Validation of 99Tcm-HMPAO leucocyte scintigraphy in ulcerative colitis by comparison with histology.

Leucocyte scintigraphy offers an alternative to more invasive techniques in the investigation of inflammatory bowel disease. The accuracy of 99Tcm-HMPAO leucocyte scintigraphy has not been assessed by comparison with colonic histology, which was the aim of this study. 15 patients with ulcerative colitis underwent 99Tcm-HMPAO leucocyte scintigraphy (TLS) less than 5 days before colonoscopy. Histological features of mucosal biopsies were compared with total and segmental colonic TLS scores. Segmental and total scintigraphy scores correlated most strongly with histological grades for acute inflammation (r = 0.75, p < 0.001 and r = 0.9, p < 0.001, respectively) and chronic inflammatory cell infiltration in the lamina propria (r = 0.76, p < 0.001 and r = 0.86, p < 0.001, respectively). 99Tcm-HMPAO leucocyte scintigraphy detected acute inflammation in the colon of patients with ulcerative colitis with a sensitivity of 91% and negative predictive value of 80% and localized acute inflammation to a particular colonic segment with a sensitivity of 82%, specificity of 94%, accuracy of 88%, positive predictive value of 94% and negative predictive value of 91%. 99Tcm-HMPAO leucocyte scintigraphy positivity predicts and localizes colonic acute inflammation with a high degree of confidence, but negative scintigraphy does not exclude acute inflammation.