Air enema radiology compared with leukocyte scintigraphy for imaging inflammation in active ulcerative colitis

To compare air enema radiology with a leukocyte scintigraphy technique using technetium-99m-hexamethyl propylene amine oxime-labelled leukocytes for imaging colonic inflammation in ulcerative colitis.

Prospective study in a University hospital. One radiologist and one nuclear physician independently graded the degree of inflammation in six colon segments per patient using radiographs and leukocyte scans.

Twenty consecutive patients with symptoms of active ulcerative colitis requiring corticosteroids, inflammation on rigid sigmoidoscopy and a positive leukocyte scan above the rectum.

Using air enema radiology, inflammation above the rectum was observed in 17 of the 20 patients. Eleven patients had the same extent of disease with both imaging techniques (total n = 5; extensive n = 3; distal n = 3). Seven patients had more widespread colitis using leukocyte scintigraphy. In the remaining two patients with extensive inflammation at scintigraphy, air enema films showed total colitis. When the colon was subdivided into six different segments, prediction of the presence of inflammation in individual segments was 0.88 for air enema radiology compared with leukocyte scintigraphy and 0.60 for the prediction of absence of inflammation. All segments with an irregular mucosal contour or ulceration on air enema films had intense inflammation at scintigraphy.

In patients with active ulcerative colitis, air enema radiology underestimates the extent of inflammation because this investigation shows secondary patho-anatomical changes, while leukocyte scintigraphy visualizes the acute cellular infiltrate. In patients with more severe inflammation, there is excellent agreement between the two methods.