The utility of cardiac MRI in diagnosis of infective endocarditis: preliminary results

Advanced Imaging Modalities to Monitor for Cardiotoxicity

Early detection and treatment of cardiotoxicity from cancer therapies is key to preventing a rise in adverse cardiovascular outcomes in cancer patients. Over-diagnosis of cardiotoxicity in this context is however equally hazardous, leading to patients receiving suboptimal cancer treatment, thereby impacting cancer outcomes. Accurate screening therefore depends on the widespread availability of sensitive and reproducible biomarkers of cardiotoxicity, which can clearly discriminate early disease. Blood biomarkers are limited in cardiovascular disease and clinicians generally still use generic screening with ejection fraction, based on historical local expertise and resources. Recently, however, there has been growing recognition that simple measurement of left ventricular ejection fraction using 2D echocardiography may not be optimal for screening: diagnostic accuracy, reproducibility and feasibility are limited. Modern cancer therapies affect many myocardial pathways: inflammatory, fibrotic, metabolic, vascular and myocyte function, meaning that multiple biomarkers may be needed to track myocardial cardiotoxicity. Advanced imaging modalities including cardiovascular magnetic resonance (CMR), computed tomography (CT) and positron emission tomography (PET) add improved sensitivity and insights into the underlying pathophysiology, as well as the ability to screen for other cardiotoxicities including coronary artery, valve and pericardial diseases resulting from cancer treatment. Delivering screening for cardiotoxicity using advanced imaging modalities will however require a significant change in current clinical pathways, with incorporation of machine learning algorithms into imaging analysis fundamental to improving efficiency and precision. In the future, we should aspire to personalized rather than generic screening, based on a patient’s individual risk factors and the pathophysiological mechanisms of the cancer treatment they are receiving. We should aspire that progress in cardiooncology is able to track progress in oncology, and to ensure that the current ‘one size fits all’ approach to screening be obsolete in the very near future.

Utility of Intracardiac Echocardiography to Diagnose Infective Endocarditis

Infective endocarditis (IE) can lead to significant morbidity and mortality without appropriate treatment. Modified Duke Criteria are accepted by many professional societies to establish the diagnosis of IE, and cardiac imaging is one of the major diagnostic criteria. Transesophageal echocardiography is an algorithmic escalation to diagnose IE when transthoracic echo does not appreciate a positive finding. In patients with contraindications to transesophageal echocardiography, cardiac magnetic resonance imaging, cardiac computed tomography (CT), cardiac CT angiography, and fluorodeoxyglucose positron emission tomography with CT or CT angiography may be alternative diagnostic tools. However, these imaging modalities have their own limitations such as local unavailability, the presence of non–magnetic resonance imaging compatible implants, or impaired renal function. Intracardiac echocardiography could be a considerable alternative under those circumstances.

Role of Cardiac Magnetic Resonance Imaging in Valvular Heart Disease: Diagnosis, Assessment, and Management

PURPOSE OF REVIEW

This article will review the current techniques in cardiac magnetic resonance imaging (CMR) for diagnosing and assessing primary valvular heart disease.

RECENT FINDINGS

The recent advancements in CMR have led to an increased role of this modality for qualifying and quantifying various native valve diseases. Phase-contrast velocity encoded imaging is a well-established technique that can be used to quantify aortic and pulmonic flow. This technique, combined with the improved ability for CMR to obtain accurate left and right ventricular volumetrics, has allowed for increased accuracy and reproducibility in assessing valvular dysfunction. Advancements in CMR technology also allows for improved spatial and temporal resolution imaging of various valves and their regurgitant or stenotic jets. Therefore, CMR can be a powerful tool in evaluation of native valvular heart disease. The role of CMR in assessing valvular heart disease is growing and being recognized in recent guidelines. CMR has the ability to assess valve morphology along with qualifying and quantifying valvular disease. In addition, the ability to obtain accurate volumetric measurements may improve more precise management strategies and may lead to improvements in mortality and morbidity.

[Infective endocarditis in the elderly: The current view of the problem]

The review gives the current views of the etiology and risk factors of infective endocarditis (IE) in the elderly. It reports the specific clinical picture of the disease at this age, including clinically apparent syndromes, comorbidity, and various clinical signs and peculiarities of IE. Particular emphasis is placed on the diagnosis of an endocardial infectious lesion, which is based on the use of the modified Duke criteria. The methods of IE diagnosis, particularly microbiological examination, imaging techniques, among which echocardiography in different modes plays a particular role, are listed. The treatment of the disease is based on the latest recommendations for antibiotic therapy with and without regard to a specific etiological factor. The issues of surgical intervention, as well as approaches to preventing IE in elderly people are discussed.

