Use of technetium-tagged white blood cells in patients with Crohn's disease and ulcerative colitis: is differential diagnosis possible?

Background. Studies have suggested that scans with technetium-tagged white blood cells (WBC-Tc-99m) may be equal to endoscopy in the assessment of extent and activity of inflammatory bowel disease (IBD). Objective. We have retrospectively examined the accuracy of WBC-Tc-99m scans in differentiating continuous from discontinuous colitis in pediatric IBD. Materials and methods. There were 207 children in the study (96 boys, 111 girls, median age 13 years). This included 29 controls - children with no gastrointestinal disease (NL) who underwent WBC-Tc-99m scans for other medical problems. Scans were obtained at 30 minutes and 2-4 hours following injection. Scans were interpreted as showing continuous colitis, discontinuous colitis, or no colitis. Results. In the 77 children with active Crohn's disease (CD) of the colon, the scans revealed discontinuous uptake in 63 children and continuous uptake in 14. In the 29 children with ulcerative colitis (UC), 23 scans showed continuous uptake and 6 revealed discontinuous uptake. Two of these 6 showed focal activity near the appendix, and subclinical appendicitis could not be excluded. Another child was bleeding and the scan could have been misinterpreted as showing small-bowel inflammation. In the last three patients, skip areas were clearly identifiable. In none of these last three patients were the biopsies typical of CD (i. e., no granuloma was identified) nor was inflammation patchy. In summary, of the 106 scans showing inflammation, 6 were classified into the wrong group. Conclusion. These data show that WBC-Tc-99m scanning can be useful in distinguishing discontinuous from continuous colitis.