Spatial-frequency approach to fibrous tissue classification in intracoronary optical images

Increased understanding about the mechanisms of coronary thrombosis in humans has been limited by the lack of imaging modalities with resolution sufficient to characterize fibrous cap tissue and determine its thickness in vivo. Intravascular optical coherence tomography (IOCT) provides images with micrometer axial (10-15 μm) and lateral resolution (40μm), enabling detailed visualization of micro-structural changes of the arterial wall. This article describes a fully automated method for identification and quantification of fibrous tissue in IOCT human coronary images based on spatial-frequency analysis by means Short-Time Fourier transform. Forty IOCT frames from nine IOCT in-vivo datasets were annotated by an expert and used to evaluate the proposed fibrous tissue characterization method.