Indirect vs direct assessment of gastric emptying: A randomized crossover trial comparing C-isotope breath analysis and MRI

BackgroundIndirect methods to assess gastric emptying (GE), such as C-13 breath tests (BT), are commonly used. However, BT usually use a sampling time of 4+hours. The current study aims to assess the validity of BT for four liquid meals differing in physicochemical properties. To this aim, we compared them to MRI GE-measurements. MethodsFifteen healthy males (age 22.62.4years, BMI 22.61.8kg/m(2)) participated in a randomized 2x2 crossover experiment. Test foods were liquid meals, which were either thin/thick and 100/500kcal, labeled with 100mg of C-13-octanoate. GE was measured with MRI and assessed by C-13 recovery from breath. Participants were scanned every 10minutes and at six time points breath samples were collected up to t=90minutes. Two curves were fitted to the data to estimate emptying halftime (t(50 Ghoos) and t(50 Bluck)). T-50 times were ranked per participant and compared between methods. Key ResultsOn average, MRI and BT showed similar t(50) rankings for the four liquid meals. In comparison to MRI, t(50 Ghoos) overestimated, while t(50 Bluck) underestimated GE time(.) Moreover, more viscous foods were overestimated. In most participants individual t(50) time rankings differed significantly between methods. Conclusions & InferencesBT can assess relative emptying differences on group level and collecting breath data for 90minutes constitutes a lower burden for participants and the research facility. However, BT has severe shortcomings compared to MRI for individual GE assessment. Notably, food matrix effects should be considered when interpreting the results of BT.