ARRS 2022 Abstracts

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E2026. Cardiac MR and PET in Cardiac Sarcoidosis: This or That
Authors
  1. Pokhraj Suthar; Rush University Medical Center
  2. Keyur Parekh ; Rush University Medical Center
  3. Sumeet Virmani; Rush University Medical Center
Background
Cardiac sarcoidosis(CS) is a rare but potentially fatal disorder with complications such as conduction abnormalities, ventricular arrhythmias, heart failure and sudden cardiac death. Implementation of early treatment in CS has favorable outcomes, but diagnosing CS is challenging. Endomyocardial biopsy will show characteristic non-caseating granulomas, however inherent patchy myocardial involvement often leads to false negative biopsy results. 18F-FDG PET and cardiac MR(CMR) play a pivotal role in diagnosis of cardiac sarcoidosis.

Educational Goals / Teaching Points
The goals of this exhibit are to review CMR findings of CS, illustrate 18F-FDG and 82Rb PET findings in CS, and learn multimodality correlation of CS.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Chest radiography provides initial clues to diagnosing pulmonary and mediastinal sarcoidosis, but it has poor sensitivity for diagnosis of CS. CT, echocardiography, CMR, Gallium-67 scan and 18F-FDG PET imaging are useful for characterizing myocardial involvement in sarcoidosis. CT findings includes cardiomegaly, pericardial effusion, ventricular aneurysms, and myocardial thinning in end stage disease and helps identify extra CS. CMR has 75-100% sensitivity and 76.9-78% specificity for the diagnosis of CS. In the inflammatory phase, there is myocardial thickening, edema, and regional wall motion abnormalities. Late gadolinium enhancement(LGE) images are more effective to detect active and chronic CS. In CS, the common pattern of LGE includes patchy sub epicardial and mid myocardial involvement at the basal septum and inferolateral wall. In advanced stages scarring leads to focal wall thinning and regional wall motion abnormalities. CMR can be used as a tool to determine prognosis by quantifying the extent of LGE. Negative CMR findings essentially excludes clinically significant CS in a patient with extracardiac disease and can guide further management. Other benefits of MRI include absence of radiation exposure and CMR does not require stringent patient preparation. 18F-FDG cardiac PET imaging is 89% sensitive and 78% specific for diagnosing CS. Increased glucose metabolism is a hallmark of inflammation. Patients with CS demonstrate patchy and focal FDG uptake throughout the myocardium. Combining concurrent myocardial 82Rb/99mTc/201Th perfusion studies with 18F-FDG PET helps to exclude coronary artery disease. Normal perfusion with focal increased FDG uptake suggests early CS. Increased FDG uptake with abnormal perfusion(mismatch pattern) suggests active sarcoidosis with myocardial damage. Absent FDG uptake with abnormal perfusion indicates scarring. PET is useful in both monitoring and predicting response to immunosuppressive therapy. Additional advantages over CMR are in patients with an implantable cardioverter-defibrillator device, patients with renal dysfunction and for evaluation of active extracardiac sarcoid elsewhere in the field-of-view.

Conclusion
Both CMR and PET have a complimentary role diagnosing in CS. Our case-based multimodality pictorial review of CS evaluation is aimed to help accurately diagnose, determine prognosis, and monitor the disease using these imaging tools.