Positron emission tomography-computed tomography for imaging of inflammatory cardiovascular diseases

MINOCA biomarkers: Non-atherosclerotic aspects

Myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) is an important subtype of myocardial infarction. Although comprising less than 50% stenosis in the main epicardial coronary arteries, it constitutes a severe health risk. A variety of approaches have been recommended, but definitive diagnosis remains elusive. In addition, the lack of a comprehensive understanding of underlying pathophysiology makes clinical management difficult and unpredictable. This review highlights ongoing efforts to identify relevant biomarkers in MINOCA to improve diagnosis, individualize treatment and better predict outcomes.

Anthracycline cardiotoxicity: current methods of diagnosis and possible role of 18F-FDG PET/CT as a new biomarker

Despite advances in chemotherapy, the drugs used in cancer treatment remain rather harmful to the cardiovascular system, causing structural and functional cardiotoxic changes. Positron-emission tomography associated with computed tomography (PET/CT) has emerged like a promising technique in the early diagnosis of these adverse drug effects as the myocardial tissue uptake of fluorodeoxyglucose labeled with fluorine-18 (¹⁸F-FDG), a glucose analog, is increased after their use. Among these drugs, anthracyclines are the most frequently associated with cardiotoxicity because they promote heart damage through DNA breaks, and induction of an oxidative, proinflammatory, and toxic environment. This review aimed to present the scientific evidence available so far regarding the use of ¹⁸F-FDG PET/CT as an early biomarker of anthracycline-related cardiotoxicity. Thus, it discusses the physiological basis for its uptake, hypotheses to justify its increase in the myocardium affected by anthracyclines, importance of ¹⁸F-FDG PET/CT findings for cardio-oncology, and primary challenges of incorporating this technique in standard clinical oncology practice.

Normal Variants and Pitfalls in Cardiac PET/CT

Positron emission tomography and/or computed tomography (PET/CT) MPI is a powerful imaging modality for the assessment of cardiovascular diseases. It offers several advantages over single-photon emission computed tomography (SPECT) MPI including robust attenuation correction and absolute quantification of radiotracer activity. PET MPI has a large evidence base and is the only clinical tool to evaluate coronary microvascular dysfunction. In addition, the clinical use and evidence base for 2-deoxy-2-[¹⁸F]fluoro-D-g1ucose (¹⁸F-FDG) cardiac PET imaging for inflammation and metabolism imaging is rising exponentially. In order to gain from the advances of this sophisticated quantitative technique, a high-quality scan is critical. It is important for readers to recognize a poor-quality scan, identify artifacts contributing to the poor image quality, and understand how to correct them prior to reporting the results. In this review, we will discuss some normal variants and pitfalls in cardiac PET/CT radionuclide MPI, myocardial viability, and inflammation imaging.

Associations of physiologic myocardial 18F-FDG uptake with fasting duration, HbA1c, and regular exercise

OBJECTIVE

The variability of physiologic ¹⁸F-FDG uptake in the myocardium has hampered the accurate evaluation of cardiac glucose metabolism. We investigated the effects of multiple factors, including fasting duration and physical activity, on the physiologic uptake of ¹⁸F-FDG by the myocardium in healthy participants.

METHODS

A total of 446 participants (predominantly male, 91%) in a health screening program were included in this retrospective study. For the visual analysis of myocardial ¹⁸F-FDG uptake, the participants were categorized into three groups according to qualitative visual scales (QVS). For the quantitative analysis, the maximum SUV of the left ventricular myocardium was measured.

RESULTS

Significant differences were observed in fasting duration (p < 0.001), SUV_max (p < 0.001), aspartate aminotransferase (AST) (p < 0.001), alanine aminotransferase (ALT) (p < 0.001), gamma-glutamyl transpeptidase (γ-GTP) (p = 0.001), and uric acid (p = 0.015) among the QVS groups. Participants who regularly exercised with vigorous activity (p = 0.032) and HbA1c > 6% (p = 0.005) showed significant association with myocardial FDG uptake in the Chi-squared test. The median value of fasting duration decreased significantly as the QVS of the myocardium increased. Twenty-nine of the 31 participants (93.5%) who fasted for 21.5 h or more showed a suppressed FDG uptake (mean SUV_max = 2.1). In multivariate logistic regression analysis, fasting duration (OR = 0.74, 95% CI 0.69-0.80, p < 0.001), HbA1c > 6% (OR = 0.29, 95% CI: 0.12 - 0.66, p = 0.004), uric acid (OR = 0.82, 95% CI 0.68-1.00, p = 0.049) and regular exercise with vigorous activity (OR = 1.75, 95% CI 1.13-2.70, p = 0.012) were significant factors for physiologic myocardial FDG uptake.

