title: The gastric emptying study: protocol design considerations.
abstract: This study evaluated the intrapatient correlation for gastric emptying times with instant oatmeal and scrambled egg meals. In addition, this study evaluated the degree of overlap between the stomach and the colon or jejunum in the anterior (AP) and left anterior oblique (LAO) projections in CT studies of the abdomen.
  
  
  METHODS
  Fifteen patients were studied twice, 1 d apart, with instant oatmeal and scrambled egg meals, both of which were labeled with (99m)Tc-sulfur colloid. Imaging was performed in the upright position with the LAO projection. One-minute digital images acquired every 15 min were used to calculate a simple half-time of emptying. The correlation coefficient between the oatmeal and egg meals was calculated. In addition, the degree of overlap between the stomach and the colon or jejunum in the AP and LAO projections in 100 CT studies of the abdomen was categorized as none, mild (up to 25%), moderate (25%-50%), or marked (>50%).
  
  
  RESULTS
  One pair of gastric emptying studies was eliminated as an outlier because the distribution of the meals in the stomach, as determined by imaging, was very different for the 2 studies. In the remaining 14 patients, the correlation coefficient for half-times of emptying for the oatmeal and egg meals was 0.77 (P < 0.01). The stomach overlapped the colon 74% of the time in the AP projection and 82% of the time in the LAO projection (P = not significant). The stomach overlapped the jejunum 77% of the time in the AP projection but only 52% of the time in the LAO projection (P < 0.05).
  
  
  CONCLUSIONS
  The significant correlation between the instant oatmeal and scrambled egg gastric emptying times suggests that similar information is provided by the 2 meals. The frequent overlap of the stomach and the colon in both the AP and the LAO projections suggests that imaging at delayed times, such as 4 h, is likely to be problematic because of colonic activity within the stomach region of interest. In addition, the frequent overlap of the stomach and the jejunum has implications for calculation of the lag time; the less frequent overlap of the stomach and the jejunum in the LAO projection than in the AP projection may be an advantage for imaging in the LAO projection.
authors.affiliation: Department of Radiology, Porter Hospital, Denver, Colorado, USA. bill.klingensmith@mac.com
authors.forename: William C
authors.initials: WC
authors.lastname: Klingensmith
authors.forename: Steven P
authors.initials: SP
authors.lastname: Lawrence
mesh_terms: D005746:Gastric Emptying; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D011877:Radionuclide Imaging / Q000379:methods*; D019275:Radiopharmaceuticals; D013270:Stomach / Q000000981:diagnostic imaging*; D013671:Technetium Tc 99m Sulfur Colloid
chemical_list: D019275:Radiopharmaceuticals; D013671:Technetium Tc 99m Sulfur Colloid