18f-Fdg Pet/Ct As A New Imaging Modality For Diagnosis Of Cardiac Device Infections (Pet-Id)

Cardiac device infection (CDI) is sometimes challenging to diagnose. Since extraction is associated with significant morbidity and mortality, new imaging modalities to confirm the infection and its dissemination would be of clinical value. Combined 18F-FDG positron emission tomography and computed tomography (PET/CT) has not been evaluated for this purpose. Three groups of patients were compared. In group A, 35 patients (24 men, 62 ± 18 years) with suspected CDI underwent PET/CT. Positive PET/CT was defined as abnormal uptake along cardiac devices. Group B included 10 patients (9 men, 65 ± 9 years) without signs of CDI who underwent PET/CT 4-8 weeks post-implant. Group C included 12 patients (9 men, 70 ± 10 years) with devices for >6 months without signs of CDI who underwent PET/CT for another indication. Attenuation-corrected and non-corrected images were reviewed. Semi-quantitative ratio (SQR) was obtained from the ratio between maximal local uptake and normal lung parenchyma uptake. Results were correlated with clinical data. In group A, 26/35 patients (74%) with suspected CDI had a positive PET/CT. Abnormal uptake was visualized around generators (n = 17), over leads (n = 14), in subcutaneous tissue (n = 8), and within the heart (n = 2). Twenty-one patients had TEE, and vegetations were suspected in 11 patients; increased uptake in the same anatomical site was seen in 6 patients. Twenty-one patients with positive PET/CT underwent extraction with excellent correlation. Four patients with positive PET/CT were treated as superficial infection with clinical improvement. One patient with positive PET/CT but negative leukocyte scan was considered a false positive due to Dacron. Nine patients with negative PET/CT were treated with antibiotics only and none has relapsed at 10.5 ± 1.8 months. In group B, patients had no or mild uptake seen only at the level of the connector. There was no abnormal uptake in any of group C patients. SQR was significantly higher in group A compared to groups B and C (A = 2.78 ± 1.76 vs. B = 0.91 ± 0.40 vs. C = 0.53 ± 0.19; P = 0.01). PET/CT is useful in differentiating between CDI and recent post-implant changes. This imaging modality may guide appropriate therapy. Absence of abnormal uptake among asymptomatic patients with devices >6 months suggest that there is no long-term uptake post implant.