The Role of 18-F FDG PET/CT in Imaging of Endocarditis and Cardiac Device Infections

Novel Diagnostic Methods for Infective Endocarditis

Infective endocarditis (IE) remains a dangerous disease and continues to have a high mortality rate. Unfortunately, despite continuous improvements in diagnostic methods, in many cases, blood cultures remain negative, and the pathogen causing endocarditis is unknown. This makes targeted therapy and the selection of appropriate antibiotics impossible. Therefore, we present what methods can be used to identify the pathogen in infective endocarditis. These are mainly molecular methods, including PCR and MGS, as well as imaging methods using radiotracers, which offer more possibilities for diagnosing IE. However, they are still not widely used in the diagnosis of IE. The article summarizes in which cases we should choose them and what we are most hopeful about in further research into the diagnosis of IE. In addition, registered clinical trials that are currently underway for the diagnosis of IE are also presented.

The Role of Multimodality Imaging in Patients with Congenital Heart Disease and Infective Endocarditis

Infective endocarditis (IE) represents an important medical challenge, particularly in patients with congenital heart diseases (CHD). Its early and accurate diagnosis is crucial for effective management to improve patient outcomes. Multimodality imaging is emerging as a powerful tool in the diagnosis and management of IE in CHD patients, offering a comprehensive and integrated approach that enhances diagnostic accuracy and guides therapeutic strategies. This review illustrates the utilities of each single multimodality imaging, including transthoracic and transoesophageal echocardiography, cardiac computed tomography (CCT), cardiovascular magnetic resonance imaging (CMR), and nuclear imaging modalities, in the diagnosis of IE in CHD patients. These imaging techniques provide crucial information about valvular and intracardiac structures, vegetation size and location, abscess formation, and associated complications, helping clinicians make timely and informed decisions. However, each one does have limitations that influence its applicability.

Role of molecular imaging in the diagnosis of prosthetic aortic valve endocarditis by Bacillus licheniformis: a case report

Background

Infective endocarditis is a challenging diagnosis that usually requires cardiovascular image confirmation as part of the approach. 18F-Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) is an imaging technique more sensible for the diagnosis of prosthetic valve endocarditis (PVE) when echocardiography is inconclusive.

Case summary

We present the case of a 35-year-old man who had a previous Bentall-De Bono procedure 4 years prior that included biological, national institute of cardiology (INC)-type, locally manufactured aortic valve replacement and woven Dacron tube graft implantation in the ascending aorta. He was admitted because of dyspnoea, oedema, fever, and syncope. A complete auriculoventricular blockade was diagnosed, requiring cardiac pacing. Also, infective endocarditis (IE) was suspected. Blood cultures showed the isolation of Bacillus licheniformis. Transthoracic echocardiography, transoesophageal echocardiography, and CT angiography were inconclusive for IE. Treatment was initiated with intravenous (IV) antibiotic therapy, and an extensive protocol for IE, including molecular imaging modalities, was ordered. 99mTc-Ubiquicidin scintigraphy was acquired without abnormal findings. Images of 18F-FDG-PET/CT revealed abnormally intense heterogeneous uptake in the prosthetic aortic annulus in a classic pattern. Applying the modified 2015 Duke criteria for PET/CT, PVE was confirmed.

Discussion

Although the other imaging modalities were negative, the high clinical suspicion made it mandatory to continue the study protocol, remarking on the utility of 18F-FDG-PET/CT on patients categorized as having 'possible' endocarditis, as in our patient.

A Rare Case of Autopsy Proven Achromobacter xylosoxidans Endocarditis Involving Tricuspid Valve: A Case Report

Infective endocarditis refers to infection of one or more valves of the heart, with Achromobacter xylosoxidans (A. xylosoxidans) being a rare cause. So far, 24 cases of A. xylosoxidans endocarditis were reported, with only one case describing tricuspid valvular involvement. Despite the rarity of A. xylosoxidans endocarditis, it is important for clinicians to be aware of atypical presentation and the high mortality associated with it. We present an autopsy-proven case of tricuspid valve endocarditis in the setting of A. xylosoxidans bacteremia in a 43-year-old female.

