Sarcoidosis is a multiorgan disease characterized by non-caseating granulomas. Cardiac involvement is associated with worse prognosis and can fortunately be assessed with complementary imaging modalities of cardiac MRI with contrast and cardiac sarcoidosis PET/CT, with MRI assessing for fibrosis and PET/CT assessing for active inflammation and assessing post-treatment changes. Both imaging modalities provide high sensitivity (>75%).
Cardiac MRI – Fibrosis Imaging
CMR allows for detection of cardiac sarcoidosis by assessing biventricular function, ventricular wall thinning and most importantly by detecting late gadolinium enhancement in typical patterns suggestive of myocardial fibrosis/scar. LGE is also associated with worse prognosis.
Cardiac Sarcoidosis – Inflammation Imaging
PET/CT allowed for detection of active inflammation. Patient’s take a special cardiac diet (high fat, low carbohydrate) prior to exam to shift normal myocardium to fatty acid metabolism and encourage abnormal myocardium to uptake FDG-glucose. Serial PET/CT can allow assessment of response to therapy.
Benefit of adding functional flow reserve imaging and quantitative calcium scoring to nuclear stress imaging: 80 year old male with history of smoking and atypical chest pain. Rb PET/CT demonstrates minor perfusion defect in lateral wall, abnormal flow reserve in all territories and elevated calcium score of 1945. Cardiac catheterization which demonstrated severe stenosis in the LAD and circumflex with patient subsequently stented.