Cardiovascular implantable electronic device infection: delayed vs standard FDG PET-CT imaging.

BACKGROUND: Positron emission tomography-computed tomography (PET-CT) with (18)F-fluorodeoxyglucose (FDG) has emerged as a rapidly evolving diagnostic tool for infectious diseases. However, the optimal imaging time in this clinical setting is not clear yet. The aim of this study is to investigate whether delayed (3 hours) FDG PET-CT could increase the diagnostic accuracy of this technique compared to standard (1 hour) imaging in the detection of septic foci involving the pocket and/or pacing leads in patients with suspected cardiovascular implantable electronic device (CIED) infection scheduled for device removal. METHODS AND RESULTS: Twenty-seven patients underwent standard and delayed imaging. PET-CT results were compared to bacteriological cultures after CIED removal. Fifteen controls free of infection underwent PET-CT imaging as part of investigation of malignancy. The diagnostic accuracy of delayed imaging was significantly higher than 1-hour scan for lead infection (70% vs 51%, P = .024). No significant difference was found between standard and delayed diagnostic accuracy for pocket or device infection. Semi-quantitative analysis showed that mean pocket and lead target-to-background ratio were significantly higher on delayed compared to standard imaging (3.7 ± 1.9 vs 1.6 ± 1.1, P = .0002; 3.0 ± 1.3 vs 0.7 ± 1.0, P = .01). CONCLUSIONS: Delayed FDG PET-CT imaging should be considered at least in patients with negative 1-hour scan and founded suspicion of pacing lead infection.

Nodular nongranulomatous vasculitis of the lung detected by 18F-FDG PET/CT.

We report a case of a nodular nongranulomatous vasculitis of the lung detected by (18)F-FDG PET/CT. A 51-year-old woman with fever of unknown origin underwent (18)F-FDG PET/CT, which showed multiple and bilateral pulmonary nodules at CT scan with increased radiopharmaceutical uptake in the largest one (20 mm in diameter). On the basis of the PET/CT findings, the patient was referred for excisional biopsy of the largest pulmonary nodules suspicious for neoplastic disease. Histological examination demonstrated the presence of an obliterative vasculitis with interstitial pulmonary perivascular inflammation.

Can "early" and "late"18F-FDG PET-CT be used as prognostic factors for the clinical outcome of patients with locally advanced head and neck cancer treated with radio-chemotherapy?

PURPOSE: To evaluate the prognostic value of "early" and "late" Fluorine-18-Fluorodeoxyglucose ((18)F-FDG) positron emission tomography-computed tomography (PET-CT) in patients with head and neck squamous cell carcinoma (HNSCC) treated with radio-chemotherapy (RTCT). MATERIALS AND METHODS: Twenty-six patients treated with RTCT for HNSCC were included. All patients underwent (18)F-FDG PET-CT at baseline ("staging" PET-CT), after 2 weeks of treatment ("early" PET-CT) and 8-12 weeks after treatment ("late" PET-CT). Changes in FDG uptake in the primary tumor (T) and lymph nodes (N) were correlated with local and regional control, respectively; overall metabolic response was correlated with relapse free survival (RFS) and disease specific survival (DSS). RESULTS: After a median follow-up of 29.2 months, 19/26 patients were living and 17/19 had no evidence of disease. When comparing "staging", "early" and "late" PET results, a significant decrease of FDG SUV(max) in T and N was documented. When correlating changes in FDG uptake in T and N with local and regional control, a statistically significant correlation only with the "late" reduction was found. Statistical analysis failed to demonstrate any correlation between the "early" metabolic response and the patient clinical outcome while the "late" metabolic response revealed a strong correlation with RFS (p = 0.01) and DSS (p = 0.009). CONCLUSIONS: In patients with HNSCC, PET-CT performed after RTCT predicts the clinical outcome, since it strongly correlates with RFS and DSS. On the other hand, the predictive role of "early" metabolic response was not confirmed by this study.