18FDG-positron emission tomography (PET) has a role to play in the diagnosis and therapy of infective endocarditis and cardiac device infection

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.

Relevance of [18F]FDG-PET/CT in the detection of colon pathology, in patients studied by bacteriemia or infectious endocarditis caused by enteropathogenic microorganisms

PURPOSE

Association between S. gallolyticus infective endocarditis (IE) and malignant lesions of the gastrointestinal tract is well described. We hypothesize that other enteropathogenic microorganisms, such as S. viridans and E. faecalis are also related with colorectal pathology. Our aim is to determine the frequency of focal colorectal FDG deposits, suggestive of tumoral lesions and their correlation with colorectal pathology, in patients with infection caused by different commensal microorganisms of the gastrointestinal tract.

METHODS

We retrospectively examined 61 patients diagnosed with bacteremia (BSI) and IE (possible or definite) according to Duke's criteria, caused by enteropathogenic microorganisms, who underwent a full-body [¹⁸F]FDG-PET/CT in our institution. We looked for colorrectal FDG deposits and morphological lesions. All IE patients underwent a complete colonoscopy and the histological results were classified into four groups: malignant lesion, premalignant lesion, benign lesion and no lesion. We evaluated the correlation between the findings of the [¹⁸F]FDG-PET/CT with the histopathological diagnosis and the involved microorganism.

RESULTS

PET/CT detected 20 colorectal FDG deposits (32.79%-OR: 47.28), 2 within bacteriemic patients (16.7%) confirmed as malignant and premalignant lesions and 18 in IE group (36.6%), 17 of them corresponding to colorrectal pathology: 11 malignant, 5 premalignant and 1 benign lesions. In the IE subgroup, the colonoscopy detected colorectal lesions in 51.02% of the patients: 11malignant, 8premalignant and 6benign. We found a higher incidence of colorectal FDG deposits in Streptococcus spp. subgroup. Regarding the anatomopathological colonic findings there was a predominance of patients affected by S. viridans, followed by E. faecalis and S. gallolyticus.

CONCLUSION

Patients studied by PET/CT for systemic infection, especially IE, caused by S. viridans or E. faecalis, in addition to S. gallolyticus, show a greater probability of presenting incidental colorectal FDG deposits, mostly corresponding to malignant or pre-malignant lesions. Therefore, it is necessary to carry out an exhaustive search of possible colorectal foci in these exams.

Diagnostic imaging in infective endocarditis: a contemporary perspective

INTRODUCTION

Infective endocarditis (IE) remains a diagnostic challenge. Prompt diagnosis is essential for accurate risk stratification and appropriate therapeutic decisions and surgical management. In recent years, the use of multimodal imaging has had a transformative effect on the diagnostic approach of IE in selected patients.

AREAS COVERED

This review assesses published literature on different imaging modalities for the diagnosis of IE published between 1 January 2009 and 1 February 2020. We illustrate the diagnostic approach to IE with three clinical cases.

EXPERT OPINION

Novel approaches to imaging for cardiac and extracardiac complications improve and individualize diagnosis, management, and prognosis in patients with suspected IE. The use of multimodal imaging should be guided by a multidisciplinary group of medical providers that includes infectious disease specialists, radiologists, cardiologists, and cardiothoracic surgeons.

Improvement of diagnostic accuracy of 18fluorine-fluorodeoxyglucose PET/computed tomography in detection of infective endocarditis using a 72-h low carbs protocol

BACKGROUND

The major challenge in diagnosing infective endocarditis using fluorine-fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) is the high physiological myocardial F-FDG uptake, which may interfere with the detection of pathological uptake. Our aim was to retrospectively analyse the impact of a low-carbohydrate, high-protein, high-fat (LCHPHF) diet starting 72 h before the examination with classic overnight fasting.

METHODS

We included 92 patients (51 with LCHPHF diet 72 h before the examination and 41 with overnight fast only). Left ventricular (LV) myocardial F-FDG uptake was visually evaluated, to estimate the effect of LCHPHF on myocardial F-FDG uptake, we used a three-point visual scale: 0, negligible uptake and evaluable examination; 1, mild uptake and doubtful examination and 2, intense uptake and not evaluable examination. SUVmax and SUVmean were calculated putting a region of interest on LV myocardium at the level of the largest cardiac footprint and on the site of suspected lesion. Thus, a ratio between SUV of the suspect lesion and SUV of LV was calculated as SUV ratio.

