功能性消化不良（FD）是一种常见的功能性胃肠疾病。目前认为：脑-肠互动异常，特别是中枢神经系统在内脏感觉处理功能异常可能是导致FD发病的主要原因。国际罗马III标准将FD分为两种压型：餐后不适综合征（PDS）和上腹痛综合征（EPS）。不同亚型的临床表征有显著的差异，然而这些不同亚型在中枢表征上是否存在特异性和相似性，目前尚无系统性的研究，它们的发病机制仍不甚清楚。因此，本项拟采用多模态神经影像学技术（PET与MRI相结合）为主要研究手段并结合行为学分析技术，从脑代谢、脑结构、脑功能的变化情况探究PDS和EPS的中枢表征特异性及其之间的关系。为进一步理解FD病理生理学机制，也为临床医师选择更为个性化、更加合理的FD治疗方式提供科学的理论依据和循证基础。

Functional dyspepsia (FD), as one of the most common clinical functional gastrointestinal diseases. Although FD has a profound impact on quality of the life of patients and yields quite high medical costs, the underlying pathogenesis of FD remains unclear. The dysfunction of the brain-gut axis involved in processing of visceral discomfort or pain has been suggested to play a critical role in FD disorder. In light of the Rome III criteria, there are two classic subgroups of FD, including postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS) with different clinical characteristics. However, it is unknown whether there exist the specific and/or similar characteristics of brain between the PDS and EPS. Therefore, in the current study, we will aim to explore the specific neural mechanism of PDS and EPS using multi-modal imaging techniques associated with positron emission computed tomography (PET) and magnetic resonance imaging (MR). To achieve this goal, we will firstly investigate the differences of glucose metabolism, arterial spin labeling (ASL), structural MRI, diffusion tensor imaging (DTI) and functional MRI (fMRI) in the patients and healthy controls, related with certain brain regions or brain networks. Correlation analysis will then be adopted for the relationships between abnormal neuroimaging findings and clinical symptoms. Results of our study will provide new evidence for the distinct pathophysiology mechanism of PDS and EPS as well as for the individual treatments of FD.