FDG-PET in cardiac infections

Characterisation and management of expected and unexpected urgent findings from positron emission tomography with 18F-fluorodeoxyglucose integrated with computed tomography in cardiovascular disease

BACKGROUND

Cardiac 18F-fluorodeoxyglucose (FDG)-PET-CT plays an important role in the assessment of cardiovascular diseases. Effective management of urgent scan findings facilitates optimal patient care.

METHODS

We characterised the management of urgent, expected and unexpected findings in patients referred for cardiac [18F]fluorodeoxyglucose integrated with computed tomography (FDG-PET-CT) at the Royal Brompton Hospital (United Kingdom). Urgent findings are escalated by the reporting physicians/radiologists raising RadAlert notifications to the referring clinician. We characterised the indications and time to management (TTM) between the RadAlert and the resulting management. As controls, we characterised the TTM of 33 urgent findings identified before the RadAlert system was implemented.

RESULTS

Of the 1497 consecutive FDG-PET-CT scans screened (April 2021 to February 2023), 93 RadAlerts were suitable for analysis (TTM 7 days [interquartile range: 2-14]). Expected urgent findings included active cardiac sarcoidosis (56%; TTM 8 days [5-18]), heart transplant rejection (12%; 6 ± 4 days), infective endocarditis (9%; 2 days [1-12]), cardiac device infections (5%; 1 day [0-2]), acute myocarditis (2%; 5 and 14 days) and epicardial mass (1%; 1 day). TTM did not differ significantly between indications (P = 0.06). RadAlert cases had significantly shorter TTM than controls without RadAlert, P = 0.001. After the RadAlerts, 81% of patients had clinical reviews, and 55% had escalation of medical/surgical therapies. Unexpected findings (total N = 45; median TTM 6 days [1-10]) included malignancies (N = 3), infections (N = 2), pneumothorax (N = 1), benign diagnosis (N = 30), unclear diagnosis (N = 5) and 4 findings disappeared on repeat imaging.

CONCLUSIONS

Cardiac FDG-PET-CT identifies expected and unexpected findings in a range of cardiovascular diseases. Serious, unexpected findings are rare and can be effectively escalated by the RadAlert system.

Assessment of Myocardial 18F-FDG Uptake at PET/CT in Asymptomatic SARS-CoV-2-vaccinated and Nonvaccinated Patients

Background Patients who developed myocarditis following SARS-CoV-2 vaccination show abnormalities on cardiac MRI. However, whether myocardial changes occur in asymptomatic individuals following vaccination is not well established. Purpose To assess myocardial 18Fluorine-fluorodeoxyglucose (18F-FDG) uptake on PET/CT in asymptomatic SARS-CoV-2 vaccinated patients compared to nonvaccinated patients. Materials and Methods This retrospective study included patients who underwent 18F-FDG PET/CT for indications unrelated to myocarditis during the period before (11/1/2020 - 2/16/2021) and after (2/17/20121 - 3/31/2022) SARS-CoV-2 vaccines were available. Myocardial and axillary FDG uptake were quantitatively assessed using maximum standardized uptake value (SUVmax). SUVmax values in all patients and in patients stratified by sex (male/female), age (<40, 41-60, >60 years), and time interval between vaccination and PET/CT were compared using Mann-Whitney U test or Kruskal-Wallis test with post ad -hoc Dwass, Steel, Critchlow-Fligner multiple comparison analysis. Results The study included 303 nonvaccinated patients (mean age, 52.9 years ± 14.9 [SD]; 157 females) and 700 vaccinated patients (mean age, 56.8 years ± 13.7 [SD]; 344 females). Vaccinated patients had overall higher myocardial FDG uptake compared to nonvaccinated patients (median SUVmax, 4.8 [IQR: 3.0-8.5] vs median SUVmax, 3.3 [IQR: 2.5-6.2]; P < .0001). Myocardial SUVmax was higher in vaccinated patients regardless of sex (median range, 4.7-4.9 [IQR: 2.9-8.6]) or patient age (median range, 4.7-5.6 [IQR: 2.9-8.6]) compared to corresponding nonvaccinated groups (sex median range, 3.2-3.9 [IQR: 2.4-7.2]; age median range, 3.3-3.3 [IQR: 2.3-6.1]; P range, <.001-.015). Furthermore, increased myocardial FDG uptake was observed in patients imaged 1-30, 31-60, 61-120, and 121-180 days after their second vaccination (median SUVmax range, 4.6-5.1 [IQR: 2.9-8.6]) and increased ipsilateral axillary uptake was observed in patients imaged 1-30, 31-60, 61-120 days after their 2nd vaccination (median SUVmax range, 1.5-2.0 [IQR: 1.2-3.4]) compared to the nonvaccinated patients (P range, <.001-<.001). Conclusion Compared to nonvaccinated patients, asymptomatic patients who received their 2nd vaccination 1-180 days prior to imaging showed increased myocardial FDG uptake on PET/CT. See also the editorial by Bluemke in this issue.

