A total of 3 patients (OFDI-01 through OFDI-03) were imaged between May and September 2007. Baseline characteristics for the patients are presented in . Imaging was performed successfully in all patients. None of the patients experienced chest pain or electrocardiogram changes during intracoronary OFDI. There were no complications related to the OFDI procedure. A range of saline flow rates (2 to 4 ml/s) and pullback speeds (0.5 to 2.0 cm/s) were used, providing imaging of arterial segments from 3 to 7 cm in length.
Patient OFDI-01 had a drug-eluting stent (DES) placed distal to a proximal left anterior descending artery (LAD) aneurysm (). The OFDI imaging of the proximal LAD originated distal to the stent and terminated within the stent (). Three-dimensional visualization () of the segmented data set, obtained at a saline purge rate of 3 ml/s and a pullback velocity of 2.0 cm/s, shows the proximal LAD stent (blue) as well as coronary atherosclerosis, including calcific nodules (white), lipid-rich plaque (yellow), and punctate macrophages (green). A longitudinal OFDI section shows a large lipid pool at the distal aspect of the coronary segment (). An expanded portion of a cross-sectional image of this lesion (obtained from location denoted by arrow in ) demonstrates that this lipid pool has OFDI features consistent with a thin-capped fibroatheroma (TCFA), including a thin fibrous cap (, black arrow), and macrophages at the cap–lipid pool junction (, green arrow). A flap of tissue can be seen over the cap (arrowhead in ), which could represent disrupted intima or fibrin. In this image, the minimum cap thickness near the shoulder is approximately 60 μm ( arrow; corrected for a refractive index n = 1.4).
Patient OFDI-01 Images of Left Anterior Descending Coronary Artery
Patient OFDI-01 Longitudinal and Cross-Sectional Images of Left Anterior Descending Artery
For Patient OFDI-02, imaging was conducted from the distal vessel, across the posterior descending artery, to the proximal segment of the right coronary artery (RCA) (). Cutaway longitudinal views of volume renderings (), acquired at a saline perfusion rate of 3.0 ml/s and a pullback velocity of 2.0 cm/s, show a bare-metal stent (BMS) (), placed 9 years previously, and a DES, placed immediately before OFDI imaging (). The entire DES can be visualized, crossing the ostia of the posterior descending artery. Only portions of the BMS can be seen in the cutaway view () because of neointimal hyperplasia covering the stent and the transparency chosen for rendering. However, some BMS struts viewed from the luminal aspect appear to have little tissue coverage.
Patient OFDI-02 Images of Right Coronary Artery (Session 2)
Fly-through views show the BMS and DES in greater detail (). Although a portion of the BMS struts () have a similar appearance to the DES struts (), further inspection of cross-sectional OFDI images reveals microscopic distinctions; as opposed to the DES struts (), the BMS struts () appear thicker, have a surface reflectivity that is comparable with that of arterial tissue, and have edges that continuously blend into the luminal surface. These observations are consistent with the presence of a covering over the BMS struts that is thinner than the resolution of the OFDI system.
Patient OFDI-02 Images of Right Coronary Artery Stents
The angiogram shows minimal luminal stenosis proximal to the DES (yellow arrowhead in ). Volume renderings depict a large lipid pool at this location (see dotted horizontal line in ), which is partially covered by the DES and present at the junction between the DES and artery wall. A fly-through view at this location () shows that the lesion is circumferential. A cross-sectional OFDI image () at the corresponding site demonstrates that this lesion is a TCFA, with cap thicknesses <65 μm at multiple locations (black arrowheads in ). As in Patient OFDI-01, this TCFA has a cap that contains many macrophages (green arrowheads in ), some of which appear to extend to the luminal surface. Cholesterol crystals can also be identified within the lipid pool (red arrows in ).
Patient OFDI-02 Images of a Distal Right Coronary Artery Thin-Capped Fibroatheroma
Imaging of Patient OFDI-03 began distal to a mid-RCA DES and terminated within the stent. and depict images obtained with the slowest pullback rate of 5 mm/s and a saline purge rate of 3.0 ml/s. The clear visualization length was 3.0 cm. The stent was deployed over a large calcific nodule, resulting in distortion of the stent struts (). Because of the finer longitudinal resolution (50 μm vs. 200 μm), the stent strut microstructure is better appreciated in 3 dimensions and contains fewer discontinuities () in comparison with the other 2 cases ( to ). Improved visualization of the stent struts is also clearly evident in the longitudinal cutaway view (). A longitudinal reconstruction from this session is shown in , demonstrating a calcific nodule beneath the DES. The longitudinal image's resolution is superior to that obtained with 200-μm longitudinal resolution () and is comparable with that of OFDI image cross sections.
Patient OFDI-03 Images of Right Coronary Artery
Patient OFDI-03 Images of Right Coronary Artery Stent