Effects of contrast medium viscosity into flushing port on artefacts during optical coherence tomography imaging.

Background: Optical coherence tomography (OCT) is becoming the standard imaging modality for percutaneous coronary intervention (PCI) because of its high resolution. To perform appropriate OCT-guided PCI, it is necessary to avoid artefacts and obtain high-quality images. We investigated the relationship between artefacts and the viscosity of contrast media, which were used to remove air before OCT imaging catheter was inserted into guiding catheter.

Methods: We retrospectively analyzed every pullback of OCT examinations from January 2020 to September 2021. Cases were divided into two groups according to the type of contrast media used for catheter flushing: low-viscosity (Iopamidol-300, Bayer, Nordrhein-Westfalen, Germany) vs. high-viscosity (Iopamidol-370, Bayer). We evaluated the artefacts and quality of each OCT image and performed ex vivo experiments to compare differences in artefact frequencies using the two contrast media.

Results: A total of 140 pullbacks in the low-viscosity group and 73 pullbacks in the high-viscosity group were analyzed. The percentage of grade 2 and 3 images (with good quality) in the low-viscosity group was significantly lower (68.1 % vs. 94.5 %, p < 0.001). Rotational artefacts were significantly more common in the low-viscosity group (49.3 % vs. 8.2 %, p < 0.001). In multivariate analysis, using low-viscosity contrast media was a significant factor influencing the appearance of rotational artefacts and affecting image quality (odds ratio, 9.42; 95 % confidence interval, 3.58 to 24.8; p < 0.001). In ex vivo experiments, using low-viscosity contrast media was also a significant predictor of artefact occurrence during OCT (p < 0.01).

Conclusions: The viscosity of the contrast agent used while flushing the OCT imaging catheter contributes to the appearance of OCT artefacts.