Diffusion MRI in Peripheral Nerves: Optimized b Values and the Role of Non-Gaussian Diffusion
Diffusion MRI in Peripheral Nerves: Optimized b Values and the Role of Non-Gaussian Diffusion
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DOI：
10.1148/radiol.2021204740
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发表时间：
2022-01-01
期刊：
影响因子：
19.7
通讯作者：
Schwarz, Daniel
中科院分区：
文献类型：
--
作者：
Foesleitner, Olivia;Sulaj, Alba;Schwarz, Daniel
背景资料：弥散加权成像（DWI）提供了关于组织微观结构的特定体内信息，这在中枢神经系统以外的各种应用中越来越受到认可。然而，标准序列参数通常采用从优化的中枢神经系统protocols，从而潜在地忽略了组织特异性diffusional behaviors.Purpose的差异：为了表征最佳的组织特异性扩散成像加权方案在B域在生理和病理条件下的外周神经.材料和方法：在这项前瞻性横断面研究中，对健康志愿者（n = 16）和2型糖尿病患者（n = 12）进行了坐骨神经的3-T MR神经造影。DWI在神经轴向和径向扩散方向上获得了16个B值，范围为0-1500 sec/mm（2）。利用基于感兴趣区域的方法，使用标准单指数、双指数和峰度拟合来估计作为B的函数的扩散加权信号行为。结果：在糖尿病患者和健康志愿者中，当B值分别为600 sec/mm（2）和800 sec/mm（2）时，轴向和径向弥散方向均出现非高斯弥散行为。因此，与标准单指数模型相比，双指数模型和峰度模型实现了更好的曲线拟合（在所有模型中Akaike信息标准>99.9%），但峰度模型在大多数情况下是优选的。健康志愿者和糖尿病参与者之间的显著差异被发现在峰度衍生参数D-k和K。结论：在MR神经成像中，B = 700 sec/mm（2）是一个理想的标准扩散加权成像/扩散张量成像方案。由于早期发生的非高斯扩散行为，这比中枢神经系统中的低得多，并且强调了对组织特异性B值优化的需要。包括较高的B值，峰度衍生的参数可能代表周围神经疾病的有前途的新的成像标志物。(C)RSNA，2021年
Background: Diffusion-weighted imaging (DWI) provides specific in vivo information about tissue microstructure, which is increasingly recognized for various applications outside the central nervous system. However, standard sequence parameters are commonly adopted from optimized central nervous system protocols, thus potentially neglecting differences in tissue-specific diffusional behavior.Purpose: To characterize the optimal tissue-specific diffusion imaging weighting scheme over the b domain in peripheral nerves under physiologic and pathologic conditions.Materials and Methods: In this prospective cross-sectional study, 3-T MR neurography of the sciatic nerve was performed in healthy volunteers (n = 16) and participants with type 2 diabetes (n = 12). For DWI, 16 b values in the range of 0-1500 sec/mm(2) were acquired in axial and radial diffusion directions of the nerve. With a region of interest-based approach, diffusion-weighted signal behavior as a function of b was estimated using standard monoexponential, biexponential, and kurtosis fitting. Goodness of fit was assessed to determine the optimal b value for two-point DWI/diffusion tensor imaging (DTI).Results: Non-Gaussian diffusional behavior was observed beyond b values of 600 sec/mm(2) in the axial and 800 sec/mm(2) in the radial diffusion direction in both participants with diabetes and healthy volunteers. Accordingly, the biexponential and kurtosis models achieved a better curve fit compared with the standard monoexponential model (Akaike information criterion >99.9% in all models), but the kurtosis model was preferred in the majority of cases. Significant differences between healthy volunteers and participants with diabetes were found in the kurtosis-derived parameters D-k and K. The results suggest an upper bound b value of approximately 700 sec/mm(2) for optimal standard DWI/DTI in peripheral nerve applications.Conclusion: In MR neurography, an ideal standard diffusion-weighted imaging/diffusion tensor imaging protocol with b = 700 sec/mm(2) is suggested. This is substantially lower than in the central nervous system due to early-occurring non-Gaussian diffusion behavior and emphasizes the need for tissue-specific b value optimization. Including higher b values, kurtosis-derived parameters may represent promising novel imaging markers of peripheral nerve disease. (C) RSNA, 2021