Infective Endocarditis Imaging with 18F-FDG PET/CT

By Guest Bloggers Gabriel Blacher Grossman, MD, PhD, FASNC, and Rafael Willain Lopes, MD, PhD, FASNC

Early diagnosis of infectious endocarditis (IE) continues to be challenging. The modified Duke criteria, which are considered a reference, include clinical, microbiological, and echocardiography findings, resulting in a general sensitivity around 80%.1 Use of the traditional modified Duke criteria is limited in patients with intracardiac devices or prosthetic valves, and the development of new diagnostic tools for IE is clinically important. In patients with suspected prosthetic valve or pacemaker/ defibrillator lead IE, these criteria are inadequate in around 24% of proven infection.

Gabriel Blacher Grossman, MD, PhD, FASNC, and Rafael Willain Lopes, MD, PhD, FASNC

18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has been shown to improve the diagnosis of prosthetic valves endocarditis (PVE) and to increase the sensitivity of the modified Duke criteria for the diagnosis of PVE.3-6 A recent meta-analysis confirmed the good diagnostic value of 18F-FDG PET/ CT in this setting. When coronary tomography angiography is added to PET/CT, there is an improvement in its performance. Recent data demonstrated that in addition to its good diagnostic performance, 18F-FDG PET/CT is predictive of major cardiac events in PVE and new embolic events within the first year following IE.7

Cardiac implantable electronic (CIED) devices have been increasingly used over recent years, with elevated rates of infection (1% to 3%), and they are associated with 1-year mortality over 10%.8 Doppler echocardiography is the first line imaging method for evaluation of suspected CIED infection, but its use is limited for investigating infection in extra-cardiac leads and device pockets. 18F-FDG PET/CT has demonstrated additional value for diagnosis of infections related to CIED or pacemaker. 18F-FDG PET/CT has been shown to be especially useful for diagnosing device pocket infections, but it is less reliable for diagnosing infections in the metallic device.9 Evidence of its use in patients suspected of transcatheter-replaced aortic valves (TAVR) endocarditis is still limited to case reports and small studies.10 The presence of a focal hotspot is considered the best criterion for infection.

A multi-imaging approach is essential in the diagnostic workup of PVE and has been integrated in the 2015 European Society of Cardiology (ESC) criteria.11,12 18F-FDG PET/CT can detect abnormal metabolic activity around the site of prosthetic valve implantation; however, the evidence on the use of 18F-FDG PET/CT in patients with native valve endocarditis is limited and non-supporting, although sometimes it may be useful in this clinical scenario.13

For PVEs, no distinction is made between biological and mechanical prosthetic valves, as PET/CT performance does not differ between the two valve types. PET/CT also allows diagnosis of embolic events or metastatic infection.14

The 2015 ESC Guidelines on Endocarditis recommend using additional imaging modalities when echocardiography and blood cultures are inconclusive (i.e., result in a "possible" diagnosis of endocarditis, or a "rejected" diagnosis with persisting high suspicion) because 18F-FDG PET can detect inflammation before structural changes occur which are required for echocardiographic detection of PVE (Figure 1). Even when Modified Duke criteria confirm the diagnosis of IE, 18F-FDG PET/CT can be useful to detect septic emboli (Figure 2).15

Figure 1. Male, 68 years old, history of bioprosthetic aortic valve in 07/16/ 2018. Patient presented with fever and sweating. He was submitted to a transesophageal echocardiogram that demonstrated no vegetations or peri-annular abscess. The clinical suspicion was high and a 18F-FDG PET/CT was performed. A high uptake of the radiotracer can be seen in the peri valvular region  with an SUV of 5.77 confirming the diagnosis of IE.

Figure 2. Flowchart of the diagnostic work-up for prosthetic valve endocarditis.

Patient preparation is crucial for an adequate performance of the method. It is important to suppress physiological myocardial 18F-FDG uptake to facilitate visualization of the heart valves, peri-annular areas and pacemaker leads (Table 1). Visual and semi-quantitative analysis to evaluate abnormal uptake of the radiotracer should be performed. However, the additional diagnostic value of semiquantitative over qualitative assessment has not been proven. It is also important to recognize positive and negative confounding factors in the interpretation of the images. (Table 2).15

