Project Summary: Novel Methods for Dynamic MRI of Gastrointestinal Motor Function Disorders of gastric motor function include gastroparesis, functional dyspepsia, gastroesophageal reflux disease, among others and can affect >20% of the U.S. population. There is an urgent need to improve the diagnosis and understanding of impaired gastrointestinal (GI) function. The dynamics of gastrointestinal motion are quite complex, for example, stomach emptying is a tightly coordinated and synchronized process with fundic accommodation, peristaltic and tonic antral contractions, pylorus opening and antral-pyloric coordination. There are imaging tools that examine general movement of labeled meals from the stomach into the intestines, but that miss the dynamic processes. Similarly, other tools like electrogastrography are able to assess the frequency and temporal characteristics of stomach contractions but lack spatial resolution to assess the coordination of different types of motor events occurring at specific locations along the gut. Magnetic resonance imaging (MRI) has the potential to provide an unprecedented and detailed visualization of gastrointestinal motor function, allowing new understanding and diagnosis of the pathophysiology of gastrointestinal disorders. The overall goal of the project, therefore, is to develop MRI methods for high spatiotemporal resolution imaging of the gut to improve the diagnosis and assessment of gastrointestinal disorders. There have been breath-hold MRI studies of motion in the gut, but most have limited resolution or volume of coverage, giving an incomplete picture of function. The slow frequency of motion of the stomach and intermittent opening of the pylorus requires longer observation times that precludes the use of breath-hold imaging. Thus, MRI methods must be fast enough and robust enough to resolve respiratory motion in addition to motion of the stomach and intestines. High spatial resolution and SNR are required to visualize small structures and allow for automatic segmentation and accurate quantitation of movement parameters. This project relies on several novel approaches to the dynamic signal modeling, image acquisition, and image reconstruction, to achieve new levels of spatiotemporal resolution for this application. The project has three main aims: (1) Develop four-dimensional spatiotemporal models to capture dynamics due to respiration, gastric accommodation, motility, emptying and coordination, (2) Design MRI acquisition and reconstruction methods for high spatiotemporal resolution, free-breathing, dynamic imaging of the stomach and the intestines, and (3) Evaluate acquisition and reconstruction methods in healthy volunteers. This project has the potential to substantially advance the state-of-the-art dynamic imaging of gastrointestinal motor function. Importantly, imaging in the free-breathing state will allow broader application to sicker populations and the methods will allow for more quantitative and accurate assessment of motion.

Project Narrative: Pathophysiology of gastrointestinal motor function underlies numerous disorders of gastrointestinal system, for example, gastroparesis. In this project, we will develop novel magnetic resonance imaging (MRI) methods for imaging the dynamic motor processes with at a high frame rate and in high resolution, all in the presence of respiratory and other motion. The success of this project will lead to an improved imaging methods to help visualize gastric motor function, enhancing the physiological understanding of a variety of gastrointestinal disorders.