Which imaging combination is considered best for suspected cardiac sarcoidosis?

• A. Echocardiography alone
• B. CMR-LGE and PET-CT with FDG
• C. CT angiography and perfusion scan
• D. MRI without contrast and CT

Answer: (B)

For suspected cardiac sarcoidosis you want to know both where the heart has scar from prior inflammation and where there is currently active inflammation. Cardiac MRI with late gadolinium enhancement (LGE) is excellent at mapping scar and fibrosis, showing patchy, often basal or mid-wall LGE patterns and giving precise details about ventricular function. But MRI alone may miss areas of ongoing inflammation if there isn’t substantial scarring yet.

FDG-PET CT adds metabolic insight by highlighting areas with active inflammatory activity, as those regions take up glucose highlighted by the tracer. With proper patient preparation to minimize normal myocardial glucose uptake, PET-CT can detect active disease that MRI might miss and can also reveal activity in other organs outside the heart, which helps confirm systemic sarcoidosis.

Using both together combines their strengths: MRI defines structural involvement and functional impact, while PET-CT identifies active inflammation. This synergy increases diagnostic confidence, helps distinguish active disease from scar, and guides treatment decisions, such as whether to intensify immunosuppression and how to monitor response over time. That broader, more actionable information is why this imaging pair is considered the best approach for suspected cardiac sarcoidosis.