F-18 Fluorodeoxyglucose PET/CT as a Diagnostic Tool in Orbital Inflammatory Disorders.

To assess the usefulness of FDG-PET/CT as a potential diagnostic tool for detecting underlying systemic diseases (SD) in patients with orbital inflammatory disorders (OID). All consecutive patients managed for new-onset OID between 2011 and 2018 in a tertiary referral center, who underwent FDG-PET/CT as part of the etiological diagnostic workup were evaluated. To quantify the incremental value of FDG-PET/CT over standard diagnostic workup, the Net Reclassification Index (NRI) and Integrated Discrimination Index (IDI) were used. Among the 22 patients enrolled, 11 (50%) had a positive FDG-PET/CT. After clinicobiological evaluation, FDG-PET/CT correctly reclassified 4(29%) of 14 patients with SD (p =.04) and 1(13%) of 8 with idiopathic orbital inflammation syndrome (p =.32). NRI and IDI were 0.41 ± 0.17 (p =.03) and 0.38 ± 0.08 (p <.001), respectively. FDG-PET/CT successfully detected asymptomatic lesions in all (n = 4) patients with lymphoma. FDG-PET/CT enabled accurate reclassification of more than one-quarter of patients with SD, especially extraorbital lymphomas. [ABSTRACT FROM AUTHOR]