We reviewed 312 Tc-99m leukocyte Tc-99m-WBC studies to evaluate the sensiti
vity and specificity of Tc-99m-WBC for identifying small-bowel and gastric
inflammation in children with Crohn's disease. The Tc-99m-WBC scans were in
terpreted blindly and compared to the results of colonoscopy with biopsies
and surgical specimens. In 46 children, total colonoscopy was done within a
few days of a Tc-99m- WBC scan and in 13 others surgical specimens were av
ailable. Of the 37 children in whom the terminal ileum was visualized endos
copically (24) or surgically (13), the WBC-Tc-99m scan showed a similar deg
ree of inflammation in 33. The sensitivity of Tc-99m-WBC scanning was 91% a
nd the specificity 96%. The scans allowed evaluation of inflammation in the
terminal ileum in 22 children in whom the endoscopist did not cannulate it
; the scans were abnormal in 10 of these 22 children. In the children with
no ileoscopy the results of the Tc-99m-WBC scan were consistent with the la
boratory values, the gastroenterologist's clinical assessment, and long-ter
m clinical follow-up. Finally, the scans of 46 controls did not reveal any
false-positive findings in the terminal ileum. Five children with gastritis
documented by gastroscopy had normal Tc-99m-WBC scans and upper gastrointe
stinal barium studies. This study demonstrates in a large number of normal
and abnormal children with different pre-test probabilities of having infla
mmatory bowel disease that scintigraphy is reliable in identifying small-bo
wel inflammation.