Cardiovascular positron emission tomography: established and emerging role in cardiovascular diseases

Cardiac positron emission tomography (PET) imaging has established themselves firmly as excellent and reliable functional imaging modalities in assessment of the spectrum of coronary artery disease. With the explosion of technology advances and the dream of flow quantification now a reality, the value of PET is now well realized. Cardiac PET has proved itself as precise imaging modality that provides functional imaging of the heart in addition to anatomical imaging. It has established itself as one of the best available techniques for evaluation of myocardial viability. Hybrid PET/computed tomography provides simultaneous integration of coronary anatomy and function with myocardial perfusion and metabolism, thereby improving characterization of the dysfunctional area and chronic coronary artery disease. The availability of quantitative myocardial blood flow evaluation with PET provides additional prognostic information and increases diagnostic accuracy in the management of patients with coronary artery disease. Hybrid imaging seems to hold immense potential in optimizing management of cardiovascular diseases and furthering clinical research.

Advances in Molecular Imaging in Infective Endocarditis

Infective endocarditis (IE) is a growing epidemiological challenge. Appropriate diagnosis remains difficult due to heterogenous etiopathogenesis and clinical presentation. The disease may be followed by increased mortality and numerous diverse complications. Developing molecular imaging modalities may provide additional insights into ongoing infection and support an accurate diagnosis. We present the current evidence for the diagnostic performance and indications for utilization in current guidelines of the hybrid modalities: single photon emission tomography with technetium99m-hexamethylpropyleneamine oxime-labeled autologous leukocytes (^99mTc-HMPAO-SPECT/CT) along with positron emission tomography with fluorodeoxyglucose (¹⁸F-FDG PET/CT). The role of molecular imaging in IE diagnostic work-up has been constantly growing due to technical improvements and the increasing evidence supporting its added diagnostic and prognostic value. The various underlying molecular processes of ^99mTc-HMPAO-SPECT/CT as well as ¹⁸F-FDG PET/CT translate to different imaging properties, which should be considered in clinical practice. Both techniques provide additional diagnostic value in the assessment of patients at risk of IE. Nuclear imaging should be considered in the IE diagnostic algorithm, not only for the insights gained into ongoing infection at a molecular level, but also for the determination of the optimal clinical therapeutic strategies.

Endocarditis in the intensive care unit: an update

PURPOSE OF REVIEW

The incidence of infective endocarditis (IE) is increasing worldwide, resulting in a higher number of patients with IE being admitted to intensive care units (ICU). Nearly half of patients with IE develop a complication during their clinical course. However, few well conducted studies or reviews are devoted to critically ill IE patients. This review discusses the contemporary perioperative and intensive care literature.

RECENT FINDINGS

IE epidemiology is changing towards elderly and frail patients. ICU patients are at risk of risk of developing IE because they are often in a pro-inflammatory state and many also have several indwelling catheters, which favors infection. Increased performance and recent advances in cardiac imaging allow for easier diagnosis of EI, but the applicability of these techniques to ICU patients is still relatively limited. New developments in antibiotic treatment and adjunctive therapies are explored further in this review.

SUMMARY

The lack of evidence on ICU patients with IE highlights the critical importance of multidisciplinary decision-making and the need for further research.

The Diagnostic Value of 99mTc-HMPAO-Labelled White Blood Cell Scintigraphy and 18F-FDG PET/CT in Cardiac Device-Related Infective Endocarditis-A Systematic Review

(1) Background: Treatment of cardiac arrhythmias and conduction disorders with the implantation of a cardiac implantable electronic device (CIED) may lead to complications. Cardiac device-related infective endocarditis (CDRIE) stands out as being one of the most challenging in terms of its diagnosis and management. Developing molecular imaging modalities may provide additional insights into CDRIE diagnosis. (2) Methods: We performed a systematic literature review to critically appraise the evidence for the diagnostic performance of the following hybrid techniques: single photon emission tomography with technetium99m-hexamethylpropyleneamine oxime–labeled autologous leukocytes (99mTc-HMPAO-SPECT/CT) and positron emission tomography with fluorodeoxyglucose (18F-FDG PET/CT). An analysis was performed in accordance with PRISMA and GRADE criteria and included articles from PubMed, Embase and Cochrane databases. (3) Results: Initially, there were 2131 records identified which had been published between 1971–2021. Finally, 18 studies were included presenting original data on the diagnostic value of 99mTc-HMPAO-SPECT/CT or 18F-FDG PET/CT in CDRIE. Analysis showed that these molecular imaging modalities provide high diagnostic accuracy and their inclusion in diagnostic criteria improves CDRIE work-up. (4) Conclusions: 99mTc-HMPAO-SPECT/CT and 18F-FDG PET/CT provide high diagnostic value in the identification of patients at risk of CDRIE and should be considered for inclusion in the CDRIE diagnostic process.

