Purpose Optical coherence tomography (OCT) has been reported for potential use for differentiation of clot composition in cardiac patients. We tried to further validate its use for stroke patients using in-vitro clots with different percentage of red blood cells (RBCs) and fibrin.
Methods Blood was collected from a healthy volunteer and separated into plasma, buffy-coat, and erythrocyte-rich layers after centrifugation. The plasma and erythrocytes were harvested separately and then recombined in controlled ratios to form five different clot analogues with 2% thrombin added (5 analogues for each composition): Group A, fibrin-rich (95% plasma:5% RBCs; Group B, fibrin-rich (75% plasma:25% RBCs); Group C, intermediate (50% plasma:50% RBCs); Group D, RBC-rich (25% plasma:75% RBCs,) and Group E, RBC-rich (5% plasma:95% RBCs). The blood mixture was injected in 6F guide angiographic catheter though a syringe. OPTISTM Integrated System (St. Jude Medical Inc., St. Paul, Minnesota) was used to perform OCT testing for each clot. A Dragonfly™ OPTIS™ imaging catheter (St. Jude Medical GmbH, St. Paul, Minnesota) was advanced into the catheter to pass the clot. The rate of automatic pullback was 0.5 mm/s. The blood clot was identified by OCT on mass images with different signal characters. OCT images were processed and analyzed according to the intensity of OCT signals from different compositions of clot.
Results Homogeneous signal of clot was shown in all the clots in Group A and B, less signal attenuation from its surface to inside was noted, which indicated high penetration (low-back scattering). Intermediate signal attenuation from its surface to inside was shown in all the clots in Group C, in which some signals still existed at the periphery of the clot. Clot in Group D and E was superficial signal rich with more signal attenuation from its surface to inside, which indicated low penetration (high-back scattering). Three clots in Group E showed signal-free shadowing (figures A to E).
Conclusion Different composition of clots can be assessed by OCT. Fibrin-rich clots have homogeneous signal with high penetration (low-back scattering), while RBC-rich clot can be recognized as superficial signal rich with low penetration (high-back scattering).
Disclosures Y. Ding: None. M. Abbassi: None. D. Jakaitis: None. D. Dai: None. R. Kadirvel: None. D. Kallmes: None. W. Brinjikji: None.
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