410. THE RELATIONSHIP BETWEEN GASTRIC CONDUIT EMPTYING, FUNCTIONAL ANATOMY AND PERISTALSIS: A DETAILED ANALYSIS USING DYNAMIC MAGNETIC RESONANCE IMAGING

Abstract Background Gastric conduit peristalsis post oesophagectomy is an important mediator of conduit emptying and consequently gastrointestinal symptoms and quality of life. The relationship between anatomical variations of the conduit, peristaltic function and transpyloric flow are incompletely defined. We aimed to analyse gastric conduit function using dynamic MRI to evaluate functional anatomy, quantify peristaltic function and measure emptying. Methods Eighteen patients with gastric conduit reconstruction post oesophagectomy and 12 controls with normal gastric anatomy were recruited. Dynamic and static sequences of MRI following ingestion of a semi solid meal were obtained. Peristalsis variables including Gastric Motor Index (GMI - Velocity x Amplitude) were measured at 4 time points throughout the MRI, and volume scans were taken at the beginning and end of the 20-minute scanning period. Nuclear Scintigraphy conduit emptying studies were obtained from 17/18 (94%) of patients. Quality of Life questionnaire data was collected. Results Nine (50%) conduits demonstrated coordinated peristalsis, 3(16.7%) had no measurable peristalsis and 6 (33.3%) had incoordinate peristalsis. Regarding conduits vs controls, there was no difference in peristaltic wave frequency (5 vs 5/90 seconds) or GMI (35.45 vs 36.5, p=0.61), but emptying was decreased (0.10% vs 15% p=0.01). Acute angulation of the conduit was associated with a slower emptying half time (444 vs 127 min, p=0.025). Conduit width and location of the pylorus relative to the hiatus made no significant difference to peristalsis or emptying. Quality of life scores were significantly better in controls compared with conduits. Conclusion Although coordinate peristalsis was present in many conduits, it did not appear to be a key mediator of conduit emptying. Conduit shape and location within the mediastinum significantly affected emptying. These data demonstrate that construction of the conduit at the index operation may be a key factor in long term function and reducing gastrointestinal symptoms. Dynamic MRI is a promising research and diagnostic tool to assess conduit function due to its capacity to accurately delineate the key elements of conduit function.