Improving the Diagnostic Performance of 18F-Fluorodeoxyglucose Positron-Emission Tomography/Computed Tomography in Prosthetic Heart Valve Endocarditis

Infective Endocarditis: The role of PET imaging in diagnosis and management

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) has recently emerged as an increasingly used alternative and supplementary imaging modality for the diagnosis of infective endocarditis. 18F-FDG PET/CT imaging for IE is given a Class I recommendation (level of evidence B) and is therefore recommended in cases of possible prosthetic valve IE to both detect valvular lesions, as well as confirm the diagnosis of IE. They have also given a class I recommendation (level of evidence B) for brain and whole-body 18F-FDG PET/CT and/or MRI imaging to detect peripheral lesions for patients with either native or prosthetic valve IE. Molecular imaging is playing an increasingly important role in the diagnosis and management of patients with IE. The important role of 18F-FDG PET/CT imaging has been acknowledged by recent guideline updates. These advanced imaging tests are not supplanting the role of echocardiography in the diagnostic pathway for IE. Rather, they are additional tools that are available where the diagnosis is complicated, difficult, or uncertain.

Infection of Transcatheter Valvular Devices

PURPOSE OF REVIEW

This review explores the epidemiology, clinical traits, and diagnosis of Transcatheter Aortic Valve Replacement-Associated Infective Endocarditis (TAVR-IE) and mitral transcatheter edge-to-edge repair infective endocarditis (TEER-IE), focusing on a multimodal imaging approach. It addresses the rising prevalence of TAVR and TEER, emphasizing the need to understand long-term complications and clinical consequences, which poses significant challenges despite advancements in valve technology.

RECENT FINDINGS

Studies report a variable incidence of TAVR-IE and TEER-IE influenced by diverse patient risk profiles and procedural factors. Younger age, male gender, and certain comorbidities emerge as patient-related risk factors. Procedure-related factors include intervention location, valve type, and technical aspects. Microbiologically, Staphylococcus aureus, Viridans Group Streptococcus, and Enterococcus are frequently encountered pathogens. TAVR-IE and TEER-IE diagnosis involves a multimodal imaging approach due to limitations in echocardiography. Blood cultures and imaging aid identification, with Fluorescence in situ hybridization is showing promise. Treatment encompasses medical management with antibiotics and, when necessary, surgical intervention. The management approach requires a multidisciplinary "Endocarditis Team." This review underscores the need for continued research to refine risk prediction, enhance diagnostic accuracy, and optimize management strategies for TAVR-IE, considering the evolving landscape of transcatheter interventions.

New developments in infective endocarditis

Infective endocarditis is a continually evolving disease. Present-day patients differ significantly from those treated a few decades ago: they tend to be older and have more comorbidities and health care-related episodes, while new groups of patients have emerged with new types of endocarditis, such as those affecting patients with percutaneous valve prostheses. There have also been changes in diagnostic techniques. Although transthoracic and transesophageal echocardiography are still the most commonly used imaging modalities, other techniques, such as 3-dimensional transesophageal ultrasound, cardiac computed tomography, and nuclear medicine tests (PET/CT and SPECT/CT), are increasingly used for diagnosing both the disease and its complications. In recent years, there have also been significant developments in antibiotic therapy. Currently, several treatment strategies are available to shorten the hospital phase of the disease in selected patients, which can reduce the complications associated with hospitalization, improve the quality of life of patients and their families, and reduce the health care costs of the disease. This review discusses the main recent epidemiological, diagnostic and therapeutic developments in infective endocarditis.

18F-FDG PET/CT and radiolabeled leukocyte SPECT/CT imaging for the evaluation of cardiovascular infection in the multimodality context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations from ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

Dual-Time-Point 18F-FDG PET/CT in Infective Endocarditis: Impact of Delayed Imaging in the Definitive Diagnosis of Endocarditis

Infective endocarditis (IE) is a major public health condition due to the associated high morbidity and mortality. Our objective was to evaluate the utility of dual-time 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG) Positron Emission Tomography/Computed Tomography (PET/CT) imaging in the diagnosis of active IE in patients with suspected native valve endocarditis (NVE) and prosthetic valve endocarditis (PVE). For this purpose, a retrospective study was carried out, including patients suspicious of NVE or PVE who underwent a dual-time-point 18F-FDG PET/CT. A final diagnosis was established by the Endocarditis Team after patient follow-up using all the available findings. Sixty-nine patients were assessed. A final diagnosis of NVE was established in 3 patients of the 34 by 18F-FDG PET/CT and in the case of PVE was established in 20 patients of the 35. A statistically significant association was found when evaluating the association between PET diagnosis at early acquisition and final diagnosis of IE (χ2 = 30.198, p < 0.001) and PET diagnosis at delayed acquisition for final diagnosis of IE (χ2 = 9.412, p = 0.002). Delayed PET/CT imaging determined the IE diagnosis in 16/58 of the studies. In conclusion, delayed 18F-FDG PET/CT imaging seems to be useful in improving the definitive diagnosis of IE.

Right ventricular papillary muscle crossing the moderator band mimicked infective endocarditis: the utility of multimodal imaging

Right-sided infective endocarditis (RSIE) generally carries a positive prognosis; however, it can result in complications such as heart failure, underscoring the importance of prompt diagnosis. While echocardiography serves as the standard diagnostic tool, it may occasionally face challenges in distinguishing between normal structures and vegetations. In this report, we present the case of a 60-year-old man diagnosed with pyogenic vertebral osteomyelitis, alongside suspected coexisting RSIE. During both transthoracic and transesophageal echocardiography, a rod-like mobile structure was observed adjacent to the right ventricular moderator band. However, confirming its nature as an infective vegetation proved challenging. Despite the inconclusive diagnosis of IE by echocardiography, the positron emission tomography/computed tomography (PET/CT) scan and cardiac magnetic resonance imaging (MRI) played a pivotal role in distinguishing between normal structures and vegetations. Since IE could develop life-threatening events, the role of multimodal imaging is of paramount importance. This case serves as a compelling example of the diagnostic value through the integration of PET/CT and MRI in ruling out IE.

