A novel MRI-based three-dimensional model of stomach volume, surface area and geometry in response to gastric filling and emptying

Abstract

ABSTRACTBackgroundGastric motility and accommodation have a critical role in maintaining normal gastrointestinal homeostasis. Different modalities can be adopted to quantify those processes, i.e., scintigraphy to measure emptying time and intragastric Barostat for accommodation assessment. However, magnetic resonance imaging (MRI) can assess the same parameters non-invasively without ionizing radiation. Our study aimed to develop a detailed three-dimensional (3D) MRI model of the stomach to describe gastric volumes, surface areas, wall tension distribution, and inter-observer agreement.MethodsTwelve healthy volunteers underwent an MRI protocol of six axial T2-weighted acquisitions. Each dataset was used to construct a 3D model of the stomach: Firstly, the volumes of the whole stomach, gastric liquid, and air were segmented. After landmark placing, a raw 3D model was generated from segmentation data. Subsequently, irregularities were removed, and the model was divided into compartments. Finally, surface area and 3D geometry parameters (inverse curvatures) were extracted. The inverse curvatures were used to as a proxy for wall tension distribution without measuring the intragastric pressure.Key ResultsThe model was able to describe changes in volume and surface geometry for each compartment with a distinct pattern in response to filling and emptying. The surface tension was distributed non-homogeneously between compartments and showed dynamical changes at various time points.Conclusion & InferencesThe presented model offers a detailed tool for evaluating gastric volumes, surface geometry, and wall tension in response to filling and emptying and will provide insights into gastric emptying and accommodation in diseases such as diabetic gastroparesis.KEY POINTS-While MRI and ultrasound are getting progressively accepted as methods for evaluating gastric emptying and accommodation, they still do not provide essential insights into those processes.-This study presents a three-dimensional stomach model able to report volume and surface data, and to describe the distribution of the gastric wall tension of gastric compartments by applying the Young-Laplace law.-We observed that volumes and surface geometry showed distinct emptying patterns in each compartment and that the wall geometry distributed non-homogeneously in the stomach, showing different dynamical changes during the emptying phase. Our observations indicate the fundus as essential in the first phase of digestion, confirming its role as reservoir.-The non-invasive model has the potential to give detailed information about the gastric volumes and surface geometry in response to filling and emptying, with the potential to understand the pathophysiology and improve treatment in patients with gastroparesis.GRAPHICAL ABSTRACT