ABSTRACT
For example, suppose that the proximal segment of the left coronary artery of a patient shows evidence of diffuse disease by angiography and that at least 3 cm of the left anterior descending artery (LAD) must be imaged to assess the characteristics of lesions within the target segment. To carry out the rapid-scan OCT procedure, the interventionist would first place the imaging catheter distal to the target segment. A bolus of saline would be injected through the guide catheter to initiate image acquisition and automatic pullback of the tip of the optical fiber inside the OCT catheter. Injection of a total of 16-20 ml of saline over a 3-s period would enable a 3-4 cm length of the vessel to be scanned at a pullback speed of 15 mm/s. During the pullback, capture and storage of images would occur at an acquisition rate of 100 frames/s, thereby providing a three-dimensional spiral image with an effective interval between adjacent frames equal to approximately 100 µm. Since the optical thickness of an OCT image slice is typically 25-40 µm (determined by the transverse spot size of the focusing lens), nearly complete coverage of the longitudinal dimension of the vessel segment would be achieved. Typically, for convenient review of the images, the video sequence of OCT images would be played back at a fraction of the rate at which the images were captured, using the L-mode display as a navigational guide.
