18F-Fluorodeoxyglucose Imaging of Inflammation
Ready to Represent a Standard in Diagnosing Endocarditis?
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For >100 years,1 the diagnosis of endocarditis has been challenging, and this has been compounded by the increasing number of patients with prosthetic materials in the heart. The clinical challenge extends beyond accuracy because any delay in disease recognition inevitably postpones treatment planning and contributes to the high mortality rate that ranges between 14% and 22% during the hospitalization and ≤40% at 1-year follow-up.2 Current standards rely on the modified Duke criteria3 that catalogues clinical, imaging, microbiological, and pathological data into major and minor criteria so as to define a diagnostic probability classified as definite, possible, or unlikely with a sensitivity of ≈80%.4 Echocardiography (either transthoracic or transesophageal) represents an essential component in this process. However, despite its high resolution and wide applicability, ultrasound imaging is limited, particularly under 2 different conditions: in early disease stages, small structural alterations can be missed, whereas in postsurgical patients, the presence of composite material generates acoustic shadowing that may hamper diagnosis of prosthetic valve endocarditis (PVE),5 leading to inconclusive diagnosis in about 30% of patients.6
See Article by Mathieu et al
To overcome this clinical uncertainty, single photon emission computed tomographic imaging of labeled leukocyte recruitment has been used for quite some time as a means to detect focal areas of infection.7,8 Overall consensus is that this technique is highly specific both in endocarditis of native structures and in PVE. However, the limited spatial resolution limits its diagnostic sensitivity even when single photon emission computed tomography is coregistered with computed tomography (CT). Radiolabeling of white blood cells also adds complexity to this procedure. Consequently, it tends to be used when other approaches remain inconclusive unless the question of endocarditis occurs in the early postsurgical phases, when the healing process impedes the analysis of other …