18F-FDG PET/CT and radiolabeled leukocyte SPECT/CT imaging for the evaluation of cardiovascular infection in the multimodality context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations from ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

18F-FDG PET/CT and radiolabeled leukocyte SPECT/CT imaging for the evaluation of cardiovascular infection in the multimodality context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations from ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

18F-FDG PET/CT and Radiolabeled Leukocyte SPECT/CT Imaging for the Evaluation of Cardiovascular Infection in the Multimodality Context: ASNC Imaging Indications (ASNC I2) Series Expert Consensus Recommendations From ASNC, AATS, ACC, AHA, ASE, EANM, HRS, IDSA, SCCT, SNMMI, and STS

This document on cardiovascular infection, including infective endocarditis, is the first in the American Society of Nuclear Cardiology Imaging Indications (ASNC I2) series to assess the role of radionuclide imaging in the multimodality context for the evaluation of complex systemic diseases with multi-societal involvement including pertinent disciplines. A rigorous modified Delphi approach was used to determine consensus clinical indications, diagnostic criteria, and an algorithmic approach to diagnosis of cardiovascular infection including infective endocarditis. Cardiovascular infection incidence is increasing and is associated with high morbidity and mortality. Current strategies based on clinical criteria and an initial echocardiographic imaging approach are effective but often insufficient in complicated cardiovascular infection. Radionuclide imaging with fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (CT) and single photon emission computed tomography/CT leukocyte scintigraphy can enhance the evaluation of suspected cardiovascular infection by increasing diagnostic accuracy, identifying extracardiac involvement, and assessing cardiac implanted device pockets, leads, and all portions of ventricular assist devices. This advanced imaging can aid in key medical and surgical considerations. Consensus diagnostic features include focal/multi-focal or diffuse heterogenous intense 18F-FDG uptake on valvular and prosthetic material, perivalvular areas, device pockets and leads, and ventricular assist device hardware persisting on non-attenuation corrected images. There are numerous clinical indications with a larger role in prosthetic valves, and cardiac devices particularly with possible infective endocarditis or in the setting of prior equivocal or non-diagnostic imaging. Illustrative cases incorporating these consensus recommendations provide additional clarification. Future research is necessary to refine application of these advanced imaging tools for surgical planning, to identify treatment response, and more.

Bacteraemia with gram-positive bacteria-when and how do I need to look for endocarditis?

BACKGROUND

Patients with bacteraemia caused by gram-positive bacteria are at risk for infective endocarditis (IE). Because IE needs long antibiotic treatment and sometimes heart valve surgery, it is very important to identify patients with IE.

OBJECTIVES

In this narrative review we present and discuss how to determine which investigations to detect IE that are needed in individual patients with gram-positive bacteraemia.

SOURCES

Published original studies and previous reviews in English, within the relevant field are used.

CONTENT

First, the different qualities of the bacteraemia in relation to IE risk are discussed. The risk for IE in bacteraemia is related to the species of the bacterium but also to monomicrobial bacteraemia and the number of positive cultures. Second, patient-related factors for IE risk in bacteraemia are presented. Next, the risk stratification systems to determine the risk for IE in gram-positive bacteraemia caused by Staphylococcus aureus, viridans streptococci, and Enterococcus faecalis are presented and their use is discussed. In the last part of the review, an account for the different modalities of IE-investigations is given. The main focus is on echocardiography, which is the cornerstone of IE-investigations. Furthermore, 18F-fluorodesoxyglucose positron emission tomography/computed tomography and cardiac computed tomography are presented and their use is also discussed. A brief account for investigations used to identify embolic phenomena in IE is also given. Finally, we present a flowchart suggesting which investigations to perform in relation to IE in patients with gram-positive bacteraemia.

IMPLICATIONS

For the individual patient as well as the healthcare system, it is important both to diagnose IE and to decide when to stop looking for IE. This review might be helpful in finding that balance.

18F- FDG PET/CT in reclassifying the probable diagnosis of IE - A review

In the diagnosis of infective endocarditis (IE), Modified Duke's criteria, coupled with clinical suspicion, serve as the guiding framework. For cases involving prosthetic valve endocarditis and infections affecting implantable devices, the use of metabolic imaging with 18 F-FDG PET/CT scans has gained prominence, as per the recommendations of the European Society of Cardiology guidelines. This imaging modality enhances sensitivity and specificity by identifying infective foci within the heart and extracardiac locations. Early utilization of these scans is crucial for confirming or ruling out IE, although caution is required to mitigate false positive responses, especially in the presence of ongoing inflammatory activity. A standardized ratio of ≥2.0 between FDG uptake around infected tissues and the blood pool has demonstrated a sensitivity of 100 % and specificity of 91 %. It is noteworthy that the sensitivity of FDG PET/CT varies, being lower for native valve and lead infections but considerably higher for prosthetic valve and pulse generator infections. This review provides a comprehensive overview of the advantages offered by FDG PET/CT in achieving a definitive diagnosis of IE.

Multimodality Imaging Diagnosis in Infective Endocarditis

Imaging is an important tool in the diagnosis and management of infective endocarditis (IE). Echocardiography is an essential examination, especially in native valve endocarditis (NVE), but its diagnostic accuracy is reduced in prosthetic valve endocarditis (PVE). The diagnostic ability is superior for transoesophageal echocardiography (TEE), but a negative test cannot exclude PVE. Both transthoracic echocardiography (TTE) and TEE can provide normal or inconclusive findings in up to 30% of cases, especially in patients with prosthetic devices. New advanced non-invasive imaging tests are increasingly used in the diagnosis of IE. Nuclear medicine imaging techniques have demonstrated their superiority over TEE for the diagnosis of PVE and cardiac implantable electronic device infective endocarditis (CIED-IE). Cardiac computed tomography angiography imaging is useful in PVE cases with inconclusive TTE and TEE investigations and for the evaluation of paravalvular complications. In the present review, imaging tools are described with their values and limitations for improving diagnosis in NVE, PVE and CIED-IE. Current knowledge about multimodality imaging approaches in IE and imaging methods to assess the local and distant complications of IE is also reviewed. Furthermore, a potential diagnostic work-up for different clinical scenarios is described. However, further studies are essential for refining diagnostic and management approaches in infective endocarditis, addressing limitations and optimizing advanced imaging techniques across different clinical scenarios.

The clinical value of quantitative cardiovascular molecular imaging: a step towards precision medicine

Cardiovascular diseases (CVD) are the leading cause of death worldwide and have an increasing impact on society. Precision medicine, in which optimal care is identified for an individual or a group of individuals rather than for the average population, might provide significant health benefits for this patient group and decrease CVD morbidity and mortality. Molecular imaging provides the opportunity to assess biological processes in individuals in addition to anatomical context provided by other imaging modalities and could prove to be essential in the implementation of precision medicine in CVD. New developments in single-photon emission computed tomography (SPECT) and positron emission tomography (PET) systems, combined with rapid innovations in promising and specific radiopharmaceuticals, provide an impressive improvement of diagnostic accuracy and therapy evaluation. This may result in improved health outcomes in CVD patients, thereby reducing societal impact. Furthermore, recent technical advances have led to new possibilities for accurate image quantification, dynamic imaging, and quantification of radiotracer kinetics. This potentially allows for better evaluation of disease activity over time and treatment response monitoring. However, the clinical implementation of these new methods has been slow. This review describes the recent advances in molecular imaging and the clinical value of quantitative PET and SPECT in various fields in cardiovascular molecular imaging, such as atherosclerosis, myocardial perfusion and ischemia, infiltrative cardiomyopathies, systemic vascular diseases, and infectious cardiovascular diseases. Moreover, the challenges that need to be overcome to achieve clinical translation are addressed, and future directions are provided.

