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 ver sion of the high-speed magnetic resonance imaging technique, echo planar im aging (EPI). Eight healthy volunteers attended fasted on three separate day s and consumed 800 mt 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 IO-min intervals for I h. Flow measurements were performed on a single slice through the antropy loric region 5 and 35 min after meal ingestion. Gastric volumes at 45 min w ere 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 forw ard and backward antral flow was observed after all three meals in the init ial 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,dagger 10% glucose = 9.9 +/- 2.2,doubl e dagger 5% glucose = 2.5 +/- 0.9,dagger P < 0.03,double dagger P < 0.007 v s 5% glucose, n = 8). Peak forward velocities for the initial phase of empt ying 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 d elayed gastric emptying, high-calorie meals were associated with substantia l to and fro movements which may be important for meal tritruration and fat emulsification.