Frequency-domain optical coherence tomography assessment of human carotid atherosclerosis using saline flush for blood clearance without balloon occlusion

Abstract

FD-OCT is a new imaging technique that allows unprecedented in vivo microlevel assessment of human carotid plaque morphologic patterns and stent-vessel interactions. Prior reports describing the use of this technique have used balloon occlusion of the target vessel or iodinated contrast media to facilitate imaging. We report, for the first time, in vivo FD-OCT imaging of human carotid arteries without the use of iodinated contrast material or balloon occlusion techniques.

Fig 1.

FD-OCT quantitative assessments with contrast and saline injections. An FD-OCT cross-sectional image of the ICA obtained after undiluted iodinated contrast injection is depicted in (A). Luminal measurements and calcified plaque (asterisks) are demonstrated. The same artery (coregistered) was imaged by FD-OCT after heparinized saline injection (B), illustrating comparable luminal dimensions and plaque morphologic patterns. Note that the dedicated software used for analysis enables the selection of different flush media to account for different index of refraction.

Fig 2.

FD-OCT qualitative assessments with contrast and saline injections. FD-OCT cross-section of the ICA was obtained with contrast injection (A). A ruptured plaque (white arrow) with overlying red thrombus (white dashed circle) is depicted. The same artery imaged by FD-OCT after saline injection (B) demonstrates similar features.

Fig 3.

Red thrombus optical properties obtained by means of FD-OCT after contrast and saline injections. FD-OCT assessment of ICA thrombus after contrast injection (A) includes a graphic representation of sharply attenuated light consistent with red thrombus. In (B), the same coregistered segment of artery was imaged by FD-OCT after saline injection, with demonstration of comparable optical properties.

Fig 4.

Satisfactory blood clearance with saline injections. Frequency-domain optical coherence tomography cross-sections of large internal carotid arteries in (A) and (B) demonstrate excellent blood clearance with saline injections, despite large lumen dimensions.

Fig 5.

FD-OCT images with contrast and saline injections. Longitudinal and cross-sectional FD-OCT images of the ICA obtained with contrast (A) and saline (B) flush media, demonstrate comparable blood clearance at the target lesion (area of luminal narrowing) within the ICA. In this particular patient, improved blood clearance with saline flush (compared with contrast) was observed in the more proximal common carotid artery (asterisks).