Can 99Tcm HMPAO leucocyte scintigraphy distinguish between Crohn's disease and ulcerative colitis?

This paper has retrospectively analysed the ability of 99Tcm HMPAO leucocyte scintigraphy to distinguish Crohn's disease from ulcerative colitis. The diagnostic criteria were established by reviewing 99Tcm HMPAO leucocyte scintigrams in 123 patients with histologically proven Crohn's disease (83) or ulcerative colitis (40). Uptake in the right iliac fossa with or without other segments of colon, irregular bowel uptake, small bowel uptake or colonic activity with rectal sparing were all strongly suggestive of Crohn's disease. Left sided colitis was found to indicate ulcerative colitis. Total colitis occurred in both ulcerative colitis and Crohn's disease. The criteria were later tested in an additional 62 patients with excellent results (accuracy 98%). In 63 patients in whom the results of barium radiology were also available, the accuracy of scintigraphy was higher (93% and 83%, respectively). We conclude that 99Tcm HMPAO leucocyte scintigraphy can accurately distinguish between Crohn's disease and ulcerative colitis in a large proportion of cases and appears to be more reliable than conventional radiology.