COMPARISON OF BODY COMPOSITION ASSESSMENT BY DUAL ENERGY X-RAY ABSORPTIOMETRY

双能 X 射线吸收法身体成分评估的比较

• 批准号: 7606632
• 负责人: DAN M COOPER
• 金额: $ 0.93万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2007-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7606632
• 关键词: Acoustics; Adult; Air; Alkaline Phosphatase; Animals; Anthropometry; Architecture; Arts; Biochemical; Biolectric Impedance; Body Composition; Body Regions; Bone Density; Bone Mineral Contents; Cardiac; Child; Clinical; Complex; Computer Retrieval of Information on Scientific Projects Database; Data; Development; Diagnosis; Disadvantaged; Dose; Dual-Energy X-Ray Absorptiometry; Elasticity; Electric Conductivity; Energy Metabolism; Environment; Epimysium; Evaluation; Event; Exercise; Fatty acid glycerol esters; Femur; Fracture; Funding; Gene Mutation; Goals; Grant; Growth; Human; Imagery; Infant; Institution; Intervention; Intervention Studies; Ionizing radiation; Journals; Life; Literature; Magnetic Resonance Imaging; Measurement; Measures; Medicine; Metabolic Bone Diseases; Methods; Minerals; Modeling; Morphologic artifacts; Movement; Muscle; Neonatal; New England; Newborn Infant; Outcome; Patients; Perinatal; Physiologic calcification; Plethysmography; Potassium; Pregnancy; Premature Infant; Process; Property; Prospective Studies; Purpose; Rattus; Reporting; Research; Research Design; Research Personnel; Resources; Respiratory Diaphragm; Risk; Scanning; Serum; Skeletal Muscle; Skin; Skinfold Thickness; Son of Sevenless Proteins; Source; Spectrum Analysis; Structure; Techniques; Thick; Third Pregnancy Trimester; Time; Tissues; Tracer; Ultrasonography; United States National Institutes of Health; Work; attenuation; base; bone; bone strength; clinically relevant; concept; cost; density; humerus; indexing; insight; instrument; muscle hypertrophy; myostatin; neonate; physical property; sound; subcutaneous; validation studies

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Understanding the dynamic changes in body composition in the perinatal and early neonatal period has been a major of focus of neonatal research for over a century. At no time in the life of humans is energy expenditure for growth so large and the process of new tissue development so rapid. Measurements of body composition and energy expenditure are essential if we are to gain insights into the mechanisms of how interventions like assisted exercise influence body composition in premature babies. For many reasons involving technical, ethical, and feasibility factors, making accurate measurements of both body composition and energy expenditure has remained a singular challenge in this field (1), and the armamentarium available for these important indexes of growth are limited in the context of the newborn. Current techniques include: anthropometry, total body electrical conductance, tracer dilution, total body potassium, bioelectrical impedance, magnetic resonance imaging and spectroscopy, acoustic plethysmography, air displacement, Dual Energy X-ray Absorptiometry (DEXA), Quantitative ultrasound (QUS), and regional ultrasonography of skeletal muscle and fat mass (2-8). Of these methods, some combination of DEXA, QUS, and regional ultrasonography is the most promising and feasible. QUS and muscle ultrasound are noninvasive, can be performed at the bedside (no need to transport the infant), have no ionizing radiation, and can be performed multiple times during the course of an intervention study. However, the determinants of QUS are complex and their relationship to bone structure and density have yet to be fully clarified. Both QUS and muscle sonography provide data on regions of the body, and it may not be possible to extrapolate the regional data to total body bone mineral density or muscle mass-a key outcome when considering the impact of assisted exercise. In contrast, DEXA can measure both bone mineralization and body composition, and these measurements can be made for the whole body and regionally. But the disadvantages of DEXA are also substantial: the baby must be studied with a minimum of movement artifact (often, a daunting challenge for a typical, unsedated neonate), and the baby must be transported to the DEXA unit rendering it difficult to perform multiple measurements in a growing, hospitalized premature baby. Finally, DEXA does involve a minimal (probably negligent) dose of ionizing radiation which can hinder recruitment. Thus, to optimize our measurements