RESULTS

By visual assessment, in LCHPHF diet group 46 patients (96.1%) had score 0, 3 patients (5.9%) had score 1 and nobody had score 2. In control group, 23 patients (56.1%) had a score 2, 12 (29.3%) patients obtained a score 1 with a doubtful examination and 6 patients (14.6%) were classified with a score 0 with reportable examination.

CONCLUSION

We demonstrated that an LCHPHF diet can adequately suppress the physiological myocardial uptake leading to a significant improvement in the interpretability and diagnostic accuracy of F-FDG PET/CT in infective endocarditis.

Meta-analysis of 18F-FDG PET/CT in the diagnosis of infective endocarditis

BACKGROUND

The current diagnosis of infective endocarditis (IE) is based on the modified Duke criteria, which has approximately 80% sensitivity for the diagnosis of native valve endocarditis (NVE), with lower sensitivity for the diagnosis of prosthetic valve endocarditis (PVE) and culture-negative endocarditis. There is preliminary evidence that 18F-FDG PET/CT is an adjunctive diagnostic test with high accuracy reported in small studies to date. We therefore performed a meta-analysis of studies evaluating the use of PET/CT in the diagnosis of IE to establish a more precise estimate of accuracy.

METHODS

PubMed, Embase, Cochrane library, CINAHL, Web of Knowledge, and www.clinicaltrials.gov were searched from January 1990 to April 2017 for studies evaluating the accuracy of PET/CT for the evaluation of possible IE.

RESULTS

We identified 13 studies involving 537 patients that were included in the meta-analysis. The pooled sensitivity of PET/CT for diagnosis of IE was 76.8% (95% CI 71.8-81.4%; Q = 39.9, P < 0.01; I2 = 69.9%) and the pooled specificity was 77.9% (95% CI 71.9-83.2%; Q = 44.42, P < 0.01; I2 = 73.0%). Diagnostic accuracy was improved for PVE with sensitivity of 80.5% (95% CI 74.1-86.0%; Q = 25.5, P < 0.01; I2 = 72.5%) and specificity of 73.1% (95% CI 63.8-81.2%; Q = 32.1, P < 0.01; I2 = 78.2%). Additional extracardiac foci of infection were found on 17% of patients on whole body PET/CT.

CONCLUSION

PET/CT is a useful adjunctive diagnostic tool in the evaluation of diagnostically challenging cases of IE, particularly in prosthetic valve endocarditis. It also has the potential to detect clinically relevant extracardiac foci of infection, malignancy, and other sources of inflammation leading to more appropriate treatment regimens and surgical intervention.

PET/Computed Tomography Evaluation of Infection of the Heart

The 2015 European Society of Cardiology guidelines for the management of infective endocarditis included 18F-fluorodeoxyglucose (18F-FDG) PET/computed tomography (CT) in the diagnostic work-up of prosthetic valve endocarditis. This article examines the literature from the last 3 years to highlight the additional role 18F-FDG-PET/CT can contribute to an accurate diagnosis of cardiac infections and associated infectious complications. The challenges and pitfalls associated with 18F-FDG-PET/CT in such clinical settings must be recognized and these are discussed along with the suggested protocols that may be incorporated in an attempt to address these issues.

18F-FDG-PET/CT Imaging to Diagnose Septic Emboli and Mycotic Aneurysms in Patients with Endocarditis and Cardiac Device Infections

PURPOSE OF REVIEW

This review analyzes recent studies evaluating the diagnostic value of ¹⁸F-FDG-PET/CT for the detection of peripheral emboli and secondary infectious foci in patients with infective endocarditis and cardiac device infections.

RECENT FINDINGS

Detection of extracardiac septic localizations in patients with infective endocarditis and cardiac device infections is crucial, as it may impact the diagnosis, prognosis, and therapeutic management. Recent literature substantiated the clinical usefulness of ¹⁸F-FDG-PET/CT in this setting. ¹⁸F-FDG-PET/CT has proven its high diagnostic value for the detection of peripheral emboli in patients with infective endocarditis and cardiac device infections, substantially affecting patients' outcome and treatment. A multimodal approach, combining the high sensitivity of ¹⁸F-FDG-PET/CT with morphological imaging seems promising.

