Evaluation of geometric characteristics and internal structure of atherosclerotic plaques on the walls of the blood vessels and their phantoms using intravascular optical coherence tomography

摘要

A method for studying atherosclerotic plaques on the walls of large blood vessels is described. The method is based on a study of raw data of intravascular optical coherence tomography (IOCT). Identification of fat constituents, calcium, cholesterol crystals, macrophage clusters, blood clots, etc. within the areas of atherosclerotic lesions of blood vessels is based on the study of two parameters only. The intensity of the A-scan interference signal is the first parameter, and the biomechanical properties (primarily Young's modulus) are the second analyzed parameter. The pulse wave is used as the least traumatic deforming effect. The magnitude of the deforming effect in blood vessels is calculated using averaging of the blood pressure differences. This data is acquired using an invasive pressure probe. Structural IOCT-images corresponding to the moments of systole and diastole are selected from the sequence of raw data. Both IOCT-images are segmented and classified by signal intensity. Primarily, identification of segments is based on reference data of the optical properties of the atherosclerotic plaques' components. The segments with similar geometrical locations and signal intensity are grouped into pairs. The centroids are calculated for all segments. The absolute displacements of the segments are estimated by the displacements of the centroids. The area of deformation is considered to be equal to the scanning area of the applied intravascular probe. The dimensions of the deformable area for the set of segments of two analyzed images are calculated with respect to the coordinate axes and then averaged. The biomechanical properties of the segments are calculated according to classical formulas and are used to update values of the primary identification of the structural components of atherosclerotic plaques. Information about the geometric characteristics and internal structure of atherosclerotic plaques are used to identify their properties and current stability.