Gignac Paul M, Kley Nathan J
Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, Tulsa, Oklahoma, USA.
Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York, USA.
Brain Behav Evol. 2018;91(3):180-190. doi: 10.1159/000485476. Epub 2018 Aug 10.
Advancements in imaging techniques have drastically improved our ability to visualize, study, and digitally share complex, often minute, anatomical relationships. The recent adoption of soft-tissue X-ray imaging techniques, such as diffusible iodine-based contrast-enhanced computed tomography (diceCT), is beginning to offer previously unattainable insights into the detailed configurations of soft- tissue complexes across Metazoa. As a contrast agent, dissolved iodine diffuses deeply throughout preserved specimens to bind fats and carbohydrates that are natural ly present within metazoan soft tissues, increasing the radiodensities of these tissues in predictable ways. Like the current "gold standard" of magnetic resonance imaging, diceCT does not require physical dissection and can differentiate between the lipid content of myelinated versus nonmyelinated tissues, thereby offering great potential for neuroanatomical studies. Within the brain, for example, diceCT distinguishes myelinated fiber tracts from unmyelinated cortices, nuclei, and ganglia and allows three-dimensional visualization of their anatomical interrelationships at previously unrealized spatial scales. In this study, we illustrate the utility of diceCT for the rapid visualization of both external and internal brain anatomy in vertebrates - alongside the intact bones of the skull and the complete, undisturbed pathways of peripheral nerves, up to and including the target organs that they innervate. We demonstrate the transformative potential of this technique for developing high-resolution neuroanatomical datasets and describe best practices for imaging large numbers of specimens for broad evolutionary studies across vertebrates.
成像技术的进步极大地提高了我们可视化、研究和数字共享复杂且通常微小的解剖关系的能力。最近采用的软组织X射线成像技术，如基于可扩散碘的对比增强计算机断层扫描（diceCT），开始为后生动物软组织复合体的详细结构提供以前无法获得的见解。作为一种对比剂，溶解的碘在保存的标本中深度扩散，以结合后生动物软组织中天然存在的脂肪和碳水化合物，以可预测的方式增加这些组织的放射密度。与当前磁共振成像的“金标准”一样，diceCT不需要进行物理解剖，并且可以区分有髓和无髓组织的脂质含量，从而为神经解剖学研究提供了巨大潜力。例如，在大脑中，diceCT可以区分有髓纤维束与无髓皮质、核和神经节，并允许在以前未实现的空间尺度上三维可视化它们的解剖学相互关系。在这项研究中，我们展示了diceCT在快速可视化脊椎动物大脑外部和内部解剖结构方面的效用——同时还能看到完整的颅骨骨骼以及外周神经完整、未受干扰的路径，直至并包括它们所支配的靶器官。我们展示了这项技术在开发高分辨率神经解剖学数据集方面的变革潜力，并描述了为跨脊椎动物进行广泛进化研究而对大量标本进行成像的最佳实践。
