A Roadmap to Investigate Human Postprandial Gastric Emptying and Metabolic Responses to Solid Meal Feeding with Varying Glycemic Load: Integrating MRI Evaluation into a Crossover Design Study

Postprandial gastric emptying is crucial to understanding the glycemic and lipemic effects mediated by varying meal compositions, yet methodologies for assessing gastric emptying of solid mixed meals remain limited. This protocol development study aimed to optimise clinical procedures for data collection involving human volunteers undergoing magnetic resonance imaging (MRI) of gastric emptying in response to rice-based solid meals, prior to its application to a larger clinical trial. The developed protocol integrated sequential MRI measurements with concurrent biospecimen collection and Visual Analogue Scale (VAS) assessments at baseline and at repeated postprandial time points up to 300 min following test meal ingestion. Three pilot test runs ( n =1-3 subjects per run) were conducted to refine MRI parameters, workflow integration and scheduling logistics. MRI acquisition settings, including slice thickness and imaging sequences, were optimised to enhance visualisation and quantification of intragastric contents. Validation of the optimised protocol demonstrated excellent agreement between axial and coronal measurements of total gastric volumes with an intraclass correlation coefficient (ICC) of 0.987 and no systematic bias. Inter-rater reliability was also high (ICC=0.996), confirming the reproducibility of gastric volume measurements. In conclusion, this study established a validated, reproducible MRI protocol capable of assessing gastric emptying of solid meals for up to three subjects per day. This study facilitated developing a robust methodological framework for investigating postprandial metabolic responses in a subsequently larger cohort ( n =12).