Fat delays emptying but increases forward and backward antral flow as assessed by flow‐sensitive magnetic resonance imaging

Flow has been assessed in the gastric antrum using a velocity‐sensitive version of the high‐speed magnetic resonance imaging technique, echo planar imaging (EPI). Eight healthy volunteers attended fasted on three separate days and consumed 800 mL of either a 5% glucose (0.2 kcal mL −1 ), 10% glucose (0.4 kcal mL −1 ) or an isotonic mixed nutrient meal, Fresubin R (1 kcal mL −1 , 27.2 g fat). Gastric volumes were obtained at 10‐min intervals for 1 h. Flow measurements were performed on a single slice through the antropyloric region 5 and 35 min after meal ingestion. Gastric volumes at 45 min were inversely proportional to the calorie density of the meal with (mean ± SEM) 89 ± 10%* of the Fresubin, 64 ± 5%* of the 10% glucose and 41 ± 5% of the 5% glucose remaining (*P < 0.005 vs 5% glucose). Substantial forward and backward antral flow was observed after all three meals in the initial 5‐min imaging period. At 35 min flow activity was significantly greater after both the high‐calorie meals relative to the 5% meal (total number of flow events: Fresubin = 6.6 ± 1.7,† 10% glucose = 9.9 ± 2.2,‡ 5% glucose = 2.5 ± 0.9,† P < 0.03,‡ P < 0.007 vs 5% glucose, n = 8). Peak forward velocities for the initial phase of emptying tended to be greater for the rapidly emptying 5% meal (5.9 ± 0.8 cm −1 ) compared with the Fresubin (3.3 ± 0.6 cm −1 , P < 0.069, n = 8) and the 10% glucose (2.9 ± 1.0 cm −1 , P < 0.068, n = 8) meals. In spite of delayed gastric emptying, high‐calorie meals were associated with substantial to and fro movements which may be important for meal tritruration and fat emulsification.