of body composition and bone mineralization in the prospective study, we plan a Methods Validation Study designed to compare the three following techniques: " DEXA " Bone Quantitative Ultrasound " Muscle Ultrasound As a result of this study, we will be able to determine the optimal combination of these three methods, or, if possible, information from QUS and muscle ultrasonagraphy alone are powerful enough to meet our objectives. DEXA: is a scanning technique that measures the differential attenuation of two x-rays as they pass through the body. DEXA has become the state-of-the-art method to estimate body composition for research purposes in adult humans [e.g., (9)]. DEXA scans measure total and regional body bone mineral content (BMC), bone mineral density (BMD), fat-free mass (FFM), and fat mass (FM). DEXA scanning has been used in infants, and our Project Consultant, Dr. Winston Koo, has done much of the pioneering work in establishing the instrumental, clinical, and analaytical approaches necessary for reproducible and accurate use of DEXA scanning for the measurement of body composition in infants (10; 11). QUS: Metabolic bone disease is a relatively common event in preterm infants because the greatest period of bone mineral accretion ordinarily occurs during the last trimester of pregnancy, and this is difficult to reproduce in the extrauterine environment (12; 13). Currently, its diagnosis is based primarily on biochemical evaluation of serum alkaline phosphatase and radiological evidence of osteopenia and/or fractures, and in some cases, on measurements of bone mineralization by DEXA (14). The use of DEXA in the clinical setting, however, is limited by its relatively high cost and the need to transport the patient to the instrument, making it relatively unfeasible for very small or sick infants, i.e., the very ones most at risk of developing metabolic bone disease. QUS measurement of bone SOS has recently become a viable alternative, and there is a substantial body of literature demonstrating its utility in assessing bone strength in infants (15-20), children (21) and adults (22; 23). QUS is predicated on the concept that the propagation of sound waves through a medium depends upon the physical properties of that medium (Figure 3). Therefore, the denser the medium, the faster the sound waves propagate through it. In addition to bone density, bone SOS is also determined by other bone properties, such as cortical thickness, elasticity and micro-architecture, and may, in conjunction with DEXA, provide a more clinically relevant picture of bone strength (24; 25). QUS is relatively inexpensive, portable, noninvasive, involves no ionizing radiation, and has, in initial studies, been shown to correlate accurately with measurements by DEXA (26; 27). Muscle Ultrasound: A major goal of this study is to assess muscle and fat mass in the newborn and preterm infant. Ultrasound (US) imaging is a useful technique for visualization of skeletal muscle tissue (28), and has been extensively used in adults (29) and more recently in children (30) and infants (31) [where it is increasingly used to measure volume of the diaphragm as well (32)]. US imaging is a portable, noninvasive method that does not involve ionizing radiation. Clear visualization of the muscle boundaries is possible since the epimysium surrounding the muscle is highly reflective and the bone echo is strong and distinct. This gives the added advantage of directly quantitating lean muscle mass compared to more indirect methods like skinfold thickness, which can include the skin and subcutaneous fat (33). In a recent New England Journal of Medicine report (34), muscle ultrasound was used to assess muscle hypertrophy in a baby with a myostatin gene mutation, and it has been used successfully to gauge cardiac and skeletal muscle mass in small animals such as the rat and small shorebirds (35; 36). A key question is whether regional measurement of bone strength or muscle/fat distribution, as will be done by the QUS and muscle ultrasound techniques, can be useful in gauging total body lean and fat distribution. We will be able to answer this question in the proposed Methods Validation Study. We have reason to be optimistic, for example, our Project Consultant Dr. Winston Koo and coworkers (37) showed in the piglet model that bone mineral content variables obtained from DEXA of the humerus and femur were highly correlated with whole body DEXA results.

