The Utility of 18F-FDG PET/CT for Diagnosis and Adjustment of Therapy in Patients with Active Chronic Sarcoidosis

The purpose of this study was to assess the utility of F-18-FDG PET/CT for detection of inflammation in granulomatous sites and management of patients with chronic sarcoidosis. The 3 specific aims were to assess differences between F-18-FDG PET/CT and multidetector CT (MDCT) findings, to compare F-18-FDG PET/CT results with serum levels of angiotensin-converting enzyme (ACE), and to determine whether F-18-FDG PET/CT findings are associated with the decision to change therapy. Methods: We studied 90 sarcoidosis patients (mean age +/- SD, 47 +/- 12 y; 32 men and 58 women) with persistent symptoms who were referred for F-18-FDG PET/CT evaluation to assess the extent of inflammation. They also underwent MDCT and measurement of serum ACE level. After the follow-up (12 +/- 5 mo after F-18-FDG PET/CT), the clinical status and changes in therapy were analyzed. Results: F-18-FDG PET/CT detected inflammation in 74 patients (82%) (maximum standardized uptake value, 8.1 +/- 3.9). MDCT was positive for sarcoidosis in 6 additional patients (80, 89%). The difference between the 2 methods was not significant (P = 0.238, McNemar test), and their agreement was fair (kappa = 0.198). Although ACE levels were significantly higher in patients with positive than negative F-18-FDG PET/CT results (P = 0.002, Mann-Whitney test), 38 patients (51%) with positive F-18-FDG PET/CT results had normal ACE levels. The therapy was initiated or changed in 73 out of 90 patients (81%). Both univariate and multivariate logistic regression analyses indicated that positive F-18-FDG PET/CT results were significantly (P < 0.001) associated with changes in therapy, with no contribution from age, sex, ACE level, CT results, or previous therapy. Conclusion: Our results indicate that F-18-FDG PET/CT is a useful adjunct to other diagnostic methods for detecting active inflammatory sites in chronic sarcoidosis patients with persistent symptoms, especially those with normal ACE levels. F-18-FDG PET/CT proved advantageous for determining the spread of active disease throughout the body and influenced the decision to adjust the therapy.