Optical Coherence Tomography

Case presentation : A 56-year-old man presented to the hospital with chest pain and a non–ST-segment elevation myocardial infarction. Thrombotic plaque rupture in the left anterior descending coronary artery was treated with an everolimus-eluting stent. After stent deployment, angiography demonstrated the presence of a hazy opacity at the distal edge of the stent, and there was concern about a possible edge dissection. Optical coherence tomography (OCT) imaging of the opacity showed residual thrombus and no dissection. Subsequent aspiration thrombectomy and balloon dilation effectively treated the lesion without deployment of an additional stent.OCT is an intravascular imaging modality that utilizes near-infrared light to generate cross-sectional blood vessel images. OCT is similar to intravascular ultrasound (IVUS), and both OCT and IVUS provide information about intravascular anatomy that far exceeds the level of detail obtained from conventional contrast cineangiography. With the use of light rather than ultrasound reflectance, OCT generates in vivo images of coronary arteries and deployed stents with up to 10 to 15 μm of spatial resolution compared with the 100- to 200-μm resolution of IVUS. Although the spatial resolution of OCT is markedly superior to that of IVUS, near-infrared light does not penetrate tissue as effectively as sound, and therefore OCT imaging depths range from 1 to 3 mm into the vessel wall, whereas IVUS imaging depths range from 4 to 10 mm (Table). Additionally, near-infrared light is scattered by red blood cells, and therefore OCT imaging requires transient blood clearing during image acquisition.View this table:Table. Comparison of FD-OCT and IVUSThe speed of light was initially a central challenge to developing a “clinically friendly” OCT system. Light travels too quickly for direct measurement of differential reflectance caused by vascular structures, and the original time delay OCT (TD-OCT) systems utilized a moving reference mirror to calibrate reflected light waves for image …