Oblique sagittal post-contrast CT image in a patient with an incidentally found probe PFO at the level of the superior part (S) of the interatrial groove (IAG). Similar to a PFO a septum primum flap (arrow) is present. However, in this entity functional closure of the foramen ovale has occurred and hence, no interatrial communication exists, in contrast to a real PFO. I inferior part of the interatrial groove, LA left atrium, RA right atrium