Neurointervention.  2021 Mar;16(1):29-33. 10.5469/neuroint.2020.00297.

Assessment of Blood Clot Composition by Spectral Optical Coherence Tomography: An In Vitro Study

• Ding Y
• Abbasi M
• Eltanahy AM
• Jakaitis DR
• Dai D
• Kadirvel R
• Kallmes DF
• Brinjikji W

• KMID: 2513340
• DOI: http://doi.org/10.5469/neuroint.2020.00297

Abstract

Purpose
Optical coherence tomography (OCT) has the potential for in vivo clot composition characterization in difficult mechanical embolectomy cases. We performed an in vitro study to determine the OCT characteristics of red blood cells (RBCs) and fibrin rich clots.
Materials and Methods
Analogues of 5 compositions of clots (5% to 95% RBCs from Group A to E) were created from human blood. The blood mixture was injected into the bifurcation of a 3D printed bifurcated silicone tube. The OPTISTM Integrated System (St. Jude Medical Inc.) was used to identify the magnitude of OCT signals from different compositions of clots. Martius Scarlett Blue trichrome (MSB) staining was performed to confirm the composition of RBCs and fibrin in each clot.
Results
Group A and B showed less signal attenuation (less than 30%) from its surface to the inside, which indicated high penetration (low-back scattering). Group C indicated intermediate signal attenuation (60%) from its surface to inside the clots, in which signals were found even at the periphery of the clot. Group D and E were superficially signal rich with more signal attenuation (more than 80%) from its surface to the inside indicating low penetration (high-back scattering). Signal-free shadowing was shown in 3 clots in Group E. MSB staining indicated color change (from red in fibrin-rich clots to yellow in RBC-rich clots).
Conclusion
Different compositions of clots can be assessed using OCT. Fibrin-rich clots have homogeneous signals with high penetration, while RBC-rich clots can be recognized as superficially signal rich with low penetration.

Keyword

Blood clot; Composition; Optical coherence tomography

Figure

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  Fig. 1. (A) Fibrin-rich clot (25% RBC); (B) RBC-rich clot (95% RBC); (C) OCT image from (A) showing less signal attenuation from the surface (white arrow); (D) OCT image from (B) showing more serious attenuation (white arrow). RBC, red blood cell; OCT, optical coherence tomography.

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  Fig. 2. Showing clot location (blue arrow), a high-resolution camera inside the OCT catheter (green arrow), and catheter advancement over the microguidewire (red arrow). OCT, optical coherence tomography.

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  Fig. 3. Correlation between RBC composition and OCT signal reduction. RBC, red blood cell; OCT, optical coherence tomography.

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  Fig. 4. Representative OCT images of different types of clots. (A) 5% RBC rich; (B) 25% RBC rich; (C) 50% RBC rich; (D) 75% RBC rich; (E) 95% RBC rich. Signal attenuation is increased from (A) (low-backscattering) to (E) (high-backscattering). Signal-free shadowing is shown in 95% RBC-rich clot (white arrow in E). Representative histological images (F–J) of 5 types of clots (MSB staining, ×20); from left to right, the percentages of RBC were 14.4%, 31.7%, 49.3%, 77.1%, and 95.4%, respectively. The color of the clot area changes from light red to dark yellow. RBC, red blood cell; OCT, optical coherence tomography; MSB, Martius Scarlett Blue trichrome.

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