Abstract 16224: Ghost Struts: A New IV-OCT Artifact
Background: We studied the mechanisms underlying two intravascular optical coherence tomography (IV-OCT) artifacts, Merry-Go-Round (MGR) - an increase in strut arc length (SAL) - and Blooming - an increase in strut reflection thickness (blooming thickness).
Methods: We conducted our study in stented vessel phantoms in vitro, allowing us to monitor and control variables that are uncontrollable in vivo. Using Xience V stents, we examined the effects of catheter offset, intimal strut coverage, and residual blood on SAL and blooming thickness in IV-OCT images. Micro-computed tomography (microCT) was used as a gold standard.
Results: Catheter offset and strut coverage both caused minor MGR, while the greatest MGR effect resulted from light scattering by residual blood in the vessel lumen, with 1% hematocrit (Hct) causing more than 4-fold increase in SAL compared to imaging in 0.9% saline (p<0.05). Residual blood also resulted in blooming artifact, with blooming thickness more than doubling when imaged in 0.5% Hct compared to saline (p<0.05). In addition, we observed a new artifact, 3D-MGR, which created ‘ghost struts’ in B-scans where no corresponding struts existed . The figure demonstrates this concept: (A) MicroCT of a 3x8 mm stent with 5 repetitive embedded link regions along the longitudinal axis (stent length 8.22 mm); (B) corresponding IV-OCT reconstruction of the stent imaged in saline (8.15 mm); (C) corresponding IV-OCT reconstruction of the stent imaged in 1% Hct demonstrates the concept of 3D-MGR with the stent length longitudinally blurred to 8.55 mm. (D-F) Corresponding B-scans from the embedded link region of the 3D reconstructions in A-C, respectively. Three struts are present by microCT and the saline image, however in 1% Hct, two ghost struts appear (arrows).
Conclusion: Light scattering by residual blood in the imaging field is the predominant cause of MGR, and also results in blooming and a newly described artifact, 3D-MGR, which creates ghost struts.
- © 2013 by American Heart Association, Inc.