Intravascular optical coherence tomography light scattering artifacts: merry-go-rounding, blooming, and ghost struts

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Cardiovascular Technology

Background:

• Intravascular optical coherence tomography (IV-OCT) is crucial for assessing metallic stents.
• Common artifacts like merry-go-rounding (MGR) and blooming can distort IV-OCT images of stents.
• Understanding these artifacts is essential for accurate stent evaluation.

Purpose of the Study:

• To elucidate the mechanisms behind MGR (increased strut arc length) and blooming (increased strut reflection thickness) in IV-OCT imaging of metallic stents.
• To investigate the impact of catheter offset, intimal strut coverage, and residual blood on these artifacts.

Main Methods:

• In vitro assessment of MGR and blooming using stented vessel phantoms (Xience V and Driver stents).
• Systematic evaluation of variables including catheter offset, intimal strut coverage, and varying concentrations of residual blood (hematocrit).
• Quantitative analysis of strut arc length (SAL) and blooming thickness in IV-OCT images.

Main Results:

• Light scattering by residual blood is the predominant cause of MGR, significantly increasing SAL (over fourfold with 1% hematocrit vs. saline).
• Residual blood also causes blooming, more than doubling blooming thickness at 0.5% hematocrit compared to saline.
• Catheter offset and strut coverage had minor effects on MGR; light scattering by blood is the primary factor.

Conclusions:

• Light scattering by residual blood is identified as the main mechanism responsible for MGR artifact in IV-OCT imaging of metallic stents.
• Light scattering also contributes to blooming artifact and a newly described artifact, three-dimensional-MGR, causing 'ghost struts'.
• Minimizing residual blood during IV-OCT procedures is critical for accurate metallic stent imaging and interpretation.