Rapid MRI Measures of Absolute Fat Mass in Adipose Tissue and Organs

描述（由申请人提供）：肥胖在美国是一种日益严重的流行病，影响着儿童、青少年和成人的多种健康结果。越来越多的数据表明，肥胖与健康状况不佳之间的联系与特定区域的脂肪堆积（例如腹腔内的内脏脂肪）和/或脂肪渗入肝脏、胰腺和其他器官有关。体内内脏脂肪和器官脂肪的定量通常是通过磁共振成像（MRI）进行的。MRI非常适合这一目的，因为它本质上是三维的，提供了一种分离水和脂肪的敏感机制，并且不涉及电离辐射，具有超低风险的无限重复性。尽管MRI在肥胖研究中的应用越来越频繁，但其直接量化脂肪量的能力尚未得到发展和验证。目前的测量方法要么是相对的（如脂肪信号分数），要么是间接的（如脂肪组织体积）。此外，目前的MRI方案受到高成本的磁铁时间，长时间和/或多次屏气的限制，不舒服，降低了准确性。本提案的目的是克服这些限制，开发并充分验证一种新的基于mri的方法，用于快速量化整个腹部的脂肪量。具体来说，我们将(1)开发信号校准程序，允许在逐体素的基础上定量脂肪量，(2)通过比较脂肪组织、整个器官和肌肉中的脂肪量测量结果，与死后化学分析（目前的金标准），评估猪体内这种定量的准确性。这项提议的意义在于开发了一种新的、有前途的、具有潜在成本效益的工具来评估脂肪量和器官脂肪浸润。该方法利用了快速MRI脂肪-水分离、校准扫描和动物模型严格验证方面的最新进展。创新之处在于应用新的信号模型和校准方案，从信号强度定量脂肪质量。研究人员包括两名具有心血管疾病评估快速MRI技术开发专业知识的MR物理学家和一名具有身体成分技术验证专业知识的肥胖研究人员。南加州大学的环境为研究提供了大量的访问-专用成像设备，动物研究支持和基础设施，用于这种转化研究。公共卫生相关性：在美国，腹部肥胖是一个日益严重的问题，它与脂肪肝、心脏病和2型糖尿病等疾病的风险增加有关。该提案将开发一种新的基于磁共振成像的非侵入性测试，该测试可以确定腹部脂肪的质量和位置，包括关键器官，并可能成为肥胖研究的有用工具。

DESCRIPTION (provided by applicant): Obesity is a growing epidemic in the United States, affecting multiple health outcomes in children, adolescents, and adults. Increasing data suggest that the link between obesity and poor health outcome is related to buildup of fat in specific areas (e.g. visceral fat inside the abdominal cavity) and/or infiltration of fat into the liver, pancreas, and other organs. Quantification of visceral fat and organ fat in vivo is generally performed by magnetic resonance imaging (MRI). MRI is well suited for this purpose because it is inherently three-dimensional, provides a sensitive mechanism for separating water and fat, and involves no ionizing radiation, leading to indefinite repeatability with ultra-low risk. Although MRI is becoming more frequently used in obesity research, its ability to directly quantify fat mass has not yet been developed and validated. Current measurements are either relative (e.g. fat signal fraction) or indirect (e.g. adipose tissue volume). Moreover, current MRI protocols are limited by the high-cost of magnet time, and the long and/or multiple breath-holds that are uncomfortable and reduce accuracy. The objective of this proposal is to overcome these limitations and develop and fully validate a novel MRI-based method for the rapid quantification of fat mass throughout the abdomen. Specifically, we will (1) develop signal calibration procedures that allow for the quantification of fat mass on a voxel-by-voxel basis, and (2) evaluate the accuracy of this quantification in swine, by comparing measurements of fat mass in adipose tissue, whole organs, and muscle, with post-mortem chemical analysis (the current gold standard). The SIGNIFICANCE of this proposal lies in the development of a new, promising, and potentially cost-effective tool for assessing fat mass and organ fat infiltration. The APPROACH utilizes recent advances in rapid MRI fat-water separation, calibration scans, and rigorous validation in an animal model. The INNOVATION lies in the application of novel signal models and calibration schemes for quantifying fat mass from signal intensity. The INVESTIGATORS include two MR physicists with expertise in the development of rapid MRI techniques for cardiovascular disease assessment and an established obesity researcher with expertise in the validation of body composition techniques. The ENVIRONMENT at USC provides generous access to research- dedicated imaging facilities, animal research support, and infrastructure for this translational research. PUBLIC HEALTH RELEVANCE: Abdominal obesity is a growing problem among Americans, and is linked with increased risks of fatty liver disease, heart disease, and type-2 diabetes, among other things. This proposal will develop a new non-invasive test based on magnetic resonance imaging that determines the mass and location of fat within the abdomen, including critical organs, and may potentially be a useful tool in obesity research.