E1683. Multimodality Imaging in Cardiac Sarcoidosis: Role in Diagnosis, Risk Stratification, and Treatment Monitoring
  1. Matthew Aitken; University Health Network
  2. Meyer Balter; Mount Sinai Hospital
  3. Juan Duero Posada; University Health Network
  4. Kate Hanneman; University Health Network
The purpose of this educational exhibit is to review the role of multi-modality cardiac imaging in the evaluation of known and suspected cardiac sarcoidosis including diagnosis, prognosis and treatment monitoring, discuss the role of cardiac magnetic resonance imaging (MRI), Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) and novel radiotracers in the evaluation of cardiac sarcoidosis, and illustrate multi-modality cardiac imaging findings in cardiac sarcoidosis.

Educational Goals / Teaching Points
Cardiac imaging plays an important role in the diagnosis, risk stratification, and treatment monitoring of patients with cardiac sarcoidosis, cardiac MRI and FDG-PET are both useful in diagnosis of cardiac sarcoidosis, although there is no consensus about which should be performed first. Late gadolinium enhancement (LGE) on cardiac MRI has higher sensitivity than focal FDG-uptake on PET and similar specificity, cardiac MRI and FDG-PET are both predictive of major adverse cardiac events in cardiac sarcoidosis. Left and right ventricular LGE are associated with arrythmia and death, and focal FDG-uptake is associated with major adverse cardiac events (MACE) but not cardiac death. Left ventricular LGE on MRI is a stronger predictor of MACE with an odds ratio (OR) of 8.0, compared with an OR of 2.1 for focal FDG-uptake on PET, and FDG-uptake is a marker of active inflammation and is useful in monitoring response to treatment.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Typical cardiac MRI findings in cardiac sarcoidosis include mid-wall T2-hyperintensity/highT2 mapping values (representing edema/active inflammation), mid-wall LGE that is frequently patchy or nodular (representing active or chronic burnt-out disease), and high native T1 and extracellular volume (ECV). Typical findings on FDG-PET include focal and focal on diffuse FDG-uptake (reflecting metabolically active immune cells in the setting of inflammation). FDG-PET is typically interpreted in conjunction with Single-Photon Emission Computerized Tomography (SPECT) or PET perfusion imaging with co-localizing defects indicating active on chronic disease, isolated FDG-uptake indicating active inflammation, and isolated perfusion defects indicating chronic burnt-out disease. Combined PET/MRI provides complementary information from both modalities and is particularly useful in the setting of cardiac sarcoidosis. Multiple novel PET radiotracers have shown promise in feasibility trials, including radiolabeled somatostatin analogues, proliferation tracers (thymidine and choline analogs) and hypoxia tracers (radiolabeled nitroimidazoles).

Cardiac MRI and PET are useful in establishing a diagnosis of cardiac sarcoidosis, risk-stratifying patients and monitoring response to treatment with potentially complementary information.