CN103961141B - A kind of gate control method aroused in interest based on image backtracking property ivus image - Google Patents

Abstract

The invention discloses a kind of gate control method aroused in interest based on image backtracking property ivus image, heart rate is estimated, it is determined that ivus image is done gate process and obtains gated image sequence by the time point in the diastole end of term foundation heart rate and diastole end of term time point according to ivus image。The method that the present invention proposes uses the normalized correlation coefficient of consecutive frame, and the method realizes the gate of IVUS data when synchronous electrocardiosignal lacks, and has calculating simplicity, efficient advantage。Not only it is greatly reduced follow-up analysis and the amount of calculation of auxiliary diagnosis, and follow-up analysis and the accuracy of auxiliary diagnosis can be improved。

Description

A kind of gate control method aroused in interest based on image backtracking property ivus image

Technical field

The present invention relates to image processing method, be specifically related to the automatic gate control method of a kind of backtracking property intravascular ultrasound (IntravascularUltrasound, IVUS) pictorial data。

Background technology

In IVUS checking process, conduit uniform speed slow is withdrawn from, and speed is generally 0.5～1mm/s, and frame speed is 30f/s, and typical longitudinal resolution is tens microns。So high longitudinal resolution makes the similarity of consecutive frame high。Once withdrawing from and can obtain several thousand two field pictures, document size is many up to hundreds of M to 1G。So big data volume, hardware configuration and software development to computer propose high requirement, bring to follow-up process and analysis and greatly challenge。It is additionally, since conduit and withdraws dirty constantly the beating of Process-centric so that IVUS image produces to beat in the axial direction。Observe blood vessel, present periodically wavy, reacted beating of heart。High longitudinal resolution makes the similarity of consecutive frame also very high。Therefore, the electrocardiogram (ECG) data of patient, the method then adopting ecg-gating can be recorded clinically in the IVUS process gathered simultaneously, only extract the frame in the diastole end of term, reach the purpose removing heart beating impact and reduction data volume。Withdrawing speed 1mm/s with conduit, frame speed is 30f/s, and heart rate 60b/m calculates, and the data volume after ecg-gating is original 1/30。Meanwhile, after removing heart beating impact, the seriality of blood vessel improves, it is simple to follow-up process and analysis。

But, in current clinical practice, usually have ignored the synchronous acquisition of electrocardiogram (ECG) data, the historical data of a lot of backtracking Journal of Sex Researchs, also without synchronous acquisition electrocardiogram (ECG) data, has gone greatly to rely on electrocardio to do the basis gated。Hence it is highly desirable to a kind of when there is no synchronous electrocardiosignal, it is possible to the method that IVUS is done heart beat cycle gate。

Summary of the invention

In order to solve the deficiencies in the prior art, observe IVUS image, it is found that although the similarity degree of consecutive frame is significantly high, but being affected by the impact that cardiac cycle is beated, the similarity degree of image consecutive frame also there will be periodic change。Therefore, the present invention proposes the gate control method of a kind of backtracking IVUS view data based on image。

The technical scheme is that a kind of gate control method aroused in interest based on image backtracking property ivus image, heart rate is estimated, it is determined that ivus image is done gate process and obtains gated image sequence by the time point in the diastole end of term foundation heart rate and diastole end of term time point according to ivus image。

Further improvement of the present invention includes:

The process of described ivus image data estimation heart rate is: first gradually calculate the normalizated correlation coefficient between neighbor map picture frame, obtain the curve of similarity change between frame, then this one-dimensional signal is done discrete Fourier transform, identification cardiac cycle in domain space。

Described in domain space the method for identification cardiac cycle be: within the scope of heart rate 50-110 beat/min, the frequency spectrum of check image correlation coefficient, wherein the frequency at maximum place is the heart rate of this patient。

Described in domain space the method for identification cardiac cycle be: within the scope of heart rate 60-100 beat/min, the frequency spectrum of check image correlation coefficient, wherein the frequency at maximum place is the heart rate of this patient。

The process that described diastole end of term time point is determined is: according to the heart rate obtained, calculate the frame number that a cardiac cycle comprises, from the first frame of intravascular ultrasound image sequence image, the maximum of interframe normalizated correlation coefficient is searched in the scope of 1.1 cardiac cycles, in this, as the location point in the diastole end of term, obtain the first two field picture of gate output。

Described foundation heart rate and diastole end of term time point do the process of gate process: start with the position of the first two field picture, the maximum of interframe normalizated correlation coefficient is searched in the scope of next 1.1 cardiac cycles, obtain the second two field picture of gate output, by that analogy, until completing all of intravascular ultrasound image sequence, finally output gate image sequence。

Normalizated correlation coefficient between described adjacent two two field pictures is:

$\mathrm{NC}(A,B)=-1\×\frac{{\mathrm{\Σ}}_{i=1}^N(A_i\·B_i)}{\sqrt{{\mathrm{\Σ}}_{i=1}^N}{A}_i^2\·{\mathrm{\Σ}}_{i=1}^N{B}_i^2},$

Wherein, Ai is the ith pixel of image A, and Bi is the ith pixel of image B, and N is the number of pixels in picture in effective coverage。

The method that the present invention proposes uses the normalized correlation coefficient of consecutive frame, has calculating simplicity, efficient advantage。Not only it is greatly reduced follow-up analysis and the amount of calculation of auxiliary diagnosis, and follow-up analysis and the accuracy of auxiliary diagnosis can be improved。

Accompanying drawing explanation

Fig. 1 is image of the present invention backtracking property gate process chart。

