Wang Z M, Visser M, Ma R, Baumgartner R N, Kotler D, Gallagher D, Heymsfield S B
Obesity Research Center, St. Luke's-Roosevelt Hospital, College of Physicians and Surgeons, Columbia University, New York 10025, USA.
J Appl Physiol (1985). 1996 Mar;80(3):824-31. doi: 10.1152/jappl.1996.80.3.824.
Although skeletal muscle (SM) is a major body component, whole body measurement methods remain limited and inadequately investigated. The aim of the present study was to evaluate the Burkinshaw in vivo neutron activation analysis (IVNA)-whole body 40K-counting and dual-energy X-ray absorptiometry (DXA) methods of estimating SM by comparison to adipose tissue-free SM measured using multiscan computerized axial tomography (CT). In the Burkinshaw method the potassium-to-nitrogen ratios of SM and non-SM lean tissue are assumed constant; in the DXA method the ratio of appendicular SM to total SM is assumed constant at 0.75. Seventeen healthy men [77.5 +/- 13.8 (SD) kg body wt] and eight men with acquired immunodeficiency syndrome (AIDS; 65.5 +/- 7.6 kg) completed CT, IVNA, and DXA studies. SM measured by CT was 34.4 +/- 6.2 kg for the healthy subjects and 27.2 +/- 4.0 kg for the AIDS patients. Compared with CT, the Burkinshaw method underestimated SM by an average of 6.9 kg (20.1%, P = 0.0001) and 6.3 kg (23.2%, P = 0.01) in the healthy men and the men with AIDS, respectively. The DXA method minimally overestimated SM in both groups (2.0 kg and 5.8% in healthy men, P = 0.001; 1.4 kg and 5.1% in men with AIDS, P = 0.16). This overestimate could be explained by a higher actual than assumed ratio of DXA-measured appendicular SM to total body SM (actual = 0.79 +/- 0.05, assumed = 0.75). The current study results reveal that large errors are present in the Burkinshaw SM method and that substantial refinements in the models that form the basis of this IVNA approach are needed. The model on which the DXA-SM method is based also needs further minor refinements, but this is a promising in vivo approach because of less radiation exposure and lower cost than the IVNA and CT methods.
尽管骨骼肌（SM）是身体的主要组成部分，但全身测量方法仍然有限且研究不足。本研究的目的是通过与使用多层计算机断层扫描（CT）测量的无脂肪组织的SM进行比较，评估Burkinshaw体内中子活化分析（IVNA）-全身40K计数和双能X线吸收法（DXA）估算SM的方法。在Burkinshaw方法中，假设SM和非SM瘦组织的钾氮比恒定；在DXA方法中，假设附属SM与总SM的比例恒定为0.75。17名健康男性[体重77.5±13.8（标准差）kg]和8名获得性免疫缺陷综合征（AIDS）男性患者（体重65.5±7.6 kg）完成了CT、IVNA和DXA研究。健康受试者通过CT测量的SM为34.4±6.2 kg，AIDS患者为27.2±4.0 kg。与CT相比，Burkinshaw方法在健康男性和AIDS男性患者中分别平均低估SM 6.9 kg（20.1%，P = 0.0001）和6.3 kg（23.2%，P = 0.01）。DXA方法在两组中均轻微高估了SM（健康男性中高估2.0 kg和5.8%，P = 0.001；AIDS男性患者中高估1.4 kg和5.1%，P = 0.16）。这种高估可以用DXA测量的附属SM与全身SM的实际比例高于假设比例来解释（实际比例 = 0.79±0.05，假设比例 = 0.75）。当前研究结果表明，Burkinshaw SM方法存在较大误差，构成这种IVNA方法基础的模型需要大幅改进。DXA-SM方法所基于的模型也需要进一步进行小的改进，但这是一种有前景的体内方法，因为与IVNA和CT方法相比，其辐射暴露更少且成本更低。
