Analysis of factors affecting the accuracy of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography in case of suspected prosthetic valve infective endocarditis

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Aim. To analyze the factors affecting the accuracy of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (PET/CT) in case of suspected prosthetic valve endocarditis (PVE).Material and methods. The results of PET/CT performed in 66 patients after heart valve replacement were analyzed: 55 patients with suspected PVE (≥3 months after surgery) and 11 comparison groups without PVE (2 months after surgery). In the group with suspected PVE (n=55) at the time of the study, 27% (15/55) had a normal body temperature, 85% (47/55) — no leukocytosis. In 16% (9/55), the examination was performed from 3 to 6 months after surgery and in 67% (37/55) — against the background of long-term antibiotic therapy (ABT). The final diagnosis of PVE was made on the basis of clinical (including 6±3 followup), laboratory, instrumental, and intraoperative (n=40) data: confirmed — in 37 patients; ruled out — in 29 patients. In order to determine the influence of factors on obtaining false PET/CT results, the odds ratio was calculated.Results. In the group with suspected PVE (n=55), the PET/CT results made it possible to establish and rule out PVE in 92% (34/37) and 67% (12/18) of patients, respectively. In 16% (9/55) of patients, false positive (n=6) and false negative (n=3) results. Thus, the sensitivity, specificity and diagnostic accuracy of PET/CT in the diagnosis of PVE were 92%, 67% and 84%, respectively; positive and negative predictive values — 85% and 80%. The analysis of the odds ratio did not reveal the relationship of low inflammatory activity, the interval between surgery and PET/CT from 3 to 6 months, and long-term ABT before PET/CT with false PET/CT results (p>0,05). In the comparison group without PVE (n=11), 91% (10/11) received false positive PET/CT results, and one patient received a true negative result.Conclusion. The data obtained indicate the high informative value of PET/CT in the diagnosis of PVE. Interval >2 months between surgery and PET/CT significantly reduces the accuracy of PET/CT results. Other factors analyzed in the presented group did not affect the accuracy of PET/CT results.