The University of Queensland, Centre for Advanced Imaging, Brisbane, Queensland, Australia.
College of Applied Medical Science, King Saud University, Riyadh, Saudi Arabia.
J Magn Reson Imaging. 2018 Feb;47(2):468-476. doi: 10.1002/jmri.25786. Epub 2017 Jun 22.
To compare mono- and bi-exponential relaxation model equations to discriminate between normal and fatty liver disease.
Six rats on a choline deficient amino acid modified (CDAA) diet and six on normal chow were studied. Multiple spin echo images with increasing echo times (TEs) were collected at 9.4T. Pixel-wise T maps were generated using mono-exponential decay function to calculate T , and a bi-exponential to calculate, short T component (T ), long T component (T ), and fractions of these components (ρ , ρ ), respectively. Statistical F-tests and Akaike's information criterion (AIC) were used to assess the relative performance of the two models.
F-test and AIC showed that in the CDAA group, T bi-exponential model described the signal of T weighted imaging of the liver better than the mono-exponential model. Controls were best described by the mono-exponential model. Mean values for T , T , T , ρ , ρ were 31.2 ± 0.7 ms, 72.8 ± 3.3 ms, 8.2 ± 0.6 ms,71.2 ± 2.1%, 30.4 ± 1.3%, respectively, in CDAA rats, compared with 18.8 ± 0.5 ms, 32.3 ± 0.7 ms, 9.2 ± 1.8 ms, 79 ± 2%, 21.0 ± 1.1% in controls.
In the fatty liver of CDAA rats we have shown that T weighted images fit the bi-exponential model better than mono-exponential decays thus providing a better description of the data.
1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:468-476.
比较单指数和双指数弛豫模型方程，以区分正常肝和脂肪肝。
本研究纳入了 6 只给予胆碱缺乏型氨基酸改良饮食（CDAA）的大鼠和 6 只给予正常饮食的大鼠。在 9.4T 下采集多个具有不同回波时间（TE）的自旋回波图像。使用单指数衰减函数生成像素级 T 图，以计算 T 1，使用双指数函数计算短 T 1 成分（T 1s）、长 T 1 成分（T 1l）和这些成分的分数（ρ 1s、ρ 1l）。统计 F 检验和赤池信息量准则（AIC）用于评估两种模型的相对性能。
F 检验和 AIC 表明，在 CDAA 组中，T 1 双指数模型比单指数模型更能描述 T 1 加权成像的肝脏信号。对照组最好用单指数模型来描述。在 CDAA 大鼠中，T 1、T 1s、T 1l、ρ 1s、ρ 1l 的平均值分别为 31.2±0.7ms、72.8±3.3ms、8.2±0.6ms、71.2±2.1%、30.4±1.3%，而在对照组中，T 1、T 1s、T 1l、ρ 1s、ρ 1l 的平均值分别为 18.8±0.5ms、32.3±0.7ms、9.2±1.8ms、79±2%、21.0±1.1%。
在 CDAA 大鼠的脂肪肝中，我们发现 T 1 加权图像更符合双指数衰减，而不是单指数衰减，因此能更好地描述数据。
1 技术功效：2 级 J. 磁共振成像 2018；47：468-476。
