基于活体 MRI 的棕色脂肪组织测量在婴儿中的实际应用。
Practical application of in vivo MRI-based brown adipose tissue measurements in infants.
机构信息
Pennington Biomedical Research Center, Baton Rouge, Louisana, USA.
Hyperfine Research, Inc., Guilford, Connecticut, USA.
出版信息
Obesity (Silver Spring). 2021 Oct;29(10):1676-1683. doi: 10.1002/oby.23237.
OBJECTIVE
The role of brown adipose tissue (BAT) in infant metabolism remains poorly understood, primarily because of the inherent limitation of positron emission tomography/computed tomography imaging to measure BAT, which is not suitable for infants. The aims of this method development study were to assess the feasibility, intra-rater reliability, interscan repeatability, and physiological relevance of measuring BAT in infants using magnetic resonance imaging (MRI).
METHODS
A total of 10 nonsedated infants (mean age, 22.6 [1.3] days old) completed two 3-T MRI exams using chemical-shift-encoded water-fat scans 6.2 (2.8) days apart. Candidate BAT voxels in the supraclavicular region were identified based on fat signal fraction (FSF). The volumes of BAT depots were manually traced, and FSF was calculated. Whole-body fat mass was determined using dual-energy x-ray absorptiometry.
RESULTS
Images were successfully obtained from 19 of 20 (95%) attempted scans. The mean BAT volume was 5.41 (SD 1.1) cm , and the mean FSF was 16.41% (SD 3.3%). Intra-rater analysis showed good reliability with no systemic bias (proportional bias for volume: p = 0.19; FSF: p = 0.30). Test-retest for interscan repeatability was good (intraclass correlation coefficients for volume: 0.92, p = 0.001 and intraclass correlation coefficients for FSF: 0.93, p < 0.001). FSF was inversely related to fat-free mass (r = -0.69, p = 0.03).
CONCLUSIONS
This method development study supports the use of MRI to obtain reliable and quantitative measurements of BAT volume in infants.
目的
棕色脂肪组织（BAT）在婴儿代谢中的作用仍知之甚少，主要是因为正电子发射断层扫描/计算机断层扫描成像测量 BAT 的固有局限性，这种方法不适合婴儿。本方法开发研究的目的是评估使用磁共振成像（MRI）测量婴儿 BAT 的可行性、内部观察者可靠性、扫描间可重复性和生理相关性。
方法
共有 10 名未镇静的婴儿（平均年龄 22.6±1.3 天）在相隔 6.2（2.8）天的两次 3-T MRI 检查中使用化学位移编码水脂扫描。根据脂肪信号分数（FSF）确定锁骨上区域的候选 BAT 体素。手动追踪 BAT 沉积物的体积，并计算 FSF。使用双能 X 射线吸收法确定全身脂肪量。
结果
20 次尝试扫描中的 19 次成功获得图像。BAT 体积的平均值为 5.41（SD 1.1）cm ，FSF 的平均值为 16.41%（SD 3.3%）。内部观察者分析显示，无系统偏差（体积的比例偏差：p=0.19；FSF：p=0.30），具有良好的可靠性。扫描间可重复性测试良好（体积的组内相关系数：0.92，p=0.001；FSF 的组内相关系数：0.93，p<0.001）。FSF 与去脂体重呈负相关（r=-0.69，p=0.03）。
结论
这项方法开发研究支持使用 MRI 获得婴儿 BAT 体积的可靠和定量测量。
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