CN-122004820-A - Blood flow velocity measurement system combined with magnetic resonance image

CN122004820ACN 122004820 ACN122004820 ACN 122004820ACN-122004820-A

Abstract

The invention relates to the technical field of medical image hemodynamic analysis, in particular to a blood flow velocity measurement system combined with a magnetic resonance image, which comprises: the signal acquisition, phase processing, flow velocity calculation, phase analysis, image optimization and blood flow analysis module is sequentially connected, and the magnetic resonance phase image is acquired, the background phase field is separated and corrected to obtain the net flow phase, and then the initial flow velocity is calculated. The method comprises the steps of dividing flow velocity data into a plurality of time phases by combining electrocardio gating, generating a time phase flow velocity diagram, drawing an interested region after space-time smoothing, generating a complete flow velocity-time curve, and finally calculating various hemodynamic parameters such as peak flow velocity, average flow velocity, flow velocity integral, blood flow and the like. The system eliminates static magnetic field interference through background phase correction, and optimizes the quality of dynamic data by utilizing space-time smoothing, thereby improving the accuracy and time resolution of blood flow measurement.

Inventors

LIU HONGXIANG
JIANG YING
LI JUANJUAN
ZHU XIAOJUN
LI LINGLING
WANG YANLI

Assignees

中国人民解放军总医院第一医学中心

Dates

Publication Date: 20260512
Application Date: 20260203

Claims (10)

