腰椎间盘营养扩散途径的DCE-MRI研究进展

Research progress of nutrition diffusion pathway in lumbar discs by dynamic contrast enhanced-magnetic resonance imaging

椎间盘退变是颈、腰椎病发生发展的根本原因，不同程度的影响患者的生活质量。流行病学研究表明营养供应减少、细胞凋亡失衡、基质酶活性改变、生物力学机制及自身免疫反应等均可能是导致椎间盘退变的重要因素，营养物质缺乏被认为是诸多因素中导致椎间盘退变的首要影响因素并被体外研究所证实。当某些病因引起营养椎体的血液供应减少时，影响了髓核营养的输送，最终导致椎间盘退变的发生。既往检测扩散途径的方法较多，但主要集中在离体研究上，如何无创检测活体对于早期预防和干预治疗具有重要意义。磁共振成像（magnetic resonance imaging，MRI）应用于医学领域已有20多年历史，动态增强磁共振扫描（dynamic contrast enhanced-MRI，DCE-MRI）通过MRI对比剂进入椎间盘的快慢及多少反映椎间盘的营养扩散过程，具有可重复、无创的优点，是一种新的分析椎间盘营养机制的方法，现将其机制进行综述。

Intervertebral discs are the largest avascular structures in the body and depend entirely on the diffusion from blood vessels at the periphery for the supply of essential nutrients for cellular activity and the removal of metabolic wastes. Diffusion is the only source of nutrition to the intervertebral discs, and alteration of diffusion is considered to be the ifnal common pathway for disc degeneration. Yet diffusion remains poorly understood due to the paucity of reliable methods to study noninvasive diffusion in human beings in vivo. In recent years, Dynamic Contrast Enhanced-Magnetic Resonance Imaging （ DCE-MRI ） has emerged as a powerful and reliable tool to analyze the diffusion in lumbar discs. Endplate structures have also been proved to have the function of controlling the process of diffusion, and can be identified by DCE-MRI. This review focuses on the current knowledge, methodology, various factors inlfuencing the diffusion properties of the discs and the quantitative analysis of the normal, aging or degenerative intervertebral discs of this promising technique.