CN103961141A - Imaged based backtracking intravascular ultrasound (IVUS) image heart-beating gating method - Google Patents

Abstract

The invention discloses an imaged based backtracking intravascular ultrasound (IVUS) image heart-beating gating method. The backtracking IVUS image heart-beating gating method includes estimating heat rate according to an IVUS image, determining a time point at the end of diastole and subjecting the IVUS image to gating processing to obtain a gating image sequence according to the heart rate and the time point at the end of diastole. The imaged based backtracking intravascular ultrasound image heart-beating gating method adopts correlation coefficient of normalization of consecutive frames, realizes gating of IVUS data under the condition of loss of synchronous electrocardio signals, and has the advantages of convenience and efficiency in calculation. Not only is calculation amount of subsequent analysis and auxiliary diagnosis greatly reduced but accuracy of the same can be improved.

Description

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

Technical field

The present invention relates to image processing method, be specifically related to the auto-door controlling method of a kind of property recalled intravascular ultrasound (Intravascular Ultrasound, 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In IVUS checking process, conduit uniform speed slow is withdrawn from, and speed is generally 0.5～1mm/s, and frame speed is 30f/s, and typical longitudinal resolution is tens microns of left and right.So high longitudinal resolution makes the similarity of consecutive frame high.Once withdraw from and can obtain several thousand two field pictures, it is many that document size can reach hundreds of M to 1G.So large data volume, has proposed high requirement to the hardware configuration of computer and software development, has brought greatly challenge to follow-up processing and analysis.And, because conduit withdraws constantly beating of process cardiac, make IVUS image produce and beat in the axial direction.Observe blood vessel, present periodically wavyly, reacted beating of heart.High longitudinal resolution makes the similarity of consecutive frame also very high.Therefore, clinically can be in the process that IVUS gathers the electrocardiogram (ECG) data of record patient simultaneously, then adopt the method for ecg-gating, only extract the frame in the diastole end of term, reach the object of removing heart beating impact and reduction data volume.With conduit, withdraw speed 1mm/s, 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, and is convenient to follow-up processing and analysis.

But, in current clinical practice, usually ignored the synchronous acquisition of electrocardiogram (ECG) data, the historical data of much recalling Journal of Sex Research does not have synchronous acquisition electrocardiogram (ECG) data yet, has gone to greatly the basis that relies on electrocardio to do gate.Therefore, be starved of a kind ofly when there is no synchronous electrocardiosignal, can do to IVUS the method for heart beat cycle gate.

Summary of the invention

In order to solve the deficiencies in the prior art, observe IVUS image, can find, although the similarity degree of consecutive frame is very high, be subject to the impact that cardiac cycle is beated, the similarity degree of image consecutive frame also there will be periodic variation.Therefore, the present invention proposes a kind of gate control method of the property the recalled IVUS view data based on image.

Technical scheme of the present invention is: a kind of gate control method aroused in interest based on the image property recalled ivus image, according to ivus image estimation heart rate, determine the time point in the diastole end of term and according to heart rate and diastole end of term time point, ivus image done to gate processing to obtain gate image sequence.

Further improvement of the present invention comprises:

The process of described ivus image data estimation heart rate is: first successively calculate the normalizated correlation coefficient between adjacent image frame, obtain the curve that between frame, similarity changes, then this one-dimensional signal is done to discrete Fourier transform, identification cardiac cycle on frequency domain space.

Described on frequency 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 this patient's heart rate.

Described on frequency 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 this patient's heart rate.

The definite process of described diastole end of term time point is: according to the heart rate obtaining, calculate the frame number that a cardiac cycle comprises, from the first frame of ivus image sequence image, in the scope of 1.1 cardiac cycles, search the maximum of interframe normalizated correlation coefficient, using this location point as the diastole end of term, obtain the first two field picture of gate output.

Describedly according to heart rate and diastole end of term time point, do the process that gate processes and be: the position with the first two field picture starts, in the scope of next 1.1 cardiac cycles, search the maximum of interframe normalizated correlation coefficient, obtain the second two field picture of gate output, by that analogy, until complete all ivus image sequences, finally export 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, i the pixel that Ai is image A, i the pixel that Bi is image B, N is the number of pixels in effective coverage in picture.