CONCLUSIONS

Reduced physiologic ¹⁸F-FDG uptake of the myocardium was associated with longer fasting duration, higher level of HbA1c, and less frequency of regular exercise with vigorous activity. For the preparation of cardiac ¹⁸F-FDG PET, inclusion of longer fasting duration (more than 18 h) might be necessary for the adequate suppression of physiologic ¹⁸F-FDG myocardial uptake.

Fatal eosinophilic coronary periarteritis leads to dissection in a young patient: A case report

Eosinophilic coronary periarteritis (ECPA) is a poorly studied type of coronary arteritis. It causes myocardial ischemia and most cases are diagnosed at autopsy. We report the case of a 35-year-old woman who presented with sudden unexpected cardiac arrest and was brought to the emergency ward. Cardiopulmonary resuscitation was started by ambulance paramedic. On arrival, the patient was transferred to the catheterization laboratory due to sudden aborted cardiac death. The angiography was performed and dissection of the left main coronary artery, extended to the left anterior descending artery was detected. Pathological study confirmed ECPA. It appears that young and healthy patients with a history of intermittent vasospastic angina should be evaluated for ECPA. <Learning objective: Young and healthy patients with a history of intermittent Prinzmetal vasospastic angina should be evaluated for eosinophilic coronary periarteritis (ECPA) prior to sudden cardiac death. Since ECPA is an unexpected and life-threatening condition, developing a diagnostic tool amongst suspicious young and healthy patients is demanded. Positron emission tomography-computed tomography might be an interesting tool, since it can detect infiltrative cells in early stages of cardiac inflammatory disease.>.

Myocardial Positron Emission Tomography for Evaluation of Cardiac Sarcoidosis: Specialized Protocols for Better Diagnosis

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology with various clinical presentations depending on the organs involved. Since cardiac sarcoidosis (CS) portends a higher risk of morbidity and mortality, early diagnosis and aggressive medical treatment are essential to improve the prognosis. ¹⁸F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) has emerged as an important tool with practical advantages in assessing disease activity and monitoring the treatment response in patients with CS. While it has high sensitivity, it also has great variability in specificity, probably due to normal physiologic myocardial FDG uptake, which interferes with the evaluation and follow-up of CS using FDG-PET. This review details the technical aspects of FDG-PET imaging for evaluating and diagnosing CS, assessing disease activity, and monitoring therapeutic response.

The role of positron emission tomography in the assessment of cardiac sarcoidosis

The myocardium and the cardiovascular system are often involved in patients with sarcoidosis. As therapy should be started as early as possible to avoid complications such as left ventricular dysfunction, a prompt and reliable diagnosis by means of non-invasive tests would be highly warranted. Among other techniques, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has emerged as a high sensitive tool to detect sites of inflammation before morphological changes are visible to conventional imaging techniques. We therefore aim at summarizing the most relevant findings in the literature on the use of 18F-fluorodeoxyglucose PET in the diagnostic workup of cardiac sarcoidosis and to underline future perspectives.

Cardiac myofibroblast induces decreased expression of major histocompatibility complex class II (Ia) on rat monocyte/macrophages

The up-regulation of HLA antigens is important during heart inflammatory events and myofibroblasts may modulate the expression of this molecule in tissues. To test this possibility, the effect of cardiac myofibroblast:macrophage contact and the production of myofibroblast inhibitor factor(s) on the macrophage HLA (Ia) expression were studied. Listeria monocytogenes-elicited Ia + peritoneal macrophages (high Ia expression) were co-cultured with cardiac myofibroblasts for 3 and 7 days (myofibroblast contact). Proteosa peptone-elicited macrophages (low Ia expression) were cultured for 3 days with interferon gamma (INF-γ) and myofibroblast conditioned medium (FCM). Ia expression was analyzed by immunofluorescence and by radioimmune assay. Myofibroblast contact induced decreased expression of Ia molecule on macrophages (p < 0.001). This was confirmed by the radioimmune analysis in macrophage: myofibroblast co-cultures (p < 0.001). Double staining for Ia and CD14 showed that only CD14 positive cells (macrophages) expressed Ia molecule. FCM was capable of diminishing Ia expression induced by INF-γ on macrophages (p < 0.001). Decreased Ia macrophage expression induced by myofibroblasts could be important in the heart inflammation's resolution, probably involving Ia redistribution on cell: cell contact and myofibroblast inhibitor factor production.

