Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan; Neuroscience and Brain Disease Center, China Medical University, Taichung, Taiwan.
Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan.
Med Eng Phys. 2023 Aug;118:104015. doi: 10.1016/j.medengphy.2023.104015. Epub 2023 Jun 25.
Diffusion tensor imaging (DTI) in animal models are essential for translational neuroscience studies. A critical step in animal studies is the use of anesthetics. Understanding the influence of specific anesthesia regimes on DTI-derived parameters, such as fractional anisotropy (FA) and mean diffusivity (MD), is imperative when comparing results between animal studies using different anesthetics. Here, the quantification of FA and MD under different anesthetic regimes, alpha-chloralose and isoflurane, is discussed. We also used a range of b-values to determine whether the anesthetic effect was b-value dependent. The first group of rats (n = 6) was anesthetized with alpha-chloralose (80 mg/kg), whereas the second group of rats (n = 7) was anesthetized with isoflurane (1.5%). DTI was performed with b-values of 500, 1500, and 1500s/mm, and the MD and FA were assessed individually. Anesthesia-specific differences in MD were apparent, as manifested by the higher estimated MD under isoflurane anesthesia than that under alpha-chloralose anesthesia (P < 0.001). MD values increased with decreasing b-value in all regions studied, and the degree of increase when rats were anesthetized with isoflurane was more pronounced than that associated with alpha-chloralose (P < 0.05). FA quantitation was also influenced by anesthesia regimens to varying extents, depending on the brain regions and b-values. In conclusion, both scanning parameters and the anesthesia regimens significantly impacted the quantification of DTI indices.
在转化神经科学研究中，动物模型中的扩散张量成像（DTI）至关重要。动物研究中的一个关键步骤是使用麻醉剂。当比较使用不同麻醉剂的动物研究结果时，了解特定麻醉方案对 DTI 衍生参数（如分数各向异性（FA）和平均弥散度（MD））的影响是必不可少的。在这里，讨论了在不同麻醉方案下，氯醛糖和异氟醚下 FA 和 MD 的定量。我们还使用了一系列 b 值来确定麻醉效果是否依赖于 b 值。第一组大鼠（n = 6）用氯醛糖（80 mg/kg）麻醉，而第二组大鼠（n = 7）用异氟醚（1.5%）麻醉。使用 b 值为 500、1500 和 1500 s/mm 进行 DTI，单独评估 MD 和 FA。麻醉特异性 MD 差异明显，异氟醚麻醉下的 MD 值高于氯醛糖麻醉下的 MD 值（P < 0.001）。在所有研究的区域中，MD 值随着 b 值的降低而增加，并且当大鼠用异氟醚麻醉时，增加的程度比用氯醛糖麻醉时更明显（P < 0.05）。FA 定量也受到麻醉方案的不同程度的影响，这取决于脑区和 b 值。总之，扫描参数和麻醉方案都显著影响 DTI 指数的定量。