Diagnosis of Fungal Infection (Candida albicans) After Heart Transplantation in a Pediatric Case with Fever of Unknown Origin: Role of 99mTc-UBI SPECT/CT and 18F-FDG PET/CT

The diagnosis of patients with fever of unknown origin (FUO) in pediatric heart transplantation is a challenging medical problem. The physician should differentiate between rejections, infections, malignancy, adrenal insufficiency, and drug fever. Immunosuppressive therapy in these patients exposes them to a high risk of developing a post-transplantation fungal infection. In this case, we discuss the diagnostic contribution of the 99mTc-UBI scan and 18F-FDG PET scan for diagnosis of fungal infection causing FUO in these patients.

18-Fluorodeoxyglucose positron emission tomography in the diagnosis of prosthetic aortic graft infection: the difference between open and endovascular repair

OBJECTIVES

18-Fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) has been reported as useful for diagnosing aortic graft infection. However, 18F-FDG uptake may depend upon various factors including open versus endovascular repair and time from surgery. We aimed to elucidate the factors influencing its uptake and the diagnostic value of 18F-FDG PET/CT after open and endovascular repair.

METHODS

Hospital database of PET/CT (N = 14 490) and our departmental database were cross-checked to identify those who underwent 18F-FDG PET/CT after aortic repair. Patient's data were retrieved from the chart. Images were reviewed by 2 nuclear medicine specialists in consensus, and the presence of increased 18F-FDG uptake was recorded. The maximum standardized uptake value (SUV max) was measured.

RESULTS

Among the 1112 patients who underwent aortic repair between 2011 and 2022, 71 patients were identified. Eighteen patients underwent 18F-FDG PET/CT for suspected graft infection and the remaining 53 patients for other purposes (malignancy, etc.). Fourteen patients were treated as aortic graft infection. They had significantly higher SUV max than those without graft infection [mean 8.64 (standard deviation 2.78) vs 3.40 (standard deviation 0.84); P < 0.01]. In the non-infected grafts, SUV max was higher early after open surgical repair, while it remained low after endovascular repair.

CONCLUSIONS

After endovascular aortic repair, a constant cut-off value of 'SUV max = 4.5' seems appropriate for diagnosing graft infection, since it remains low and stable from the early postoperative period. After open surgical repair, it seems acceptable to have 'stepwise cut-off value' depending on the time from surgery.

Infective endocarditis - A review of current therapy and future challenges

Etiological, microbiological and epidemiological factors changed over time, but mortality rates remain high in infective endocarditis (IE). Healthcare-associated IE is nowadays responsible for a significant proportion of cases due to increasing numbers of cardiac devices. Cardiac implantable electronic devices, transcatheter aortic valve replacement, and percutaneous valve repair are meanwhile used, especially in old and sick patients. In suspected IE modified Duke criteria, integrating clinical results, imaging, and biomarkers are traditionally applied. Newer imaging technologies such as multi-slice computed tomography, photon-emission computed tomography, and magnetic resonance imaging might add value to conventional echocardiography in diagnosis and management of IE. Treatment consists of long-term antibiotic therapy, infectiological source control and/or cardiac surgery. Recently, antibiotic parenteral outpatient regimens and partial oral treatment strategies were shown to shorten hospital stays in patients suffering from IE. However, it remains unclear how to best select patients for partial oral therapy. This review describes new trends in diagnosing, imaging, and treating IE in a changing patient collective with particular focus on patients with implantable cardiac devices.

Cardiac PET/MRI: Current Clinical Status and Future Perspectives

Combined PET/MRI has now been in clinical routine for almost 10 years. Since then, it has not only had to face validation, comparison and research questions, it has also been increasingly used in clinical routine. A number of cardiovascular applications have become established here, whereby viability imaging and assessment of inflammatory and infiltrative processes in the heart are to be emphasized. However, further interesting applications are expected in the near future. This review summarizes the most important clinical applications on the one hand and mentions interesting areas of application in research on the other.

