Department of Imaging and Interventional Radiology, Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong SAR.
Department of Medicine and Therapeutics, Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong SAR.
J Magn Reson Imaging. 2017 Sep;46(3):758-768. doi: 10.1002/jmri.25632. Epub 2017 Jan 16.
To develop a technique for the separation and quantification of brown adipose tissue (BAT) and white adipose tissue (WAT) using fat fraction and T2* intensity based on the Gaussian mixture model (GMM).
Chemical-shift water-fat and T2* images were acquired at the neck, supraclavicular, interscapular, and paravertebral regions in 24 volunteers (Obese: n = 12, female/male = 6/6, body mass index [BMI] = 31.3 ± 2.3 kg/m , age = 16.1 ± 0.6; Normal weight: n = 12, female/male = 6/6, BMI = 21.2 ± 2.4 kg/m , age = 12.9 ± 2.4) using a 3T scanner with the chemical-shift water-fat mDixon sequence. BAT and WAT were clustered based on the Gaussian mixture model using the expectation-maximization algorithm. Results and reproducibility were compared and assessed using independent t-tests and intraclass correlation coefficient.
BAT in obese participants was predominately found at the supraclavicular region and in normal-weight participants it was more scattered and distributed in interscapular-supraclavicular, axillary, and spine regions. Absolute volume of BAT was higher in the obese group (Obese: 315.2 mL [±89.1], Normal weight: 248.5 mL [±86.4]), but BAT/WAT ratios were significantly higher (P = 0.029) in the normal group. T2* of BAT (P = 0.04) and volume of WAT (P < 0.001) were significantly lower in the normals. Within-group comparison between male and female indicated no significant differences were found in volume (P = 0.776 (normal), 0.501 [obese]), T2* (P = 0.908 [normal], 0.249 [obese]) and fat-fraction of BAT (P = 0.985 [normal], 0.108 [obese]). The intraclass correlation coefficient showed a good reproducibility in volume (BAT: 0.997, WAT: 0.948), T2* (BAT: 0.969, WAT: 0.983), and fat-fraction (BAT: 0.952, WAT: 0.517).
BAT identified by this method was in agreement with other studies in terms of location, fat-fraction value, and T2* intensity. The proposed GMM-based segmentation could be a useful nonradiation imaging method for assessment of adipose tissue, in particular for serial follow-up of volume changes after drug or lifestyle interventions for obesity.
2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:758-768.
基于高斯混合模型（GMM）开发一种使用脂肪分数和 T2*强度分离和定量棕色脂肪组织（BAT）和白色脂肪组织（WAT）的技术。
使用化学位移水脂 mDixon 序列在 24 名志愿者的颈部、锁骨上、肩胛间和椎旁区域采集化学位移水脂和 T2*图像（肥胖组：n=12，男女=6/6，体重指数 [BMI]=31.3±2.3kg/m2，年龄=16.1±0.6；正常体重组：n=12，男女=6/6，BMI=21.2±2.4kg/m2，年龄=12.9±2.4）。使用 3T 扫描仪，基于 GMM 使用期望最大化算法对 BAT 和 WAT 进行聚类。使用独立 t 检验和组内相关系数比较和评估结果和可重复性。
肥胖参与者的 BAT 主要位于锁骨上区域，而正常体重参与者的 BAT 分布更为分散，分布在肩胛间-锁骨上、腋窝和脊柱区域。肥胖组 BAT 的绝对体积较高（肥胖组：315.2mL[±89.1]，正常体重组：248.5mL[±86.4]），但正常组的 BAT/WAT 比值明显更高（P=0.029）。正常组的 BAT 的 T2*（P=0.04）和 WAT 体积（P<0.001）明显较低。男女组内比较显示，体积（P=0.776[正常]，0.501[肥胖]）、T2*（P=0.908[正常]，0.249[肥胖]）和 BAT 脂肪分数（P=0.985[正常]，0.108[肥胖]）无显著差异。组内相关系数显示 BAT（0.997，WAT：0.948）、T2*（BAT：0.969，WAT：0.983）和脂肪分数（BAT：0.952，WAT：0.517）的体积具有良好的可重复性。
本研究采用的方法在位置、脂肪分数值和 T2*强度方面与其他研究一致。基于 GMM 的分割方法可能是一种有用的非辐射成像方法，可用于评估脂肪组织，特别是在肥胖药物或生活方式干预后的体积变化的连续随访。
2 级，技术功效，阶段 1 J.Magn.Reson.Imaging2017；46：758-768。
