Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, China.
Department of Neurology, Wayne State University School of Medicine, Detroit, Michigan, USA.
J Magn Reson Imaging. 2023 Feb;57(2):337-352. doi: 10.1002/jmri.28414. Epub 2022 Aug 26.
MRI has been used to develop biomarkers for movement disorders such as Parkinson disease (PD) and other neurodegenerative disorders with parkinsonism such as progressive supranuclear palsy and multiple system atrophy. One of these imaging biomarkers is neuromelanin (NM), whose integrity can be assessed from its contrast and volume. NM is found mainly in certain brain stem structures, namely, the substantia nigra pars compacta (SNpc), the ventral tegmental area, and the locus coeruleus. Another major biomarker is brain iron, which often increases in concert with NM degeneration. These biomarkers have the potential to improve diagnostic certainty in differentiating between PD and other neurodegenerative disorders similar to PD, as well as provide a better understanding of pathophysiology. Mapping NM in vivo has clinical importance for gauging the premotor phase of PD when there is a greater than 50% loss of dopaminergic SNpc melanized neurons. As a metal ion chelator, NM can absorb iron. When NM is released from neurons, it deposits iron into the intracellular tissues of the SNpc; the result is iron that can be imaged and measured using quantitative susceptibility mapping. An increase of iron also leads to the disappearance of the nigrosome-1 sign, another neuroimage biomarker for PD. Therefore, mapping NM and iron changes in the SNpc are a practical means for improving early diagnosis of PD and in monitoring disease progression. In this review, we discuss the functions and location of NM, how NM-MRI is performed, the automatic mapping of NM and iron content, how NM-related imaging biomarkers can be used to enhance PD diagnosis and differentiate it from other neurodegenerative disorders, and potential advances in NM imaging methods. With major advances currently evolving for rapid imaging and artificial intelligence, NM-related biomarkers are likely to have increasingly important roles for enhancing diagnostic capabilities in PD. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.
磁共振成像（MRI）已被用于开发运动障碍的生物标志物，例如帕金森病（PD）和其他具有帕金森表现的神经退行性疾病，如进行性核上性麻痹和多系统萎缩。这些影像学生物标志物之一是神经黑色素（NM），其完整性可以通过对比度和体积来评估。NM 主要存在于某些脑干结构中，即黑质致密部（SNpc）、腹侧被盖区和蓝斑。另一个主要的生物标志物是脑铁，它通常与 NM 变性一起增加。这些生物标志物有可能提高区分 PD 和其他类似 PD 的神经退行性疾病的诊断确定性，并更好地了解病理生理学。NM 的体内测绘对于在多巴胺能 SNpc 黑素神经元丧失超过 50%时评估 PD 的运动前期具有临床重要意义。作为一种金属离子螯合剂，NM 可以吸收铁。当 NM 从神经元中释放出来时，它会将铁沉积到 SNpc 的细胞内组织中；结果是可以使用定量磁化率映射进行成像和测量的铁。铁的增加也导致黑质 1 号征的消失，这是 PD 的另一个神经影像生物标志物。因此，SNpc 中 NM 和铁变化的测绘是改善 PD 早期诊断和监测疾病进展的实用方法。在这篇综述中，我们讨论了 NM 的功能和位置、如何进行 NM-MRI、NM 和铁含量的自动测绘、如何使用 NM 相关的成像生物标志物来增强 PD 的诊断并将其与其他神经退行性疾病区分开来，以及 NM 成像方法的潜在进展。随着目前快速成像和人工智能方面的重大进展，NM 相关的生物标志物很可能在增强 PD 诊断能力方面发挥越来越重要的作用。证据水平：1 技术功效：2 期。
