Feasibility of combined use of intravascular ultrasound radiofrequency data analysis and optical coherence tomography for detecting thin-cap fibroatheroma

Aims: To evaluate the feasibility of the combined use of virtual histology (VH)-intravascular ultrasound (IVUS) and optical coherence tomography (OCT) for detecting in vivo thin-cap fibroatheroma (TCFA). Methods and results: In 56 patients with angina, 126 plaques identified by IVUS findings were analysed using both VH-IVUS and OCT. IVUS-derived TCFA was defined as an abundant necrotic core (>10% of the cross-sectional area) in contact with the lumen (NCCL) and %plaque-volume >40%. OCT-derived TCFA was defined as a fibrous cap thickness of <65 μm overlying a low-intensity area with an unclear border. Plaque meeting both TCFA criteria was defined as definite-TCFA. Sixty-one plaques were diagnosed as IVUS-derived TCFA and 36 plaques as OCT-derived TCFA. Twenty-eight plaques were diagnosed as definite-TCFA; the remaining 33 IVUS-derived TCFA had a non-thin-cap and eight OCT-derived TCFA had a non-NCCL (in discord with NCCL visualized by VH-IVUS, mainly due to misreading caused by dense calcium). Based on IVUS findings, definite-TCFA showed a larger plaque and vessel volume, %plaque-volume, higher vessel remodelling index, and greater angle occupied by the NCCL in the lumen circumference than non-thin-cap IVUS-derived TCFA. Conclusion: Neither modality alone is sufficient for detecting TCFA. The combined use of OCT and VH-IVUS might be a feasible approach for evaluating TCFA.

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