Understanding the mechanisms of atrophy associated with spinal cord injury: the application of MRI-based in vivo histology and ex vivo histology

脊髓损伤(SCI)主要由暴力、交通和运动事故等创伤性事件引起。截瘫(腿部瘫痪)和四肢瘫痪(腿部和手臂瘫痪)永久性地、严重地和极大地降低患者的生活质量以及他们作为劳动力的能力。这些负面后果的产生是因为脊髓损伤后的功能恢复仍然有限，而且大多数患者在长期内会留下严重的损害。虽然康复训练可以改善脊髓损伤后的临床结果，这是对患者生活质量的一大好处，但支持神经和功能恢复的退行性过程和机制尚不清楚。磁共振成像(MRI)领域的最新进展极大地改善了我们可以可视化和询问中枢神经系统的结构、组织和功能的方式。在这些进步中，值得注意的是正在形成的研究人类中枢神经系统“微观”变化的能力。这包括区分白质和灰质--脊髓、脑干和大脑结构的两个基本部分。使用显微磁共振成像方案，我们已经证明了结构变化随着时间的推移而发生，遵循特定的空间和时间模式。事实上，这些变化发生在损伤后的早期，发生在脊髓和大脑中。然而，到目前为止，可能是所观察到的变化背后的生物变化的范围还不能解开。通过使用磁共振成像(HMRI)的体内组织学-MRI的一个新兴领域-我们的目标是建立测量的MRI信号和潜在组织微观结构变化之间缺失的联系，这将有助于我们解释和更好地了解与脊髓损伤相关的疾病过程。

Spinal cord injuries (SCI) are mainly caused by traumatic events such as violence and traffic and sports accidents. Paraplegia (paralysis of the legs) and tetraplegia (paralysis of both legs and arms) permanently, severely and dramatically reduce the quality of life of the affected person as well as their ability to remain a member of the workforce. These negative consequences arise because functional recovery following SCI remains limited and the majority of patients are left with severe impairments in the longer term. While rehabilitative training can improve clinical outcome following SCI, which is a major benefit to the patients' quality of life, the degenerative processes and the mechanisms underpinning any neurological and functional recovery are not well understood. Recent advances in the field of magnetic resonance imaging (MRI) have vastly improved how we can visualize and interrogate the structural organisation and functioning of the central nervous system. Notable among these advances is the emerging ability to investigate "microscopic" changes in the human central nervous system. This includes distinguishing white and grey matter - two fundamental divisions of structure in the spinal cord, brainstem and brain. Using microscopic MRI protocols we have shown that structural changes occur over time following a specific spatial and temporal pattern. In fact these changes occur early after the injury and happen both in the cord and in the brain. However so far, the range of biological changes that may underlie the observed changes cannot be disentangled. By means of in vivo histology using MRI (hMRI) - an emerging field in MRI - we aim to establish the missing link between measured MRI signals and changes in the underlying tissue microstructure, which will help us to explain and better understand the disease processes associated with spinal cord injury.