1050 Normal imaging findings after aortic valve implantation on 18f-fluorodeoxyglucose positron emission tomography with computed tomography and computed tomography angiography
Authors: Wahadat A R , Tanis W , Scholtens A , Bekker M , Graven L , Swart L E , Den Harder A , Lam M , De Heer L , Roos-Hesselink J W , Budde R P J 
Published: January 2020

Abstract

Purpose
Although 18F-Fluorodeoxyglucose (18F-FDG) Positron Emission Tomography (PET) with computed tomography (CT) and cardiac computed tomography angiography (CTA) are essential tools in diagnosing prosthetic heart valve (PHV) endocarditis, the normal imaging findings in the first year after PHV implantation on 18F-FDG-PET/CT and CTA have not been studied prospectively. We prospectively assessed the perivalvular FDG uptake at different time points after aortic PHV implantation and assessed the normal imaging findings on CTA.

Materials and methods
Patients who had undergone uncomplicated aortic PHV implantation were included and underwent 18F-FDG PET/CT and CTA at 5(±1) weeks (group 1), 12(±2) weeks (group 2) or 52(±8) weeks (group 3) after implantation. After a preparatory diet to suppress normal myocardial glucose uptake, FDG uptake in the myocardium as well as around the PHV was scored using the Qualification Visual Score for Hypermetabolism (QVSH) as "none" (&lt; mediastinum), "low" (&gt; mediastinum but &lt; liver), "intermediate" (&gt; liver), or "high" (intense uptake) and quantitative analysis was performed with maximum Standardized Uptake Value (SUVmax) and target to background ratio (SUVratio) on standardized European Association of Nuclear Medicine Research Ltd. (EARL) reconstructions by an experienced nuclear medicine physician. CTA was analysed for image quality, artefacts and stranding of the peri-aortic fat by a cardiac radiologist.

Results
In total 37 patients (group 1: n = 12, group 2: n = 12, group 3: n = 13) (age 66 ± 8 years) were included. Myocardial FDG uptake was intermediate or less in 29/37 scans (78%). QVSH around the PHV was 8/12(67%) low and 4/12(33%) intermediate in group 1, 7/12(58%) low and 5/12(42%) intermediate in group 2 and 8/13(62%) low and 5/13(38%) intermediate in group 3 (p = 0.91). No scan was scored as "none" or "high". EARL SUVmax was 3.48 ± 0.57, 3.50 ± 0.59 and 3.34 ± 0.55 (mean ± SD, p = 0.77) and EARL SUVratio was 2.00 ± 0.29, 1.96 ± 0.41 and 1.71 ± 0.26 (mean ± SD, p = 0.07) for groups 1, 2 and 3, respectively.
One patient in group 3 refused to undergo the additional CTA and one CTA in group 3 could not be analysed for image quality and artefacts due to techniqual difficulties. Overall CTA image quality was "good" or "excellent" with an artefact score of "virtually none" or "mild" in most cases (n = 33, 94%). Stranding of peri-aortic fat was seen in 27/35 (77%) of these patients (group 1: n = 11; group 2: n = 9; group 3: n = 7) with no signs of FDG uptake on PET/CT scan.

Conclusion
Baseline FDG uptake around aortic PHV at 5, 12 and 52 weeks after implantation is similar and mild in the majority of cases with an overall mean SUVmax and SUVratio of 3.44 ± 0.56 and 1.89 ± 0.34 respectively. CTA revealed baseline post-surgical findings in the first year after PHV implantation.