Radiolabelled unprocessed bran: validation of a practical labelling technique and evaluation of gastrointestinal transit profiles in health.

Using a radiolabelled bran preparation, a large field of view gamma-camera and a computer, a method has been developed to define and analyse the gastrointestinal transit profile of solids. Unprocessed bran, labelled with technetium (99mTc) sulphur colloid is incorporated into biscuits cooked in a microwave oven. With this preparation, less than 3.4% of the isotope dissociated from the bran in a gastric milieu, and more than 90% of recovered radionuclide activity, were retained with the solid phase during small intestinal transit in subjects with stable ileostomy function. A normal range for gastric emptying (GE), small intestinal transit (IT) and colonic filling (CF) was established in 15 healthy volunteers. Anterior and posterior images were taken until all isotope was present in the colon. Using regions of interest for the stomach and colon, decay corrected geometric mean curves for GE and CF were generated. GE was characterized by a lag phase followed by a linear emptying phase. The GE profile (mean and standard deviation) was described by 'power exponential' parameters of half-emptying time (1.6 +/- 0.4 h) and beta (1.5 +/- 0.2). The IT time was 3.9 +/- 1.5 h. The onset of CF was determined visually (4.1 +/- 1.5 h), and the time of 50% CF filling was determined from the colonic filling curve (5.5 +/- 1.4 h). This technique should provide a useful, practical, clinical and research test to study the pathophysiology and pharmacology of intestinal motor disorders.