The Role of 18F-FDG PET/CT in Cardiac Sarcoidosis

Abstract

Cardiac sarcoidosis (CS) is a rare and potentially fatal condition, characterized by the presence of non-necrotizing granulomatous inflammation and concomitant fibrosis. A variety of clinical manifestation has been described, such as conduction disorders, ventricular arrythmias, congestive heart failure and sudden cardiac death, making a prompt diagnosis and early treatment desirable. Endomyocardial biopsy is the gold-standard diagnostic test, but has a low sensitivity due to the multifocal aspect of the disease. Advanced imaging modalities, such as cardiac magnetic resonance and positron emission tomography (PET) with 18F-fluorodeoxyglucose are now part of the diagnostic criteria and also assist in determining treatment response. However, the interpretation of those studies can be challenging and needs to be made by specialists, as the misdiagnosis could be harmful for the patient. This article describes the pathophysiology of CS and advanced imaging modalities (with a major focus on PET) that should be considered for diagnostic approach and therapy monitoring. Also, newer clinical trials evaluating treatment strategies are described.

BMIPP SPECT in cardiac sarcoidosis: A marker of risk?

“…Because of the higher patient radiation exposure and the lower sensitivity in comparison with FDG-PET, 67 Ga scintigraphy is used in areas with limited access to PET. 3 FDG-PET has emerged as a powerful tool for assessment of myocardial inflammation in patients with known or suspected CS. 10 Inflammatory cells like macrophages and lymphocytes utilize glucose as their primary energy source.…”

“…Accumulation of FDG (a glucose analog) in these activated cells is the underlying mechanism for detection of active granulomatous sarcoid lesions. [1][2][3] FDG crosses the membrane via glucose transporter (GLUT 1 and 3) and is trapped by the myocardium after being phosphorylated by hexokinase. 3,4 The sensitivity and specificity of FDG-PET as an initial diagnostic tool for CS are 89% and 78%, respectively, using the JMHW criteria as the gold standard.…”

“…1 The rate of cardiac involvement by sarcoidosis is variable and ranges from 20% to 75%. 2,3 Granulomas in cardiac sarcoidosis (CS) can be found in any part of the heart, but the left ventricle, interventricular septum, and the papillary muscle are the most frequently involved. 3,4 The prevalence of clinically evident cardiac involvement is * 5% and is one of the major causes of disease-related death.…”

“…2,3 Granulomas in cardiac sarcoidosis (CS) can be found in any part of the heart, but the left ventricle, interventricular septum, and the papillary muscle are the most frequently involved. 3,4 The prevalence of clinically evident cardiac involvement is * 5% and is one of the major causes of disease-related death. 4 Patients with CS might start with asymptomatic myocardial injury followed by congestive heart failure, ventricular tachyarrhythmia, conduction disturbances, or sudden cardiac death.…”

“…However, accurate diagnosis of CS remains challenging because of the limitations of existing clinical criteria and the low diagnostic yield of EMB related to the patchy and mid-myocardial involvement. 1,3,5 Since sarcoidosis can affect the myocardium causing inflammation, edema, scarring, and remodeling, contemporary non-invasive imaging techniques can be of clinical help for detecting the whole spectrum of the disease. 1,6…”