Case of isolated cardiac sarcoidosis diagnosed by newly developed abnormal uptake during serial follow-up fluorine-18 fluorodeoxyglucose positron emission tomography

Current uses and understanding of PET imaging in cardiac sarcoidosis

Sarcoidosis is a systemic disease with unclear etiology characterized by the accumulation of noncaseating, immune granulomas in affected tissues. In cardiac sarcoidosis (CS), white blood cells build up within the heart muscles, causing cardiac abnormalities. Accurate and early diagnosis of CS proves challenging. However, usage of positron emission tomography (PET) imaging, namely 18F-FDG-PET, has proven successful in diagnosing inflammatory cardiomyopathy. This review seeks to examine the role of PET in managing ventricular tachycardia in cardiac sarcoidosis. PET, in conjunction with cardiac magnetic resonance imaging (CMR) is also endorsed as the premier method for diagnosis and management of arrhythmias associated with CS by The Heart Rhythm Society. After a CS diagnosis, risk stratification of ventricular arrhythmias is a necessity given the potential for sudden cardiac death. 18F-FDG-PET has been successful in monitoring disease advancement and treatment responses in CS patients. Early stages of CS are often treated with immunosuppression drugs if there are additional signs of VT. Currently, corticosteroid and anti-arrhythmia compounds: methotrexate, cyclophosphamide, infliximab, amiodarone, and azathioprine are used to suppress inflammation. 18F-FDG-PET has certainly proven to be an incredibly useful and accurate diagnostic tool of CS. While late gadolinium enhancement by CMR is efficient in detecting myocardial necrosis and/or advanced fibrosis scarring, 18F-FDG portrays the increased uptake level of glucose metabolism. In combination PET/MRI has proven to be more successful in improving the efficacy of both scans, addressing their drawbacks, and highlighting their advantages. Managing CS patients is highly involved in detecting inflammatory regions of the heart. Early recognition prevents cardiac abnormality, mainly VT and VF in CS patients, and extends lifespan.

Activation of cardiac sarcoidosis associated with development of gastric cancer: a case report

Background

The high ¹⁸F-fluorodeoxyglucose (FDG) uptake in sarcoidosis lesions reflects infiltration of inflammatory cells such as macrophages. An increased incidence of cancer in patients with sarcoidosis has been suggested, and some combination of the following mechanisms has been proposed: chronic inflammation, immune dysfunction, shared aetiologic agents, and genetic susceptibility to both cancer and autoimmune diseases.

Case summary

A 73-year-old man was admitted to our hospital due to effort dyspnoea. Initial investigations showed complete atrioventricular block on electrocardiography, basal thinning of the interventricular septum, and preserved left ventricular (LV) systolic function on echocardiography, and late gadolinium enhancement (LGE) in all layers of the basal interventricular septum on cardiac magnetic resonance imaging. FDG positron emission tomography/computerized tomography (FDG-PET/CT) showed no abnormal uptake in the whole-body including myocardium. After discussion, corticosteroid was not initiated then. One year later, he developed stomach adenocarcinoma. Repeated investigations demonstrated enlargement of the LV (LV diastolic diameter 63 mm) and diffuse systolic impairment of LV function (LV ejection fraction 31%) on echocardiography, and abnormal focal uptake at the lateral walls of LV and hilar lymph nodes on FDG-PET/CT imaging. One more year after the surgery for gastric cancer and corticosteroid initiation, echocardiography showed recovery of systolic function and FDG-PET/CT showed no uptake in either the myocardium or hilar lymph nodes.

Discussion

In the present case, it is speculated that the first inflammation which left scarred areas showing LGE was already completed before the first FDG-PET/CT. The development of gastric cancer may be associated with the reactivation of cardiac sarcoidosis.

Case of isolated cardiac sarcoidosis diagnosed by newly developed abnormal uptake during serial follow-up fluorine-18 fluorodeoxyglucose positron emission tomography

Cardiac sarcoidosis (CS) causes lethal arrhythmia and heart failure and has a poor prognosis; therefore, early detection and early stage treatment are important. However, diagnosis of isolated CS may be difficult in some cases owing to the low sensitivity of myocardial biopsy. Herein, we describe the case of a patient with isolated CS, showing change from negative to positive fluorine‐18 fluorodeoxyglucose (¹⁸F‐FDG) positron emission tomography (PET) uptake results within 9 months. The patient showed rapid reduction in left ventricular systolic function with sustained ventricular tachycardia. The diagnosis of isolated CS is often under‐recognized in clinical practice because it commonly requires the diagnosis of extracardiac disease in the absence of a positive endomyocardial biopsy. The Japanese Circulation Society recently published guidelines for CS diagnosis stating that isolated CS can be clinically diagnosed with positive ¹⁸F‐FDG PET or ⁶⁷Gallium result. In this case, serial follow‐up ¹⁸F‐FDG PET was useful for diagnosing isolated CS.