Thank you both @Khaled Sleik and @Ahmed Torshani for your great input. I discussed the case with a cardiothoracic surgeon and an imaging cardiology colleagues. The differential diagnosis was largely in favor of tumor. They leaned towards "fibroelastoma" given the fact it is very close to the valve, and the very smooth rounded edges on both CT and TEE, although fibroelastoma is typically on the left side. Our imaging expert thought even after MRI we may not be very conclusive.

We decided to start on Xarelto empirically (given high DD) and will repeat imaging (CT) in 3 months. After this discussion, I will discuss the PET option with my imaging colleague.

Will keep this post updated ISA.