18F-Fluorodeoxyglucose positron emission tomography and infectious diseases: current applications and future perspectives

PURPOSE OF REVIEW

18F-Fluorodeoxyglucose positron emission tomography/computed tomography is a well-established technique for diagnosis and management of a number of neoplastic conditions. However, in recent years the body of literature regarding its potential role in infectious diseases has progressively increased, with promising results.

RECENT FINDINGS

So far 18F-fluorodeoxyglucose positron emission tomography/computed tomography has a well-established role and is recommended by guidelines only in a few settings, such as prosthetic valve endocarditis, vascular device infections, and chronic osteomyelitis. However, even the lack of large, prospective randomized trials, an increasing number of small series and case reports suggest a potential role in the diagnosis, disease staging, and monitoring of treatment response of several other infective conditions.

SUMMARY

In this article, we summarize the available evidence and potential future applications of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in the diagnosis and management of infectious diseases.

Novel Noninvasive Nuclear Medicine Imaging Techniques for Cardiac Inflammation

PURPOSE OF REVIEW

Inflammation is a key player in a wide range of cardiovascular and myocardial diseases. Given the numerous implications of inflammatory processes in disease initiation and progression, functional imaging modalities including positron emission tomography (PET) represent valuable diagnostic, prognostic, and monitoring tools in patient management. Since increased glucose metabolism is a hallmark of inflammation, PET using the radiolabeled glucose analog [18F]-2-deoxy-2-fluoro-d-glucose (FDG) is the mainstay diagnostic test for nuclear imaging of (cardiac) inflammation. Recently, new approaches using more specific tracers to overcome the limited specificity of FDG have emerged.

RECENT FINDINGS

PET imaging has proven its value in a number of inflammatory conditions of the heart including myocarditis, endocarditis, sarcoidosis, or reactive changes after myocardial infarction. In infection-related endocarditis, FDG-PET and white blood cell scintigraphy have been implemented in current guidelines. FDG-PET is considered as nuclear medical gold standard in myocarditis, pericarditis, or sarcoidosis. Novel strategies, including targeting of somatostatin receptors or C-X-C motif chemokine receptor CXCR4, have shown promising results in first studies.

SUMMARY

Nuclear medicine techniques offer valuable information in the assessment of myocardial inflammation. Given the possibility to directly visualize inflammatory activity, they represent useful tools for diagnosis, risk stratification, and therapy monitoring.

18F-FDG positron emission tomography/computed tomography in infective endocarditis

BACKGROUND

The diagnosis of infective endocarditis (IE), especially the diagnosis of prosthetic valve endocarditis (PVE) is challenging since echocardiographic findings are often scarce in the early phase of the disease. We studied the use of 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in IE.

METHODS

Sixteen patients with suspected PVE and 7 patients with NVE underwent visual evaluation of 18F-FDG-PET/CT. 18F-FDG uptake was measured also semiquantitatively as maximum standardized uptake value (SUVmax) and target-to-background ratio (TBR). The modified Duke criteria were used as a reference.

RESULTS

There was strong, focal 18F-FDG uptake in the area of the affected valve in all 6 cases of definite PVE, in 3 of 5 possible PVE cases, and in 2 of 5 rejected cases. In all patients with definite PVE, SUVmax of the affected valve was higher than 4 and TBR higher than 1.8. In contrast to PVE, only 1 of 7 patients with NVE had uptake of 18F-FDG by PET/CT in the valve area. Embolic infectious foci were detected in 58% of the patients with definite IE.

CONCLUSIONS

18F-FDG-PET/CT appears to be a sensitive method for the detection of paravalvular infection associated with PVE. Instead, the sensitivity of PET/CT is limited in NVE.

Impact of tissue photon attenuation in small animal cardiac PET imaging

OBJECTIVES

Tissue photon attenuation is one of the essential artifacts requiring correction in clinical cardiac positron emission tomography (PET) imaging. However, due to small body size its impact on diagnostic accuracy in small rodents is considered to be limited or even ignorable. The present cardiac PET study compares lean and obese rats to determine the influence of tissue attenuation on quantitative assessment as well as regional tracer distribution.

