18F-FDG PET/CT in the diagnosis of prosthetic valve endocarditis

Raymund Augustus Conlu, Lucille T Puracan. MD

Introduction: This case report aims to support the role of 18F-FDG PET-CT as an important tool in diagnosing prosthetic valve endocarditis (PVE).

Presentation of Case: A 74-year old female with post transcatheter aortic valvular implantation (TAVI) presented with fever of unknown origin and persistent leukocytosis and thrombocytopenia. Work-ups showed negative blood cultures, equivocal bone marrow aspiration biopsy, unremarkable 99mTc-HMPAO-WBC scintigraphy, and negative transesophageal echocardiography. Initial 18F-FDG PET/CT scan showed increased FDG uptake surrounding the aortic valve prosthesis, more intense posteriorly. Computed tomography angiography supported the finding of an abscess and perigraft pseudoaneurysms. Post-surgical findings confirmed a prosthetic valve infection, endocarditis, abscess and pseudoaneurysm of the ascending aorta and aortic root.

Discussion: Early diagnosis of endocarditis is crucial yet difficult because of the presence of foreign materials such as prosthetic valves/prosthetic materials and pacemaker/defibrillator leads which compromises the sensitivity and specificity of echocardiography. 18F-FDG PET/CT combines the assessment of metabolic activity of tissues with the spatial resolution of CT which provides 73% sensitivity and 80% specificity in detecting endocarditis.

Conclusion: This report highlights the potential benefits of evaluating patients with suspected prosthetic valve endocarditis using 18F-FDG PET/CT particularly in the early stages of the disease.