改良两点 dixon 法与化学位移编码 MRI 水脂分离法在胎儿脂肪定量中的比较。
Comparison of modified two-point dixon and chemical shift encoded MRI water-fat separation methods for fetal fat quantification.
机构信息
Department of Medical Biophysics, Western University, London, Ontario, Canada.
Division of Maternal, Fetal and Newborn Health, Children's Health Research Institute, London, Ontario, Canada.
出版信息
J Magn Reson Imaging. 2018 Jul;48(1):274-282. doi: 10.1002/jmri.25929. Epub 2018 Jan 10.
BACKGROUND
Fetal fat is indicative of the energy balance within the fetus, which may be disrupted in pregnancy complications such as fetal growth restriction, macrosomia, and gestational diabetes. Water-fat separated MRI is a technique sensitive to tissue lipid content, measured as fat fraction (FF), and can be used to accurately measure fat volumes. Modified two-point Dixon and chemical shift encoded MRI (CSE-MRI) are water-fat separated MRI techniques that could be applied to imaging of fetal fat. Modified two-point Dixon has biases present that are corrected in CSE-MRI which may contribute to differences in the fat measurements.
PURPOSE
To compare the measurement of fetal fat volume and FF by modified two-point Dixon and CSE-MRI.
STUDY TYPE
Cross-sectional study for comparison of two MRI pulse sequences.
POPULATION
Twenty-one pregnant women with singleton pregnancies.
FIELD STRENGTH/SEQUENCE: 1.5T, modified two-point Dixon and CSE-MRI.
ASSESSMENT
Manual segmentation of total fetal fat volume and mean FF from modified 2-point Dixon and CSE-MRI FF images.
STATISTICAL TESTS
Reliability was assessed by calculating the intraclass correlation coefficient (ICC). Agreement was assessed using a one-sample t-test on the fat measurements difference values (modified two-point Dixon - CSE-MRI). The difference scores were tested against a value of 0, which would indicate that the measurements were identical.
RESULTS
The fat volume and FF measured by modified two-point Dixon and CSE-MRI had excellent reliability, demonstrated by ICCs of 0.93 (P < 0.001) and 0.90 (P < 0.001), respectively. They were not in agreement, with CSE-MRI giving mean fat volumes 180 mL greater and mean FF 3.0% smaller than modified two-point Dixon.
DATA CONCLUSION
The reliability between modified two-point Dixon and CSE-MRI indicates that either technique can be used to compare fetal fat measurements in different participants, but they are not in agreement possibly due to uncorrected biases in modified two-point Dixon.
LEVEL OF EVIDENCE
4 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018.
背景
胎儿脂肪是胎儿能量平衡的指标，在胎儿生长受限、巨大儿和妊娠期糖尿病等妊娠并发症中可能会受到干扰。水脂分离 MRI 是一种对组织脂质含量敏感的技术，以脂肪分数（FF）表示，可用于准确测量脂肪体积。改良两点 Dixon 和化学位移编码 MRI（CSE-MRI）是两种可用于胎儿脂肪成像的水脂分离 MRI 技术。改良两点 Dixon 存在偏倚，在 CSE-MRI 中得到了校正，这可能导致脂肪测量值的差异。
目的
比较改良两点 Dixon 和 CSE-MRI 测量胎儿脂肪体积和 FF 的差异。
研究类型
两种 MRI 脉冲序列比较的横截面研究。
人群
21 名单胎妊娠孕妇。
磁场强度/序列：1.5T，改良两点 Dixon 和 CSE-MRI。
评估
手动分割改良两点 Dixon 和 CSE-MRI 总胎儿脂肪体积和平均 FF 图像。
统计检验
通过计算组内相关系数（ICC）评估可靠性。使用改良两点 Dixon-CSE-MRI 脂肪测量差值的单样本 t 检验评估一致性。差值与 0 进行比较，如果测量值相同，则差值为 0。
结果
改良两点 Dixon 和 CSE-MRI 测量的脂肪体积和 FF 具有极好的可靠性，ICC 分别为 0.93（P < 0.001）和 0.90（P < 0.001）。两种方法不一致，CSE-MRI 测量的平均脂肪体积比改良两点 Dixon 多 180mL，平均 FF 小 3.0%。
数据结论
改良两点 Dixon 和 CSE-MRI 之间的可靠性表明，两种技术都可用于比较不同参与者的胎儿脂肪测量值，但它们不一致，可能是由于改良两点 Dixon 中未校正的偏倚。
证据水平
4 级 技术功效：1 期 J. 磁共振成像 2018 年。
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