Department of Radiology, Maastricht University Medical Center, Maastricht University Medical Center, 6202 AZ Maastricht, The Netherlands.
Invest Radiol. 2013 Oct;48(10):708-14. doi: 10.1097/RLI.0b013e31829363b8.
The objective of this study was to explore the use of magnetic resonance imaging (MRI) to identify and quantify active brown adipose tissue (BAT) in adult humans. 2-Deoxy-2-[F]fluoro-D-glucose (FDG) positron emission tomography (PET) combined with computed tomography was used as a reference method to identify active BAT depots and to guide the MRI data analysis.
The ethics committee of the institute approved the protocol, and all participants provided written informed consent before participation. Both PET combined with computed tomography and MRI of BAT were performed in 11 healthy volunteers. Brown adipose tissue was activated by cooling the participants using a dedicated water-perfused suit. For the MRI examination of BAT, water-fat imaging and dynamic T2* imaging were performed at an effective temporal resolution of 2 minutes per volume. Water-fat images were derived from a multiecho MRI sequence using the Dixon technique.
2-Deoxy-2-[F]fluoro-D-glucose-PET identified active BAT in 8 of the 11 participants. Water-fat MRI showed that BAT depots had a fat fraction of 65.2% (7.0%) compared with 81.5% (5.4%) for the subcutaneous white adipose tissue (paired difference of 16.3% [4.9%]; P < 0.05). Dynamic T2* imaging during cold stimulation revealed signal fluctuations that were sensitive to BAT activation. The presence of these components correlated with BAT activation quantified from FDG-PET (r = 0.63; P < 0.05).
Although FDG-PET has superior contrast for identifying active BAT, the MRI temporal resolution provides insight in activation dynamics. In addition, the flexibility of MRI allows for simultaneous mapping of tissue fat content and functional responses. The results indicate that MRI is a promising addition to PET for the identification of BAT and its activity responses to stimulation. An MRI-based methodology to quantify BAT activity is a highly desirable step in addressing the role of BAT in obesity disorders.
本研究旨在探索磁共振成像（MRI）在识别和量化成人棕色脂肪组织（BAT）活性中的应用。2-脱氧-2-[F]氟-D-葡萄糖（FDG）正电子发射断层扫描（PET）结合计算机断层扫描被用作识别活性 BAT 储备并指导 MRI 数据分析的参考方法。
该研究所的伦理委员会批准了该方案，所有参与者在参与前均提供了书面知情同意书。11 名健康志愿者均进行了 FDG-PET 结合计算机断层扫描和 BAT 的 MRI 检查。通过专用水灌注服冷却参与者以激活棕色脂肪组织。对于 BAT 的 MRI 检查，使用基于 Dixon 技术的多回波 MRI 序列进行水脂成像和动态 T2*成像，有效时间分辨率为每体积 2 分钟。水脂图像源自多回波 MRI 序列，使用 Dixon 技术。
11 名参与者中有 8 名 FDG-PET 识别出活性 BAT。水脂 MRI 显示，BAT 储备的脂肪分数为 65.2%（7.0%），而皮下白色脂肪组织的脂肪分数为 81.5%（5.4%）（配对差值为 16.3%[4.9%]；P<0.05）。冷刺激期间的动态 T2*成像显示出对 BAT 激活敏感的信号波动。这些成分的存在与 FDG-PET 量化的 BAT 激活相关（r=0.63；P<0.05）。
尽管 FDG-PET 对识别活性 BAT 具有更高的对比度，但 MRI 的时间分辨率提供了对激活动力学的深入了解。此外，MRI 的灵活性允许同时对组织脂肪含量和功能反应进行映射。结果表明，MRI 是识别 BAT 及其对刺激的活性反应的 PET 的有前途的补充。一种基于 MRI 的量化 BAT 活性的方法是解决 BAT 在肥胖症中的作用的高度理想的步骤。
