and used to determine the patency and configuration of the coronary artery lumens. intravascular ultrasound an intravascular ultrasound image of the ostium of the left main coronary artery intravascular ultrasound, also known as a percutaneous echocardiogram is an imaging methodology using specially designed, long, thin, complex manufactured catheters attached to computerized ultrasound equipment to visualize the lumen and the interior wall of blood vessels. ffr fractional flow reserve (ffr) examines the pressure drop across the stenosis in suspected ischemic coronary artery that may require percutaneous coronary intervention (pci) or coronary artery bypass surgery.