Fig. 2 is image of the present invention backtracking property gate flow chart。

Detailed description of the invention

Below in conjunction with accompanying drawing, the present invention is elaborated。

It is block diagram and the flow chart of the automatic gate control method of the backtracking IVUS pictorial data of the present invention as shown in Figure 1 to Figure 2, a kind of gate control method aroused in interest based on image backtracking property ivus image of the present invention, including following 3 steps: estimate heart rate from IVUS view data；The determination of diastole end of term time point；Do gate process according to heart rate and diastole end of term point。

The detailed process of the inventive method:

Calculating the normalizated correlation coefficient of consecutive frame one by one, the normalization coefficient obtained is sequentially arranged, and becomes one-dimensional digital signal。The normalizated correlation coefficient computing formula of image is as follows:

$\mathrm{NC}(A,B)=-1\×\frac{{\mathrm{\Σ}}_{i=1}^N(A_i\·B_i)}{\sqrt{{\mathrm{\Σ}}_{i=1}^N}{A}_i^2\·{\mathrm{\Σ}}_{i=1}^N{B}_i^2};$

Normalizated correlation coefficient is carried out Fourier transformation, obtains the frequency spectrum of correlation coefficient；Searching the maximum of frequency spectrum within the scope of the preferred 60-100HZ of 50-110Hz scope, the frequency at place is the estimation of heart rate；According to the heart rate estimated, calculate the frame number that a cardiac cycle comprises, from the first frame of IVUS sequence image, in the scope of 1.1 cardiac cycles, search the maximum of normalizated correlation coefficient, in this, as the location point in first diastole end of term, obtain the first two field picture of gate output。

The process of described ivus image data estimation heart rate is: first gradually calculate the normalizated correlation coefficient between neighbor map picture frame, obtain the curve of similarity change between frame, then this one-dimensional signal is done discrete Fourier transform, identification cardiac cycle in domain space。

The process that described diastole end of term time point is determined is: according to the heart rate obtained, calculate the frame number that a cardiac cycle comprises, from the first frame of intravascular ultrasound image sequence image, the maximum of interframe normalizated correlation coefficient is searched in the scope of 1.1 cardiac cycles, in this, as the location point in the diastole end of term, obtain the first two field picture of gate output。

Described foundation heart rate and diastole end of term time point do the process of gate process: start with the position of the first two field picture, the maximum of interframe normalizated correlation coefficient is searched in the scope of next 1.1 cardiac cycles, obtain the second two field picture of gate output, by that analogy, until completing all of intravascular ultrasound image sequence, finally output gate image sequence。Select 1.1 cardiac cycles to be to compensate for the change of heart rate (10%) by a small margin, both improved the quality of gated image, and again the analysis of speckle had not been caused big impact。

The ultimate principle of the present invention and principal character and advantages of the present invention have more than been shown and described。Skilled person will appreciate that of the industry; the present invention is not restricted to the described embodiments; described in above-described embodiment and description is that principles of the invention is described; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements both fall within the claimed scope of the invention。Claimed scope is defined by appending claims and equivalent thereof。

Claims (4)

1. the gate control method aroused in interest based on image backtracking property ivus image, it is characterized in that, heart rate is estimated, it is determined that ivus image is done gate process and obtains gated image sequence by the time point in the diastole end of term foundation heart rate and diastole end of term time point according to ivus image；The process of described ivus image data estimation heart rate is: first gradually calculating the normalizated correlation coefficient between neighbor map picture frame, the normalization coefficient obtained is sequentially arranged, and becomes one-dimensional digital signal；Then this one-dimensional signal is done discrete Fourier transform, identification cardiac cycle in domain space；The process that described diastole end of term time point is determined is: according to the heart rate obtained, calculate the frame number that a cardiac cycle comprises, from the first frame of intravascular ultrasound image sequence image, the maximum of interframe normalizated correlation coefficient is searched in the scope of 1.1 cardiac cycles, in this, as the location point in the diastole end of term, obtain the first two field picture of gate output；Described foundation heart rate and diastole end of term time point do the process of gate process: start with the position of the first two field picture, the maximum of interframe normalizated correlation coefficient is searched in the scope of next 1.1 cardiac cycles, obtain the second two field picture of gate output, by that analogy, until completing all of intravascular ultrasound image sequence, finally output gate image sequence。

2. a kind of gate control method aroused in interest based on image backtracking property ivus image according to claim 1, it is characterized in that, described in domain space the method for identification cardiac cycle be: within the scope of heart rate 50-110 beat/min, the frequency spectrum of check image correlation coefficient, wherein the frequency at maximum place is the heart rate of this patient。

3. a kind of gate control method aroused in interest based on image backtracking property ivus image according to claim 1, it is characterized in that, described in domain space the method for identification cardiac cycle be: within the scope of heart rate 60-100 beat/min, the frequency spectrum of check image correlation coefficient, wherein the frequency at maximum place is the heart rate of this patient。

4. a kind of gate control method aroused in interest based on image backtracking property ivus image according to any one of claim 1-3, it is characterised in that the normalizated correlation coefficient between described adjacent two two field pictures is:

$NC\left(A,B\right)=-1\×\frac{{\Σ}_{i=1}^N\left(A_i,B_i\right)}{\sqrt{{\Σ}_{i=1}^N{A}_i^2\·{\Σ}_{i=1}^N{B}_i^2}}$

Wherein, Ai is the ith pixel of image A, and Bi is the ith pixel of image B, and N is the number of pixels in picture in effective coverage。