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.