METHODS

A dedicated small animal PET system equipped with a ⁵⁷Co rotating source for transmission was used. To assess the impact of tissue attenuation in rats with different body sizes, cardiac ¹⁸F-FDG -PET studies for Zucker diabetic fatty rats (obese rats) and Zucker lean rats (lean rats) were performed. The radiotracer activity reduction by attenuation was compared between the two groups. Regional tracer distribution calculated with and without attenuation correction was also assessed.

RESULTS

The chest diameter was significantly longer in obese than in lean rats (5.6±0.3cm in obese and 4.5±0.2cm in lean rats, p<0.0001). Whereas the activity reduction by attenuation was significantly greater in obese than in lean rats (44.1±2.5% and 5.1±3.1%, p<0.0001), the regional variation of tissue attenuation among the ventricular walls was minimal in both lean (p=0.73) and obese rats (p=0.65).

CONCLUSION

Attenuation correction is indispensable for accurate comparison of cardiac tracer activity between animals with different body size, whereas it can be omitted for evaluation of regional tracer distribution.

Cross-sectional imaging of aortic infections

Aortic infections are uncommon clinical entities, but are associated with high rates of morbidity and mortality. In this review, we focus on the cross-sectional imaging appearance of aortic infections, including aortic valve endocarditis, pyogenic aortitis, mycotic aneurysm and aortic graft infections, with an emphasis on CT, MRI and PET/CT appearance. Teaching Points • Aortic infections are associated with high morbidity and mortality. • CT, MRI and FDG PET/CT play complementary roles in aortic infection imaging. • Radiologists should be vigilant for aortic infection manifestations to ensure timely diagnosis.

Diagnostic value of imaging in infective endocarditis: a systematic review

Sensitivity and specificity of the modified Duke criteria for native valve endocarditis are both suboptimal, at approximately 80%. Diagnostic accuracy for intracardiac prosthetic material-related infection is even lower. Non-invasive imaging modalities could potentially improve diagnosis of infective endocarditis; however, their diagnostic value is unclear. We did a systematic literature review to critically appraise the evidence for the diagnostic performance of these imaging modalities, according to PRISMA and GRADE criteria. We searched PubMed, Embase, and Cochrane databases. 31 studies were included that presented original data on the performance of electrocardiogram (ECG)-gated multidetector CT angiography (MDCTA), ECG-gated MRI, ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET/CT, and leucocyte scintigraphy in diagnosis of native valve endocarditis, intracardiac prosthetic material-related infection, and extracardiac foci in adults. We consistently found positive albeit weak evidence for the diagnostic benefit of ¹⁸F-FDG PET/CT and MDCTA. We conclude that additional imaging techniques should be considered if infective endocarditis is suspected. We propose an evidence-based diagnostic work-up for infective endocarditis including these non-invasive techniques.

Management of bacteremia in patients living with cardiovascular implantable electronic devices

Cardiovascular implantable electronic devices (CIEDs) have become a critical component in management of patients with cardiac rhythm disturbances, heart failure, and prevention of sudden cardiac death. However, infection remains a major complication of CIED implantation and is associated with significant morbidity and mortality for device recipients. Early-onset CIED infections frequently originate from the generator pocket, secondary to device or pocket contamination at the time of implantation, and may progress to involve device leads or cardiac valves. However, hematogenous seeding of the device leads from a remote source of bacteremia is not infrequent in patients with late-onset CIED infections. Whereas CIED pocket infection can be diagnosed in the majority of cases based on physical findings at the pulse generator site, device lead infection may only manifest with fever and positive blood cultures. However, not every patient with a CIED and positive blood cultures has underlying CIED lead infection. Consequently, management of bacteremia in a CIED recipient without local signs of infection presents a significant challenge. The risk of underlying CIED lead infection in patients presenting with bacteremia depends on several factors, including the type of microorganism isolated in blood cultures, duration and source of bacteremia, type of CIED, and number of device-related procedures. These risk factors must be considered when making decisions regarding the need for further diagnostic imaging and whether to retain or remove the device. In this article, we review the published data regarding risk of CIED infection in patients presenting with bacteremia and propose an algorithm for appropriate evaluation and management.

