Measuring Gastric Emptying: Comparison of 13C-Octanoic Acid Breath Test and Scintigraphy

The aim of this study was to compare scintigraphy, the standard method, and the 13 C-octanoic acid breath test (OBT) for measuring gastric emptying. Patients with functional dyspepsia ( N = 21, 8 men and 13 women; ages, 40–75) underwent standardized dynamic scintigraphy and OBT. Scintigraphic images were obtained for 90 min and breath samples for 4 hr. The gastric half-emptying time for solids ( T 1/2 ) was calculated by two previously described mathematical models for the OBT samples: the nonlinear least-squares method and the geometrical method. T 1/2 was significantly longer measured by OBT than by scintigraphy (167 ± 50 min for the nonlinear least-squares method ( P < 0.05) and 185± 52 min for the geometrical method ( P < 0.005) vs. 109 ± 74 min for scintigraphy). No correlation appeared between T 1/2 measured by scintigraphy and T 1/2 measured by OBT ( r = 0.26) for nonlinear least-squares method and ( r = −0.13) for geometrical method). Furthermore, the correlation between the two mathematical models appeared to be low ( r = 0.15). Although OBT is simple and safe, its correlation with scintigraphy appears to be weak. The usefulness of this test for measuring gastric emptying thus requires further validation.