQCT衍生脂肪与化学提取法得到的脂肪，来确定pQCT的准确性。为了确定pQCT是否能够测量活体动物肝脏脂肪（%）的变化，两组旅鼠在麻醉状态下连续4天进行扫描。对照组（n = 3）可自由进食，而禁食组（n = 5）在第2天测量前禁食18小时，然后再喂食。使用pQCT测定小鼠体脂百分比的变异系数（CV）为3.9%（±1.8标准差）。pQCT测定的体脂百分比显著高估了化学提取法测得的脂肪百分比（分别为14.5±3.2%和12.3±2.9%，P < 0.01，均值±标准差）。然而 pQCT测定的体脂百分比与化学提取法测得的脂肪百分比高度相关（r = 0.95，P < 0.001）。旅鼠肝脏的pQCT衰减值与肝脏脂肪百分比高度相关（r = 0.98，P < 0.001）。该技术显示出极佳的精密度，CV为0.3±0.1%。两组（对照组与禁食组）在第1天的肝脏脂肪百分比无差异（5.4%对5.8%）。在第2天，禁食组的肝脏脂肪百分比显著高于对照组（5.9%对17.3%；p < 0.05）。再喂食后，第3天和第4天两组的肝脏脂肪百分比无显著差异。我们的数据表明，pQCT在测定小动物的体脂百分比和肝脏脂肪方面具有良好的准确性和精密度，可用于追踪肝脏脂肪随时间的变化。
