18F-FDG-PET/CT-Angiography in Infective Endocarditis
Is there added value associated with 18F-FDG-PET/CT (positron emission tomography/computed tomography [PET/CT]) or 18F-FDG-PET/CT-angiography (PET/CTA) in diagnosing infective endocarditis (IE) among patients with a prosthetic valve or an intracardiac device?
A cohort of 92 patients admitted to a referral center with a multidisciplinary IE unit with suspected prosthetic valve or cardiac device IE between November 2012 and November 2014 were prospectively included. All patients underwent echocardiography (echo) and PET/CT, and 76 underwent cardiac CTA. PET/CT and echo findings were evaluated and compared, with concordant results in 54% of cases (kappa: 0.23). Initial diagnoses with Duke criteria at admission, PET/CT, and Duke criteria plus PET/CT were compared with the final diagnostic consensus reached by the IE unit.
Duke criteria plus PET/CT enabled reclassification of 90% of cases initially classified by Duke criteria alone as possible IE, and provided a conclusive diagnosis (definite/rejected) in 95% of cases. Sensitivity, specificity, and positive and negative predictive values were 52%, 94.7%, 92.9%, and 59.7% for Duke criteria alone; 87%, 92.1%, 93.6%, and 84.3% for PET/CT alone; and 90.7%, 89.5%, 92%, and 87.9% for Duke criteria plus PET/CT. Use of PET/CTA yielded even better diagnostic performance values than PET/non-enhanced CT (PET/NECT) (sensitivity, specificity, and positive and negative predictive values were 91%, 90.6%, 92.8%, and 88.3% vs. 86.4, 87.5, 90.2, and 82.9) and substantially reduced the rate of doubtful cases from 20% to 8% (p < 0.001). Duke criteria plus PET/CTA reclassified an additional 20% of cases classified by Duke criteria plus PET/NECT as possible IE. In addition, PET/CTA enabled detection of a significantly larger number of anatomical lesions associated with active endocarditis compared to PET/NECT (p = 0.006) or echo (p < 0.001).
The authors concluded that 18F-FDG-PET/CT improves the diagnostic accuracy of the modified Duke criteria in patients with suspected IE and a prosthetic valve or cardiac device. PET/CTA yielded the highest diagnostic performance and provided additional diagnostic benefits.
The diagnosis of IE can be clinically challenging in general; and even more so in the setting of a patient with a prosthetic heart valve or intracardiac device, owing to limitations associated with the echocardiographic detection of vegetations in the setting of prosthetic material. This study suggests that the use of 18F-FDG-PET/CT or 18F-FDG-PET/CT-angiography can improve on the ability to reliably diagnose IE in this challenging patient population.
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