Wang Chenyu, Klistorner Alexander, Ly Linda, Barnett Michael H
Sydney Neuroimaging Analysis Centre, Sydney, New South Wales, Australia.
Brain and Mind Centre, University of Sydney, Sydney, New South Wales, Australia.
PLoS One. 2018 Jan 17;13(1):e0191131. doi: 10.1371/journal.pone.0191131. eCollection 2018.
The posterior visual pathway is commonly affected by multiple sclerosis (MS) pathology that results in measurable clinical and electrophysiological impairment. Due to its highly structured retinotopic mapping, the visual pathway represents an ideal substrate for investigating patho-mechanisms in MS. Therefore, a reliable and robust imaging segmentation method for in-vivo delineation of the optic radiations (OR) is needed. However, diffusion-based tractography approaches, which are typically used for OR segmentation are confounded by the presence of focal white matter lesions. Current solutions require complex acquisition paradigms and demand expert image analysis, limiting application in both clinical trials and clinical practice. In the current study, using data acquired in a clinical setting on a 3T scanner, we optimised and compared two approaches for optic radiation (OR) reconstruction: individual probabilistic tractography-based and template-based methods. OR segmentation results were applied to subjects with MS and volumetric and diffusivity parameters were compared between OR segmentation techniques. Despite differences in reconstructed OR volumes, both OR lesion volume and OR diffusivity measurements in MS subjects were highly comparable using optimised probabilistic tractography-based, and template-based, methods. The choice of OR reconstruction technique should be determined primarily by the research question and the nature of the available dataset. Template-based approaches are particularly suited to the semi-automated analysis of large image datasets and have utility even in the absence of dMRI acquisitions. Individual tractography methods, while more complex than template based OR reconstruction, permit measurement of diffusivity changes along fibre bundles that are affected by specific MS lesions or other focal pathologies.
视觉后通路通常会受到多发性硬化症（MS）病理的影响，导致可测量的临床和电生理损伤。由于其高度结构化的视网膜拓扑映射，视觉通路是研究MS病理机制的理想对象。因此，需要一种可靠且强大的成像分割方法来在体内描绘视辐射（OR）。然而，通常用于OR分割的基于扩散的纤维束成像方法会因局灶性白质病变的存在而受到干扰。目前的解决方案需要复杂的采集模式，且需要专业的图像分析，这限制了其在临床试验和临床实践中的应用。在本研究中，我们使用在临床环境中通过3T扫描仪获取的数据，优化并比较了两种视辐射（OR）重建方法：基于个体概率纤维束成像的方法和基于模板的方法。将OR分割结果应用于MS患者，并比较了OR分割技术之间的体积和扩散率参数。尽管重建的OR体积存在差异，但使用优化的基于概率纤维束成像的方法和基于模板的方法，MS患者的OR病变体积和OR扩散率测量结果具有高度可比性。OR重建技术的选择应主要由研究问题和可用数据集的性质决定。基于模板的方法特别适合对大型图像数据集进行半自动分析，即使在没有扩散磁共振成像（dMRI）采集的情况下也有用。个体纤维束成像方法虽然比基于模板的OR重建更复杂，但可以测量受特定MS病变或其他局灶性病理影响的纤维束的扩散率变化。
