Inclusion Criteria:

• Male and female volunteers aged 18-80 years old.
• Persistent upper gastrointestinal symptoms (nausea, vomting, bloating, post prandial fullness or post prandial pain) for > 6 months.
• Having capacity to provide written informed consent before participating in the study.
• Able to communicate adequately with the investigator and to comply with the requirements for the entire study.
• Undergoing a clinically indicated a gastric emptying study or having completed a gastric emptying study.

Exclusion Criteria:

• Severe nausea or vomiting, which may preclude study assessments.
• Use of medications that, in the opinion of the investigator have the potential, to alter GI motility (e.g., narcotics, medications with significant anticholinergic effects, prokinetic agents) and which cannot be discontinued for 4 half-lives prior to the imaging studies.
• Clinical evidence of significant cardiovascular, respiratory, renal, hepatic, gastrointestinal, hematological, neurological, psychiatric or other disease that may interfere with the objectives of the study.  A history of inflammatory bowel disease (e.g, Crohn’s disease or ulcerative colitis).  However, participants with microscopic or collagenous colitis will be eligible to participate.
• Prior gastric or major intestinal (i.e., resection of > 50 cm) or colonic surgery (i.e., hemi or subtotal colectomy).  Appendectomy, cholecystectomy, tubal ligation,  hysterectomy, herniorrhaphy, and limited colonic resection are permissible.
• Participants who are allergic to eggs or decline to consume milk.
• History of radiation therapy to the abdomen.
• Anxiety or depression as assessed by the Hospital Anxiety and Depression Questionnaire 11.
• Contraindications for MR imaging: i.e. pacemakers, aneurysm clips, cochlear implants.*
• Pregnant women, breast-feeding women, prisoners and institutionalized individuals.*
• Treatment with GLP-1 agonists and amlyin which cause vagal blockade and may affect central processing of pain.
• Positive tissue transglutaminase antibodies (TTG).
• Poor peripheral venous access, if central venous access is not available.
• Any other condition or prior therapy that, in the opinion of the investigator, would make the patient unsuitable for the study.