Li Li, Zhu Wenzhen, Chen Weiwei, Fang Jicheng, Li Jing
Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hu Bei 430000, China.
Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hu Bei 430000, China.
Magn Reson Imaging. 2017 Oct;42:101-106. doi: 10.1016/j.mri.2017.06.010. Epub 2017 Jun 17.
The aim of this study was to use DKI to detect the microstructural change of the discs in matured normal rats.
Total 24 normal SD rats (12 males/12 females) underwent DWI/DKI and T2 sequences with a 3T MRI scanner to get the values of ADC, FA, MD, Da, Dr, MK, Ka and Kr. The discs were categorized using a five-grade degeneration grading system in the T2-images. The height of the discs and the parameters in DWI/DKI were measured to compare between the different grades and sexes. The histological images and the images of fiber tracking were also done in the discs.
There were 30 Grade 1 and 18 Grade 2 in the discs. Compared with Grade 1, decreased ADC, increased FA and MK values were observed in Grade 2 (P<0.05). By the ROC analysis of grades of the discs, there was low diagnostic accuracy in ADC value, while FA and MK showed higher accuracy. In Grade 1, there were lower ADC value, lower Dr, higher MK, Ka and Kr in male's group than them in female's group. There were no differences in the parameters except the ADC value in the two sexes in Grade 2. The different microstructure of the normal discs in the male and female rats had been proved by the histological images and the images of fiber tracking.
DKI is a noninvasive and sustainable means to test the changes of intervertebral discs. The discs in Grade 2 were also found in the normal matured SD rat tails. The assessment of the grade of the discs in T2-images should be done before the experimental management. There was microstructural difference in the nucleus pulposus in the discs in Grade 1 and 2. FA and MK showed higher diagnostic accuracy. The laboratory rats should be the same sex because the microstructure of the normal discs weren't the same.
本研究旨在利用扩散峰度成像（DKI）检测成熟正常大鼠椎间盘的微观结构变化。
24只正常SD大鼠（12只雄性/12只雌性）接受3T磁共振成像扫描仪的扩散加权成像（DWI）/DKI和T2序列扫描，以获取表观扩散系数（ADC）、各向异性分数（FA）、平均扩散率（MD）、轴向扩散系数（Da）、径向扩散系数（Dr）、峰度值（MK）、轴向峰度系数（Ka）和径向峰度系数（Kr）的值。在T2图像中使用五级退变分级系统对椎间盘进行分类。测量椎间盘高度及DWI/DKI参数，比较不同分级和性别的差异。同时对椎间盘进行组织学成像和纤维追踪成像。
椎间盘有30个1级和18个2级。与1级相比，2级的ADC值降低，FA和MK值升高（P<0.05）。通过对椎间盘分级的ROC分析，ADC值诊断准确性低，而FA和MK显示出较高的准确性。在1级中，雄性组的ADC值、Dr较低，MK、Ka和Kr较高。2级中除ADC值外，两性参数无差异。组织学图像和纤维追踪图像证实了雄性和雌性大鼠正常椎间盘的微观结构不同。
DKI是一种检测椎间盘变化的无创且可持续的方法。正常成熟SD大鼠尾部也发现了2级椎间盘。在实验处理前应在T2图像中对椎间盘分级进行评估。1级和2级椎间盘髓核存在微观结构差异。FA和MK显示出较高的诊断准确性。实验大鼠应性别相同，因为正常椎间盘的微观结构不同。
