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18F-FDG PET/CT and Prosthetic Valve Endocarditis
Quick Takes
- 18F-FDG PET/CT is useful in the diagnosis of prosthetic valve infective endocarditis, and responsible for the higher sensitivity of ESC compared to Duke criteria albeit with a resulting lower specificity.
- Diffuse splenic uptake on 18F-FDG PET/CT may be a new criterion for the diagnosis of infective endocarditis.
Study Questions:
What is the value of the European Society of Cardiology (ESC) criteria that include 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) for the diagnosis of prosthetic valve infective endocarditis (PVE)? And, what is the reproducibility of 18F-FDG-PET/CT, how does its diagnostic value compare with echocardiography, and what is the diagnostic value of diffuse splenic uptake on 18F-FDG-PET/CT?
Methods:
Between 2014 and 2017, 175 patients with suspected PVE admitted to one of three French medical centers were prospectively included. The diagnosis of infective endocarditis (IE) was based on an expert consensus of the Endocarditis Team performed 3 months after admission; and based on clinical, microbiologic, and imaging data throughout the follow-up interval. After exclusion of some patients, including 32 with uninterpretable 18F-FDG PET/CT, 115 patients were evaluated, including 91 with definite PVE and 24 with rejected IE.
Results:
Cardiac uptake by 18F-FDG PET/CT was observed in 67 of 91 patients with definite PVE and in six patients with rejected IE (sensitivity, 73.6%; 95% confidence interval [CI], 63.3%-82.3%, specificity 75%; 95% CI, 53.3%-90.2%). The ESC 2015 classification increased the sensitivity of Duke criteria from 57.1% (95% CI, 46.3%-67.5%) to 83.5% (95% CI, 74.3%-90.5%; p < 0.001), but decreased its specificity from 95.8% (95% CI, 78.9%-99.9%) to 70.8% (95% CI, 48.9%-87.4%). Intraobserver reproducibility of 18F-FDG PET/CT was good (kappa = 0.84), but interobserver reproducibility was less satisfactory (kappa = 0.63). Diffuse splenic uptake was observed in 24 (20.3%) patients, including 23 (25.3%) of those with definite PVE, and only one (4.2%) with rejected PVE (p = 0.024).
Conclusions:
The authors concluded that 18F-FDG PET/CT was a useful diagnostic tool in suspected PVE, and explains the greater sensitivity of ESC criteria compared to the Duke criteria. However, 18F-FDG PET/CT also had important limitations involving feasibility, specificity, and reproducibility. Finally, the authors concluded that diffuse splenic uptake on 18F-FDG PET/CT is a new criterion for IE.
Perspective:
18F-FDG-PET/CT has been shown to improve the sensitivity of the modified Duke criteria for the diagnosis of PVE, and has been integrated into the 2015 ESC diagnostic criteria. Limitations include its availability; and its specificity, affected by postoperative inflammation, surgical adhesives, and physiological uptake by an aortic root graft. This study found that including 18F-FDG-PET/CT was associated with higher sensitivity but lower specificity for the diagnosis of PVE, but also was associated with substantial interobserver variability. In addition, diffuse splenic (relative to hepatic) uptake appeared to have a high specificity for the diagnosis of PVE. Notably, the gold standard used for the diagnosis of PVE was an IE Team that was not blinded to the results of 18F-FDG-PET/CT, potentially affecting the study outcomes. Duke criteria notwithstanding, 18F-FDG-PET/CT certainly has become incorporated in the clinical diagnosis of PVE. Additional study will be of interest in attempts to optimize test specificity, and to further test the finding of diffuse splenic uptake among patients with IE.
Clinical Topics: Noninvasive Imaging, Valvular Heart Disease, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging
Keywords: Diagnostic Imaging, Echocardiography, Endocarditis, Fluorodeoxyglucose F18, Heart Valve Diseases, Positron-Emission Tomography, Reproducibility of Results, Sensitivity and Specificity, Tomography, X-Ray Computed
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