Both MRI and [18 F]FDG PET were accurate in diagnosing OM in a tertiary referral hospital population. Simulation of imaging strategies showed that a combined sequential strategy was optimal. It seems preferable to use MRI as a primary imaging tool for uncomplicated unifocal cases, whereas in cases with (possible) multifocal disease or a contraindication for MRI, PET is preferred. This combined sequential strategy looks promising, but needs to be confirmed in a larger prospective study.

Objectives:Radiation pneumonitis (RP) can be an adverse complication of radiotherapy (RT) and can limit the application of the already planned radiation dose. It is often associated with RT of lung carcinoma and is occasionally caused by radiation therapy of breast carcinoma and lymphomas located in the mediastinum. Positron emission tomography/computed tomography (PET/CT) emerges lately as a prospective modality for early diagnostics of RP. The aim of this study was to summarize the initial data from diagnostic application of PET/CT in patients suspicious of RP and to derive criteria, which can help differentiate RP from early recurrence of the disease and/or residual tumor.Methods:The current study included 23 patients who had metabolic (PET) and anatomical (CT) changes consistent with RP. We additionally defined metabolic activity (SUVmax) in the lung parenchyma of 20 patients without RT.Results:All patients had increased metabolic activity in the lung parenchyma involved in the irradiated area with a mean SUVmax 3.45 (ranging between 1 and 7.1). The control group had a physiological background metabolic activity-SUVmax 0.61 +/- 0.11.Conclusion:Metabolic changes in patients suspicious of RP involved diffusely increased metabolic activity coinciding with the anatomical changes in the irradiated area. Three out of 23 patients had a proven recurrence of the primary neoplastic process in the irradiated area. The metabolic changes in those patients involved an increase in metabolic activity at follow-up or lack of tendency towards normalization after chemotherapy, which implied the existence of viable tumor cells. Our initial experience in the diagnostic application of 18F-FDG PET/CT in patients suspicious of RP allows us to summarize the following: PET/CT is a reliable imaging modality in the diagnostics of RP. Through its sequential use, we can differentiate inflammatory changes related to RP from early recurrence of the primary neoplastic process.

Fever of unknown origin (FUO) represents a challenge in diagnosis and treatment. The role of 18Ffluorodeoxyglucose positron emission tomography (FDG-PET) / computed tomography (CT) in the differential diagnosis of this entity is presently well established. We report the case of a patient with infectious/inflammatory symptoms but no evident localization and subsequent relapse, in which PET/CT showed its ability to not only determine the exact localization of a thrombophlebitic focus as cause of FUO, but also to monitor and determine the success of treatment. After performing a FDG-PET/CT and detecting a thrombophlebitis in the brachiocephalic vein, low molecular heparins were introduced in the course of therapy. Soon (about 24 hours) thereafter, clinical symptoms significantly decreased and could no longer be observed. After continuing the antibiotic and anticoagulant therapy for 4 weeks, a follow-up PET/CT scan was performed. That scan no longer showed abnormal uptake in the previous intravascular localization. Consequently, we suggest that PET/CT is a diagnostic modality feasible to identify and monitor therapy response of intravascular thrombophlebitic foci.