Table 1. Pet patient acquisition and preparation

Table 2.
 Image interpretation


1. Habib G, Derumeaux G, Avierinos JF, Casalta JP, Jamal F, Volot F, et al. Value and limitations of the Duke criteria for the diagnosis of infective endocarditis. J Am Coll Cardiol. 1999;33(7):2023-9.
2. Thuny F, Grisoli D, Collart F, Habib G, Raoult D. Management of infective endocarditis: challenges and perspectives. Lancet. 2012;379(9819):965-75.
3. Saby L, Laas O, Habib G, Cammilleri S, Mancini J, Tessonnier L et al. Positron emission tomography/computed tomography for diagnosis of prosthetic valve endocarditis: increased valvular 18F-fluorodeoxyglucose uptake as a novel major criterion. J Am Coll Cardiol. 2013 11;61(23):2374-82.
4. Pizzi MN, Roque A, Fernández-Hidalgo N, Cuéllar-Calabria H, Ferreira-González I, Gonzàlez-Alujas MTet al. Improving the diagnosis of infective endocarditis in prosthetic valves and intracardiac devices with 18F-fluordeoxyglucose positron emission tomography/computed tomography angiography: Initial results at an infective endocarditis referral center. Circulation. 2015 Sep 22;132(12):1113-26.
5. Granados U, Fuster D, Pericas JM, Llopis JL, Ninot S, Quintana E, et al. Diagnostic accuracy of 18F-FDG PET/CT in infective endocarditis and implantable cardiac electronic device infection: A cross-sectional study. J Nucl Med. 2016;57(11):1726-32.
6. Swart LE, Gomes A, Scholtens AM, Sinha B, Tanis W, Lam MGEH, et al. Improving the diagnostic performance of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography in prosthetic heart valve endocarditis. Circulation. 2018 2;138(14):1412-27.
7. San S, Ravis E, Tessonier L, Philip M, Cammilleri S, Lavagna F, et al. Prognostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in infective endocarditis. J Am Coll Cardiol. 2019;74(8):1031-40.
8. Tarakji KG, Chan EJ, Cantillon DJ, Doonan AL, Hu T, Schmitt S, et al. Cardiac implantable electronic device infections: Presentation, management, and patient outcomes. Heart Rhythm. 2010;7(8):1043-7.
9. Bensimhon L, Lavergne T, Hugonnet F, Mainardi JL, Latremouille C, Maunoury C, et al. Whole body [(18) F] fluorodeoxyglucose pósitron emission tomography imaging for the diagnosis of pacemaker or implantable cardioverter defibrillator infection: A preliminary prospective study. Clin Microbiol Infect. 2011;17(6):836-44.
10. Swart LE, Scholtens AM, Liesting C, Mieghem NMDA. V, Krestin GP, Roos-Hesselink JW, Budde RPJ. Serial 18F-fluorodeoxyglucose positron emission tomography/CT angiography in transcatheter-implanted aortic valve endocarditis. Eur Heart J. 2016;37:3059.
11. Habib G, Lancellotti P, Antunes MJ, Bongiorni MG, Casalta JP, Del Zotti F et al.  2015 ESC Guidelines for the management of infective endocarditis: The task force for the managment of infective endocarditis of the European Society of Cardiology (ESC). Endorsed by: European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Nuclear Medicine (EANM). Eur Heart J. 2015 Nov 21;36(44):3075-128.
12. Philip M, Tessonier L, Mancini J, Mainardi JL, Fernandez-Gerlinger MP, Lussato D, et al. Comparison between ESC and Duke criteria for the diagnosis of prosthetic valve infective endocarditis. JACC Cardiovasc Imaging. 2020 17;S1936-878X(20)30335-1. 
13. Abikhzer G, Martineau P, Grégoire J, Finnerty V, Harel F, Pelletier-Galarneau M. [(18)F] FDG-PET CT for the evaluation of native valve endocarditis. J Nucl Cardiol. 2020 Mar 16. doi: 10.1007/s12350-020-02092-6.
14. Amraoui S, Tlili G, Sohal M, Berte B, Hindié E, Ritter P, et al. Contribution of PET imaging to the diagnosis of septic embolism in patients with pacing lead endocarditis. JACC Cardiovasc Imaging. 2016;9(3):283-90.
15. Swart LE, Scholtens AM, Tanis W, Nieman K, Bogers AJJC, Verzijlbergen FJ, et al. 18F-fluorodeoxyglucose positron emission/computed tomography and computed tomography angiography in prosthetic heart valve endocarditis: From guidelines to clinical practice. Eur Heart J. 2018 1;39(41):3739-49.

BLOGGER BIOS:  Dr. Gabriel Blacher Grossman is Director of the Department of Nuclear Medicine at Hospital Moinhos de Vento in Porto Alegre, Brazil. Dr. Rafael Willain Lopes is Technical Director of the Nuclear Medicine Department at Hospital do Coração - HCor in São Paulo, Brazil.