Pilot study using PET/CT as a novel, noninvasive assessment of disease activity in inflammatory bowel disease

A pilot study was performed investigating the possibility that positron emission tomography (PET) activity using 18-fluorodeoxyglucose (FDG) with nearly simultaneous computerized tomography (CT) for anatomic accuracy would identify regions of active inflammation in both ulcerative colitis (UC) and Crohn's disease (CD).

Prospective clinical data was collected in 12 patients experiencing an exacerbation of their inflammatory bowel disease; 7 with CD and 5 with UC. A PET/CT scan (GE Discovery LS PET/CT scanner) was performed in all patients. Twenty patients undergoing PET/CT because of solitary pulmonary nodules served as controls. We graded the small bowel and 4 colon regions (ascending, transverse, descending, and rectosigmoid) with PET activity scores assigned to each region based on the amount of FDG uptake using the liver as the reference organ.

In UC patients, PET activity was seen in 13 of 24 (52%) regions. There was high (23 of 24; 95.8%) correlation between PET activity and disease activity as determined by colonoscopy, disease activity indices, and radiology. In patients with CD, PET activity was seen in 19 of 32 (59.4%) regions. Again, there was a high (26 of 32; 81.3%) correlation between PET activity and clinical disease activity. Of the 20 controls, significant PET activity (Grades 2 and 3) was seen in only 2 of 100 regions (2%).

We found that PET activity correlated well with active inflammation in both UC and CD, suggesting that this may be a noninvasive method of identifying disease activity in patients with inflammatory bowel disease.