The 99mTc-HMPAO leukocyte scan: an alternative to radiology and endoscopy in evaluating the extent and the activity of inflammatory bowel disease.

Seventy-eight patients, 47 with Crohn's disease and 31 with ulcerative colitis, were studied using 99mTc-HMPAO-labelled leukocytes, in order to assess the reliability of the scan in evaluating the location and activity of the disease. The granulocyte integrity was assessed by evaluating the lung wash-out and the early liver and spleen uptake using a 20 minute initial dynamic study. The results of the leukocyte scan revealed a high correlation with radiological and endoscopic findings in the diagnosis of the inflamed bowel segments. The disease activity correlated well with uptake in the bowel, graded from 0 to 3. The leukocyte scan exactly documented the activity in the 9 cases of Crohn's disease located in the ileum and in 5 cases in which the endoscopic exploration was hampered by scarring. Four fistulae were correctly visualized. Moreover, the change in activity after therapy in 6 patients was documented. This technique provides images of excellent quality, superior to those obtainable with indium-111.