The method that the present invention proposes is used the normalized correlation coefficient of consecutive frame, has calculating easy, efficiently advantage.Not only greatly reduce follow-up analysis and the amount of calculation of auxiliary diagnosis, and can improve follow-up analysis and the accuracy of auxiliary diagnosis.

Accompanying drawing explanation

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

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

The specific embodiment

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

Block diagram and the flow chart of the auto-door controlling method of the property recalled 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 the image property recalled ivus image of the present invention, comprises following 3 steps: from IVUS view data, estimate heart rate; Determining of diastole end of term time point; According to heart rate and diastole end of term point, doing gate processes.

The detailed process of the inventive method:

Calculate one by one the normalizated correlation coefficient of consecutive frame, the normalization coefficient obtaining is arranged in turn, becomes one dimension 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 to Fourier transformation, obtain the frequency spectrum of correlation coefficient; Within the scope of the preferred 60-100HZ of 50-110Hz scope, search the maximum of frequency spectrum, the frequency at place is the estimation of heart rate; According to the heart rate of estimating, 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, using this location point as 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 successively calculate the normalizated correlation coefficient between adjacent image frame, obtain the curve that between frame, similarity changes, then this one-dimensional signal is done to discrete Fourier transform, identification cardiac cycle on frequency domain space.

The definite process of described diastole end of term time point is: according to the heart rate obtaining, calculate the frame number that a cardiac cycle comprises, from the first frame of ivus image sequence image, in the scope of 1.1 cardiac cycles, search the maximum of interframe normalizated correlation coefficient, using this location point as the diastole end of term, obtain the first two field picture of gate output.

Describedly according to heart rate and diastole end of term time point, do the process that gate processes and be: the position with the first two field picture starts, in the scope of next 1.1 cardiac cycles, search the maximum of interframe normalizated correlation coefficient, obtain the second two field picture of gate output, by that analogy, until complete all ivus image sequences, finally export gate image sequence.Selecting 1.1 cardiac cycles is in order to compensate the heart rate variation of (10%) by a small margin, has both improved the quality of gate image, again the analysis of speckle is not caused to large impact.

More than show and described ultimate principle of the present invention and principal character and advantage of the present invention.The technical staff of the industry should understand; the present invention is not restricted to the described embodiments; that in above-described embodiment and description, describes just illustrates principle of the present invention; 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 all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.

Claims (7)

1. the gate control method aroused in interest based on the image property recalled ivus image, it is characterized in that, according to ivus image estimation heart rate, determine the time point in the diastole end of term and according to heart rate and diastole end of term time point, ivus image done to gate processing to obtain gate image sequence.

2. a kind of gate control method aroused in interest based on the image property recalled ivus image according to claim 1, it is characterized in that, the process of described ivus image data estimation heart rate is: first successively calculate the normalizated correlation coefficient between adjacent image frame, obtain the curve that between frame, similarity changes, then this one-dimensional signal is done to discrete Fourier transform, identification cardiac cycle on frequency domain space.

3. a kind of gate control method aroused in interest based on the image property recalled ivus image according to claim 2, it is characterized in that, described on frequency 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 this patient's heart rate.

4. a kind of gate control method aroused in interest based on the image property recalled ivus image according to claim 2, it is characterized in that, described on frequency 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 this patient's heart rate.

5. a kind of gate control method aroused in interest based on the image property recalled ivus image according to claim 1, it is characterized in that, the definite process of described diastole end of term time point is: according to the heart rate obtaining, calculate the frame number that a cardiac cycle comprises, from the first frame of ivus image sequence image, in the scope of 1.1 cardiac cycles, search the maximum of interframe normalizated correlation coefficient, using this location point as the diastole end of term, obtain the first two field picture of gate output.

6. a kind of gate control method aroused in interest based on the image property recalled ivus image according to claim 1, it is characterized in that, describedly according to heart rate and diastole end of term time point, do the process that gate processes and be: the position with the first two field picture starts, in the scope of next 1.1 cardiac cycles, search the maximum of interframe normalizated correlation coefficient, obtain the second two field picture of gate output, by that analogy, until complete all ivus image sequences, finally export gate image sequence.

7. according to a kind of gate control method aroused in interest based on the image property recalled ivus image described in claim 2-6 any one, it is characterized in that, the 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, A _ifor i pixel of image A, B _ifor i pixel of image B, N is the number of pixels in effective coverage in picture.