FDG-PET Identification of Infected Pulmonary Artery Conduit Following Tetralogy of Fallot (TOF) Repair

Tetralogy of Fallot (TOF) is one of the most common forms of cyanotic congenital heart disease usually managed by serial surgical repairs. The repaired prosthetic valve or conduit is susceptible to life-threatening infection. FDG-PET is an effective alternative to evaluate the source of infection when other examinations are inconclusive. We report an unusual case of an infected pulmonary artery conduit after TOF repair although the echocardiogram was negative for vegetation, which was later confirmed by surgery and pathology. The case highlights the role of FDG-PET as a problem-solving tool for potential endocarditis and cardiac device infection cases after complex cardiac surgery.

Cardiovascular PET-CT imaging: a new frontier?

Cardiovascular positron-emission tomography combined with computed tomography (PET-CT) has recently emerged as an imaging technology with the potential to simultaneously describe both anatomical structures and physiological processes in vivo. The scope for clinical application of this technique is vast, but to date this promise has not been realised. Nonetheless, significant research activity is underway to explore these possibilities and it is likely that the knowledge gained will have important diagnostic and therapeutic implications in due course. This review provides a brief overview of the current state of cardiovascular PET-CT and the likely direction of future developments.

Lomentospora prolificans endocarditis--case report and literature review

BACKGROUND

Lomentospora prolificans (formally Scedosporium prolificans) is an environmental mould with a global distribution. Endocarditis caused by L. prolificans is a rare but serious emerging disease in immunocompromised patients. Prior to this case there have only been eight cases reported in the literature. Diagnosis can be challenging and there are no evidence-based guidelines for treatment.

CASE PRESENTATION

We report a 75-year-old woman with ovarian carcinoma who presented with fever after chemotherapy. Repeated sterile site cultures remained negative until day 22 of admission, when Lomentospora prolificans was isolated from blood cultures. Following extensive investigations, including Fluoro-D-glucose positron emission tomography (FDG-PET) and transoephageal echocardiography (TOE), the patient was diagnosed with endocarditis complicated by cerebral emboli. The patient was considered unsuitable for surgical intervention and passed away five days after the fungus was isolated.

CONCLUSION

Endocarditis caused by Lomentospora prolificans is a rare but emerging condition, with limited treatment options and a high mortality. Awareness of the increasing incidence of Lomentospora prolificans infection, diagnosed often at an advanced stage, with potential for endocarditis may prompt earlier echocardiography or FDG-PET imaging. Further studies are needed to determine the optimal combination and duration of anti-fungal agents, used in conjunction with aggressive surgical excision where feasible.

Radionuclide Imaging of Cardiovascular Infection

Owing to expanding clinical indications, cardiac implantable electronic devices (CIEDs) are being increasingly used. Despite improved surgical techniques and the use of prophylactic antimicrobial therapy, the rate of CIED-related infection is also increasing. Infection is a potentially serious complication, with clinical manifestations ranging from surgical site infection and local symptoms in the region of the generator pocket to fulminant endocarditis. The utility of radionuclide imaging as a stand-alone noninvasive diagnostic imaging test in patients with suspected endocarditis has been less frequently examined. This article summarizes the recent advances in radionuclide imaging for evaluation of patients with suspected cardiovascular infections.

High performances of (18)F-fluorodeoxyglucose PET-CT in cardiac implantable device infections: A study of 40 patients

BACKGROUND

Cardiovascular implantable electronic devices (CIED) infections are life-threatening complications. The diagnosis can be difficult to establish. Our purpose is to evaluate the diagnostic value of (18)F-FDG PET.

METHODS

Forty patients who received work-up for suspected CIED infection were retrospectively included (group 1) and compared with 40 controls (group 2); CIED patients were referred for oncologic PET. PET-CT data were blindly assessed. Interpretation was based on visual analysis of both attenuation-corrected and non-corrected images and a semi-quantitative analysis was performed. The gold standard was bacteriological data of explanted devices or clinical follow-up for at least 1 year.

