Author + information
- Gijs van Soest, PhD⁎,⁎ (, )
- Evelyn Regar, MD, PhD⁎,
- Thadé P.M. Goderie, MSc⁎,
- Nieves Gonzalo, MD, PhD⁎,
- Senada Koljenović, MD, PhD†,
- Geert J.L.H. van Leenders, MD, PhD†,
- Patrick W. Serruys, MD, PhD⁎ and
- Anton F.W. van der Steen, PhD⁎,‡
- ↵⁎Address for Correspondence:
Dr. Gijs van Soest, Erasmus Medical Center, Thorax Center, Biomedical Engineering, Ee23.02, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands
ONE OF THE GOALS OF INTRAVASCULAR IMAGING IS SPECIFIC IN VIVO IDENTIFICATION OF VULNERABLE PLAQUES, which are likely to cause acute coronary syndrome. Intravascular optical coherence tomography (OCT) is a recent technique that is used for coronary plaque characterization, and is rapidly gaining popularity as a diagnostic tool in catheterization laboratories worldwide. OCT uses infrared light to image arterial wall structure with a high resolution (10 to 15 μm). The appearance of various tissues in the vessel wall has been classified as follows: 1) fibrous—homogeneous signal-rich; 2) calcified—signal-poor with well-defined borders; and 3) lipid-rich—signal-poor with diffuse borders (1). Image artifacts inherent to the technique can lead to misclassification of pathology. Knowledge of systematic confounders in intravascular OCT data may be used to guide image interpretation. In the images presented here, we identify and explain 2 distinct artifacts in OCT imaging, based on ex vivo imaging of human coronary arteries, and show examples of their occurrence in clinical data.
The artifacts, superficial shadowing (Figs. 1 and 2⇓) and tangential signal dropout (TSD) (Figs. 3 and 4⇓⇓), can produce images with the appearance of thin-cap fibroatheroma (2): signal-poor regions overlaid by a thin signal rich layer. The thickness of this layer was measured to be typically 60 to 100 μm, which is very similar to the reported dimensions of OCT-measured thin caps.
In the signal-poor areas caused by these artifacts, the image does not provide adequate information on tissue below the surface. The imaging beam cannot penetrate the vessel wall due to strong scattering or attenuation along an oblique line-of-sight.
Figure 1 demonstrates that superficial shadowing occurs due to a strongly scattering macrophage concentration in the innermost intima (3). In clinical data (Fig. 2), well-delineated radial borders to the shadows were often observed. TSD occurs only in specific imaging geometries that lead to glancing incidence of the OCT imaging beam (Figs. 3 and 4); such sections should be interpreted with care. Some TSD instances observed in vivo exhibited a specific dark radial feature, shown in Figure 5, which we hypothesize to be a result of interface reflection.
The authors have reported that they have no relationships to disclose.
- American College of Cardiology Foundation