Targeting Cardiovascular Implant Infection: Multimodality and Molecular Imaging

Owing to their success in clinical practice, the prevalence of cardiovascular implants is continuously increasing. Implant infection is a relevant complication but remains a diagnostic challenge because echocardiography as a first-line test may be limited. Accordingly, a multimodality approach is increasingly used for diagnostic workup and supported by recent guidelines. As reviewed here, computed tomography and nuclear imaging provide incremental diagnostic value and may be combined in a single hybrid imaging session using positron emission tomography/computed tomography or single photon emission computed tomography/computed tomography. Molecular or cellular imaging helps to overcome the limitations of morphological imaging in implants. Larger-scale clinical studies, earlier application in the time course of diagnosis, monitoring of therapy success, technical advances, and novel radiopharmaceuticals will all contribute to sustained growth of advanced infection-targeted imaging in cardiovascular medicine.

18F-FDG-PET/CT angiography in the diagnosis of infective endocarditis and cardiac device infection in adult patients with congenital heart disease and prosthetic material

OBJECTIVES

Infective endocarditis (IE) and cardiac device infection (CDI) are a major complication in the growing number of patients with congenital heart disease (CHD) reaching adulthood. We aimed to evaluate the added value of ¹⁸F-FDG-PET/CT angiography (PET/CTA) in the diagnosis of IE-CDI in adults with CHD and intravascular or intracardiac prosthetic material, in whom echocardiography (ECHO) and modified Duke Criteria (DC) have limitations because of the patients' complex anatomy.

METHODS

A prospective study was conducted in a referral center with multidisciplinary IE and CHD Units. PET/CTA and ECHO findings were compared in consecutive adult (≥18years) patients with CHD who have prosthetic material and suspected IE-CDI. The initial diagnosis using the DC and the diagnosis with the additional PET/CTA data (DC+PET/CTA) were compared with the final diagnostic consensus established by an expert team at three months.

RESULTS

Between November-2012 and April-2017, 25 patients (15 men; median age 40years) were included. Cases were initially classified as definite in 8 (32%), possible in 14 (56%) and rejected in 3 (12%). DC+PET/CTA allowed reclassification of 12/14 (86%) cases initially identified as possible IE. The sensitivity, specificity, PPV, NPV, and accuracy of DC at IE suspicion were 39.1%/83.3%/90.4%/25.5%/61.2%, respectively. The diagnostic performance increased significantly with addition of PET/CTA data: 87%/83.3%/95.4%/61.5%/85.1%, respectively. PET/CTA also provided an alternative diagnosis in 3 patients with rejected IE, and detected pulmonary embolisms in 3 patients.

CONCLUSIONS

PET/CTA was a useful diagnostic tool in the complex group of adult patients with CHD who have cardiac or intravascular prosthetic material and suspected IE or CDI, providing added diagnostic value to the modified DC (increased sensitivity) and improving case classification.

Cardiac calcified amorphous tumors: CT and MRI findings

PURPOSE

We aimed to evaluate computed tomography (CT) and magnetic resonance imaging (MRI) findings of cardiac calcified amorphous tumors (CATs).

METHODS

CT and MRI findings of cardiac CATs in 12 patients were included. We retrospectively examined patient demographics, location, size, shape configuration, imaging features, calcification distribution of tumors, and accompanying medical problems.

RESULTS

There was a female predominance (75%), with a mean age at presentation of 65 years. Patients were mostly asymptomatic on presentation (58.3%). The left ventricle of the heart was mostly involved (91%). CT findings of CATs were classified as partial calcification with a hypodense mass in four patients or a diffuse calcified form in eight. Calcification was predominant with large foci appearance as in partially calcified masses. On T1- and T2-weighted magnetic resonance images, CATs appeared hypointense and showed no contrast enhancement.

CONCLUSION

The shape and configuration of cardiac CATs are variable with a narrow spectrum of CT and MRI findings, but large foci in a partially calcified mass or diffuse calcification of a mass on CT is very important in the diagnosis of cardiac CATs. Masses show a low signal intensity on T1- and T2-weighted images with no contrast enhancement on MRI.