18F-FDG PET/CT-derived total lesion glycolysis predicts abscess formation in patients with surgically confirmed infective endocarditis: Results of a retrospective study at a tertiary center

BACKGROUND

Abnormal activity of 18F-FDG PET/CT is a major Duke criterion in the diagnostic work-up of infective prosthetic valve endocarditis (IE). We hypothesized that quantitative lesion assessment by 18F-FDG PET/CT-derived standard maximum uptake ratio (SURmax), metabolic volume (MV), and total lesion glycolysis (TLG) might be useful in distinct subgroups of IE patients (e.g. IE-related abscess formation).

METHODS

All patients (n = 27) hospitalized in our tertiary IE referral medical center from January 2014 to October 2018 with preoperatively performed 18F-FDG PET/CT and surgically confirmed IE were included into this retrospective analysis.

RESULTS

Patients with surgically confirmed abscess formation (n = 10) had significantly increased MV (by ~ fivefold) and TLG (by ~ sevenfold) as compared to patients without abscess (n = 17). Receiver operation characteristics (ROC) analyses demonstrated that TLG (calculated as MV × SURmean, i.e. TLG (SUR)) had the most favorable area under the ROC curve (0.841 [CI 0.659 to 1.000]) in predicting IE-related abscess formation. This resulted in a sensitivity of 80% and a specificity of 88% at a cut-off value of 14.14 mL for TLG (SUR).

CONCLUSION

We suggest that 18F-FDG PET/CT-derived quantitative assessment of TLG (SUR) may provide a novel diagnostic tool in predicting endocarditis-associated abscess formation.

Diagnostic benefits of 18F-FDG PET/CT in cases of prosthetic infective endocarditis

Infective endocarditis (IE) is a difficult-to-diagnose provocative disease that causes significant morbidity and mortality. The first-line imaging test for the diagnosis of IE is echocardiography. However, in cases of prosthetic IE or IE associated with intracardiac devices, its sensitivity is limited. A new diagnostic tool, 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT), improves diagnosis in these difficult cases. The most recent European guidelines for IE (2015) include this imaging modality as a primary diagnostic criterion. We present a case of culture-negative prosthetic IE diagnosed with 18F-FDG PET/CT.

[Positron emission tomography in cardiological practice]

The utility of positron emission tomography in cardiology currently goes beyond the ischemic heart disease and covers an increasingly wider range of non-coronary pathology, which requires timely expert diagnostics, including chronic heart disease of any etiology, valvular and electrophysiology disorders, cardiooncology. Authors emphasize the importance of the development of positron emission tomography technologies in the Russian Federation. This includes the development and implementation of new radiopharmaceuticals for the diagnosis of pathological processes of the cardiovascular system, systemic and local inflammation, including atherosclerosis, impaired perfusion and myocardial metabolism, and also for solving specific diagnostic tasks in comorbid pathology.

Meta-analysis assessing the sensitivity and specificity of 18F-FDG PET/CT for the diagnosis of prosthetic valve endocarditis (PVE) using individual patient data (IPD)

IMPORTANCE

The use of ¹⁸F-FDG PET/CT in diagnostic algorithms for PVE has increased since publication of studies and guidelines advocating its use. The assessment of test accuracy has been limited by small study sizes. We undertook a systematic review using individual patient data (IPD) meta-analysis techniques.

OBJECTIVE

To estimate the summary sensitivity and specificity of ¹⁸F-FDG PET/CT in diagnosing PVE. We also assessed the effect of patient factors on test accuracy as defined by changes in the odds ratios associated with each factor. The effect of the PET/CT study on the final diagnosis was also assessed when compared to the preliminary Duke classification to determine in which patient group ¹⁸F-FDG PET/CT had the greatest utility.

STUDY SELECTION

Studies were included if PET/CT was performed for suspicion of PVE and IPD of both the PET/CT result and final diagnosis defined by a gold-standard assessment was available. There were 3 possible final diagnoses ("definite PVE," "possible PVE," and "rejected PVE").

RESULTS

Seventeen studies were included with IPD available for 537 patients (from 538 scans). The summary sensitivity and specificity were 85% (95% CI 74.2%-91.8%) and 86.5% (95% CI 75.8%-92.9%) respectively when patients with final diagnosis of "possible PVE" were classified as positive for PVE. When this group was classified as negative for PVE, sensitivity was 87.4% (95% CI 80.4%-92.1%) and specificity was 84.9% (95% CI 71.5%-92.6%). Patients with a known pathogen (especially coagulase negative staphylococcal species), elevated CRP, a biological or aortic valve infection appeared more likely to have an accurate PET/CT diagnosis. Those with a mechanical valve, prior antibiotic treatment or a transcatheter aortic valve replacement valve were less likely to have an accurate test. Time since valve implantation and the presence of surgical adhesive did not appear to affect test accuracy. Of the patients with a preliminary Duke classification of "possible PVE," 84% received a more conclusive final diagnosis of "definite" or "rejected" PVE after the PET/CT study.

CONCLUSIONS AND RELEVANCE

¹⁸F-FDG PET/CT has high sensitivity and specificity in diagnosing PVE and the diagnostic utility is greatest in patients with a preliminary Duke classification of "possible PVE." Some patient factors appear to affect test accuracy, though these results should be interpreted with caution given low patient numbers for subgroup analyses.

Acute heart failure and valvular heart disease: A scientific statement of the Heart Failure Association, the Association for Acute CardioVascular Care and the European Association of Percutaneous Cardiovascular Interventions of the European Society of Cardiology

Acute heart failure (AHF) represents a broad spectrum of disease states, resulting from the interaction between an acute precipitant and a patient's underlying cardiac substrate and comorbidities. Valvular heart disease (VHD) is frequently associated with AHF. AHF may result from several precipitants that add an acute haemodynamic stress superimposed on a chronic valvular lesion or may occur as a consequence of a new significant valvular lesion. Regardless of the mechanism, clinical presentation may vary from acute decompensated heart failure to cardiogenic shock. Assessing the severity of VHD as well as the correlation between VHD severity and symptoms may be difficult in patients with AHF because of the rapid variation in loading conditions, concomitant destabilization of the associated comorbidities and the presence of combined valvular lesions. Evidence-based interventions targeting VHD in settings of AHF have yet to be identified, as patients with severe VHD are often excluded from randomized trials in AHF, so results from these trials do not generalize to those with VHD. Furthermore, there are not rigorously conducted randomized controlled trials in the setting of VHD and AHF, most of the data coming from observational studies. Thus, distinct to chronic settings, current guidelines are very elusive when patients with severe VHD present with AHF, and a clear-cut strategy could not be yet defined. Given the paucity of evidence in this subset of AHF patients, the aim of this scientific statement is to describe the epidemiology, pathophysiology, and overall treatment approach for patients with VHD who present with AHF.