Multimodality Imaging in Infective Endocarditis: An Imaging Team Within the Endocarditis Team

Infective endocarditis (IE) is a complex disease with cardiac involvement and multiorgan complications. Its prognosis depends on prompt diagnosis that leads to an aggressive therapeutic management combining antibiotic therapy and early cardiac surgery when indicated. However, IE diagnosis always poses a challenge, and echocardiography remains diagnostically imperfect in cases of prosthetic valve IE or cardiac implantable electronic device infection. In recent years, other imaging modalities (computed tomography, magnetic resonance imaging, nuclear imaging) have experienced significant technical improvements, and their application to the detection of cardiac and extracardiac IE-related lesions seems to be a strategic way forward in the management of patients with suspected IE. However, the scientific evidence in the literature remains limited; current guidelines address the use of the multimodality imaging in the field of IE with caution; the incremental value of each technique and their combinations is debated; and their use varies across countries. Despite these limitations, healthcare providers and surgeons should be aware of the possibilities offered by the multimodal imaging approach when appropriate. Here, we emphasize the value of a multidisciplinary heart valve team, the endocarditis team, underlining the importance of cardiac and extracardiac imaging experts in playing a key role in informing the diagnosis and management of patients with IE. Illustrative cases, critical appraisal of contemporary data, and conceptual and practical suggestions for clinicians that may help to improve the prognosis of patients with IE are provided in this review article.

Cardiac PET/MRI-an update

It is now about 8 years since the first whole-body integrated PET/MRI has been installed. First, reports on technical characteristics and system performance were published. Early after, reports on the first use of PET/MRI in oncological patients were released. Interestingly, the first article on the application in cardiology was a review article, which was published before the first original article was put out. Since then, researchers have gained a lot experience with the PET/MRI in various cardiovascular diseases and an increasing number on auspicious indications is appearing. In this review article, we give an overview on technical updates within these last years with potential impact on cardiac imaging and summarize those scenarios where PET/MRI plays a pivotal role in cardiovascular medicine.

Hybrid cardiac imaging using PET/MRI: a joint position statement by the European Society of Cardiovascular Radiology (ESCR) and the European Association of Nuclear Medicine (EANM)

Positron emission tomography (PET) and magnetic resonance imaging (MRI) have both been used for decades in cardiovascular imaging. Since 2010, hybrid PET/MRI using sequential and integrated scanner platforms has been available, with hybrid cardiac PET/MR imaging protocols increasingly incorporated into clinical workflows. Given the range of complementary information provided by each method, the use of hybrid PET/MRI may be justified and beneficial in particular clinical settings for the evaluation of different disease entities. In the present joint position statement, we critically review the role and value of integrated PET/MRI in cardiovascular imaging, provide a technical overview of cardiac PET/MRI and practical advice related to the cardiac PET/MRI workflow, identify cardiovascular applications that can potentially benefit from hybrid PET/MRI, and describe the needs for future development and research. In order to encourage its wide dissemination, this article is freely accessible on the European Radiology and European Journal of Hybrid Imaging web sites.

KEY POINTS

• Studies and case-reports indicate that PET/MRI is a feasible and robust technology. • Promising fields of application include a variety of cardiac conditions. • Larger studies are required to demonstrate its incremental and cost-effective value. • The translation of novel radiopharmaceuticals and MR-sequences will provide exciting new opportunities.

Clinical use of cardiac PET/MRI: current state-of-the-art and potential future applications

Combined PET/MRI is a novel imaging method integrating the advances of functional and morphological MR imaging with PET applications that include assessment of myocardial viability, perfusion, metabolism of inflammatory tissue and tumors, as well as amyloid deposition imaging. As such, PET/MRI is a promising tool to detect and characterize ischemic and non-ischemic cardiomyopathies. To date, the greatest benefit may be expected for diagnostic evaluation of systemic diseases and cardiac masses that remain unclear in cardiac MRI, as well as for clinical and scientific studies in the setting of ischemic cardiomyopathies. Diagnosis and therapeutic monitoring of cardiac sarcoidosis has the potential of a possible 'killer-application' for combined cardiac PET/MRI. In this article, we review the current evidence and discuss current and potential future applications of cardiac PET/MRI.

