THE USE OF DUAL-ISOTOPE IMAGING TO COMPARE THE GASTROINTESTINAL TRANSIT OF FOOD AND PANCREATIC-ENZYME PELLETS IN CYSTIC-FIBROSIS PATIENTS

Cystic fibrosis patients require pancreatic enzyme supplements to aid food digestion. It is suspected that incorrect delivery of this enzyme may result in both significant malabsorption and the development of s trictures in the proximal colon caused by the high-dose supplement rea ching this region before the food. Investigations into the drug's deli very were performed using dual-isotope imaging; a method was developed to directly label the enteric-coated enzyme pellets with In-111, re-a pplying the enteric coating afterwards, and this was then ingested wit h a pancake meal labelled with Tc-99(m)-tin colloid. Consecutive image data, acquired over a period of greater than or equal to 4 h using a dual-headed gamma camera, were analysed to assess intestinal transit. In-vitro stability checks on these labelling techniques were encouragi ng, showing < 2% Tc-99(m) and < 7% In-111 elution over 90 min in hydro chloric acid. In 5 of the 12 patients studied to date, the pellets wer e seen to pass through significantly faster than the food, with a mean difference in 50% gastric emptying time of greater than 93 min. The m ean absolute difference in emptying time for all 12 patients was > 67 min. Thus, a technique has been developed to effectively radiolabel pa ncreatic enzyme pellets, and analysis of dual-isotope images using thi s preparation, together with radiolabelled solid food, has demonstrate d significant differences in the transit of these two substances throu gh the gastrointestinal tract of some cystic fibrosis patients. ((C) 1 998 Lippincott Williams & Wilkins).