METHOD FOR FLOW-DIRECTING STENT SELECTION Russian patent published in 2017 - IPC A61B6/00 

FIELD: medicine.

SUBSTANCE: size of the flow-directing stent is determined by the empirical formula: 0.9⋅(prox+dist)/2. The availability of flow-directed stents of the required size is checked by selection of the closest size of the flow-directing stent from the list of standard sizes. Properties of the cerebral artery wall are determined, for which structural images of the cerebral artery aneurysm wall for systole and diastole are obtained by endoscopic optical coherence tomography. Thickness of the cerebral artery aneurysm wall is determined on the basis of structural images obtained by endoscopic optical coherence tomography by multiplying the number of pixels corresponding to the thinnest part of the cerebral aneurysm wall by the axial resolution of the structural image. Young's modulus is calculated for the cerebral artery aneurysm wall based on the ratio of axial tension of the cerebral artery aneurysm wall to its axial deformation. Axial deformation is determined by pixel-by-pixel analysis of the structural images of the cerebral artery aneurysm wall made for systole and diastole using the cross-correlation function. The axial stress is found as the ratio of the empirically estimated force of the pulse wave acting on the scan area to the pixel-by-pixel estimated cross-sectional area of this region. The Poisson ratio is determined as the ratio of the axial deformation of the cerebral artery aneurysm wall to the axial deformation of the cerebral artery aneurysm wall; and these deformations are found from strain-strain curves calculated on the basis of a pixel-by-pixel analysis of a series of at least several tens of structural images of the aneurysm wall that describe the process of pulse wave propagation. Only a pulse wave is used as a source of mechanical influence on the object being studied. Based on pixel-by-pixel analysis of images using cross-correlation function, relative changes in the vessel wall sections thickness are determined. Compression elastography in optical coherence tomography with a direct-scan probe is used to determine the biomechanical parameters of the cerebral artery aneurysm wall, associated with the mathematical model oflocal hemodynamics of the cerebral artery. Based on the conjugate mathematical model, changes in the three-dimensional distribution of blood velocity, pressure in the aneurysm area and the value of the parietal shear stress are determined and comparative analysis is applied to select a flow-directing stent that allows the maximum decrease of average blood velocity inside the aneurysm cavity and restoration of the blood flow through the cerebral artery.

EFFECT: method cllows to increase the accuracy of selection of the flow-directing stent for endovascular operations due to mathematical modeling of blood flow through the flow-directing stent.

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