Leukocyte migration in acute colonic inflammatory bowel disease: comparison of histological assessment and Tc-99m-HMPAO labeled leukocyte scan.

UNLABELLED: Noninvasive leukocyte scintigraphy for assessment of localization, extent, and degree of active inflammation in acute colonic inflammatory bowel disease have been shown to correlate well with endoscopy. This study compared findings of mucosal leukocyte migration assessed histologically with those of technetium 99m hexamethylpropylene-amineoxime-labeled leukocyte scintigraphy. PATIENTS AND METHODS: Twenty-one patients hospitalized because of a first attack or a relapse of known inflammatory bowel disease were investigated using leukocyte scintigraphy followed by total colonoscopy with multiple biopsies within 24 h. Histological interpretation focused on the degree of segmental mucosal leukocyte infiltration. RESULTS: Fourteen patients with ulcerative colitis (UC) and seven with colonic Crohn's disease (CD) were included. With the use of histology as the reference method, maximal proximal disease extent was correctly assessed by the leukocyte scan in 11 patients (8 with UC, 3 with CD), although the rectal involvement was not visualized in 5. In seven patients, the extent assessments almost matched (+/- one segment), and in the remaining three patients (two UC, one CD) the scan grossly misinterpreted active histological inflammation (> or = +/- two segments). In patients with UC, the sensitivity, specificity, and diagnostic accuracy concerning the extent of inflammation were 0.84, 0.79, and 0.83, respectively. In patients with CD, the sensitivity was 0.79, and the diagnostic accuracy was 0.78. The relative leukocyte scan activity score was less concordant with the degree of mucosal leukocyte infiltration but still significantly correlated (r = 0.616, p < 0.0001 in UC patients and r = 0.441, p < 0.003 in CD patients). CONCLUSION: Images created by the technetium 99m hexamethylpropylene-amineoxime-labeled leukocyte scan in acute colonic inflammatory bowel disease correlate to mucosal leukocyte migration in terms of proximal disease extent and, to a lesser degree, also to the intensity of mucosal inflammatory infiltration.