Added value of perfusion and inflammatory PET imaging to monitor therapy response in cardiac sarcoidosis

Introduction: Cardiac involvement in sarcoidosis is a complex disorder with challenging therapy options and often inadequate long-term clinical measures of treatment response. Cardiac PET imaging offers the unique ability of non-invasively assess the presence of myocardial inflammation by 18F-Fluorodeoxyglucose (18F-FDG), and to monitor the overall perfusion and left ventricular ejection fraction (LVEF) during the same imaging session. We aimed to assess the potential added value of the combined perfusion and metabolic cardiac PET imaging in patients treated for suspected cardiac sarcoidosis for assessing therapy response. Following the appropriate sarcoid diet, twenty-five patients were imaged with 40 mCi of Rubidium-82 (Rb82) at rest, and 10 mCi of 18-FDG PET imaging at baseline, after 6 months to one year, and at least after two years of having started clinical therapies with a combination of prednisone, metrotrexate or adalimumab. The standard 17-segment left ventricle model was used for regional assessment. The overall resting LVEF increased from 45±12% at baseline to 53±6.8% after six months, and to a 51±10% after two years of starting the treatment. The change in LVEF was more pronounced between baseline and six months for those patients where the resting perfusion was normal at baseline or normalized at six months, compared to those where the summed resting score remained positive (9.63±6% and 3.25±8.1, respectively, P<0.05). Similarly, the maximum standardized uptake value (SUVm) for the myocardial segments that showed an abnormal increased of 18F-FDG uptake diminished from 11.78±10 at baseline, to 3.83±3.1 after six months, P<0.03, to remain similar after two years, 4.38±3.2 , P=NS). These pilot data suggest that the combination of perfusion and inflammatory PET imaging can add prognostic value in the management of patients with cardiac sarcoidosis for assessing the potential changes in the microvasculature along the inflammatory myocardial status during the treatment course, indicating that the different stages of this disorder may be adequately measured with PET imaging.