Sa1112 Three-Dimensional Myoarchitecture of Porcine Gastro-Esophageal Junction With Diffusion Tensor Imaging

Abstract

Introduction: The anatomy and function of the gastro-esophageal junction (GEJ) is complex with mucosa-submucosa layers and smooth muscle layers organized into circular and longitudinal muscle layers. These layers continue from the esophagus into the GEJ and the stomach. Furthermore, the crura of the diaphragm and the lower esophageal sphincter are components of the GEJ. Little is known about the microstructure of the GEJ. Diffusion tensor imaging (DTI) allows mapping of the diffusion process of molecules, mainly water, in biological tissues. Water molecule diffusion patterns can therefore reveal microscopic details about tissue architecture. Its main clinical application has been in the study of neurological disorders such as acute stroke. Until now DTI has not be used much in esophagology. Aims: This study aims to reconstruct an anatomically realistic 3D model of the GEJ on the basis of DTI and more specifically to distinguish the muscle fiber transition between the esophagus, the stomach, and the diaphragmatic crura. Methods: Three 40-60kg pigs were used for obtaining the GEJ and adjacent parts of the esophagus, stomach and diaphragm. The pig was sacrificed during deep anesthesia before opening the abdominal and thoracic cavities. The intestines were removed whereas the liver and stomach was kept in place for maintaining the anatomical position of GEJ. The abdominal cavity and thoracic cavities were filled with formalin and closed. After 24h of tissue fixation, the pigs were reopened and the esophagus, upper part of stomach and intact diaphragm were dissected out and fixed with 4% formalin in an organ bath for further 2-3 days. A 7x7x7cm3 block including the entire GEJ region and lower part of the esophagus, upper part of the stomach, and the diaphragmatic crura was prepared for Magnetic Resonance (MR) scanning. Scanning was done in a Philips Intera, 1.5T MR scanner for obtaining anatomy imaging and DTI. The wall thickness at different layers of the GEJ as well as the helical angles of the longitudinal muscle fiber, the circular muscle fiber, the gastric sling fiber, gastric oblique fibers and diaphragm crura fiber along the central axis of the GEJ were calculated on the basis of the anatomic imaging and DTI. Results: It was possible to visualize the anatomical features of GEJ using DTI. The figure shows the total muscle fibers 3D distribution along the GEJ in a traced DT image. Differences in diffusion properties between the GEJ structures such as the sling fibers were easy to recognize and detailed layer data were obtained and used as input for an ongoing development of a realistic functional model of the GEJ. Conclusions and perspectives: This study clearly demonstrated that DTI may be useful in esophagology and moved a step further by establishing an anatomical-functional realistic computer model of the GEJ.