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 multisocietal 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/multifocal 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 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.

Imaging of Cardiac Infections: A Comprehensive Review and Investigation Flowchart for Diagnostic Workup.

Infections of the cardiovascular system may present with nonspecific symptoms, and it is common for patients to undergo multiple investigations to arrive at the diagnosis. Echocardiography is central to the diagnosis of endocarditis and pericarditis. However, cardiac computed tomography (CT) and magnetic resonance imaging also play an additive role in these diagnoses; in fact, magnetic resonance imaging is central to the diagnosis of myocarditis. Functional imaging (fluorine-18 fluorodeoxyglucose-positron emission tomography/CT and radiolabeled white blood cell single-photon emission computed tomography/CT) is useful in the diagnosis in prosthesis-related and disseminated infection. This pictorial review will detail the most commonly encountered cardiovascular bacterial and viral infections, including coronavirus disease-2019, in clinical practice and provide an evidence basis for the selection of each imaging modality in the investigation of native tissues and common prostheses.

Persistent Coxiella burnetii cardiovascular infection on Bentall-De Bono prosthesis.

Coxiella burnetii cardiovascular prosthetic infections are associated with high morbidity and mortality and represent a major health problem due to the lack of standardized management. We were confronted with a C. burnetii infection on Bentall-De Bono prosthesis characterized by a history of vascular infection with relapse that prompted us to screen for cases of C. burnetii on Bentall-De Bono vascular prosthesis monitored in our center. We screened patients between 1991 and 2019, from the French national reference center for Q fever. A microbiological criterion in addition to a lesional criterion was necessary to diagnose C. burnetii persistent vascular infection. Two thousand five hundred and eighty two patient were diagnosed with Coxiella burnetii infection and 160 patients with persistent C. burnetii vascular infection prosthesis, 95 of whom had a vascular prosthesis, including 12 with Bentall-De Bono prosthesis. Among patients with persistent C. burnetii prosthetic vascular infection, patients with Bentall-De Bono prostheses were significantly more prone to develop complications such as aneurysm, fistula, and abscess (62 versus 32%, two-sided Chi-square test, p = 0.04). All but one patient were treated with doxycycline and hydroxychloroquine for a mean (± standard deviation) period of 29.4 ± 13.6 months. Among the 12 patients, 5 had cardio-vascular complications, and 5 had prolonged antibiotherapy with doxycycline and hydroxychloroquine. Patients with C. burnetii vascular infection on Bentall-De Bono tend to be at high risk of developing complications (fistula, aneurysm, abscess, death). Surgery is rarely performed. Clinical, serological, and PET scanner imaging follow-up is recommended.

The "3M" Approach to Cardiovascular Infections: Multimodality, Multitracers, and Multidisciplinary.

Cardiovascular infections are associated with high morbidity and mortality. Early diagnosis is crucial for adequate patient management, as early treatment improves the prognosis. The diagnosis cannot be made on the basis of a single symptom, sign, or diagnostic test. Rather, the diagnosis requires a multidisciplinary discussion in addition to the integration of clinical signs, microbiology data, and imaging data. The application of multimodality imaging, including molecular imaging techniques, has improved the sensitivity to detect infections involving heart valves and vessels and implanted cardiovascular devices while also allowing for early detection of septic emboli and metastatic infections before these become clinically apparent. In this review, we describe data supporting the use of a Multimodality, Multitracer, and Multidisciplinary approach (the 3M approach) to cardiovascular infections. In particular, the role of white blood cell SPECT/CT and [18F]FDG PET/CT in most prevalent and clinically relevant cardiovascular infections will be discussed. In addition, the needs of advanced hybrid equipment, dedicated imaging acquisition protocols, specific expertise for image reading, and interpretation in this field are discussed, emphasizing the need for a specific reference framework within a Cardiovascular Multidisciplinary Team Approach to select the best test or combination of tests for each specific clinical situation.

Usefulness of scintigraphy with labelled leucocytes and SPECT/CT in vascular graft infection. / Utilidad de la gammagrafía con leucocitos marcados y SPECT/TC en la infección de injertos vasculares.

Vascular graft infections are a rare complication in this type of procedure. However, when they do occur, they usually have high morbidity, and even a high mortality. Proper identification and location is crucial for the appropriate and early management, whether medical or surgical, thus knowledge of the right tools is paramount. Nuclear medicine studies play an important role in this regard, either by using labelled white blood cells scintigraphy or 18F-FDG. The choice, among other factors, will depend on the experience with both techniques by the different groups, their knowledge of them, as well as their availability. Two cases are presented in which 99mTc-HMPAO-white blood cells SPECT/CT scintigraphy was very useful in the diagnosis and location of the suspected infectious compromise, which led to the subsequent appropriate and guided management. Both cases were confirmed clinically and microbiologically.