RESULTS

Infection was present in 18 out of 40 patients of group 1. Sensitivity, specificity, positive predictive value, and negative predictive value of PET-CT were 83%, 95%, 94%, and 88%, respectively. Accuracy was 90%. PET-CT revealed the presence of additional pathological hypermetabolic foci in 28% of cases. PET-CT was negative at implanted devices in all patients of group 2.

CONCLUSION

(18)F-FDG PET-CT is helpful in the work-up of suspected CIED infections. It is a potential tool to make the accurate diagnosis of CIED infection and to assess the extent of infection. The promising results in this indication need to be validated in a prospective multicenter study.

Nuclear medicine in diagnosis of prosthetic valve endocarditis: an update

Over the past decades cardiovascular disease management has been substantially improved by the increasing introduction of medical devices as prosthetic valves. The yearly rate of infective endocarditis (IE) in patient with a prosthetic valve is approximately 3 cases per 1,000 patients. The fatality rate of prosthetic valve endocarditis (PVE) remains stable over the years, in part due to the aging of the population. The diagnostic value of echocardiography in diagnosis is operator-dependent and its sensitivity can decrease in presence of intracardiac devices and valvular prosthesis. The modified Duke criteria are considered the gold standard for diagnosing IE; their sensibility is 80%, but in clinical practice their diagnostic accuracy in PVE is lower, resulting inconclusively in nearly 30% of cases. In the last years, these new imaging modalities have gained an increasing attention because they make it possible to diagnose an IE earlier than the structural alterations occurring. Several studies have been conducted in order to assess the diagnostic accuracy of various nuclear medicine techniques in diagnosis of PVE. We performed a review of the literature to assess the available evidence on the role of nuclear medicine techniques in the diagnosis of PVE.

Molecular imaging in Libman-Sacks endocarditis

We present a 54-year-old woman with systemic lupus erythematosus (SLE), fever, pericardial effusion and a mitral valve vegetation. (18)F-Fluorodesoxyglucose positron emission tomography CT ((18)F-FDG-PET-CT) showed very high accumulation of the isotope at the mitral valve. The patient underwent cardiothoracic surgery and pathologic examinations showed characteristic morphology of Libman-Sacks vegetations. All microbiological examinations including blood cultures, microscopy, culture and 16s PCR of the valve were negative and the diagnosis of Libman-Sacks endocarditis was convincing. It is difficult to distinguish Libman-Sacks endocarditis from culture-negative infective endocarditis (IE). Molecular imaging techniques are being used increasingly in cases of suspected IE but no studies have previously reported the use in patients with Libman-Sacks endocarditis. In the present case, (18)F-FDG-PET-CT clearly demonstrated the increased glucose uptake caused by infiltrating white blood cells in the ongoing inflammatory process at the mitral valve. In conclusion, (18)F-FDG-PET-CT cannot be used to distinguish between IE and non-infective Libman-Sacks vegetations.

18-Fluoro-2-deoxyglucose positron emission tomography-computed tomography: an additional tool in the diagnosis of prosthetic valve endocarditis

OBJECTIVES

To evaluate the role of 18-fluoro-2-deoxyglucose positron emission tomography-computed tomography ((18)F-FDG-PET-CT) in the diagnosis of infectious endocarditis (IE).

METHODS

We retrospectively examined 27 consecutive patients who were admitted to the Infectious Diseases Department of Tor Vergata University Hospital between 2009 and 2013 with a suspicion of IE. The final IE diagnosis was defined according to the modified Duke criteria, and the microbiological and diagnostic results were collected for each patient.

RESULTS

Twenty out of 27 patients had a suspected prosthetic valve endocarditis (PVE) and seven had a suspected native valve endocarditis (NVE). Twenty-five out of 27 patients (92%) had a confirmed diagnosis of IE (18/25 PVE and 7/25 NVE); 16 had a positive echocardiography evaluation and 16 had positive (18)F-FDG-PET-CT findings. Echocardiography showed a higher sensitivity as a diagnostic tool for the detection of IE compared to (18)F-FDG-PET-CT (80% vs. 55%). However, a greater number of PVE had positive (18)F-FDG-PET-CT results compared to those with positive echocardiography findings (11/13 vs. 9/13), and overall 89% (16/18) of confirmed PVE resulted (18)F-FDG-PET-CT positive. Analyzing only the cases who underwent transoesophageal echocardiography, (18)F-FDG-PET-CT showed a sensitivity of 85% in PVE (vs. 69% for echocardiography and 77% for the Duke criteria). All seven patients with NVE had a positive echocardiography and negative (18)F-FDG-PET-CT findings (p<0.001).