1. A blood flow velocity measurement system incorporating magnetic resonance imaging, comprising the steps of: the signal acquisition module acquires magnetic resonance original signals of a target blood vessel region to obtain a magnetic resonance phase image containing a flowing phase; the phase processing module separates a background phase field from the magnetic resonance phase image, carries out background phase correction on the magnetic resonance phase image and acquires a net flow phase image of a blood vessel region; The flow rate calculation module is used for calculating an initial flow rate value of each pixel point in the vascular area in the coding direction based on the net flow phase image and the preset flow rate coding sensitivity; The time phase analysis module is used for carrying out time phase division on the initial flow velocity value by combining an electrocardio gating signal synchronously acquired with the magnetic resonance original signal to generate a plurality of time phase flow velocity images in a complete cardiac cycle; the image optimization module performs space-time smoothing on the plurality of time phase flow velocity graphs so as to reduce image noise and isolated flow velocity abnormal values; And the blood flow analysis module is used for manually or automatically sketching a region of interest along the anatomical trend of a target blood vessel on the plurality of time phase flow velocity diagrams, calculating the average flow velocity of each time phase in the region of interest, generating a flow velocity-time curve of the region of interest in a complete cardiac cycle, and calculating the peak flow velocity, the average flow velocity, the flow velocity integral and the blood flow parameters of the blood vessel according to the morphological characteristics and the numerical values of the flow velocity-time curve.
2. The system for measuring blood flow velocity in combination with magnetic resonance imaging according to claim 1, wherein acquiring the magnetic resonance raw signals of the target vessel region to obtain the magnetic resonance phase image including the flow phase comprises: collecting a magnetic resonance original signal of a target blood vessel region, and performing spatial coding on the magnetic resonance original signal; Applying a preset flow velocity encoding gradient pulse to the magnetic resonance original signal after spatial encoding to obtain a magnetic resonance complex signal containing phase information; Performing Fourier transform reconstruction on the magnetic resonance complex signals to obtain a magnetic resonance phase image containing a flowing phase; The method for acquiring the magnetic resonance original signal of the target blood vessel region and carrying out space coding on the magnetic resonance original signal specifically comprises the following steps: exciting a target blood vessel region by using magnetic resonance scanning equipment according to preset scanning sequence parameters and receiving magnetic resonance original signals generated by the target blood vessel region; performing spatial position coding on the magnetic resonance original signal by applying a frequency coding gradient and at least one phase coding gradient, and filling the spatial position coding into a K space; repeating the steps of excitation, encoding and filling until all preset K space data acquisition is completed, and obtaining a full K space data matrix; And filling the complete K space data matrix to obtain the magnetic resonance original signal with the space coding completed.
3. The system for measuring blood flow velocity in combination with magnetic resonance image according to claim 2, wherein the applying a preset flow velocity encoding gradient pulse to the spatially encoded magnetic resonance raw signal to obtain a magnetic resonance complex signal containing phase information specifically comprises: applying a pair of equal and opposite flow velocity encoding gradient pulses along at least one measurement direction at a specific point in time of the scan sequence; the amplitude, duration and time interval of the flow velocity encoding gradient pulse are set according to the expected maximum measurement flow velocity; respectively acquiring magnetic resonance echo signals before and after the flow velocity encoding gradient pulse is applied; carrying out complex combination treatment on the magnetic resonance echo signals acquired after the flow velocity encoding gradient pulse is applied and the magnetic resonance echo signals acquired before the flow velocity encoding gradient pulse is applied; The complex combined signal is the magnetic resonance complex signal containing the phase change caused by flow.
4. A blood flow velocity measurement system according to claim 3 wherein the fourier transform reconstruction of the magnetic resonance complex signal yields a magnetic resonance phase image comprising a flow phase, comprising: filling a complete K space data matrix corresponding to the magnetic resonance complex signal, and respectively performing two-dimensional Fourier transformation along a phase encoding direction and a frequency encoding direction; converting the magnetic resonance complex signal from a K space domain to an image space domain through the two-dimensional Fourier transform to obtain a complex magnetic resonance image; respectively calculating an amplitude value and a phase value of each pixel point from the complex-form magnetic resonance image; mapping the phase value to a preset phase display range, and generating the magnetic resonance phase image containing the flowing phase.
5. The system of claim 1, wherein the separating the background phase field from the magnetic resonance phase image, performing background phase correction on the magnetic resonance phase image, and obtaining a net flow phase image of the blood vessel region, comprises: Selecting a tissue region known to be stationary or to flow very slowly as a background phase reference region on the magnetic resonance phase image; Constructing a background phase field model with continuous space change based on the phase value of the background phase reference area through a curve fitting or polynomial fitting algorithm; subtracting the estimated phase value of the background phase field model at each pixel point from the original phase value of the pixel point in the magnetic resonance phase image; Adjusting the range of the phase difference value to a phase interval corresponding to the flow velocity coding range to obtain a corrected phase image; and on the corrected phase image, a blood vessel region is identified by applying a blood vessel segmentation technology, and phase information in the region is extracted, so that a net flow phase image of the blood vessel region is obtained.
6. The system for measuring blood flow velocity in combination with magnetic resonance image according to claim 5, wherein the calculating the initial flow velocity value of each pixel point in the vascular region in the encoding direction based on the net flow phase image and the preset flow velocity encoding sensitivity comprises: acquiring parameters of amplitude, duration and time interval of an applied flow velocity encoding gradient pulse; According to the amplitude, duration and time interval parameters, calculating the flow rate coding sensitivity of the system, namely a phase change value caused by unit flow rate; Reading a phase value of each pixel point in a blood vessel region on the net flow phase image; According to the linear relation between the flow velocity and the phase, the phase value of each pixel point is converted into a velocity component along the flow velocity coding gradient direction by using the flow velocity coding sensitivity; the velocity component is the initial flow velocity value of the pixel point in the encoding direction, and the initial flow velocity values of all the pixel points jointly form an initial flow velocity distribution diagram.
7. The system for measuring blood flow velocity in combination with magnetic resonance imaging according to claim 6, wherein the step of generating a plurality of phase flow velocity maps in a complete cardiac cycle by phase dividing the initial flow velocity value in combination with an electrocardiographic gating signal acquired in synchronization with the magnetic resonance raw signal comprises: continuously recording an electrocardiographic gating signal of a subject while acquiring a magnetic resonance original signal; Identifying R waves in the electrocardio gating signals, and equally dividing a complete cardiac cycle into a preset number of time intervals by taking each R wave as a trigger point; Classifying the calculated initial flow velocity distribution diagram into a corresponding time interval according to the relative time relation between the K space data acquisition time and the nearest R wave trigger point; Averaging or interpolating all initial flow velocity distribution graphs belonging to the same time interval to form a representative flow velocity distribution graph of the time interval; the representative flow velocity profiles for all time intervals are arranged in time sequence, i.e. a plurality of phase flow velocity profiles over the one complete cardiac cycle are generated.
8. The system for measuring blood flow velocity in combination with magnetic resonance image according to claim 7, wherein the performing the spatiotemporal smoothing on the plurality of phase flow velocity maps to reduce image noise and isolated flow velocity outliers comprises: in the space dimension, a Gaussian filter or a median filter is applied to each phase-time flow velocity map, and abrupt changes of flow velocity values between adjacent pixel points are smoothed; In the time dimension, smoothing is carried out by applying a low-pass filter of a time domain on a time sequence formed by flow velocity values of different time phases aiming at the same space pixel point; checking each time phase flow velocity diagram after smoothing, and identifying and eliminating isolated abnormal pixel points which obviously deviate from the flow velocity statistical characteristics of surrounding areas; Performing spatial interpolation filling on the position of the isolated abnormal pixel point by using the flow velocity value of the adjacent pixel point; And obtaining a series of time phase flow velocity diagrams with reduced noise and higher data consistency through the space-time smoothing processing.
9. The system for measuring blood flow velocity in combination with magnetic resonance imaging according to claim 8, wherein the manually or automatically delineating the region of interest along the anatomical trend of the target vessel on the plurality of phase flow velocity maps comprises: Displaying the anatomical structure of the target blood vessel on any time phase flow velocity diagram, and manually clicking along the intima of the blood vessel cavity by an operator, wherein the system generates a closed region of interest contour; or based on the gray level or phase characteristic of the blood vessel, automatically detecting the boundary of the blood vessel by using a region growing or active contour model algorithm, and generating the contour of the region of interest; Propagating and fine-tuning the contour of the region of interest on different two-dimensional layers or multiple phases of the same blood vessel, so as to ensure consistency in three-dimensional space; Calculating and storing a space coordinate set of all pixel points contained in the outline of the region of interest; The region of interest will be used for flow parameter calculations for all subsequent phase flow diagrams.
10. A blood flow velocity measurement system according to claim 9 in combination with magnetic resonance imaging, wherein the calculating of the average flow velocity for each phase in the region of interest and generating a flow velocity-time curve for the region of interest over a complete cardiac cycle comprises: extracting flow velocity values of all pixel points in the contour of the region of interest for each graph in the series of time-phase flow velocity graphs; calculating an arithmetic average value of flow velocity values of all pixel points in the outline of the region of interest, and taking the arithmetic average value as the average flow velocity of the region of interest in the time phase; According to the time sequence of the cardiac cycle, the average flow velocity values obtained by calculation of each time phase are sequentially arranged; drawing a scatter diagram by taking time as an abscissa and average flow velocity as an ordinate, and connecting all the scatter diagrams through a curve; The drawn curve is the flow velocity-time curve of the region of interest in the complete cardiac cycle, and is used for subsequent analysis of hemodynamic parameters.

