Park Hyo Jung, Sung Yu Sub, Lee Seung Soo, Lee Yedaun, Cheong Hyunhee, Kim Yeong Jae, Lee Moon-Gyu
Department of Radiology and Research Institute of Radiology, University of Ulsan, College of Medicine, Asan Medical Center, 86, Asanbyeongwon-gil, Songpa-gu, Seoul, Korea.
Department of Radiology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, South Korea.
J Magn Reson Imaging. 2017 Jun;45(6):1637-1647. doi: 10.1002/jmri.25535. Epub 2016 Nov 16.
To evaluate the influence of fitting methods on the accuracy and reliability of intravoxel incoherent motion (IVIM) parameters, with a particular emphasis on the constraint function.
Diffusion-weighted (DW) imaging data were analyzed using IVIM-based full-fitting (simultaneous fit of all parameters) and segmented-fitting (step-by-step fit of each parameter), each with and without the constraint function, to estimate the molecular diffusion coefficient (D ), perfusion fraction (f), and flow-related diffusion coefficient (D ). Computational simulations were performed at variable signal-to-noise ratios to evaluate the relative error (RE) and coefficient of variation (CV) of the estimated IVIM parameters. DW imaging of the abdomen was performed twice at 1.5 Tesla using nine b-values (0-900 s/mm ) in 12 health volunteers (6 men and 6 women; mean age: 30 years). The measurement repeatability of IVIM parameters in the liver and the pancreas was evaluated using the within-subject coefficient of variation ( CV).
In simulations, full-fitting without the constraint function yielded the largest RE (P < 0.001 for D and f; P ≤ 0.044 for D ) and CV (P ≤ 0.033 for D and f; P ≤ 0.473 for D ) for IVIM parameters among all four algorithms. In volunteer imaging, full-fitting without the constraint function also resulted in the poorest repeatability for D ( CV, 17.12%-65.45%) and f ( CV, 19.35%-42.84%) in the liver and pancreas, while the other algorithms had similar repeatability values ( CV, 4.05%-11.99% for D and 9.65%-18.66% for f). Measurement repeatability of D ( CV, 29.52%-85.01%) was the poorest among the IVIM parameters.
For accurate and reliable measurement of IVIM parameters, segmented fitting or full-fitting with the constraint function should be used for IVIM-based analysis of DW imaging.
3 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1637-1647.
评估拟合方法对体素内不相干运动（IVIM）参数准确性和可靠性的影响，特别关注约束函数。
使用基于IVIM的全拟合（所有参数同时拟合）和分段拟合（每个参数逐步拟合）分析扩散加权（DW）成像数据，每种方法分别使用和不使用约束函数，以估计分子扩散系数（D）、灌注分数（f）和血流相关扩散系数（D*）。在可变信噪比下进行计算模拟，以评估估计的IVIM参数的相对误差（RE）和变异系数（CV）。在1.5特斯拉对12名健康志愿者（6名男性和6名女性；平均年龄：30岁）进行腹部DW成像，使用9个b值（0 - 900 s/mm²），共进行两次。使用受试者内变异系数（CV）评估肝脏和胰腺中IVIM参数的测量重复性。
在模拟中，在所有四种算法中，不使用约束函数的全拟合产生的IVIM参数的RE最大（D和f的P < 0.001；D的P ≤ 0.044）和CV最大（D和f的P ≤ 0.033；D的P ≤ 0.473）。在志愿者成像中，不使用约束函数的全拟合在肝脏和胰腺中D（CV，17.12% - 65.45%）和f（CV，19.35% - 42.84%）的重复性也最差，而其他算法具有相似的重复性值（D的CV，4.05% - 11.99%；f的CV，9.65% - 18.66%）。在IVIM参数中，D*的测量重复性（CV，29.52% - 85.01%）最差。
为了准确可靠地测量IVIM参数，基于IVIM的DW成像分析应使用分段拟合或带约束函数的全拟合。
3 技术效能：2级 《磁共振成像杂志》2017年；45:1637 - 1647。
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