Cardiovascular infection and inflammation.

Infectious and inflammatory processes, in particular those involving the cardiovascular system, are not a story of the past. New aggressive pathogens are responsible for difficult-to-treat infections. Present-day problems such as diabetes are associated with frequent and at times severe infectious processes, with high morbidity related to the disease or to available therapeutic options. Infections involving the heart or vessels pose clinical challenges in diagnosing and planning the most appropriate therapeutic strategy. Inflammatory processes are diagnosed more frequently today, acknowledged as pathologic conditions of high clinical significance, and much is invested in developing efficient therapeutic options. Nuclear medicine procedures are an important component of the evaluation armamentarium used in patients with suspected or confirmed infectious and inflammatory processes. Their role relies on the strength of noninvasive scintigraphic imaging tests that provide functional and metabolic information early during the course of the disease. Drawbacks of nuclear medicine procedures related to either the use of specific radiolabeled tracers or to their rather low resolution are overcome to a large extent during the last decade by the introduction of hybrid positron emission tomography/computed tomography and single-photon emission computed tomography/computed tomography imaging devices. Initial validated results regarding the role of nuclear medicine and of hybrid imaging using various radiotracers in the evaluation of cardiovascular infections and inflammatory processes are emerging over the last few years. They indicate the potentially important role of these modalities for early and precise diagnosis, in defining the whole extent of disease, for individualized treatment tailoring and for monitoring response to treatment. Attention needs to be given to match the appropriate imaging test and radiolabeled agent to the clinical question at hand. Nuclear medicine in general and hybrid imaging procedures in particular will redefine in future the diagnostic and therapeutic capabilities in patients with suspected or known infections and inflammations of the cardiovascular system.

Positron emission tomography as a diagnostic tool in infection: present role and future possibilities.

The past decade has witnessed the emergence of yet another promising application of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging in the detection and management of patients with infection and inflammatory disorders. This phenomenon is quite evident when the peer-reviewed scientific literature is searched for on this topic. Among these scientific communications, the 6 conditions in which FDG-PET has demonstrated its greatest utility include (1) chronic osteomyelitis, (2) complicated lower-limb prostheses, (3) complicated diabetic foot, (4) fever of unknown origin, (5) acquired immunodeficiency syndrome (ie, AIDS), and (6) vascular graft infection and fistula. On the basis of published literature, orthopedic infections, particularly those related to implanted prostheses and osteomyelitis (including that occurring in the setting of a complicated diabetic foot), can be detected successfully by the use of FDG-PET and, therefore, this modality has great promise for becoming the study of choice in these complex settings. Increasingly, this technique is being used to detect infection in soft tissues, including those representing the sources of fever of unknown origin. The ability of FDG-PET to diagnose vascular graft infection and fistula, even when the anatomical imaging modalities are inconclusive, is of considerable interest to practitioners of vascular surgery. Combined PET/computed tomography (CT) imaging has the potential to determine the sites of infection or inflammation with high precision. The data on the role of PET/CT imaging in the assessment of infection and inflammation is sparse, but this combined modality approach may prove to be the study of choice in foreseeable future for precise localization of involved sites. However, the role of PET/CT may be limited in the presence of metallic artifacts (such as those caused by prostheses) adjacent to the sites of infection.

Pericardial tamponade masquerading as septic shock.

A 53-year-old man with steroid dependent rheumatoid arthritis presented with fever and serous articular drainage. Oral antibiotics were initially prescribed. Subsequent hemodynamic instability was attributed to septic shock. Further evaluation revealed a pericardial effusion with tamponade. Pericardiocentesis of purulent fluid promptly corrected the hypotension. Proteus mirabilis was later isolated from both the infected joint and the pericardial fluid. This is the first report of combined Proteus mirabilis septic arthritis and purulent pericarditis. It documents the potential for atypical transmission of Gram-negative pathogens, to the pericardium, in patients with a high likelihood of preexisting pericardial disease. In immunocompromised patients, the typical signs and symptoms of pericarditis may be absent, and the clinical presentation of pericardial tamponade may be misinterpreted as one of septic shock. This case underscores the value of a careful physical examination and proper interpretation of ancillary studies. It further illustrates the importance of initial antibiotic selection and the need for definitive treatment of septic arthritis in immunocompromised patients.