18F-FDG PET/CT in cardiovascular infection and inflammation

The diagnosis of cardiovascular infection and inflammation by [¹⁸F]FDG PET/CT in Nuclear Cardiology is of growing interest, because with respect to echocardiography this technique has improved the certainty in the diagnosis of infective endocarditis in patients with prosthetic valves, the increasing number of patients with implantable cardiac devices because of the progressive ageing of the population, as well as in patients with suspected large vessel vasculitis. All are serious clinical situations which require correct diagnosis and appropriate treatment as soon as possible, because they can cause severe complications, high mortality and also increased health care costs. We review the use of [¹⁸F]FDG PET/CT in cardiovascular infection and inflammation, including the clinical point of view and the contribution of other image modalities. We focus on the appropriate methodology for this exploration, patient preparation, image acquisition and correct interpretation and the quantification possibilities, defining the specific characteristics of the diagnosis in patients with prosthetic valves, implantable cardiac devices and large vessel vasculitis in the initial diagnosis as well as during follow-up to assess treatment response. We analyze the possible causes of false positive and false negative results and emphasize the special value of a multidisciplinary team for optimal management of these patients.

PET Cardiac Imaging (Perfusion, Viability, Sarcoidosis, and Infection)

Cardiovascular disease is the leading cause of death worldwide. Given the increased availability of radiopharmaceuticals, improved positron emission tomography (PET) camera systems and proven higher diagnostic accuracy, PET is increasingly utilized in the management of various cardiovascular diseases. PET has high temporal and spatial resolution, when compared to Single Photon Emission Computed Tomography. In clinical practice, hybrid imaging with sequential PET and Computed Tomography acquisitions (PET/CT) or concurrent PET and Magnetic Resonance Imaging are standard. This article will review applications of cardiovascular PET/CT including myocardial perfusion, viability, cardiac sarcoidosis/inflammation, and infection.

Optimizing cardiovascular imaging in Staphylococcus aureus endocarditis

INTRODUCTION

The shift toward value-based health care drives physicians to examine opportunities to optimize use of healthcare resources. There is discordance between providers' use of cardiovascular imaging (CVI) in assessing patients for infective endocarditis (IE) with Staphylococcus aureus bacteremia (SAB). An evidence-based algorithm was created to minimize variation of CVI use. The primary objective was to ensure sensitivity of the algorithm to recommend CVI in patients suspected of IE.

METHODS

A retrospective review evaluated patients at Ochsner Medical Center who developed SAB between 1/1/13 and 12/31/14. Predefined patient demographics, use of CVI, outcomes, and 12-week follow-up for readmission after first positive blood culture were collected from chart review. The created algorithm was applied retrospectively to determine its sensitivity and specificity in recommending the right CVI test.

RESULTS

181 patients admitted were admitted with SAB, of which 114 (63%) were male. There were 115 TTEs and 55 TEEs performed. Out of 15 patients diagnosed with IE, 3 were found on TTE and 12 were found on TEE. The algorithm would have recommended a TEE in all 15 patients who had high-risk features for IE and a true diagnosis of IE, suggesting a sensitivity of 100% and specificity of 74.7% for the algorithm to have recommended a highly sensitive CVI modality.

CONCLUSION

This algorithm optimizes CVI for diagnosing IE in patients with SAB. As healthcare adapts to a value-based system, use of best-practice algorithms will promote consistency in practice among providers and help optimize patient outcomes and use of resources.