Contemporary management of infective endocarditis in pregnancy

INTRODUCTION

Infective endocarditis (IE) during pregnancy is a rare condition that is associated with a high level of morbidity and mortality. The epidemiology, diagnosis, treatment, and prognosis have changed significantly in the last two decades. The declining incidence of rheumatic heart disease, improved life expectancy with congenital heart disease, advances in cardiac surgery and cardiac devices, rise in resistant microorganisms, complications of the opioid epidemic, and increasing maternal age are some of the many factors contributing to these changes.

AREAS COVERED

This article explores existing literature on the topic including case reports, case series, registry data, and clinical guidelines. The focus of this article is the evolving epidemiology, predisposing factors and preventative measures, clinical presentation, investigation, management, and potential complications of IE in pregnancy.

EXPERT OPINION

Robust prospective data on the management of IE in pregnancy is lacking, and obtaining these data will be very challenging. It is imperative that international registries are used to provide data on best clinical practices and inform future clinical guidelines. Multimodal imaging should be incorporated in the investigation of complicated cases. A multidisciplinary approach to the management of this rare and life-threatening condition is essential to ensure the best outcomes for both the mother and the fetus.

Added value of semi-quantitative analysis of [18F]FDG PET/CT for the diagnosis of device-related infections in patients with a left ventricular assist device

AIMS

Left ventricular assist devices (LVADs) improve quality of life and survival in patients with advanced heart failure, but device-related infections (DRIs) remain cumbersome. We evaluated the diagnostic capability of [18F]FDG PET/CT, factors affecting its accuracy, and the additive value of semi-quantitative analysis for the diagnosis of DRI.

METHODS AND RESULTS

LVAD recipients undergoing [18F]FDG PET/CT between 2012 and 2020 for suspected DRI were retrospectively included. [18F]FDG PET/CT was performed and evaluated in accordance with EANM guidelines. The final diagnosis of DRI, based on multidisciplinary consensus and findings during surgery, whenever performed, was used as the reference for diagnosis. 41 patients were evaluated for 59 episodes of suspected DRI. The clinical evaluation established driveline infection in 32 (55%) episodes, central device infection in 6 (11%), and combined infection in 2 (4%). Visual analysis of [18F]FDG PET/CT achieved a sensitivity and specificity for driveline infections of 0.79 and 0.71, respectively, whereas semi-quantitative analysis achieved a sensitivity and specificity of 0.94 and 0.83, respectively. For central device component infection, visual analysis of [18F]FDG PET/CT achieved a sensitivity and specificity of 0.75 and 0.60, respectively. Semi-quantitative analysis using SUVratio achieved a sensitivity and specificity of 1.0 and 0.8, respectively. The increase of specificity for central component infection was statistically significant (P = 0.05).

CONCLUSIONS

[18F]FDG PET/CT reliably predicts the presence of DRI in LVAD recipients. Semi-quantitative analysis may increase the specificity of [18F]FDG PET/CT for the analysis of central device component infection and should be considered in equivocal cases after visual analysis.

The Role of Positron Emission Tomography in Advancing the Understanding of the Pathogenesis of Heart and Vascular Diseases

Cardiovascular disease remains the leading cause of morbidity and mortality worldwide. For developing new therapies, a better understanding of the underlying pathology is required. Historically, such insights have been primarily derived from pathological studies. In the 21st century, thanks to the advent of cardiovascular positron emission tomography (PET), which depicts the presence and activity of pathophysiological processes, it is now feasible to assess disease activity in vivo. By targeting distinct biological pathways, PET elucidates the activity of the processes which drive disease progression, adverse outcomes or, on the contrary, those that can be considered as a healing response. Given the insights provided by PET, this non-invasive imaging technology lends itself to the development of new therapies, providing a hope for the emergence of strategies that could have a profound impact on patient outcomes. In this narrative review, we discuss recent advances in cardiovascular PET imaging which have greatly advanced our understanding of atherosclerosis, ischemia, infection, adverse myocardial remodeling and degenerative valvular heart disease.

18F-FDG-Based Radiomics and Machine Learning: Useful Help for Aortic Prosthetic Valve Infective Endocarditis Diagnosis?

BACKGROUND

Fluorine-18 fluorodeoxyglucose (¹⁸F-FDG)-positron emission tomography (PET)/computed tomography (CT) results in better sensitivity for prosthetic valve endocarditis (PVE) diagnosis, but visual image analysis results in relatively weak specificity and significant interobserver variability.

OBJECTIVES

The primary objective of this study was to evaluate the performance of a radiomics and machine learning-based analysis of ¹⁸F-FDG PET/CT (PET-ML) as a major criterion for the European Society of Cardiology score using machine learning as a major imaging criterion (ESC-ML) in PVE diagnosis. The secondary objective was to assess performance of PET-ML as a standalone examination.

METHODS

All ¹⁸F-FDG-PET/CT scans performed for suspected aortic PVE at a single center from 2015 to 2021 were retrospectively included. The gold standard was expert consensus after at least 3 months' follow-up. The machine learning (ML) method consisted of manually segmenting each prosthetic valve, extracting 31 radiomics features from the segmented region, and training a ridge logistic regressor to predict PVE. Training and hyperparameter tuning were done with a cross-validation approach, followed by an evaluation on an independent test database.

RESULTS

A total of 108 patients were included, regardless of myocardial uptake, and were divided into training (n = 68) and test (n = 40) cohorts. Considering the latter, PET-ML findings were positive for 13 of 22 definite PVE cases and 3 of 18 rejected PVE cases (59% sensitivity, 83% specificity), thus leading to an ESC-ML sensitivity of 72% and a specificity of 83%.

CONCLUSIONS

The use of ML for analyzing ¹⁸F-FDG-PET/CT images in PVE diagnosis was feasible and beneficial, particularly when ML was included in the ESC 2015 criteria. Despite some limitations and the need for future developments, this approach seems promising to optimize the role of ¹⁸F-FDG PET/CT in PVE diagnosis.

Radionuclide Imaging of Infective Endocarditis

Infective endocarditis (IE) is associated with high morbidity and mortality. Early diagnosis is crucial for adequate patient management. Due to difficulties in the diagnosis, a multidisciplinary discussion in addition to the integration of clinical signs, microbiology data, and imaging data is used. Imaging, including echocardiography, molecular imaging techniques, and coronary CT angiography (CTA) is central to detect infections involving heart valves and implanted cardiovascular devices, also allowing for early detection of septic emboli and metastatic. This article describes the main clinical application of white blood cell SPECT/CT and [¹⁸F]FDG-PET/CT and CTA in IE and infections associated with cardiovascular implantable electronic devices.

Imaging of Endocarditis and Cardiac Device-Related Infections: An Update

IE is a deadly disease requiring prompt diagnosis for adequate patient's management. The diagnosis requires the integration of clinical signs, microbiology data and imaging data and proper discussion within a multidisciplinary team, the endocarditis team. Since the introduction of ¹⁸F-FDG-PET/CT and WBC SPECT/CT in the diagnostic algorithm of PVE the nuclear medicine imaging specialists is active part of the Endocarditis Team, requiring proper knowledge of dedicated imaging acquisition protocols, expertise for imaging reading and interpretations to select the best test or combination of tests for each specific clinical situation. In this manuscript, we will review the main technical aspects of each imaging procedure, the most recent literature with specific regards to special challenging populations and provide clinical examples.

