Diagnostic contribution of positron emission tomography with [18F]fluorodeoxyglucose for invasive fungal infections

Optimal staging and evaluation of residual lesions of invasive fungal infections (IFIs) are major challenges in the immunocompromised host. Preliminary data have suggested that [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) uptake may be observed in the course of active invasive fungal infections. The aim of this study was to assess the role of positron emission tomography with [¹⁸F]FDG ([¹⁸F]FDG-PET) in the diagnosis and staging of IFI. A prospective monocentric study evaluating [¹⁸F]FDG-PET in 30 consecutive adults and children with European Organization for Research and Treatment of Cancer/Mycoses Study Group probable or proven IFI was performed. Twenty males and ten females (median age, 45 years (range 6-7 years)) were enrolled. Twenty-six were immunocompromised, as follows: haematological malignancy (18) with allogeneic stem cell transplantation (16/18), solid tumour (three), solid organ transplantation (two), diabetes mellitus (two) and cystic fibrosis (one). IFIs were acute invasive aspergillosis (ten), chronic disseminated candidiasis (ten), zygomycosis (two), black grains eumycetoma (two), pulmonary Histoplasma capsulatum var. capsulatum histoplasmosis (two), and Phomopsis sp. osteoarthritis, Scedosporium apiospermum and Candida krusei spondylodiscitis, and acute pulmonary coccidioidomycosis in one case each. An increased uptake of [¹⁸F]FDG was observed in all areas previously identified by computed tomography and/or magnetic resonance imaging to be involved by IFI. In 4/10 chronic disseminated candidiasis cases, [¹⁸F]FDG-PET revealed small splenic abscesses that were unapparent on the corresponding computed tomography scan. [¹⁸F]FDG uptake disappeared after 6 months of antifungal therapy in three patients with chronic disseminated candidiasis for whom the [¹⁸F]FDG-PET was performed to assess the evolution of the disease. [¹⁸F]FDG-PET could potentially be useful for the initial diagnosis and staging of IFI. Whether or not [¹⁸F]FDG-PET might be useful for assessing the optimal duration of IFI therapy should now be assessed in a specific prospective study.