Pušnik Luka, Gabor Aljoša, Radochová Barbora, Janáček Jiří, Saudek František, Alibegović Armin, Serša Igor, Cvetko Erika, Umek Nejc, Snoj Žiga
Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
Laboratory of Biomathematics, Institute of Physiology, The Czech Academy of Sciences, Prague, Czech Republic.
J Neuroimaging. 2025 Jan-Feb;35(1):e70025. doi: 10.1111/jon.70025.
The primary objective was to compare diffusion tensor imaging (DTI) scalar parameters of peripheral nerves between subjects with type 2 diabetes mellitus (T2DM) and those without diabetes. Secondarily, we aimed to correlate DTI scalar parameters with nerve morphometric properties.
Median, tibial, and sural nerves were harvested from 34 male cadavers (17 T2DM, 17 nondiabetic). Each nerve was divided into three segments. The initial segment was scanned using 9.4 Tesla MRI system (three-dimensional pulsed-gradient spin-echo sequence). DTI scalars were calculated from region-average diffusion-weighted signals. Second segment was optically cleared, acquired with optical projection tomography (OPT), and analyzed for morphometrical properties. Toluidine-stained sections were prepared from last segment, and axon- and myelin-related properties were evaluated.
DTI scalar parameters of median and tibial nerves were comparable between the groups, while sural nerves of T2DM exhibited on average 41% higher mean diffusivity (MD) (p = 0.03), 38% higher radial diffusivity (RD) (p = 0.03), and 27% lower fractional anisotropy (FA) (p = 0.005). Significant differences in toluidine-evaluated parameters of sural nerves were observed between the groups, with a positive correlation between FA with fiber density (p = 0.0001) and with myelin proportion (p < 0.0001) and an inverse correlation between RD and myelin proportion (p = 0.003). OPT-measured morphometric properties did not correlate with DTI scalar parameters.
High-field DTI shows promise as an imaging technique for detecting axonal and myelin-related changes in small sural nerves ex vivo. The reduced fiber density and decreased myelin content, which can be observed in T2DM, likely contribute to observed FA reduction and increased MD/RD.
主要目的是比较2型糖尿病（T2DM）患者与非糖尿病患者外周神经的扩散张量成像（DTI）标量参数。其次，我们旨在将DTI标量参数与神经形态学特性相关联。
从34具男性尸体（17例T2DM患者，17例非糖尿病患者）中获取正中神经、胫神经和腓肠神经。每根神经分为三段。第一段使用9.4特斯拉MRI系统（三维脉冲梯度自旋回波序列）进行扫描。DTI标量由区域平均扩散加权信号计算得出。第二段进行光学清除，采用光学投影断层扫描（OPT）获取图像，并分析其形态学特性。最后一段制备甲苯胺染色切片，评估轴突和髓鞘相关特性。
两组正中神经和胫神经的DTI标量参数相当，而T2DM患者的腓肠神经平均扩散率（MD）平均高41%（p = 0.03），径向扩散率（RD）高38%（p = 0.03），各向异性分数（FA）低27%（p = 0.005）。两组之间观察到腓肠神经甲苯胺评估参数存在显著差异，FA与纤维密度（p = 0.0001）和髓鞘比例（p < 0.0001）呈正相关，RD与髓鞘比例呈负相关（p = 0.003）。OPT测量的形态学特性与DTI标量参数无关。
高场DTI作为一种成像技术，有望用于检测离体小腓肠神经中轴突和髓鞘相关的变化。在T2DM中可观察到的纤维密度降低和髓鞘含量减少，可能导致观察到的FA降低和MD/RD增加。