Infective endocarditis after transcatheter pulmonary valve implantation in patients with congenital heart disease: Distinctive features

The introduction of transcatheter pulmonary valve implantation (TPVI) has greatly benefited the management of right ventricular outflow tract dysfunction. Infective endocarditis (IE) is a feared complication of TPVI that affects valve durability and patient outcomes. Current recommendations provide only limited guidance on the management of IE after TPVI (TPVI-IE). This article, by a group of experts in congenital heart disease in children and adults, interventional cardiology, infectious diseases including IE, and microbiology, provides a comprehensive review of the current evidence on TPVI-IE, including its incidence, risk factors, causative organisms, diagnosis, and treatment. The incidence of TPVI-IE varies from 13-91/1000 person-years for Melody valves to 8-17/1000 person-years for SAPIEN valves. Risk factors include history of IE, DiGeorge syndrome, immunosuppression, male sex, high residual transpulmonary gradient and portal of bacteria entry. Staphylococci and streptococci are the most common culprits, whereas Staphylococcus aureus is associated with the most severe disease. In addition to the modified Duke criteria, a high residual gradient warrants a strong suspicion. Imaging studies are helpful for the diagnosis. Intravenous antibiotics guided by blood culture results are the mainstay of treatment. Invasive re-intervention may be required. TPVI-IE in patients with congenital heart disease exhibits several distinctive features. Whether specific valve types are associated with a higher risk of TPVI-IE requires further investigation. Patient and parent education regarding IE prevention may have a role to play and should be offered to all patients.

Contemporary Review of Multi-Modality Cardiac Imaging Evaluation of Infective Endocarditis

Infective endocarditis (IE) remains to be a heterogeneous disease with high morbidity and mortality rates, which can affect native valves, prosthetic valves, and intra-cardiac devices, in addition to causing systemic complications. The combination of clinical, laboratory, and cardiac imaging evaluation is critical for early diagnosis and risk stratification of IE. This can facilitate timely medical and surgical management to improve patient outcomes. Key imaging findings for IE include vegetations, valve perforation, prosthetic valve dehiscence, pseudoaneurysms, abscesses, and fistulae. Transthoracic echocardiography continues to be the first-line imaging modality of choice, while transesophageal echocardiography subsequently provides an improved structural assessment and characterization of lesions to facilitate management decision in IE. Recent advances in other imaging modalities, especially cardiac computed tomography and 18F-fluorodeox-yglucose positron emission tomography, and to a lesser extent cardiac magnetic resonance imaging and other nuclear imaging techniques, have demonstrated important roles in providing complementary IE diagnostic and prognostic information. This review aims to discuss the individual and integrated utilities of contemporary multi-modality cardiac imaging for the assessment and treatment guidance of IE.

The Emerging Role of FDG PET/CT in Diagnosing Endocarditis and Cardiac Device Infection

Infective endocarditis and cardiac implantable electronic device infection (CIEDI) have witnessed an increasing incidence in clinical practice and associated with increasing health care expenditure. Expanding indications of CIED in various cardiovascular conditions have also contributed to the surge of these infections. Early diagnosis of these infections is associated with a favorable prognosis. Given the lack of a single definitive diagnostic method and the limitations of echocardiography, which is considered a central diagnostic imaging modality, additional imaging modalities are required. Recent studies have highlighted the diagnostic utility of FDG PET and CT. In this review article, we discuss the existing limitations of echocardiography, acquisition protocols of PET/CT, and indications of these advanced imaging modalities in infective endocarditis and CIEDI diagnosis.

Cardiac Anesthesia Intraoperative Interpretation Accuracy of Transesophageal Echocardiograms: A Review of the Current Literature and Meta-Analysis

Background

In the United States, echocardiography is an essential component of the care of many cardiac patients. Recently, increased attention has been given to the accuracy of interpretation of cardiac-based procedures in different specialties, amongst them the field of cardiac anesthesiology and primary echocardiographers for transesophageal echocardiogram (TEE). The purpose of this study was to assess the TEE skills of cardiac anesthesiologists in comparison to primary echocardiographers, either radiologists or cardiologists. In this systematic review, we evaluated available current literature to identify if cardiac anesthesiologists interpret TEE procedures at an identical level to that of primary echocardiographers.

Methods

A PRISMA systematic review was utilized from PubMed from the years 1952-2022. A broad keyword search of "Cardiology Anesthesiology Echocardiogram" and "Echocardiography Anesthesiology" to identify the literature was used. From reviewing 1798 articles, there were a total of 9 studies included in our systematic review, 3 of which yielded quantitative data and 6 of which yielded qualitative data. The mean accuracy from each of these three qualitative studies was calculated and used to represent the overall accuracy of cardiac anesthesiologists.

Results

Through identified studies, a total of 8197 TEEs were interpreted by cardiac anesthesiologists with a concordance rate of 84% to the interpretations of primary echocardiographers. Cardiac anesthesiologists had a concordance rate of 83% when compared to radiologists. On the other hand, cardiac anesthesiologists and cardiologists had a concordance rate of 87% in one study and 79% in another study.

Conclusion

Based on these studies, cardiac anesthesiologists are shown to interpret TEEs similarly to that of primary echocardiographers. At this time, there is no gold standard to evaluate the accuracy of TEE readings. One way to address this is to individually assess the TEE interpretation of anesthesiologists and primary echocardiographers with a double-blind study.

Molecular Imaging of Valvular Diseases and Cardiac Device Infection

The use of positron emission tomography imaging with 18F-fluorodeoxyglucose in the diagnostic workup of patients with suspected prosthetic valve endocarditis and cardiac device infection (implantable electronic device and left ventricular assist device) is gaining momentum in clinical practice. However, in the absence of prospective randomized trials, guideline recommendations about 18F-fluorodeoxyglucose positron emission tomography in this setting are currently largely based on expert opinion. Measurement of aortic valve microcalcification occurring as a healing response to valvular inflammation using 18F-sodium fluoride positron emission tomography represents another promising clinical approach, which is associated with both the risk of native valve stenosis progression and bioprosthetic valve degeneration in research trials. In this review, we consider the role of molecular imaging in cardiac valvular diseases, including aortic stenosis and valvular endocarditis, as well as cardiac device infections.

CASSIA (cardiology software suite for image analysis): a potential new tool for the evaluation of [18F]FDG PET/CT in the setting of infective endocarditis

PURPOSE

Due to the high morbidity and mortality of infective endocarditis (IE), medical imaging techniques are combined to ensure a correct diagnosis. [¹⁸F]FDG PET/CT has demonstrated the ability to improve diagnostic accuracy compared with the conventional modified Duke criteria in patients with suspected IE, especially those with prosthetic valve infective endocarditis (PVIE). The aim of this study is to provide an adjunctive diagnostic tool to improve the diagnostic accuracy in cardiovascular infections, specifically PVIE.