CONCLUSIONS

The results of this study further highlight the limitations of echocardiography in the diagnosis of PVE and the potential advantages of (18)F-FDG-PET-CT in these cases.

Late prosthetic graft infection after frozen elephant trunk presenting by haemoptysis and positive ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography

In cardiothoracic surgery, prosthetic graft infection represents a diagnostic and therapeutic challenge. Although clinical assessment, imaging techniques and microbiological investigations are helpful, late graft infection can be difficult to identify using classical diagnostic tools. An aggressive surgical approach involving removal and replacement of all prosthetic materials is technically demanding but remains the best strategy to eradicate infection. Herein, we report a case of a late aortic graft infection, after frozen elephant trunk implantation with atypical presentation, diagnosed with (18)F-fluorodeoxyglucose-positron emission tomography and treated successfully through a radical surgical strategy. This case emphasizes the emerging diagnostic role of positron emission tomography and encourages the adoption of an aggressive surgical approach.

Evaluation of fever and infections in cardiac surgery patients

Fever following cardiac surgery is common and may be infectious or noninfectious in etiology. In this article, we review the major causes of postoperative fever while highlighting special considerations in cardiac surgery patients. We also outline a structured approach to evaluation and present an overview of diagnostic and management considerations for mediastinitis, postpericardiotomy syndrome, prosthetic valve endocarditis, aortic vascular graft infections, and ventricular assist device infections.

The pivotal role of FDG-PET/CT in modern medicine

The technology behind positron emission tomography (PET) and the most widely used tracer, 2-deoxy-2-[18F]fluoro-D-glucose (FDG), were both conceived in the 1970s, but the latest decade has witnessed a rapid emergence of FDG-PET as an effective imaging technique. This is not least due to the emergence of hybrid scanners combining PET with computed tomography (PET/CT). Molecular imaging has enormous potential for advancing biological research and patient care, and FDG-PET/CT is currently the most widely used technology in this domain. In this review, we discuss contemporary applications of FDG-PET and FDG-PET/CT as well as novel developments in quantification and potential future indications including the emerging new modality PET/magnetic resonance imaging.

Combined computed tomography and fluorodeoxyglucose positron emission tomography in the diagnosis of prosthetic valve endocarditis: a case series

Background

The diagnosis of prosthetic valve endocarditis is challenging. The gold standard for prosthetic valve endocarditis diagnosis is trans-esophageal echocardiography. However, trans-esophageal echocardiography may result in negative findings or yield images difficult to differentiate from thrombus in patients with prosthetic valve endocarditis. Combined computed tomography and fluorodeoxyglucose positron emission tomography is a potentially promising diagnostic tool for several infectious conditions and it has also been employed in patients with prosthetic valve endocarditis but data are still scant.

Case presentations

We reviewed the charts of 6 patients with prosthetic aortic valves evaluated for suspicion of prosthetic valve endocarditis, at two different hospital, over a 3-year period. We found 3 patients with early-onset PVE cases and blood cultures yielding Pseudomonas aeruginosa, Staphylococcus epidermidis and Staphylococcus lugdunensis, respectively; and 3 late-onset cases in the remaining 3 patients with isolation in the blood of Streptococcus bovis, Candida albicans and P. aeruginosa, respectively. Initial trans-esophageal echocardiography was negative in all the patients, while fluorodeoxyglucose positron emission tomography showed images suspicious for prosthetic valve endocarditis. In 4 out of 6 patients valve replacement was done with histology confirming the prosthetic valve endocarditis diagnosis. After an adequate course of antibiotic therapy fluorodeoxyglucose positron emission tomography showed resolution of prosthetic valve endocarditis in all the patients.

Conclusion

Our experience confirms the potential role of fluoroseoxyglucose positron emission tomography in the diagnosis and follow-up of prosthetic valve endocarditis.