Normative Data of Liquid Gastric Emptying and Small-bowel Transit: A Prospective Cross-sectional Study

The primary objective was to establish the reference values for liquid gastric emptying and small bowel. The secondary objectives encompassed comparing the anterior view and geometric mean methods, assessing gender differences, and exploring potential correlations with age.

Thirty-five consecutive healthy participants (28 females and 7 males) with a mean age of 42 ± 11 years (median, 42; range, 23-65) underwent liquid gastric emptying scintigraphy at five intervals (0, 0.5, 1, 2, and 4 h), with optional additional imaging at 24 h. Liquid gastric emptying was evaluated using percent retention and half-time (T1/2). Small-bowel transit was assessed using the index of small-bowel transit (ISBT), calculated as the ratio of terminal ileal reservoir counts to total abdominal counts at 4 h. Reference values were established based on percentiles or mean and standard deviation (SD). Rapid small-bowel transit was determined through visual inspection. Statistical analysis involved paired Samples t-test or Wilcoxon signed-rank test for comparing imaging methods, independent Samples t-test or Mann-Whitney U-test for gender comparison, and Spearman's rank correlation for assessing age-related associations. A 2-tailed P < 0.05 indicated significance.

Rapid liquid gastric emptying based on the geometric mean method was defined as percent retention <8% at 30 min, while delayed emptying as percent retention >33%, >20%, and >4% at 1, 2, and 4 h, respectively. The reference range of T1/2 of gastric emptying was 10-60 min. The reference value for small-bowel transit using the geometric mean method was established as ISBT >30% at 4 h, while rapid small-bowel transit was defined as the first visualization of activity in the cecum-ascending colon within 1 h. Parameters for liquid gastric emptying and small-bowel transit were notably higher in the anterior view method compared to the geometric mean method (P ≤ 0.019), except for percent retention at 2 h (P = 0.510). Nevertheless, the obtained reference values, whether based on percentiles or mean and SD, showed no notable variance between the two methods to warrant clinical significance. Gender did not display an impact on liquid gastric emptying or small-bowel transit in either method (P ≥ 0.173), and age demonstrated no significant moderate or strong correlations (Spearman's ρ ≤ 0.397).

The study determined reference values for liquid gastric emptying and small-bowel transit through a standard gastric emptying scintigraphy protocol, avoiding additional complex procedures or extended imaging sessions. The established normative data can apply to individuals of both genders aged ≥18 years. While advocating the geometric mean method as the primary choice, the study acknowledges that in busy centers handling multiple studies with limited resources and a single-head gamma camera catering to multiple studies, the anterior view method remains a feasible alternative.