Cardiac 18F-FDG PET/CT procedure for the diagnosis of prosthetic endocarditis and intracardiac devices

Infective endocarditis (IE) is a serious condition with a poor prognosis, its mortality unchanged significantly despite diagnostic and therapeutic advances in the last 30years. The diagnostic ability of the modified Duke criteria in prosthetic endocarditis and/or devices does not exceed 50%, so new tools are necessary for the diagnosis of this entity in this context. The ¹⁸F-FDG PET/CTA combines a highly sensitive technique to detect inflammatory-infectious activity with a technique with high anatomical resolution to assess the structural lesions associated with endocarditis. With a diagnostic sensitivity between 91-97%, this hybrid technique has become a useful diagnostic tool for patients with prosthetic valves or devices and suspicion of IE, becoming a major criterion in the diagnostic algorithm of current guidelines. This excellent diagnostic ability depends directly on the quality of the obtained exploration and the knowledge at the time of interpreting the images. The aim of this review is to describe and standardize the methodology of cardiac ¹⁸F-FDG PET/CTA in the diagnosis of endocarditis in prosthetic valves and intracardiac devices, with special emphasis on the particularities of the patient's preparation, the PET and CT acquisition procedures, and the subsequent imaging postprocessing and interpretation.

Molecular Imaging for the diagnosis of infective endocarditis: A systematic literature review and meta-analysis

BACKGROUND

Infective endocarditis (IE) is a serious, potentially life-threatening condition. Currently, the modified Duke criteria is used to assist with the diagnosis of IE, but it can still remain difficult. Growing data supports the potential use of molecular imaging to assist in the diagnosis of IE. Our objective was to understand the potential utility of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography (PET-CT), ⁶⁷Ga citrate and radiolabeled white blood cell (WBC) scintigraphy in the diagnosis of IE.

METHODS AND RESULTS

A systematic review of the literature and meta-analysis on the use of all 3 modalities in IE was conducted. The literature search identified 2753 articles. A total of 14 studies met the inclusion criteria (10 for ¹⁸F-FDG, 3 for WBC and 1 for both modalities). No ⁶⁷Ga citrate study met the inclusion criteria. Pooled sensitivity of ¹⁸F-FDG studies with adequate cardiac preparation for the diagnosis of IE was 81% (95% CI, 73%-86%) and pooled specificity was 85% (95% CI, 78%-91%). There was good overall accuracy with an area under the curve (AUC) of 0.897. Pooled sensitivity of WBC for the diagnosis of IE was 86% (95% CI, 77%-92%) and pooled specificity was 97% (95% CI, 92%-99%). The overall accuracy of WBC was excellent with an AUC of 0.957.

CONCLUSIONS

Both ¹⁸F-FDG and WBC have good sensitivity, specificity and accuracy for the diagnosis of IE. Both modalities are useful in the investigation of IE, and should be considered in cases where the diagnosis is uncertain.

Positron Emission Tomography and Single-Photon Emission Computed Tomography Imaging in the Diagnosis of Cardiac Implantable Electronic Device Infection: A Systematic Review and Meta-Analysis

BACKGROUND

The use of cardiac implantable electronic devices (CIED) is increasing, and their associated infections result in significant morbidity and mortality. The introduction of better cardiac imaging techniques could be useful for diagnosing this condition and guiding therapy. Our objective was to systematically assess the diagnostic accuracy of Fluor-18-fluorodeoxyglucose positron emission tomography and computed tomography, labeled leukocyte scintigraphy (LS), and Gallium-67 citrate scintigraphy for the diagnosis of CIED infection.

METHODS AND RESULTS

A systematic review of the literature and meta-analysis on the use of all 3 modalities in CIED infection were conducted. Pooled sensitivity, specificity, and summary receiver operating characteristic curves of each imaging modalities were determined. The literature search identified 2493 articles. A total of 13 articles (11 studies for ¹⁸F-FDG PET-CT and 2 for LS), met the inclusion criteria. No studies for ⁶⁷Ga citrate scintigraphy met the inclusion criteria. The pooled sensitivity of ¹⁸F-FDG PET-CT for the diagnosis of CIED infection was 87% (95% CI, 82%-91%) and pooled specificity was 94% (95% CI, 88%-98%). The summary receiver operating characteristic curve analysis demonstrated good overall accuracy, with an area under the curve of 0.935. There were insufficient data to do a meta-analysis for LS, but both studies reported sensitivity above 90% and specificity of 100%.