METHODS

A segmentation tool to extract quantitative measures of [¹⁸F]FDG PET/CT image studies of prosthetic heart valve regions was developed and validated in 20 cases of suspected PVIE, of which 9 were confirmed. For that, Valvular Heterogeneity Index (VHI) and Ring-to-Center Ratio (RCR) were defined.

RESULTS

Results show an overall increase in the metabolic uptake of the prosthetic valve ring in the studies with confirmed PVIE diagnosis (SUV_max from 1.70 to 3.20; SUV_mean from 0.86 to 1.50). The VHI and RCR showed areas under the curve of 0.727 and 0.808 in the receiver operating characteristics curve analyses, respectively, for PVIE diagnosis. Mann-Whitney U tests showed statistically significant differences between groups for RCR (p = 0.02). Visual analyses and clinical reports were concordant with the extracted quantitative metrics.

CONCLUSION

The proposed new method and presented software solution (CASSIA) provide the capability to assess quantitatively myocardial metabolism along the prosthetic valve region in routine [¹⁸F]FDG PET/CT scans for evaluating heart valve infectious processes. VHI and RCR are proposed as new potential adjunctive measures for PVIE diagnosis.

Does 18F-FDG PET/CT add value to conventional imaging in clinical assessment of chronic disseminated candidiasis?

Background

Chronic disseminated candidiasis (CDC) classically occurs after profound and prolonged neutropenia. The aim of the CANHPARI study was to assess the clinical value of adding ¹⁸F-fluorodeoxyglucose PET/CT to conventional radiology for initial and subsequent evaluations of CDC.

Materials and methods

A pilot prospective study was conducted in 23 French onco-hematological centers from 2013 to 2017 (NCT01916057). Patients ≥ 18 y.o. suspected for CDC on abdominal conventional imaging (CT or MRI) were included. PET/CT and conventional imaging were performed at baseline and month 3 (M3). Follow-up was assessed until M12. The primary outcome measure was the global response at M3, i.e., apyrexia and complete response to PET/CT. The secondary outcome measure consists in comparison between responses to PET/CT and conventional imaging at diagnosis and M3.

Results

Among 52 included patients, 44 were evaluable (20 probable and 24 possible CDC); 86% had acute leukemia, 55% were male (median age 47 years). At diagnosis, 34% had fever and conventional imaging was always abnormal with microabscesses on liver and spleen in 66%, liver in 25%, spleen in 9%. Baseline PET/CT showed metabolic uptake on liver and/or spleen in 84% but did not match with lesion localizations on conventional imaging in 32%. M3 PET/CT showed no metabolic uptake in 13 (34%) patients, 11 still having pathological conventional imaging. Global response at M3 was observed in eight patients.

Conclusion

Baseline PET/CT does not replace conventional imaging for initial staging of CDC lesions but should be performed after 3 months of antifungal therapy.

Clinical trial registration

[www.clinicaltrials.gov], identifier [NCT01916057].

Value of 18F-FDG pet/CT for prognostic assessment in patients with infective endocarditis

BACKGROUND

¹⁸F-FDG PET/CT is a valuable diagnostic tool in infective endocarditis (IE). However, the prognostic value is unclear. This study aims to evaluate the prognostic performance of ¹⁸F-FDG PET/CT in native valve endocarditis (NVE) and prosthetic valve endocarditis (PVE).

METHODS

We retrospectively included 76 patients treated for definite IE (NVE and PVE) that underwent ¹⁸F-FDG PET/CT between January 2016 and December 2018. Clinical, echocardiographic and ¹⁸F-FDG PET/CT (pathologic valvular ¹⁸F-FDG uptake, extracardiac complications (ECC)) data were collected. The primary endpoint was defined as mortality or recurrence of IE at a one-year follow-up.

RESULTS

Pathologic valvular ¹⁸F-FDG uptake was detected in 32 of 57 (56.1%) patients, 30% (9/30) in NVE and 85.2% (23/27) in PVE group. Atrial fibrillation (OR 3.90, 95% CI = 1.14-16.3), prior anticoagulation treatment (OR 6.37, 95% CI = 1.89-26.7), large vegetation (≥ 10 mm) (OR 4.05, 95% CI = 1.14-16.1), perivalvular complications (OR 7.22, 95% CI = 1.68-55.1) and abscess (OR 10.9, 95% CI = 1.84-283) were associated with positive PET/CT. Extracardiac complications were found in 27 of 76 (35.5%) patients, 42.9% (18/42) in the NVE and 26.5% (9/34) in the PVE group. Pathological valvular tracer uptake (HR 1.20, 95% CI = 0.43-3.37) or extracardiac complications (HR 0.58, 95% CI = 0.21-1.62) were not associated with the occurrence of the primary endpoint.

CONCLUSION

Our study could not demonstrate a prognostic value of ¹⁸F-FDG PET/CT in IE, but confirms high diagnostic performance, which may compromise prognostic significance by accelerated optimal treatment because of earlier diagnostic certainty.

Real-world assessment of the clinical utility of whole body 18F-FDG PET/CT in the diagnosis of infection

Few studies have aimed to capture the full spectrum of 18fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) use for evaluation of infections in a real-world context. We performed a retrospective chart review of hospitalized patients who underwent 18F-FDG PET/CT for the workup of infection between April, 2013 and September, 2019. The clinical indications for and impact of 18F-FDG PET/CT on diagnostic and antimicrobial management were evaluated across different infectious indications. Sixty-one patients met the inclusion criteria. The most common indication was identifying a source of a known infection (46%), followed by fever of unknown etiology (FUE)/fever of unknown origin (FUO) (38%), and other (16%). 18F-FDG PET/CT was determined to have had a diagnostic or management clinical impact for a total of 22 patients (36%) including 12/28 (43%) of patients with known infection, 7/23 (30%) of patients with FUE/FUO, and 3/10 (30%) of patients with other indications. 18F-FDG PET/CT confirmed suspected prosthetic endovascular infection for 6/16 (38%) patients. In this study,18F-FDG PET/CT led to a clinical impact on diagnostic and treatment management of hospitalized patients across a variety of syndromes and particularly for source identification in the setting of known infection.

18F-FDG PET/CT improves diagnostic certainty in native and prosthetic valve Infective Endocarditis over the modified Duke Criteria

BACKGROUND

International guidance recognizes the shortcomings of the modified Duke Criteria (mDC) in diagnosing infective endocarditis (IE) when transoesophageal echocardiography (TOE) is equivocal. 18F-FDG PET/CT (PET) has proven benefit in prosthetic valve endocarditis (PVE), but is restricted to extracardiac manifestations in native disease (NVE). We investigated the incremental benefit of PET over the mDC in NVE.

