Elucidating Mechanisms That Underlie Symptomatology of Functional Dyspepsia Using Novel Imaging Technique of SPECT/CT, MRI, High-Resolution Manometry and Biomarkers; and the Therapeutic Validation of Elucidated Mechanisms Using Neuromodulator Compounds
The goal of this study is to investigate the mechanisms of impaired gastric accommodation and emptying, dysfunctional duodenum, and micro-inflammation using novel imaging techniques of SPECT/CT, gastric emptying scintigraphy, MRI, high-resolution manometry, and inflammatory biomarkers, as well as to validate these mechanisms using a therapeutic trial of neuromodulator (mirtazapine) in functional dyspepsia (FD) and health. The main objective\[s\] it aims to answer are: * to investigate impaired gastric accommodation through SPECT/CT imaging and high-resolution manometry findings of the stomach fundus. * to investigate impaired gastric emptying through gastric emptying scintigraphy * to investigate for a dysfunctional duodenum through MRI imaging of the duodenum. * to investigate micro-inflammation through SPECT/CT standard uptake value (SUV), inflammatory biomarkers (eosinophils, mast cells, IL-6, IL-10) and mucosal barrier marker (E-cadherin). * to investigate if a therapeutic trial of a neuromodulator agent, mirtazapine, ameliorates symptoms of FD through improvement in impaired gastric accommodation. For objectives 1-4, FD patients and healthy volunteers will be consecutively recruited, and all will undergo SPECT/CT, MRI, high-resolution manometry and biomarkers, and data acquired from these tests will be analyzed. For objective 5, the enrolled participants who did all baseline tests/markers are given mirtazapine for four weeks, and all tests/markers, except biomarkers and MRI, are repeated at the end of the trial
• Age 18 and above, up to 65 years old
• No current GI symptoms (as assessed by history taking during screening and based on the investigators' collective judgement)
• No previous GI illness (as determined by clinically significant findings from medical history taking and vital signs)
• No chronic medical illness e.g., chronic neurological, cardiovascular, pulmonary, endoscirne and hematological disorders, as well as psychiatric disorders
• Age 18 and above, up to 65 years old
• Satisfy the diagnosis of FD as per Rome IV criteria
• Absence of organic disorders that explain dyspepsia in patients such as autoimmune disease, inflammatory disease or brain trauma
• No other chronic medical illnesses (including chronic neurological, cardiovascular, pulmonary, endocrine and hematological disorders) and psychiatric disorders