Diabetic foot infections (DFIs) represent one of the most frequent and disabling morbidities of longstanding diabetes; therefore, early diagnosis is mandatory. The aim of this multicenter retrospective study was to compare the diagnostic accuracy of white blood cell scintigraphy (WBC), ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography ((¹⁸F) FDG PET/CT), and Magnetic Resonance Imaging (MRI) in patients with suspected DFI. Images and clinical data from 251 patients enrolled by five centers were collected in order to calculate the sensitivity, specificity, and accuracy of WBC, FDG, and MRI in diagnosing osteomyelitis (OM), soft-tissue infection (STI), and Charcot osteoarthropathy. In OM, WBC acquired following the European Society of Nuclear Medicine (EANM) guidelines was more specific and accurate than MRI (91.9% vs. 70.7%, p < 0.0001 and 86.2% vs. 67.1%, p = 0.003, respectively). In STI, both FDG and WBC achieved a significantly higher specificity than MRI (97.9% and 95.7% vs. 83.6%, p = 0.04 and p = 0.018, respectively). In Charcot, both MRI and WBC demonstrated a significantly higher specificity and accuracy than FDG (88.2% and 89.3% vs. 62.5%, p = 0.0009; 80.3% and 87.9% vs. 62.1%, p < 0.02, respectively). Moreover, in Charcot, WBC was more specific than MRI (89.3% vs. 88.2% p < 0.0001). Given the limitations of a retrospective study, WBC using EANM guidelines was shown to be the most reliable imaging modality to differentiate between OM, STI, and Charcot in patients with suspected DFI.

Conventional diagnostic imaging is often ineffective in revealing the underlying cause in a considerable proportion of patients with fever of unknown origin (FUO). The aim of this study was to assess the diagnostic value of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) in patients with FUO. We retrospectively reviewed ¹⁸F-FDG-PET/CT scans performed on 50 consecutive adult patients referred to our department for further investigation of classic FUO. Final diagnosis was based on histopathological and microbiological findings, clinical criteria, or clinical follow-up. Final diagnosis was established in 39/50 (78%) of the patients. The cause of FUO was infection in 20/50 (40%), noninfectious inflammatory diseases in 11/50 (22%), and malignancy in 8/50 (16%) patients. Fever remained unexplained in 11/50 (22%) patients. ¹⁸F-FDG-PET/CT scan substantially contributed to the diagnosis in 70% of the patients, either by identifying the underlying cause of FUO or by directing to the most appropriate site for biopsy. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of ¹⁸F-FDG-PET/CT for active disease detection in patients with FUO were 94.7%, 50.0%, 84.0%, 85.7%, and 75.0%, respectively. In conclusion, whole-body ¹⁸F-FDG-PET/CT is a highly sensitive method for detection of the underlining cause of FUO or for correctly targeting suspicious lesions for further evaluation.

Tuberculous vertebral osteomyelitis (TVO) is an extrapulmonary tuberculosis form characterized by difficulty and delay in diagnosis. PET/CT is a valuable, well-established tool in the diagnostic workup of cancer and fever of unknown origin, which is increasingly appreciated in the management of infectious diseases. We report a TVO case where PET/CT had a valuable contribution towards diagnosis and monitoring of treatment response, highlighting its advantages and future perspectives when dealing with infectious diseases.