Advantages of 18F-FDG PET/CT Imaging over Modified Duke Criteria and Clinical Presumption in Patients with Challenging Suspicion of Infective Endocarditis

Abstract

According to European Society of Cardiology guidelines (ESC2015) for infective endocarditis (IE) management, modified Duke criteria (mDC) are implemented with a degree of clinical suspicion degree, leading to grades such as “possible” or “rejected” IE despite a persisting high level of clinical suspicion. Herein, we evaluate the 18F-FDG PET/CT diagnostic and therapeutic impact in IE suspicion, with emphasis on possible/rejected IE with a high clinical suspicion. Excluding cases of definite IE diagnosis, 53 patients who underwent 18F-FDG PET/CT for IE suspicion were selected and afterwards classified according to both mDC (possible IE/Duke 1, rejected IE/Duke 0) and clinical suspicion degree (high and low IE suspicion). The final status regarding IE diagnosis (gold standard) was based on the multidisciplinary decision of the Endocarditis Team, including the ‘imaging specialist’. PET/CT images of the cardiac area were qualitatively interpreted and the intensity of each focus of extra-physiologic 18F-FDG uptake was evaluated by a maximum standardized uptake value (SUVmax) measurement. Extra-cardiac 18F-FDG PET/CT pathological findings were considered to be a possible embolic event, a possible source of IE, or even a concomitant infection. Based on the Endocarditis Team consensus, final diagnosis of IE was retained in 19 (36%) patients and excluded in 34 (64%). With a sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and global accuracy of 79%, 100%, 100%, 89%, and 92%, respectively, PET/CT performed significantly better than mDC (p = 0.003), clinical suspicion degree (p = 0.001), and a combination of both (p = 0.001) for IE diagnosis. In 41 patients with possible/rejected IE but high clinical suspicion, sensitivity, specificity, PPV, NPV, and global accuracies were 78%, 100%, 100%, 85%, and 90%, respectively. Moreover, PET/CT contributed to patient management in 24 out of 53 (45%) cases. 18F-FDG PET/CT represents a valuable diagnostic tool that could be proposed for challenging IE cases with significant differences between mDC and clinical suspicion degree. 18F-FDG PET/CT allows a binary diagnosis (definite or rejected IE) by removing uncertain diagnostic situations, thus improving patient therapeutic management.

CASSIA (cardiology software suite for image analysis): a potential new tool for the evaluation of [18F]FDG PET/CT in the setting of infective endocarditis

“…VHI and RCR also follow an increasing tendency. As stated in the literature [ 28 – 30 ], uptake with homogeneous distribution throughout the valve is interpreted as inflammatory, due to a physiological phenomenon of foreign body reaction (macrophages reacting to prosthetic material without infection and without damage to the tissue). Conversely, irregular uptake with foci of increased metabolic activity in one or more areas of the periprosthetic tissue is interpreted as a focus of infection.…”

18F- FDG PET/CT in reclassifying the probable diagnosis of IE - A review

“…In addition, in cases of PVE high uptake near the area of the valve was reported to be a marker of high embolic risk warranting early surgical intervention. 7 Using mDC the clinical probability of IE can be low or high, adding FDG PET/CT in the diagnostic workup of 53 patients with a possible diagnosis of IE, Valentin et al 7 reported that it helped in reclassifying Duke 1 cases as Duke 0 or Duke 2 with a sensitivity of 79 %, specificity of 100 %, positive predictive value (PPV) of 100 % and negative predictive value (NPV) of 89 % based on the final diagnosis confirmed by the Institutional multidisciplinary endocarditis team ( Table 1 ). Similar observations were reported by others, that the addition of FDG PET/CT to standard workup has enhanced the detection of 15–32 % additional foci 8 , 9 , 10 , 11 and the number needed to test was only 7 for this additional detection.…”

“…This test is devoid of nephrotoxicity and covers the area of interest ie the heart and also extra-cardiac structures and even it can pick up extra-cardiac sources of infective foci. By integrating this test with mDC, Valentin et al 7 could confirm definitive diagnosis of IE in 36 % of their cases and excluded in the rest 64 %. They classified cases into 4 categories.…”

“…In 41 cases of possible or rejected diagnosis of IE but with high clinical suspicion, the sensitivity, specificity, PPV, and NPV were 78 %, 100 %, 100 % and 85 % respectively. 7 FDG PET/CT is particularly helpful in confirming or ruling out the diagnosis of IE in PVE, Cardiac device-related infective endocarditis (CDRIE) and vascular conduit infections. Table 2 shows the sensitivity and specificity of IE affecting different structures.…”

Contemporary Review of Multi-Modality Cardiac Imaging Evaluation of Infective Endocarditis

“…In 2015, the European Society of Cardiology (ESC) revised guidelines that highlight the importance of imaging in the management of patients with suspected IE. Indeed, new techniques are increasingly being used when TTE/TEE results are negative with a persistent high level of clinical suspicion [ 14 ]. Nuclear molecular imaging techniques provide additional value in diagnosing patients with possible IE using the modified Duke criteria.…”