CONCLUSIONS

Both ¹⁸F-FDG PET-CT and LS yield high sensitivity, specificity, and accuracy, and thus seem to be useful for the diagnosis of CIED infection, based on robust data for ¹⁸F-FDG PET-CT but limited data for LS. When available,¹⁸F-FDG PET-CT may be preferred.

F-18 FDG PET/CT imaging of cardiac and vascular inflammation and infection

INTRODUCTION

Inflammation forms an important core of the aetiopathogenic process involved in many diseases affecting the heart and the blood vessels. These diseases include infections as well as inflammatory non-infectious cardiovascular conditions. The common feature of this is invasion of the heart or blood vessel by inflammatory cells. F-18 2-fluoro 2-deoxy-D glucose (FDG) is an analogue of glucose and like glucose it is taken up by activated inflammatory cells that accumulate at the site of infection. This has formed the basis of the use of F-18 FDG PET/CT in the non-invasive evaluation of human inflammatory diseases.

SOURCES OF DATA

This review is based on the published academic articles as well as our clinical experience.

AREAS OF AGREEMENT

F-18 FDG PET/CT is a useful imaging modality in the evaluation of cardiovascular inflammatory disorders. Accumulation and distribution of F-18 FDG at the site of inflammation/infection corresponds to severity of the inflammation/infection and extent of involvement.

AREAS OF CONTROVERSY

Most studies evaluating utility of F-18 FDG PET/CT in imaging cardiovascular inflammation are small observational studies hence are potentially prone to bias.

GROWING POINTS

Being a hybrid metabolic and morphologic imaging technique, F-18 FDG PET/CT offers combined advantage of complementary anatomic and metabolic information in disease process. This makes it a useful modality in the diagnosis, determination of extent of disease, prognostication as well as treatment monitoring.

AREAS TIMELY FOR DEVELOPING RESEARCH

Larger prospective studies are needed to validate the superiority of F-18 FDG PET/CT imaging over conventional anatomic imaging modalities.

Alternative Cardiac Imaging Modalities to Echocardiography for the Diagnosis of Infective Endocarditis

Infective endocarditis (IE) is a life-threatening disease. Considered the gold standard for the diagnosis of IE, the modified Duke criteria rely on echocardiographic findings to satisfy its major criterion. Echocardiography is an invaluable tool in the evaluation of patients with suspected IE but suffers from certain limitations. For example, it cannot differentiate vegetation from clot, or between infected and noninfected vegetation, and may miss vegetation and periannular extensions in the presence of prosthetic material. Therefore, alternative cardiac imaging modalities are needed. Nuclear imaging, particularly ¹⁸F-fluorodesoxyglucose positron emission tomography-computed tomography (CT), is becoming increasingly popular in the evaluation of patients for IE and has shown promise in diagnosing valvular and device-related IE when echocardiography results were inconclusive. Other techniques such as radiolabeled leukocyte scintigraphy and single-photon emission computed tomography with or without CT are less well studied, however. Cardiac CT angiography is also evolving as a powerful supplementary tool to echocardiography for the detection of perivalvular complications of IE and for preoperative evaluation of coronary anatomy. The combination of cardiac CT angiography and echocardiography is superior to either test alone in the diagnosis of IE and its complications. Although brain magnetic resonance imaging may impact prognosis and clinical management by identifying cerebral emboli in patients with IE, the role of cardiac and abdominal magnetic resonance imaging is less clear. In conclusion, with these additional diagnostic tools at our disposal, the diagnosis of IE may be achieved in a more timely and accurate manner to secure better clinical outcomes.

PET/MR Imaging in Heart Disease

Hybrid PET/MR imaging is a complex imaging modality that has raised high expectations not only for oncological and neurologic imaging applications, but also for cardiac imaging applications. Initially, physicians and physicists had to become accustomed to technical challenges including attenuation correction, gating, and more complex workflow and more elaborate image analysis as compared with PET/CT or standalone MR imaging. PET/MR imaging seems to be particularly valuable to assess inflammatory myocardial diseases (such as sarcoidosis), to cross-validate PET versus MR imaging data (eg, myocardial perfusion imaging), and to help validate novel biomarkers of various disease states (eg, postinfarction inflammation).