Description

Blood flow velocity measurement system combined with magnetic resonance image Technical Field The invention relates to the technical field of medical image hemodynamic analysis, in particular to a blood flow velocity measurement system combined with a magnetic resonance image. Background In the medical imaging field, magnetic resonance phase contrast imaging is an important means for non-invasively measuring blood flow velocity. The traditional magnetic resonance flow velocity measurement technology directly utilizes the acquired phase images to calculate the flow velocity. In addition to reflecting the target phase of blood flow, these phase signals inevitably contain background phase fields due to factors such as non-uniformity of the main magnetic field, differences in tissue susceptibility, and the like. The prior art solutions generally do not effectively identify and isolate this complex background disturbance, resulting in systematic errors in the calculated flow velocity values, especially in low velocity blood flow or vessel boundary regions, where the errors are more pronounced. Conventional magnetic resonance blood flow analysis focuses on peak flow rate at a single time or on average flow rate assessment throughout the scan. Even if electrocardiographic gating is used, the data processing is often limited to a few time phases, or the data of each time phase is simply and independently averaged, and the fine characterization of the dynamic change of blood flow in continuous cardiac cycles is lacked. This approach loses the instantaneous change in blood flow with heart beat, making it difficult to generate a smooth, consistent flow-time curve. Meanwhile, noise and isolated outliers inherent to the original magnetic resonance flow velocity image also directly affect the reliability of subsequent quantitative parameters, and the existing method has limitations in improving the quality of the space-time data. Disclosure of Invention The invention aims to solve the defects in the prior art and provides a blood flow velocity measurement system combined with magnetic resonance images. In order to achieve the above object, the present invention adopts the following technical scheme that a blood flow velocity measurement system combined with magnetic resonance image includes: the signal acquisition module acquires magnetic resonance original signals of a target blood vessel region to obtain a magnetic resonance phase image containing a flowing phase; the phase processing module separates a background phase field from the magnetic resonance phase image, carries out background phase correction on the magnetic resonance phase image and acquires a net flow phase image of a blood vessel region; The flow rate calculation module is used for calculating an initial flow rate value of each pixel point in the vascular area in the coding direction based on the net flow phase image and the preset flow rate coding sensitivity; The time phase analysis module is used for carrying out time phase division on the initial flow velocity value by combining an electrocardio gating signal synchronously acquired with the magnetic resonance original signal to generate a plurality of time phase flow velocity images in a complete cardiac cycle; the image optimization module performs space-time smoothing on the plurality of time phase flow velocity graphs so as to reduce image noise and isolated flow velocity abnormal values; And the blood flow analysis module is used for manually or automatically sketching a region of interest along the anatomical trend of a target blood vessel on the plurality of time phase flow velocity diagrams, calculating the average flow velocity of each time phase in the region of interest, generating a flow velocity-time curve of the region of interest in a complete cardiac cycle, and calculating the peak flow velocity, the average flow velocity, the flow velocity integral and the blood flow parameters of the blood vessel according to the morphological characteristics and the numerical values of the flow velocity-time curve. As a further aspect of the present invention, acquiring a magnetic resonance raw signal of a target blood vessel region to obtain a magnetic resonance phase image including a flow phase includes: collecting a magnetic resonance original signal of a target blood vessel region, and performing spatial coding on the magnetic resonance original signal; Applying a preset flow velocity encoding gradient pulse to the magnetic resonance original signal after spatial encoding to obtain a magnetic resonance complex signal containing phase information; Performing Fourier transform reconstruction on the magnetic resonance complex signals to obtain a magnetic resonance phase image containing a flowing phase; The method for acquiring the magnetic resonance original signal of the target blood vessel region and carrying out space coding on the magnetic resonance original signal specifically comprises the