Can sarcoidosis cause diffuse increased Fluorodeoxyglucose (FDG) avidity in the thoracic aortic wall?

From the Guidelines

Yes, sarcoidosis can cause diffuse increased Fluorodeoxyglucose (FDG) avidity in the thoracic aortic wall. This occurs because sarcoidosis is a multisystem inflammatory disorder characterized by non-caseating granulomas that can affect any organ system, including blood vessels like the thoracic aorta. When sarcoidosis involves the vascular system, it can lead to large vessel vasculitis, which appears as increased FDG uptake on PET/CT imaging. The inflammatory cells within granulomas have high metabolic activity and glucose utilization, resulting in increased FDG uptake. This finding can sometimes be mistaken for other conditions such as large vessel vasculitis (like giant cell arteritis or Takayasu arteritis) or atherosclerosis. When evaluating a patient with increased FDG avidity in the thoracic aortic wall, it's essential to correlate these findings with clinical symptoms, laboratory markers of inflammation, and potentially histopathological confirmation to establish the correct diagnosis of sarcoidosis-related vascular involvement. Some key points to consider in the diagnosis and management of sarcoidosis include:

• The use of cardiac MRI or positron emission tomography with fluorodeoxyglucose imaging to diagnose cardiac sarcoidosis or follow response to therapy 1
• The role of echocardiography and Holter monitoring in the diagnostic workup of patients with suspected cardiac sarcoidosis 1
• The consideration of other immunosuppressive therapies, such as methotrexate or azathioprine, in patients who cannot tolerate corticosteroids or continue to worsen clinically despite treatment with corticosteroids 1
• The importance of correlating imaging findings with clinical symptoms and laboratory markers of inflammation to establish the correct diagnosis of sarcoidosis-related vascular involvement 1 Treatment typically involves immunosuppressive therapy, often starting with corticosteroids like prednisone at doses of 20-40 mg daily, with potential addition of steroid-sparing agents such as methotrexate or azathioprine for long-term management. It is crucial to prioritize the patient's morbidity, mortality, and quality of life when making treatment decisions, and to consider the most recent and highest quality evidence available, such as the 2020 American Thoracic Society clinical practice guideline on the diagnosis and detection of sarcoidosis 1.

From the Research

Sarcoidosis and FDG Avidity

• Sarcoidosis is a multisystem disease that can cause increased Fluorodeoxyglucose (FDG) avidity in various parts of the body, including the thoracic aortic wall 2, 3.
• The use of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has been demonstrated to be valuable in diagnosing extrathoracic involvement in sarcoidosis 2.
• Studies have shown that sarcoidosis can cause diffuse increased FDG avidity in the thoracic aortic wall, as well as in other areas such as the mediastinal lymph nodes, extrathoracic lymph nodes, and lung 3, 4.

Clinical Presentation and FDG Uptake

• The location and extent of myocardial involvement of cardiac sarcoidosis, as assessed by 18F-fluorodoexyglucose positron emission tomography, may be associated with clinical presentation 5.
• Patients with cardiac sarcoidosis presenting with ventricular tachycardia (VT) have been shown to have higher FDG uptake compared to those with advanced atrioventricular block (AVB) or asymptomatic controls 5.

Diagnosis and Follow-up

• FDG-PET/CT can be used for follow-up in nondiagnostic situations to detect decreases in FDG uptake due to the presence of sarcoidal granulomas 6.
• Sarcoidosis or sarcoid reactions should be considered in the differential diagnosis of oncologic patients who have developed FDG-avid lesions at any time after antineoplastic therapy 6.