Schulz Julia, Zimmermann Juliana, Sorg Christian, Menegaux Aurore, Brandl Felix
Department of Neuroradiology, School of Medicine, Technical University of Munich, Munich, Germany.
TUM-NIC Neuroimaging Center, School of Medicine, Technical University of Munich, Munich, Germany.
Front Psychiatry. 2022 Sep 20;13:925476. doi: 10.3389/fpsyt.2022.925476. eCollection 2022.
For decades, aberrant dopamine transmission has been proposed to play a central role in schizophrenia pathophysiology. These theories are supported by human molecular imaging studies of dopamine transmission, particularly positron emission tomography. However, there are several downsides to such approaches, for example limited spatial resolution or restriction of the measurement to synaptic processes of dopaminergic neurons. To overcome these limitations and to measure complementary aspects of dopamine transmission, magnetic resonance imaging (MRI)-based approaches investigating the macrostructure, metabolism, and connectivity of dopaminergic nuclei, i.e., substantia nigra pars compacta and ventral tegmental area, can be employed. In this scoping review, we focus on four dopamine MRI methods that have been employed in patients with schizophrenia so far: neuromelanin MRI, which is thought to measure long-term dopamine function in dopaminergic nuclei; morphometric MRI, which is assumed to measure the volume of dopaminergic nuclei; diffusion MRI, which is assumed to measure fiber-based structural connectivity of dopaminergic nuclei; and resting-state blood-oxygenation-level-dependent functional MRI, which is thought to measure functional connectivity of dopaminergic nuclei based on correlated blood oxygenation fluctuations. For each method, we describe the underlying signal, outcome measures, and downsides. We present the current state of research in schizophrenia and compare it to other disorders with either similar (psychotic) symptoms, i.e., bipolar disorder and major depressive disorder, or dopaminergic abnormalities, i.e., substance use disorder and Parkinson's disease. Finally, we discuss overarching issues and outline future research questions.
几十年来，异常的多巴胺传递被认为在精神分裂症的病理生理学中起着核心作用。这些理论得到了多巴胺传递的人体分子成像研究的支持，尤其是正电子发射断层扫描。然而，这些方法存在几个缺点，例如空间分辨率有限或测量仅限于多巴胺能神经元的突触过程。为了克服这些局限性并测量多巴胺传递的互补方面，可以采用基于磁共振成像（MRI）的方法来研究多巴胺能核团（即黑质致密部和腹侧被盖区）的宏观结构、代谢和连通性。在本综述中，我们重点关注目前已应用于精神分裂症患者的四种多巴胺MRI方法：神经黑色素MRI，被认为可测量多巴胺能核团中的长期多巴胺功能；形态计量MRI，假定用于测量多巴胺能核团的体积；扩散MRI，假定用于测量多巴胺能核团基于纤维的结构连通性；以及静息态血氧水平依赖性功能MRI，被认为可基于相关的血氧波动来测量多巴胺能核团的功能连通性。对于每种方法，我们描述了潜在信号、结果测量指标和缺点。我们介绍了精神分裂症的当前研究现状，并将其与具有相似（精神病性）症状的其他疾病（即双相情感障碍和重度抑郁症）或多巴胺能异常的其他疾病（即物质使用障碍和帕金森病）进行比较。最后，我们讨论了总体问题并概述了未来的研究问题。
