Fig. 1

FE-MUSIC images of a twenty-one-day old boy (1.1 kg) with a patent ductus arteriosus (a-e). A mobile right atrial mass of uncertain etiology was noted on echocardiography after birth. Three of 8 frames from FE-MUSIC show a large mobile mass (white arrow) in the right atrium (RA) abutting the tricuspid annulus and valve leaflets (green arrow). The mass has to-and-fro motion and connects via a thin stalk to thrombus (d, Additional file 3: online video 1a) in the inferior vena cava, which in turn, is continuous with thrombus in the ductus venosus originating from an infected umbilical vein catheter. A patent ductus arteriosus measuring 700 microns at its waist is shown bridging the pulmonary artery and descending aorta in the FE-MUSIC image (e, Additional file 3: online video 1b)