Figure 6a. Sagittal oblique 2D cine MR images of the inferior vena cava. (a) Image obtained with the left atrium (straight white arrow) at maximal volume shows the greatest protrusion of the right disk of the ASO (black arrow) into the vein (curved white arrow). (b) Image obtained with the left atrium (straight white arrow) at minimal volume shows less protrusion of the disk (black arrow) into the vein (curved white arrow).