Cardiac PET Provides Clinically Useful Assessment for Measuring Treatment Response to Adjuvant High Dose Methotrexate in a Complex Case of Cardiac Sarcoidosis

Abstract

Sarcoidosis is a multisystem granulomatous disease in which cardiac involvement is a serious condition with diagnostic challenges. The mainstay of therapy involves corticosteroids, however treatment algorithms beyond this remain undefined. We report a case of sarcoidosis in a morbidly obese patient with claustrophobia who had primarily cardiac and lymph node involvement. Diagnosis involved the use of multi imaging modalities including computed tomography, echocardiography, cardiac magnetic imaging (CMR) and 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET). Progression of the disease lead to the the insertion of an implantable cardiac device, which precluded follow up with CMR to monitor disease activity. Echocardiography revealed progressive left ventricular decline, the aetiology of which was thought to be either high burden of right ventricular pacing or increased disease activity. Follow-up 18F-FDG PET scanning demonstrated a substantial initial response to high dose corticosteroids, however this was limited by severe steroid related side effects. Additionally, 18F-FDG PET scanning was used to demonstrate disease reactivation with steroid weaning and an initial lack of response to adjunctive oral methotrexate and cyclosporin. Finally, it was used to demonstrate an impressive response to adjunctive high dose subcutaneous methotrexate. Furthermore, the initial 18F-FDG PET scan guided localisation of active superficial lymph nodes to facilitate a positive tissue biopsy. Although radiation exposure is a concern, the use of serial 18F-FDG PET scanning in this complex case proved invaulable in the diagnosis, assessment of disease activity and response to treatment in a perplexing evidence lacking area.