Utility of cardiac magnetic resonance for evaluation of mitral regurgitation prior to mitral valve surgery

Mitral regurgitation (MR) is a common cause of morbidity worldwide and an accepted indication for interventional therapies which aim to reduce or resolve adverse clinical outcomes associated with MR. Cardiac magnetic resonance (CMR) provides highly accurate means of assessing MR, including a variety of approaches that can measure MR based on quantitative flow. Additionally, CMR is widely accepted as a reference standard for cardiac chamber quantification, enabling reliable detection of subtle changes in cardiac chamber size and function so as to guide decision-making regarding timing of mitral valve directed therapies. Beyond geometric imaging, CMR enables tissue characterization of ischemia and infarction in the left ventricular (LV) myocardium as well as within the mitral valve apparatus, thus enabling identification of structural substrates for MR. This review provides an overview of established and emerging CMR approaches to measure valvular regurgitation, including relative utility of different approaches for patients with primary or secondary MR. Clinical outcomes studies are discussed with focus on data demonstrating advantages of CMR for guiding diagnosis, risk stratification, and management of patients with known or suspected MR. Comparative data is reviewed with focus on diagnostic performance of CMR in comparison to conventional assessment via echocardiography (echo). Emerging literature is reviewed concerning potential new approaches that utilize CMR tissue characterization to guide clinical decision-making in order to improve therapeutic outcomes and clinical prognosis for patients with MR.

Infectious Diseases of the Heart: Pathophysiology, Clinical and Imaging Overview

Myriad infectious organisms can infect the endocardium, myocardium, and pericardium, including bacteria, fungi, parasites, and viruses. Significant cardiac infections are rare in the general population but are associated with high morbidity and mortality as well as increased risk in certain populations, such as the elderly, those undergoing cardiac instrumentation, and intravenous drug abusers. Diagnostic imaging of cardiac infections plays an important role despite its variable sensitivity and specificity, which are due in part to the nonspecific manifestations of the central inflammatory process of infection and the time of onset with respect to the time of imaging. The primary imaging modality remains echocardiography. However, cardiac computed tomography and magnetic resonance (MR) imaging have emerged as the modalities of choice wherever available, especially for diagnosis of complex infectious complications including abscesses, infected prosthetic material, central lines and instruments, and the cryptic manifestations of viral and parasitic diseases. MR imaging can provide functional, morphologic, and prognostic value in a single examination by allowing characterization of inflammatory changes from the acute to chronic stages, including edema and the patterns and extent of delayed gadolinium enhancement. We review the heterogeneous and diverse group of cardiac infections based on their site of primary cardiac involvement with emphasis on their cross-sectional imaging manifestations. Online supplemental material is available for this article. (©)RSNA, 2016.

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.

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.

Clinical Utility and Future Applications of PET/CT and PET/CMR in Cardiology

Over the past several years, there have been major advances in cardiovascular positron emission tomography (PET) in combination with either computed tomography (CT) or, more recently, cardiovascular magnetic resonance (CMR). These multi-modality approaches have significant potential to leverage the strengths of each modality to improve the characterization of a variety of cardiovascular diseases and to predict clinical outcomes. This review will discuss current developments and potential future uses of PET/CT and PET/CMR for cardiovascular applications, which promise to add significant incremental benefits to the data provided by each modality alone.

Diagnosing pulmonic valve infective endocarditis with positron emission tomography-CT

Infective endocarditis (IE) affects the pulmonic valve in less than 2% of cases. Not only is pulmonary valve IE rare, it is also challenging to visualise with commonly used imaging modalities. In this vignette, we present a 50-year-old patient with a history of repaired Tetralogy of Fallot who underwent a prolonged hospitalisation and extensive work up for fever of unknown origin. Although we suspected IE as the source of his fevers, he had persistently negative transthoracic and transoesophageal echocardiograms. We were ultimately able to establish the diagnosis with the use of positron emission tomography-CT (PET-CT). Although PET-CT is not part of the traditional work up for IE, it can be a useful imaging modality when there is a high index of suspicion for IE with negative echocardiography findings.

Unexpected Pathologic Diagnosis of the Mitral Valvular Mass

A 59-year-old man with multifocal cerebral infarction was found to have the large obstructive mitral valvular mass. Although benign tumor was under suspicion before surgery, he was finally diagnosed as chronic infective endocarditis by microscopic evaluation. The precise diagnosis and the proper management of a cardiac mass are very important since even the benign tumor may cause fatal complications. However, primary cardiac mass has the broad spectrum from pseudo-tumor to malignancy and the differential diagnosis using non-invasive methods is not easy even with the currently available imaging techniques.