The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Siemens Healthcare, Baltimore, MD, USA.
Abdom Radiol (NY). 2020 Jan;45(1):203-210. doi: 10.1007/s00261-019-02206-w.
To explore the utility of two different fat quantification methods in the liver and pancreas and to test the accuracy of multi-echo Dixon as a single sequence in detecting early stage of fat deposition.
58 healthy potential liver donors underwent abdominal 3T MRI, prospectively. Single-voxel MR Spectroscopy (MRS), dual-echo Dixon, and multi-echo Dixon were performed. Two independent readers obtained proton density fat fraction (PDFF) of the liver and pancreas by placing ROIs on the 2 Dixon sequences. Correlation between the two PDFF measurements was assessed in the liver and pancreas. Values in the liver were also compared to those obtained by MRS.
PDFF in the liver was 6.3 ± 4.2%, 5.5 ± 3.9%, and 5.1 ± 4.1% by MRS, dual-echo Dixon, and multi-echo Dixon, respectively. Dual-echo Dixon and multi-echo Dixon showed good correlation in PDFF quantification of the liver (r = 0.82, p < 0.0005). Multi-echo Dixon showed a good correlation (r = 0.72, p = 0.0005) between the fat measured in the liver and in the pancreas. To differentiate between normal (PDFF ≤ 6%) and mild fat deposition (PDFF: 6-33%) in the liver, analysis showed sensitivity, specificity, and accuracy of 74%, 81%, and 80% for dual-echo Dixon and 85%, 96%, and 89% for multi-echo Dixon, respectively. Mean PDFF in the pancreas was 7.2 ± 2.8% and 6.7 ± 3.3%, by dual-echo and multi-echo Dixon, respectively. Dual-echo Dixon and multi-echo Dixon showed good correlation in PDFF quantification of the pancreas (r = 0.58, p < 0.0005).
Multi-echo Dixon in liver has high accuracy in distinguishing between subjects with normal liver fat and those with mildly elevated liver fat. Multi-echo Dixon can be used to screen for early fat deposition in the liver and pancreas.
探索两种不同的肝脏和胰腺脂肪定量方法的应用，并检验多回波 Dixon 序列作为一种单一序列检测早期脂肪沉积的准确性。
58 例拟行肝移植的健康志愿者行腹部 3T MRI 检查，前瞻性研究。单体素磁共振波谱（MRS）、双回波 Dixon 和多回波 Dixon 序列均行检查。两名独立的阅片者在双回波 Dixon 序列上放置 ROI 以获得肝脏和胰腺的质子密度脂肪分数（PDFF）。评估肝脏和胰腺中两种 PDFF 测量之间的相关性。还将肝脏中的值与 MRS 获得的值进行比较。
MRS、双回波 Dixon 和多回波 Dixon 测得的肝脏 PDFF 分别为 6.3±4.2%、5.5±3.9%和 5.1±4.1%。双回波 Dixon 和多回波 Dixon 在肝脏 PDFF 定量方面具有良好的相关性（r=0.82，p<0.0005）。多回波 Dixon 显示肝脏（r=0.72，p=0.0005）和胰腺（r=0.72，p=0.0005）之间脂肪测量的良好相关性。为了区分肝脏正常（PDFF≤6%）和轻度脂肪沉积（PDFF：6-33%），分析显示双回波 Dixon 的灵敏度、特异性和准确率分别为 74%、81%和 80%，多回波 Dixon 分别为 85%、96%和 89%。胰腺的平均 PDFF 分别为双回波 Dixon 和多回波 Dixon 分别为 7.2±2.8%和 6.7±3.3%。双回波 Dixon 和多回波 Dixon 在胰腺 PDFF 定量方面具有良好的相关性（r=0.58，p<0.0005）。
多回波 Dixon 在区分正常肝脏脂肪和轻度升高肝脏脂肪的受试者方面具有很高的准确性。多回波 Dixon 可用于筛查肝脏和胰腺的早期脂肪沉积。