Cardiac Sarcoidosis Concomitant with Large-vessel Aortitis Detected by 18F-fluorodeoxyglucose Positron Emission Tomography

We herein report a case of concurrent cardiac sarcoidosis and large-vessel aortitis detected by ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) and followed up during immunosuppressive therapy. After high-dose prednisolone administration (1 mg/kg), serial FDG-PET showed that almost all of the abnormal FDG uptake in the heart and extracardiac region, including the abdominal to bilateral iliac arteries, had been disappeared. During the tapering of prednisolone, additive methotrexate therapy was needed to treat the recurrence of cardiac sarcoidosis. FDG-PET is a useful tool for detecting cardiac sarcoidosis concomitant with large-vessel aortitis and monitoring the effectiveness of immunosuppressive therapy.

Cardiac applications of hyperpolarised magnetic resonance

Cardiovascular disease is the leading cause of death world-wide. It is increasingly recognised that cardiac pathologies show, or may even be caused by, changes in metabolism, leading to impaired cardiac energetics. The heart turns over 15 times its own weight in ATP every day and thus relies heavily on the availability of substrates and on efficient oxidation to generate this ATP. A number of old and emerging drugs that target different aspects of metabolism are showing promising results with regard to improved cardiac outcomes in patients. A non-invasive imaging technique that could assess the role of different aspects of metabolism in heart disease, as well as measure changes in cardiac energetics due to treatment, would be valuable in the routine clinical care of cardiac patients. Hyperpolarised magnetic resonance spectroscopy and imaging have revolutionised metabolic imaging, allowing real-time metabolic flux assessment in vivo for the first time. In this review we summarise metabolism in the healthy and diseased heart, give an introduction to the hyperpolarisation technique, 'dynamic nuclear polarisation' (DNP), and review the preclinical studies that have thus far explored healthy cardiac metabolism and different models of human heart disease. We furthermore show what advances have been made to translate this technique into the clinic, what technical challenges still remain and what unmet clinical needs and unexplored metabolic substrates still need to be assessed by researchers in this exciting and fast-moving field.

Patient preparation for cardiac fluorine-18 fluorodeoxyglucose positron emission tomography imaging of inflammation

Although the number of clinical applications for fluorine-18 fluorodeoxyglucose (18F-FDG) cardiac positron emission tomography (PET) has continued to grow, there remains a lack of consensus regarding the ideal method of suppressing normal myocardial glucose utilization for image optimization. This review describes various patient preparation protocols that have been used as well as the success rates achieved in different studies. Collectively, the available literature supports using a high-fat, no-carbohydrate diet for at least two meals with a fast of 4-12 hours prior to 18F-FDG PET imaging and suggests that isolated fasting for less than 12 hours and supplementation with food or drink just prior to imaging should be avoided. Each institution should adopt a protocol and continuously monitor its effectiveness with a goal to achieve adequate myocardial suppression in greater than 80% of patients.

Clinical Features of Acute and Fulminant Myocarditis in Children - 2nd Nationwide Survey by Japanese Society of Pediatric Cardiology and Cardiac Surgery

BACKGROUND

The 1st nationwide survey by the Japanese Society of Pediatric Cardiology and Cardiac Surgery of acute or fulminant myocarditis (AMC/FMC) in children revealed that the survival rate of FMC was only 51.6%. The 2nd nationwide survey was performed to evaluate the recent outcomes of pediatric myocarditis.Methods and Results:Questionnaires regarding patients aged ≤18 years with AMC/FMC during the period from January 2006 to December 2011 were mailed. A total of 221 cases (age 6.5±5.3 years, 116 boys and 105 girls) were reported. There were 145 (65.6%) and 74 cases (33.5%) of AMC/FMC, respectively; the type of myocarditis was not reported in the remaining 2 cases (0.9%). Viruses were identified in 56 cases (25.3%), including coxsackie B in 9 and influenza A in 8. Histopathology by either endomyocardial biopsy or autopsy was obtained in 38 cases (19.2%). Intravenous immunoglobulin was effective in 49 (34.3%) of 143 cases. Steroid therapy was effective in 20 (32.8%) of 61 cases. Mechanical circulatory support was given in 54 cases (24.4%) and 94.2% of them were patients with FMC. The survival rates for the whole study population, acute myocarditis, and FMC were 75.6%, 91.0%, and 48.6%, respectively.

