Early appearance of small bowel activity predicts normal gastric emptying at four hours on scintigraphy

Introduction: With normal gastric emptying, the stomach titurates food to prepare it to enter the small bowel. This gastric lag phase prior to small bowel emptying has been estimated at 15-30 minutes. We observed that some patients undergoing T-99m sulfur colloid gastric emptying scintigraphy show activity in the small bowel on initial imaging immediately after meal ingestion (Time 0). We aimed to correlate this with rates of rapid gastric transit (<30% retention at 1 h) and rates of normal gastric emptying at 4 h (<10% retention).

Methods: In this observational study, we retrospectively reviewed Tc-99m sulfur colloid gastric emptying scans of 18 patients with activity in the small bowel on Time 0 imaging. All patients received a standardized egg sandwich meal. Patients with meal commencement to imaging time <15 minutes were included. Anterior and posterior planar images were obtained at time 0 and at 1, 2, 3 hours. Images were obtained at 4 hours if percent retention at three hours was >9%. Region of interest (ROI) analysis was performed on simultaneously acquired conjugate views using mirrored ROIs. Time 0 geometric mean counts were drawn over stomach and small bowel, which defined 100% of the meal. ROIs for subsequent images were drawn over stomach only. Geometric mean analysis was performed. Counts were corrected for decay.

Results: Data were analyzed for 18 pts (age = 52±20 years, 4 males, 14 females) with small bowel activity on the Time 0 image. Mean time to consume the meal was 8±2 minutes and mean time from the end of meal consumption to the beginning of imaging was 2±1 minutes. All 18 pts had normal gastric retention (GR) of < 10% at 4 h, significantly more prevalently (P = .0006) than if appearance of small bowel activity in the initial image were unrelated to normal GR. Imaging was ended before 4 h for 12/18 (67%) of pts, and for the remaining 6 pts mean GR at 4 h was 4±2%. 15/18 (83%) of pts had normal GR of < 60% at 2 h (mean GR at 2 h = 33±27% for all 18 pts). Rapid gastric transit defined as <30% retention at 1 h was present in 1/18 pts (6%), with mean GR at 1 h = 74±34% for all 18 pts.

Conclusions: Early appearance of activity in the small bowel at Time 0 on Tc-99m sulfur colloid gastric emptying scan predicted normal gastric emptying at 4 hours.

• Download figure
• Open in new tab
• Download powerpoint