Usefulness of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography angiography in a patient with blood culture-negative prosthetic valve endocarditis complicated with perivalvular abscess: a case report

BACKGROUND: Prosthetic valve endocarditis (PVE) is a life-threatening systemic infection involving a high mortality rate and severe complications, including perivalvular abscess. Early diagnosis and detection of PVE continue to be challenging in clinical settings. CASE SUMMARY: A 64-year-old man with a history of mechanical aortic valve implantation 12 years prior was referred to our hospital with a major complaint of high fever and was admitted. Although results of three blood culture tests at admission were negative, transthoracic echocardiography, and transoesophageal echocardiography (TOE) were performed to exclude the possibility of PVE; both, however, were inconclusive. Subsequently, (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) was performed; revealing intense hyper-metabolism above the aortic valve prosthesis with a greater intensity at the posterior end, confirming a diagnosis of aortic PVE complicated with perivalvular abscess. DISCUSSION: Considering the intermediate suspicion of PVE despite negative TOE and negative blood culture tests, (18)F-FDG PET/CT can play a central role in diagnosing PVE. However, this new imaging modality often fails to differentiate thrombi, soft atherosclerotic plaques, or foreign body reactions on the surface of prosthetic valves. In this report, we have successfully enhanced the diagnostic accuracy of (18)F-FDG PET/CT by focusing on perivalvular involvement, which could be a key finding, because intense (18)F-FDG uptake surrounding the aortic annulus was consistent with the thickened area within the aortic annular region observed in the TOE examinations.