CONCLUSIONS

The survival rate of children with myocarditis was almost identical to that of 10 years ago. (Circ J 2016; 80: 2362-2368).

Febrile syndrome of unknown origin: Indications for 18F-FDG PET/CT in inflammatory and infectious processes

Fever of unknown origin is defined as a body temperature greater than 38.3°C lasting more than three weeks for which the cause could not be found within one week of hospital admission. More than 200 causes have been reported, and these can be classified into four categories: infections, inflammatory diseases, oncologic processes, and miscellaneous conditions. Noninvasive diagnostic techniques are used in 69.2% of cases and invasive techniques in 30.8%. Structural imaging techniques show the morphological changes from infectious, inflammatory, and tumor-related processes, but they do not allow the detection of the early changes brought about by these processes. The metabolic information provided by ¹⁸F-FDG PET/CT has a promising role in these patients. ¹⁸F-FDG uptake is based on the cells' use of glucose as a source of energy, so it can be observed in infectious, inflammatory, and tumor-related processes. The established non-oncologic indications for ¹⁸F-FDG PET/CT are sarcoidosis, osteomyelitis, spondylodiscitis, fever of unknown origin, and vasculitis, which together account for more than 85% of studies.

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.

Cardiac Sarcoidosis: Is it More Common in Men?

INTRODUCTION

Sarcoidosis is a systemic granulomatous disease which predominantly affects the lungs, although granulomas can also involve all other organs, including the heart. Cardiac sarcoidosis (CS) may occur at any stage of the disease and may be the cause of sudden cardiac death, even in a previously asymptomatic patient. The aim of this study was to evaluate the incidence of CS in a large group of patients diagnosed or followed up due to sarcoidosis.

METHODS

We performed a retrospective analysis of patients at our institution discharged with the final diagnosis "sarcoidosis" (ICD-10: D86) from January 2008 to October 2012. Only those with biopsy (from respiratory tract or lymph nodes) confirmed diagnosis of sarcoidosis were included. We then selected the subset of patients with cardiac involvement due to sarcoidosis confirmed by positive magnetic resonance imaging.

RESULTS

The study covered 1375 consecutive sarcoidosis patients (51 % men), who were hospitalized during 5 years. Multiorgan disease was detected in 160 cases (11.7 %), and cardiac involvement was found in 64 patients (4.7 % of all), 70.3 % of whom were men. Twelve of those with CS were in stage I, 48 in stage II, and four in stage III. The odds ratio for having cardiac involvement in men compared to women was 2.3 (95 % CI 1.36-4.0, p = 0.002).

CONCLUSIONS

Cardiac involvement in sarcoidosis was diagnosed in the similar percentage as in previously published data but was significantly more frequently in men.

Current status of nuclear cardiology in Japan: Ongoing efforts to improve clinical standards and to establish evidence

Nuclear cardiology imaging tests are widely performed in Japan as clinical practice. The Japanese nuclear cardiology community has developed new diagnostic imaging tests using (123)I-beta-methyl-p-iodophenyl-pentadecanoic acid, (123)I-metaiodobenzylguanidine, and (18)F-fluorodeoxyglucose PET for detecting cardiac involvement in sarcoidosis. These tests have become popular worldwide. The Japanese Circulation Society and the Japanese Society of Nuclear Cardiology have published clinical imaging guidelines showing indications and standards for the new imaging tests. JSNC is currently striving to improve the standard of clinical practice and is promoting research activities.

Effect of Corticosteroid Therapy on Long-Term Clinical Outcome and Left Ventricular Function in Patients With Cardiac Sarcoidosis

BACKGROUND

Cardiac involvement is the worst prognostic determinant in patients with sarcoidosis, but the long-term prognostic significance of corticosteroid therapy for cardiac sarcoidosis (CS) remains unclear.

