Pilot studies have shown good sensitivity and specificity for (18)F-FDG PET in detecting gastrointestinal lesions of Crohn's disease. The combination of (18)F-FDG PET with CT may further improve the localization and characterization of lesions with increased (18)F-FDG uptake. Our aim was to assess the use of (18)F-FDG PET/CT in evaluating the activity and location of Crohn's disease along the gastrointestinal tract.
Methods: After giving informed consent, 22 patients with Crohn's disease were prospectively studied. They underwent (18)F-FDG PET/CT, followed by ileocolonoscopy within 1 wk (mean, 2 d). The Crohn's disease activity index (CDAI) was calculated, and serum C-reactive protein (CRP) and fecal calprotectin were measured before endoscopy. The Crohn's disease endoscopy index of severity (CDEIS) was calculated during endoscopy. The global CDEIS score and endoscopic subscores for various ileocolonic segments were used for analysis.
Results: Globally, 95 intestinal and colonic segments in 22 patients were analyzed. (18)F-FDG PET/CT detected 35 of 48 endoscopically affected segments (sensitivity for the detection of endoscopic lesions, 72.9%). The sensitivity of (18)F-FDG PET/CT for the detection of severe endoscopic lesions (deep ulcers and strictures) was 100% (14/14). The global PET/CT score significantly correlated with CDEIS (r = 0.51; 95% confidence interval [CI], 0.09-0.77; P = 0.017), CDAI (r = 0.58; 95% CI, 0.17-0.80; P = 0.005), and CRP (r = 0.56; 95% CI, 0.19-0.81; P = 0.007).
Conclusion: (18)F-FDG PET/CT was globally well correlated to the clinical, endoscopic, and biologic activity of Crohn's disease. Above all, this technique had a good sensitivity for the detection of intestinal and colonic segments with moderate to severe mucosal lesions. The potential impact of this promising tool on the global management of patients with Crohn's disease should be further evaluated in prospective studies.