Incremental value of PET and MRI in the evaluation of cardiovascular abnormalities

Abstract

The cardiovascular system is affected by a wide range of pathological processes, including neoplastic, inflammatory, ischemic, and congenital aetiology. Magnetic resonance imaging (MRI) and positron emission tomography (PET) are state-of-the-art imaging modalities used in the evaluation of these cardiovascular disorders. MRI has good spatial and temporal resolutions, tissue characterization and multi-planar imaging/reconstruction capabilities, which makes it useful in the evaluation of cardiac morphology, ventricular and valvar function, disease characterization, and evaluation of myocardial viability. FDG-PET provides valuable information on the metabolic activity of the cardiovascular diseases, including ischemia, inflammation, and neoplasm. MRI and FDG-PET can provide complementary information on the evaluation of several cardiovascular disorders. For example, in cardiac masses, FDG-PET provides the metabolic information for indeterminate cardiac masses. MRI can be used for localizing and characterizing abnormal hypermetabolic foci identified incidentally on PET scan and also for local staging. A recent advance in imaging technology has been the development of integrated PET/MRI systems that utilize the advantages of PET and MRI in a single examination. The goal of this manuscript is to provide a comprehensive review on the incremental value of PET and MRI in the evaluation of cardiovascular diseases.

Main Messages

• MRI has good spatial and temporal resolutions, tissue characterization, and multi-planar reconstruction

• FDG-PET provides valuable information on the metabolic activity of cardiovascular disorders

• PET and MRI provide complementary information on the evaluation of cardiovascular disorders

Electronic supplementary material

The online version of this article (doi:10.1007/s13244-016-0494-5) contains supplementary material, which is available to authorized users.

How to approach the great mimic? Improving techniques for the diagnosis of myocarditis

Myocarditis is characterized by inflammation of the myocardium, assessed by histological, immunological and immunohistochemical criteria, due to exogenous or endogenous causes. Abnormal QRS, increased troponin T and left ventricular regional or global dysfunction may be detected. Strain Doppler echocardiography can detect longitudinal segmental dysfunction of the myocardium, due to edema, which is in agreement with cardiac magnetic resonance imaging. Nuclear imaging shows a good sensitivity, but carries serious limitations. Somatostatin receptor positron emission tomography/computed tomography seems promising. Cardiac magnetic resonance imaging, using T2-weighted, early T1-weighted, delayed enhanced images and recently T2 and T1 mapping, has the best diagnostic capability. Endomyocardial biopsy has further contributed to the etiologic diagnosis of myocarditis. To conclude, cardiac magnetic resonance and endomyocardial biopsy have both significantly increased our diagnostic performance. However, further assessment by multicenter studies is needed to establish a clinically useful algorithm.

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.

Rheumatic fever: a forgotten but still existing cause of fever of unknown origin detected on FDG PET/CT

We present a case of heterogeneous and strongly increased myocardial and valvular 18F-FDG uptake on 18F-FDG PET/CT in an HIV-positive patient with productive cough, fever, weight loss, and progressive dyspnea for 6 months. Contrast-enhanced CT did not reveal the cause of fever, but hyperechogenic valvular lesions on echocardiography in combination with PET/CT findings are suggestive of endocarditis/myocarditis. Postmortem histology 3 weeks after PET/CT showed Aschoff bodies with Anitschkow cells, pathognomonic for rheumatic carditis. This case illustrates that rheumatic heart disease can be detected on 18F-FDG PET/CT and demonstrates the value of 18F-FDG PET/CT in patients with fever of unknown origin.

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.

Update on cardiac imaging techniques 2013

Cardiac imaging is a cornerstone of diagnosis in heart conditions, and an essential tool for assessing prognosis and establishing treatment decisions. This year, echocardiography stands out as a guide in interventional procedures and in choosing the size of the prosthesis. It is also proving to be a valuable technique in low-flow, low-gradient aortic stenosis. Three-dimensional echocardiography is advancing our knowledge of cardiac anatomy and valvular measurements. The parameters indicating tissue deformation have predictive power in valve disease and in the follow-up of drug-induced cardiotoxicity. Single-photon emission computed tomography and positron emission tomography are proving useful in ischemic heart disease and in the diagnosis of cardiac inflammation and infections. The role of computed tomography has been strengthened in noninvasive coronary angiography, the emergency room management of chest pain, assessment of chronic occlusions, and morphologic study of coronary plaque. Cardiac magnetic resonance imaging remains the gold standard for tissue characterization in ischemic heart disease and cardiomyopathies, and is assuming a greater role in stress studies and in the assessment of myocardial viability.