METHODS AND RESULTS

We examined 83 consecutive patients diagnosed with CS. Patients were divided into 2 groups based on the presence or absence of corticosteroid therapy at diagnosis. Patients with corticosteroid therapy had lower age and higher rate of positive findings in the myocardium on gallium scintigraphy (Ga) at diagnosis than those without. LVEF, biomarkers, and use of cardiovascular medication were similar between the 2 groups. During the follow-up (7.6±4.4 years), corticosteroid therapy was associated with fewer long-term adverse events (overall, P=0.005; cardiac death, P=0.92; symptomatic arrhythmias, P=0.89; heart failure admission, P<0.0001) and a greater % increase in LVEF than those without (7.9±36.3% vs. -16.7±34.8%, P=0.03). On Cox proportional hazards modeling, corticosteroid therapy (HR, 0.41; 95% CI: 0.20-0.89) was an independent determinant of long-term adverse event-free survival, but age, sex, LVEF, and Ga findings were not.

CONCLUSIONS

Corticosteroid therapy might have a beneficial effect on long-term clinical outcome in CS patients, particularly by reduction of heart failure admission and retarding the progression of LV systolic dysfunction.

Circulating CD14++CD16+ Monocyte Subsets as a Surrogate Marker of the Therapeutic Effect of Corticosteroid Therapy in Patients With Cardiac Sarcoidosis

BACKGROUND

We aimed to evaluate whether specific monocyte subsets could serve as surrogate markers of disease activity in cardiac sarcoidosis (CS) evaluated by 18F-fluoro-2-deoxyglucose positron emission tomography (18F-FDG PET).

METHODS AND RESULTS

We studied 28 patients with CS (8 men; mean age: 61±9 years) diagnosed according to consensus criteria. We divided the patients into 2 groups: known CS receiving corticosteroid therapy (Rx(+); n=13) and new-onset CS (Rx(-); n=15), and analyzed 3 distinct monocyte subsets (CD14+CD16-, CD14++CD16+, and CD14+ -CD16+). Monocyte subsets were also analyzed in 10 Rx(-) patients before and 12 weeks after starting corticosteroid therapy. Inflammatory activity was quantified by 18F-FDG PET using the coefficient of variation (COV) of the standardized uptake value (SUV). The proportion of CD14++CD16+ monocytes in Rx(+) patients (10.8 [0.2-23.5] %) was significantly lower than in Rx(-) patients (23.0 [11.5-38.4] %, P=0.001). After corticosteroid therapy, the COV of the SUV was significantly improved from 0.32 [0.14-0.62] to 0.17 [0.04-0.43] (P=0.017). The proportion of CD14++16+ monocytes showed a significant decrease from 22.2 [8.8-38.4] % to 8.4 [1.8-16.8] % (P=0.001). The decrease in the proportion of CD14++16+ monocytes significantly correlated with the decrease in the COV of the SUV (r=0.495, P=0.027).

CONCLUSIONS

CD14++16+ monocytes are a possible surrogate marker of the therapeutic effect of corticosteroid therapy in CS.

Immunosuppressive therapy in myocarditis

Although there is general agreement on the favorable effect of immunosuppression in eosinophilic, granulomatous, giant-cell myocarditis and in lymphocytic myocarditis associated with connective tissue disorders and with rejection of a transplanted heart, its therapeutic role in lymphocytic inflammatory cardiomyopathy (ICM) is still debated. Previous retrospective studies reported a relevant clinical benefit in 90% of patients with virus-negative ICM and no response or cardiac impairment in 85% of those with virus-positive ICM following immunosuppression. Other studies identified cardiomyocyte HLA upregulation as an additional indicator of ICM susceptibility to immunosuppressive therapy. Recently in a single-center randomized prospective double-blind trial using a combination of prednisone and azathioprine in addition to supportive treatment in 85 virus-negative ICM patients, a significant improvement in left ventricular (LV) ejection fraction and a significant reduction in LV dimensions in 88% of 43 treated patients compared with 42 patients receiving placebo who showed a cardiac impairment in 83% of cases (TIMIC study) was reported. These data confirm the efficacy of immunosuppression in virus-negative ICM. Lack of response in 12% of cases suggests the presence of unscreened viruses or mechanisms of damage and inflammation not susceptible to immunosuppression. Recovery of cardiac function in responders to immunosuppression was associated with inhibition of cardiomyocyte death, increased cell proliferation and with newly synthesized contractile material.