Blood vessel tail artifact removal method and system for blood flow signal intensity layered filtering

Abstract

The invention discloses a blood vessel tail artifact removal method and system based on blood flow signal intensity layered filtering. The method comprises the following steps: collecting OCT scattered signals in a three-dimensional space from a biological tissue sample through a signal acquisition method; combining a blood flow signal intensity calculation method with the intensity of an OCT scattered signal and decorrelation to represent the intensity of the blood flow signal; enabling the blood flow signal intensity to be subjected to layered comparison in the depth direction through a layered filtering method for the blood flow signal intensity, and removing artifacts at the tail of the blood vessel. According to the method, the distinction degree between the blood vessel signal and the blood vessel tail artifact signal can be improved, the blood vessel tail artifacts are effectively removed, and meanwhile the capacity of recovering the shape of the blood vessel shielded by the artifacts is achieved.

Description

technical field [0001] The present invention relates generally to the field of biomedical imaging, and more particularly to angiography associated with Optical Coherence Tomography (OCT) and OCT Angiography (OCT-A). Background technique [0002] The monitoring of the morphology of blood perfusion (new blood vessels, lack of blood vessels, etc.) and the quantification of related indicators (vascular density, connectivity, etc.) can provide important references for the study of physiological functions and the evaluation of pathological conditions. Vascular imaging techniques currently commonly used in clinical practice include invasive imaging methods such as fluorescein angiography and indocyanine green angiography, which are based on exogenous intravenous dye injection to image blood vessels. This kind of dye injection may cause side effects such as vomiting and dye leakage, so it is not suitable for long-term and frequent follow-up monitoring. Optical coherence tomography ...

AI Technical Summary

Problems solved by technology

However, in the process of OCTA imaging of blood flow, the signal scattered back to the detector from the static tissue area located below the blood vessel will be mistaken for dynamic due to the path passing through the dynamic blood vessel area above it that changes with time. signal, resulting in tail artifacts below the blood vessel, which seriously affects the resolution in the depth direction of the OCTA blood flow image

Moreover, if the vascular distribution of the biological tissue is a multi-layered structure along the depth direction, when the artifacts of the upper blood vessels extend downward to the position of the next layer of blood vessels, the shape of the lower blood vessels will be blocked by the artifacts.

[0004] In order to remove this kind of vascular tail artifact, the commonly used method is based on the method of layer subtraction, which subtracts the shallow vascular distribution projection from the deep vascular distribution projection, but this layered subtraction method will be in the deep vascular distribution. The original artifact position in the projection leaves an obvious gap area, which destroys the connectivity of deep blood vessels, and the shape of the blocked blood vessels cannot be restored

The exponential attenuation filter based on the depth direction is also a method of artifact removal, but the effect of this type of method depends on the selection of the specific attenuation function, and it is easy to cause the overall attenuation of the blood vessel signal

In addition, there is a PR OCTA method based on filtering in the depth direction. This method removes the artifact signal by comparing the ratio of the decorrelation coefficient and the amplitude of the OCT signal along the depth direction. However, this method is more suitable for artifacts. In the special case of retinal IS / OS layer and RPE layer with high signal intensity, for the general case of OCT signal intensity gradually attenuating with depth, this processing method may reduce the difference between blood vessel and artifact signal, and at the same time, this This method uses the maximum value of all signals above the current position as the standard to filter out artifacts. The conditions for filtering artifacts are too strong, and it is easy to cause blood vessels with weak signals in the deep layer to be mistakenly filtered out.

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