METHODS

Dual-center retrospective study (2010-2018) of patients undergoing myocardial suppression PET for NVE and PVE. Cases were classified by mDC pre- and post-PET, and evaluated against discharge diagnosis. Receiver Operating Characteristic (ROC) analysis and net reclassification index (NRI) assessed diagnostic performance. Valve standardized uptake value (SUV) was recorded.

RESULTS

69/88 PET studies were evaluated across 668 patients. At discharge, 20/32 had confirmed NVE, 22/37 PVE, and 19/69 patients required surgery. PET accurately re-classified patients from possible, to definite or rejected (NRI: NVE 0.89; PVE 0.90), with significant incremental benefit in both NVE (AUC 0.883 vs 0.750) and PVE (0.877 vs 0.633). Sensitivity and specificity were 75% and 92% in NVE; 87% and 86% in PVE. Duration of antibiotics and C-reactive Protein level did not impact performance. No diagnostic SUV cut-off was identified.

CONCLUSION

PET improves diagnostic certainty when combined with mDC in NVE and PVE.

New criteria for the diagnosis of infective endocarditis using 18F-FDG PET/CT imaging

OBJECTIVES

The purpose of this study was to examine a qualitative scoring system and a semi-quantitative method of FDG-PET/CT imaging in the diagnosis of infective endocarditis (IE).

METHODS

We retrospectively included 108 patients who underwent 18F-FDG-PET/CT for suspected IE. PET/CT scans were interpreted using a 4-point score (0 = no uptake; 1 = cardiac uptake < blood-pool activity; 2 = blood-pool < uptake < liver activity; 3 = uptake > liver) and semi-quantitatively using SUVmax and SUVmean of the suspected valve lesion, liver, spleen, and of the bone marrow (BM). BM and spleen SUVmean were normalized to the liver, and hypermetabolism (HSBM) was defined as a BM or spleen-to-liver ratio > 1.

RESULTS

Comparing the score criteria results with the clinical final diagnosis, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of qualitative criteria were 93%, 81%, 84%, 91%, and 87%, respectively. A definite IE was documented in 83% of patients showing HSBM and abnormal cardiac uptake, 44% with abnormal cardiac uptake, 28% with HSBM, and 10% with neither one.

CONCLUSION

The qualitative scoring system is helpful in the diagnosis of IE. The HSBM is an additional, reliable indirect sign of IE.

FDG PET/CT in Cardiac Infection: Does It Matter? A Narrative Review

The limited performance of echocardiography in specific infectious processes involving the heart led to the search for additional diagnostic tools. Fluorodeoxyglucose positron emission tomography computed tomography (FDG PET/CT) has been proposed for its diagnostic abilities in several infectious diseases including cardiac infections. A literature review of studies evaluating FDG PET/CT in native valve infective endocarditis (IE), prosthetic valve IE, cardiac implantable electrical device (CIED) infection, and left ventricular assist device (LVAD) infection is presented, focusing on studies published in recent years. Overall, in prosthetic valve endocarditis (PVE), FDG PET/CT demonstrate high sensitivity (73-93%) and specificity (80-95%), while in native valve endocarditis (NVE) the sensitivity is very low (22-68%), with high specificity (97-100%) similar to PVE. For CIED, LVAD infection, and transcatheter aortic valve implantation associated endocarditis, data come from small studies and show good diagnostic performance of FDG PET/CT. International guidelines are increasingly recommending FDG PET/CT for the diagnosis of specific conditions of cardiac infections. Beyond the diagnostic performance ability, few studies have evaluated the added benefit of FDG PET/CT in terms of clinical outcomes of patients with suspected cardiac infection. This should be the focus in future studies.

Expanding utility of cardiac computed tomography in infective endocarditis: A contemporary review

There is increasing evidence on the utility of cardiac computed tomography (CCT) in infective endocarditis (IE) to investigate the valvular pathology, the extra-cardiac manifestations of IE and pre-operative planning. CCT can assist in the diagnosis of perivalvular complications, such as pseudoaneurysms and abscesses, and can help identify embolic events to the lungs or systemic vasculature. CCT has also been shown to be beneficial in the pre-operative planning of patients by delineating the coronary artery anatomy and the major cardiovascular structures in relation to the sternum. Finally, hybrid nuclear/computed tomography techniques have been shown to increase the diagnostic accuracy in prosthetic valve endocarditis. This manuscript aims to provide a contemporary update of the existing evidence base for the use of CCT in IE.

Diagnostic value of FDG PET/CT imaging in patients with surgically managed infective endocarditis: results of a retrospective analysis at a tertiary center

BACKGROUND

We assessed the diagnostic value of FDG PET/CT in a real-world cohort of patients with surgically managed infective endocarditis (IE).

METHODS

We performed a retrospective analysis of all patients hospitalized in a tertiary IE referral medical center from January 2014 to October 2018 fulfilling the following criteria: ICD-10 code for IE and OPS code for both, heart surgery and FDG PET/CT.

RESULTS

Final analysis included 29 patients, whereof 28 patients had surgically proven IE. FDG PET/CT scan was true-positive in 15 patients (sensitivity (SEN) 56%) and false-negative in 12 patients. Combination of Duke criteria (DC) with FDG PET/CT scan resulted in gain of SEN for all patients with confirmed IE (SEN of DC 79% vs SEN of combination DC and FDG PET/CT 89%), driven by a relevant gain in PVE patients only (SEN of DC 78% vs SEN of combination DC and FDG PET/CT 94%). Interestingly, higher prosthesis age was observed in patients with false-negative scans.

CONCLUSIONS

We found a SEN of 56% for FDG PET/CT in a real-world cohort of patients with surgically proven IE which was associated with a 16% gain of IE diagnosis in patients with PVE when combined with DC.

Diagnosis and Management of Infective Endocarditis in People Who Inject Drugs: JACC State-of-the-Art Review

The incidence of injection drug use-associated infective endocarditis has been increasing rapidly over the last decade. Patients with drug use-associated infective endocarditis present an increasingly common clinical challenge with poor long-term outcomes and high reinfection and readmission rates. Their care raises issues unique to this population, including antibiotic selection and administration, indications for and ethical issues surrounding surgical intervention, and importantly management of the underlying substance use disorder to minimize the risk of reinfection. Successful treatment of these patients requires a broad understanding of these concerns. A multidisciplinary, collaborative approach providing a holistic approach to treating both the acute infection along with effectively addressing substance use disorder is needed to improve short-term and longer-term outcomes.

Accuracy of 18F-FDG PET/CT in patients with the suspicion of cardiac implantable electronic device infections

BACKGROUND

Utility of 18F-FDG PET/CT in diagnosing infective endocarditis (IE) associated with cardiac implantable electronic devices (CIEDs) is not well established. Current ESC guidelines recommend the use of FDG-PET imaging in patients with CIEDs and positive blood cultures, but the number of studies evaluating the diagnostic performance of FDG-PET imaging in these patients remain limited. Our objective was to assess the diagnostic yield of 18F-FDG PET/CT in patients with suspected CIED infections, differentiating between pocket infection (PI) and lead infection (CIED-IE).

