QUANTITATIVE ASSESSMENT OF OVERALL INFLAMMATORY BOWEL-DISEASE ACTIVITY USING LABELED LEUKOCYTES - A DIRECT COMPARISON BETWEEN IN-111 AND TC-99M HMPAO METHODS

The ideal imaging method in inflammatory bowel disease would reliably detect inflammation, identify the correct intestinal location, and ass ess the severity of the disease. The aim of this study was to compare scintigraphic methods of quantifying overall disease activity using bo th indium-111 (In-111) and technetium-99M (Tc-99m) HMPAO labelled leuc ocyte scans. The four day faecal excretion of In-111 was measured afte r In-111 scintigraphy in 24 patients known to have inflammatory bowel disease. The same patients also underwent Tc-99m HMPAO scanning. The s cans were performed 10 days or less apart with no changes in treatment between scans. Bowel activity on the Tc-99m HMPAO scans was assessed using a computer based method (scan score) and a visual grading method in a further 54 Tc-99m HMPAO. The results showed a close correlation between inflammatory activity defined by faecal In-111 excretion and t he scan score generated from the computer analysis of the Tc-99m HMPAO image (Spearman rank correlation: r(s)=0.78; p<0.001). Accurate infor mation to localise inflammatory activity could be obtained by simple v isual assessment of both types of scan images, although image quality was superior with Tc-99m HMPAO. Qualification of disease activity from Tc-99m HMPAO images by visual grading was associated with a large var iability, only 69% of scans had similar scores when graded by three ob servers. Computer generated image analysis was more reproducible. In c onclusion, in inflammatory bowel disease Tc-99m HMPAO scintigraphy and faecal In-111 excretion correlated web. Either method can quantify an d localise the inflammation. As Tc-99m HMPAO scanning provides a quick er result, with a lower radiation dose, and avoids faecal collection, it may be the preferred method.