18F-FDG PET/CT in diagnosis and management of Mycobacterium chimaera infection following cardiac surgery: a single-centre experience with nine consecutive patients

Abstract

Abstract Purpose to evaluate the role of seriated 18-fluoro-2-deoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) in the diagnosis and management of disseminated Mycobacterium chimaera infection following cardiac surgery. Methods we retrospectively describe nine consecutive confirmed cases of disseminated M. chimaera infection after cardiac surgery who underwent seriated 18F-FDG PET/CT to facilitate the diagnosis and treatment monitoring. Clinical characteristics, laboratory tests and microbial culture microbiological findings, transthoracic (TTE) and transesophageal (TOE) echocardiography, brain MR and other tests are also discussed. Results The mean time between cardiac surgery and symptoms onset was 32 months (range 10 months to 7.7 years). Echocardiography (TTE + TOE ) detected endocarditis (IE) signs in 3/9 patients (sensibility 33%, 6/9 pts having mechanical aortic valve); blood culture was positive in 5/9 patients (sens. 56%). At diagnosis 7/9 PET/CT scans were positive for IE and/or aortic root prosthesis infection (sens. 78%). All diagnostic PET/CT scans were suggestive for systemic infection with hypermetabolism in one or more extracardiac sites (e.g.: lymph nodes, lung, muscle, liver spleen, kidney, CNS, axial skeleton). Conclusions 18F-FDG PET/CT proved to be a useful tool in diagnosis of disseminated M. chimaera infection to assess the extent and to identify potential sites of biopsy when routine microbiological work-up does not isolate M. chimaera. Seriated scans define the activity of disease over time and contribute to clinical work-up as prolongation or modulation of antimicrobial therapy, prognosis formulation and referral to revision surgery.