METHODS AND RESULTS

From 2013 to 2018, all patients (n = 63) admitted to a hospital with suspected CIED infection were prospectively recruited, undergoing a diagnostic work-up including a PET/CT. Explanted devices and material from the pocket were cultured. 14 cases corresponded to isolated PI and 13 were categorized as CIED-IE. Considering radionuclide uptake in the intracardiac portion of the lead, sensitivity and specificity of PET/CT for CIED-IE were 38.5% and 98.0%, respectively. Positive (19.2) and negative (0.6) likelihood ratio values, suggest that a positive PET/CT is much more probable to correspond to a patient with CIED-IE, whereas it is not possible to exclude this diagnosis when negative. For PI, sensitivity and specificity were 72.2% and 95.6%, respectively.

CONCLUSIONS

The yield of 18F-FDG PET/CT for suspected CIED infections differs depending on the site of infection. Due to very high specificity but poor sensitivity, negative studies must be interpreted with caution if the suspicion of CIED-IE is high.

The valve uptake index: improving assessment of prosthetic valve endocarditis and updating [18F]FDG PET/CT(A) imaging criteria

Aims

Diagnosis of prosthetic valve endocarditis (PVE) by positron emission computed tomography angiography (PET/CTA) is based on visual and quantitative morpho-metabolic features. However, the fluorodeoxyglucose (FDG) uptake pattern can be sometimes visually unclear and susceptible to subjectivity. This study aimed to validate a new parameter, the valve uptake index [VUI, maximum standardized uptake value (SUVmax)−mean standardized uptake value (SUVmean)/SUVmax], designed to provide a more objective indication of the distribution of metabolic activity. Secondly, to re-evaluate the utility of traditionally used PVE imaging criteria and determine the potential value of adding the VUI in the diagnostic algorithm of PVE.

Methods and results

Retrospective analysis of 122 patients (135 prosthetic valves) admitted for suspicion of endocarditis, with a conclusive diagnosis of definite (N = 57) or rejected (N = 65) PVE, and who had undergone a cardiac PET/CTA scan as part of the diagnostic evaluation. We measured the VUI and recorded the SUVmax, SUVratio, uptake pattern, and the presence of endocarditis-related anatomic lesions. The VUI, SUVmax, and SUVratio values were 0.54 ± 0.1 vs. 0.36 ± 0.08, 7.68 ± 3.07 vs. 3.72 ± 1.11, and 4.28 ± 1.93 vs. 2.16 ± 0.95 in the ‘definite’ PVE group vs. the ‘rejected’ group, respectively (mean ± SD; P < 0.001). A cut-off value of VUI > 0.45 showed a sensitivity, specificity, and diagnostic accuracy for PVE of 85%, 88%, and 86.7% and increased diagnostic ability for confirming endocarditis when combined with the standard diagnostic criteria.

Conclusions

The VUI demonstrated good diagnostic accuracy for PVE, even increasing the diagnostic power of the traditionally used morphometabolic parameters, which also confirmed their own diagnostic performance. More research is needed to assess whether the integration of the VUI into the PVE diagnostic algorithm may clarify doubtful cases and thus improve the diagnostic yield of PET/CTA.

Nuclear Imaging in Infective Endocarditis

Infective endocarditis (IE) is a life-threatening disease with stable prevalence despite prophylactic, diagnostic, and therapeutic advances. In parallel to the growing number of cardiac devices implanted, the number of patients developing IE on prosthetic valves and cardiac implanted electronic device (CIED) is increasing at a rapid pace. The diagnosis of IE is particularly challenging, and currently relies on the Duke-Li modified classification, which include clinical, microbiological, and imaging criteria. While echocardiography remains the first line imaging technique, especially in native valve endocarditis, the incremental value of two nuclear imaging techniques, ¹⁸F-fluorodeoxyglucose positron emission tomography with computed tomography (¹⁸F-FDG-PET/CT) and white blood cells single photon emission tomography with computed tomography (WBC-SPECT), has emerged for the management of prosthetic valve and CIED IE. In this review, we will summarize the procedures for image acquisition, discuss the role of ¹⁸F-FDG-PET/CT and WBC-SPECT imaging in different clinical situations of IE, and review the respective diagnostic performance of these nuclear imaging techniques and their integration into the diagnostic algorithm for patients with a suspicion of IE.

Best Practices for Imaging Cardiac Device-Related Infections and Endocarditis: A JACC: Cardiovascular Imaging Expert Panel Statement

The diagnosis of cardiac device infection and, more importantly, accurate localization of the infection site, such as defibrillator pocket, pacemaker lead, along the peripheral driveline or central portion of the left ventricular assist device, prosthetic valve ring abscesses, and perivalvular extensions, remain clinically challenging. Although transthoracic and transesophageal echocardiography are the first-line imaging tests in suspected endocarditis and for assessing hemodynamic complications, recent studies suggest that cardiac computed tomography (CT) or CT angiography and functional imaging with ¹⁸F-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) with CT (FDG PET/CT) may have an incremental role in technically limited or inconclusive cases on echocardiography. One of the key benefits of FDG PET/CT is in its detection of inflammatory cells early in the infection process, before morphological damages ensue. However, there are many unanswered questions in the literature. In this document, we provide consensus on best practices among the various imaging studies, which includes the detection of cardiac device infection, differentiation of infection from inflammation, image-guided patient management, and detailed recommendations on patient preparation, image acquisition, processing, interpretation, and standardized reporting.

Hypermetabolism of the spleen or bone marrow is an additional albeit indirect sign of infective endocarditis at FDG-PET

PURPOSE

This study aimed at determining the diagnostic implications of indirect signs of infection at FDG-PET-i.e., hypermetabolisms of the spleen and/or bone marrow (HSBM)-when documented in patients with known or suspected infective endocarditis (IE).

METHODS

HSBM were defined by higher mean standardized uptake values comparatively to that of the liver on FDG-PET images from patients with a high likelihood of IE and prospectively included in a multicenter study.

RESULTS

Among the 129 included patients, IE was ultimately deemed as definite in 88 cases. HSBM was a predictor of definite IE (P = 0.014; odds ratio (OR) 3.2), independently of the criterion of an abnormal cardiac FDG uptake (P = 0.0007; OR 9.68), and a definite IE was documented in 97% (29/30) of patients showing both HSBM and abnormal cardiac uptake, 78% (7/9) of patients with only abnormal cardiac uptake, 67% (42/63) of patients with only HSBM, and 37% (10/27) of patients with neither one.

CONCLUSION

In this cohort with a high likelihood of IE, HSBM is an additional albeit indirect sign of IE, independently of the criterion of an abnormal cardiac uptake, and could reinforce the suspicion of IE in the absence of any other infectious, inflammatory, or malignant disease.