Normal Gastric Emptying Scintigraphy Values for Limited Meal Ingestion.

Introduction: Patients with symptoms of gastroparesis are assessed with gastric emptying scintigraphy (GES). However, patients may not eat the entire meal due to their symptoms. The aim of this study was to quantify in normal subjects the effect of different ingested meal sizes and how these results could affect interpretation of patients' GES.

Methods: Normal subjects underwent three GES tests ingesting the currently established Tc-99 m radiolabeled liquid egg white sandwich served as a full (100%), half (50%), or quarter (25%) meal. Percent gastric retention was calculated for each imaging time (0, 0.5, 1, 2, 3, 4 h). T1/2 for GE was calculated using power exponential curve fit.

Results: 24 normal subjects completed three GES tests. Percent gastric retention at 0.5, 1, 2, 3 h postprandially were significantly less for half and quarter meal compared to the full meal. Mean + 2SD gastric retention values at 2 h for 50% meal and 25% meal were 41.6% and 59.5%. Compared to T1/2 for the full-size meal (94 ± 21 (SD) min), T1/2 for half meal (67 ± 19 min; p < 0.01) and quarter meal (69 ± 28 min; p < 0.01) were significantly shorter. Mean + 2SD T1/2 emptying values for 50% and 25% meal ingestion were 105.2 and 125.8 min.

Conclusion: Gastric emptying is affected by amount of the meal ingested. T1/2 was shorter, and percent retention at 0.5, 1, 2, 3 h postprandially were less for half- and quarter-size meals compared to the full meal. Based on our results, if a patient ingests 50% of the standard GES meal, > 41.6% retention at 2 h or T1/2 is > 105.2 min is consistent with delayed GE.