A longitudinal study of FDG-PET in Crohn disease patients receiving granulocyte/monocyte apheresis therapy.

BACKGROUND AIMS Endoscopy is the gold standard for the diagnosis and follow-up of patients with Crohn disease (CD). However, a less invasive approach is now being sought for the management of these patients. The objective of this study was to examine whether (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) might be relevant for monitoring the disease activity in CD patients undergoing granulocyte/monocyte apheresis (GMA). METHODS This study was conducted in 12 patients with CD who were receiving treatment with 10 once-a-week GMA sessions with the Adacolumn. The response to treatment was monitored by measuring standard laboratory variables, Crohn's Disease Activity Index (CDAI) score, International Organization for the Study of Inflammatory Bowel Diseases (IOIBD) score, and regional and global bowel uptakes on FDG-PET. RESULTS In 6 of the 12 patients, significant improvement of the CDAI was observed after the final session of GMA. The patients who showed clinical response to GMA had a decrease in the regional and global bowel uptakes on FDG-PET, whereas those who did not respond showed no change. In the patients who responded to the GMA, the decrease in regional bowel uptake on FDG-PET in each disease area of the same patient varied in parallel. There was a significant correlation between decrease in the global bowel uptake on FDG-PET and improvement of the CDAI and IOIBD scores. CONCLUSIONS The longitudinal changes in FDG-PET uptakes are of potential clinical interest for assessing the regional and global bowel disease activity in CD patients undergoing GMA therapy.