Simple linear regression

1319 Objectives: The rate of gastric emptying of a solid meal varies depending on many factors, including meal volume and composition, patient position, and imaging methodology. We have found published standardized methods that report normal reference values to be difficult to implement. Our objective was to establish normal reference values using a protocol that any nuclear medicine department can adopt, using an easily duplicated and palatable meal, image aquisition that is well tolerated by patients, and simple processing. Methods: The meal consisted of an egg white sandwich, prepared with 1 mCi of Tc99 sulfur colloid cooked into 50 cc of egg white (separated from fresh whole eggs), an English Muffin, and 150 cc of water. Twenty nine healthy volunteers were imaged using simultaneous anterior and posterior one minute static images, acquired every 15 minutes for two hours. Imaging was supine, but the subjects were allowed off the table to sit in a chair between images. Percent gastric emptying at each time point was calculated using decay corrected geometric mean counts. The upper and lower limits of normal were calculated for each time point using the mean + and - 2.048SD (t critical value = 2.048 with 28 df). Results: The results are in the attached table. Because nearly all our of our clinical exams are done for gastroparesis, we were most interested in the lower limits of normal gastric emptying. At 60 minutes, the lower limit of normal is 18%, with mean emptying of 54%. At 90 minutes the lower limit is 46%, with mean emptying of 75%. Conclusions: We have described a standardized method for scintigraphic measurement of gastric emptying of solids, which can be duplicated in nearly any nuclear medicine department, and have established normal values based on 29 normal subjects.