Le Ster Caroline, Gambarota Giulio, Lasbleiz Jérémy, Guillin Raphaël, Decaux Olivier, Saint-Jalmes Hervé
INSERM, UMR 1099, Rennes, France.
Université de Rennes 1, LTSI, Rennes, France.
J Magn Reson Imaging. 2016 Sep;44(3):549-55. doi: 10.1002/jmri.25205. Epub 2016 Feb 26.
To assess the feasibility of measuring the fat fraction, T1 and T2 * relaxation times of water and fat signals in vertebral bone marrow using breath-hold magnetic resonance imaging (MRI) gradient echo images of the spine.
MRI experiments were performed at 1.5T on eight healthy volunteers (35.1 ± 15.7 years, five men and three women) using two sagittal four-echo 3D gradient echo volumetric interpolated breath-hold examination (VIBE Dixon) sequences acquired at two different flip angles (5° and 15°). The water/fat decomposition was performed in the vertebral bodies of L1 to L5 by fitting the signal to a function that depends on the echo time and the flip angle to calculate the fat fraction (FF) and T1 and T2 * relaxation times of water and fat signals. Repeatability was assessed by scanning one volunteer six times.
The mean fat fraction over L1 to L5 was 33 ± 8%. The mean T1 and T2 * of water and fat signals were respectively T1w = 701 ± 151 msec, T2 *w = 13.7 ± 2.9 msec, T1f = 334 ± 113 msec, and T2 *f = 11.4 ± 2.7 msec. When considering each vertebra separately, the fat fraction increased from L1 to L5 and the T1w decreased from L1 to L5. The mean coefficients of variation obtained from the repeatability study were 8% (FF), 11% (T1w ), 17% (T1f ), 8% (T2 *w ), and 27% (T2 *f ).
The method introduced in the current study allows for the measurement of the fat fraction and water and fat relaxation times, with a total acquisition time of less than 40 seconds. J. Magn. Reson. Imaging 2016;44:549-555.
通过脊柱屏气磁共振成像（MRI）梯度回波图像评估测量椎体骨髓中水和脂肪信号的脂肪分数、T1和T2*弛豫时间的可行性。
在1.5T场强下，对8名健康志愿者（年龄35.1±15.7岁，5名男性和3名女性）进行MRI实验，使用两个矢状面四回波3D梯度回波容积内插屏气检查（VIBE Dixon）序列，在两个不同的翻转角（5°和15°）下采集图像。通过将信号拟合到一个依赖于回波时间和翻转角的函数，对L1至L5椎体进行水/脂肪分解，以计算脂肪分数（FF）以及水和脂肪信号的T1和T2*弛豫时间。通过对一名志愿者进行6次扫描来评估重复性。
L1至L5的平均脂肪分数为33±8%。水和脂肪信号的平均T1和T2分别为T1w = 701±151毫秒，T2w = 13.7±2.9毫秒，T1f = 334±113毫秒，以及T2f = 11.4±2.7毫秒。当分别考虑每个椎体时，脂肪分数从L1至L5逐渐增加，而T1w从L1至L5逐渐降低。重复性研究获得的平均变异系数分别为8%（FF）、11%（T1w）、17%（T1f）、8%（T2w）和27%（T2*f）。
本研究中介绍的方法能够测量脂肪分数以及水和脂肪的弛豫时间，总采集时间少于40秒。《磁共振成像杂志》2016年；44：549 - 555。
