Ishikita A, Sakamoto I, Yamamura K, Umemoto S, Nagata H, Kitamura Y, Yamasaki Y, Sonoda H, Tatewaki H, Shiose A, Tsutsui H.Circ J. 2021 Apr 1. doi: 10.1253/circj.CJ-20-1067. Online ahead of print. PMID: 33790144
Take Home Points:
- 18F-FDG PET/CT improves diagnostic sensitivity of infective endocarditis from 39% to 88%
- It helps detect echocardiogram-elusive infective endocarditis in right-sided lesions
- However, the test was less sensitive in native valve infective endocarditis
Commentary from Dr. M.C. Leong (Kuala Lumpur, Malaysia), section editor of ACHD Journal Watch:
Fluorine-18 Fluorodeoxyglucose (18F-FDG) is a radioactively labeled glucose analogue that is taken up by the cells. High glycolytic activities which signal high glucose metabolism helps to identify foci of concentrated inflammations. These inflammations are then picked up by the PET scan and when superimposed with the CT scan, detects the location of the inflammation. The 2015 ESC modified diagnostic criteria states that 18F-FDG PET/CT can be performed gives additional diagnostic value when there is (1) positive blood cultures consistent with infective endocarditis (IE); (2) vegetation detected on echocardiography; or (3) minor criteria that suggest the presence of IE. This article examined the use of the diagnostic accuracy of 18F-FDG PET/CT in various ACHD-associated IE and characterized its advantages.
This is a small retrospective study of 22 patients (age: 35 (24, 43) years; 72% male) who have undergone 18F-FDG PET/CT scans for investigation of IE (Table 1). During the clinical course, 18 out of the 22 patients were diagnosed to have IE. Seven patients were diagnosed to have IE on an echocardiogram. Eleven patients who were missed by echocardiogram were diagnosed to have IE by 18F-FDG PET/CT, increasing the detection rate from 39% to 88% (Figure 2). Of interesting note is the number of right-sided infection which was detected (Table 3). The authors reasoned that the right-sided lesions, especially those at the right ventricular outflow tract, were not well delineated by transthoracic echocardiogram and at the same time, too anterior for clear visualization on transoesophageal echocardiogram. 18F-FDG PET/CT scans were negative in 5 patients with IE although echocardiograms detected vegetations in them. Patients who were had a negative 18F-FDG PET/CT scan were found to be older, had a left-sided IE, native valves, less likely to have a history of device implantation, and a lower maximal standardized uptake value (Table 4). The 4 patients who were not diagnosed to have IE had negative echocardiographic and 18F-FDG PET/CT findings.
This study is an easy-to-understand study. The main drawback of the study is its small cohort of patients which underpowers analyses. Nevertheless, it provides a real-world experience of utilising 18F-FDG PET/CT to improve the sensitivity of IE detection. One should note, however, that the 18F-FDG PET/CT is less sensitive in detecting IE in native valves.