该副本是利用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这不一定是调查员的机构。 了解围产期和新生儿早期的身体成分的动态变化已成为新生儿研究的重点。 人类生命中的任何时候都没有能量消耗如此大的生长，而新组织发育的过程如此迅速。 如果我们要深入了解辅助运动等干预措施如何影响早产婴儿的身体成分，那么人体成分和能量消耗的测量至关重要。 由于许多原因，涉及技术，道德和可行性因素，对身体成分和能量消耗进行准确的测量仍然是该领域的奇异挑战（1），并且在新生儿的背景下，可用于这些重要增长的武器库受到限制。 当前技术包括：人体测量法，总体电导，示踪剂稀释，全身钾，生物电阻阻抗，磁共振成像和光谱学，声学论文占空气占空气，空气位移，二元能量X射线X射线吸收仪（DEXA），DEXA），定量（QUS）和速度（QUS）和序列（QUS）和2级序曲（QUS），以及2级序列（QUS）和2次序列（QUS）和2级序列。 在这些方法中，DEXA，QUS和区域超声检查的某种组合是最有前途和可行的。 QUS和肌肉超声是无创的，可以在床边进行（无需运输婴儿），没有电离辐射，并且可以在干预研究的过程中多次进行。 但是，QUS的决定因素很复杂，它们与骨骼结构和密度的关系尚未得到充分阐明。 QUS和肌肉超声检查提供了有关人体区域的数据，并且在考虑辅助运动的影响时，可能无法将区域数据推断为总体骨矿物质密度或肌肉质量-A关键结果。 相比之下，DEXA可以测量骨矿化和身体成分，并且可以针对整个身体和区域进行这些测量。 但是DEXA的缺点也很重要：必须对婴儿进行最少的运动伪像（通常是典型的未经文章的新生儿的艰巨挑战），并且必须将婴儿运送到DEXA单元中，使其难以在成长中生长的，住院的早产婴儿中进行多次测量。 最后，DEXA确实涉及电离辐射的最小（可能疏忽），这可能会阻碍募集。 因此，为了优化我们对身体成分和骨矿化的测量，我们计划了一项方法验证研究，旨在比较以下三种技术： “ dexa 骨骼定量超声 “肌肉超声 这项研究的结果是，我们将能够确定这三种方法的最佳组合，或者（如果可能），仅QU和肌肉超声波处理的信息就足够强大，足以实现我们的目标。 DEXA：是一种扫描技术，可以测量两种X射线通过体内的差异衰减。 DEXA已成为成人人类研究目的的人体组成的最新方法[例如（9）]。 DEXA扫描测量总体骨矿物质含量（BMC），骨矿物质密度（BMD），无脂肪质量（FFM）和脂肪质量（FM）。 DEXA扫描已用于婴儿，我们的项目顾问Winston Koo博士在建立仪器，临床和分析方法方面做了许多开创性的工作，用于重复且准确地使用DEXA扫描以测量婴儿的身体成分（10; 11; 11; 11; 11; 11; 11）。 QUS：代谢骨病是早产儿相对常见的事件，因为通常在怀孕的最后三个月期间发生骨矿物质的最大时期，这在外部环境中很难繁殖（12; 13; 13）。目前，其诊断主要基于对血清碱磷酸酶的生化评估以及骨质减少症和/或骨折的放射学证据，在某些情况下，dexa的测量（14）。 但是，在临床环境中使用DEXA受到其相对较高的成本的限制，并且需要将患者运送到该仪器上，从而使其对非常小或病人的婴儿（即，它最有可能患有代谢骨病的风险。 骨SOS的QUS测量最近已成为一种可行的替代方法，并且有大量文献证明了其在评估婴儿（15-20），儿童（21）和成人（22; 23）的骨骼强度方面的效用。 QU是基于这样一个概念，即声波通过介质的传播取决于该介质的物理特性（图3）。因此，介质的密度，声波通过它传播的速度就越快。除骨密度外，骨SO还由其他骨骼特性（例如皮质厚度，弹性和微构造）确定，并且可能与Dexa结合使用，提供了骨骼强度的更临床相关的图片（24; 25）。 QUS相对便宜，便携，无创涉及无电离辐射，并且在初步研究中已证明与DEXA的测量非常相关（26; 27）。 肌肉超声检查：这项研究的主要目标是评估新生儿和早产儿的肌肉和脂肪肿块。超声（US）成像是一种可视化骨骼肌组织（28）的有用技术（28），并且已广泛用于成人（29）（29），最近在儿童（30）和婴儿（31）中使用（31）[越来越多地用于测量隔膜的体积（32）]。 US成像是一种便携式，无创方法，不涉及电离辐射。由于肌肉周围的附属物具有高度反射性，并且骨头回声强烈且独特，因此可以清楚地看到肌肉边界。与皮肤折叠厚度（包括皮肤和皮下脂肪）等更间接的方法相比，这给出了直接定量瘦肌肉质量的额外优势（33）。 在最近的新英格兰医学杂志（34）中，使用肌肉超声来评估患有肌生抑素基因突变的婴儿的肌肉肥大，并且已成功地用于衡量小动物（如大鼠和小shorebirds）的小动物的心脏和骨骼肌质量（35; 36）。 一个关键的问题是，像QUS和肌肉超声技术一样，骨骼强度或肌肉/脂肪分布的区域测量是否可以用于测量全身和脂肪分布。 我们将能够在拟议的方法验证研究中回答这个问题。 我们有理由保持乐观，例如，我们的项目顾问温斯顿·库（Winston Koo）和同事（37）在小猪模型中表明，从肱骨和股骨的dexa获得的骨矿物质含量变量与全身DEXA结果高度相关。