CN103735284B - Based on RF signal estimation method in the three-D ultrasonic elastogram of linear scanning - Google Patents

Abstract

The invention discloses a method for estimating RF signals in three-dimensional ultrasonic elastography based on linear scanning, which includes the following steps: first, the position of the RF signal to be estimated is obtained from the RF signal sequence scanned by a linear moving probe; and then the distance to the RF signal to be estimated is obtained The distance-weighted average of the amplitudes of the two closest RF signals before and after is taken as its amplitude, and the phase of the RF signal closest to the RF signal to be estimated is taken as its phase, and the RF signal to be estimated is calculated by using its amplitude and its phase. The method of the invention can solve the problem of inhomogeneous collected RF signals caused by different moving speeds of the probes, and the method is simple and practical.

Description

RF signal estimation method in 3D ultrasound elastography based on linear scan

technical field

The invention relates to the technical field of computer-aided medical imaging, in particular to a method for estimating RF signals in three-dimensional ultrasonic elastography based on linear scanning.

Background technique

Ultrasound elastography is a new ultrasonic diagnostic technology that can image the hardness information of tumors and diffuse diseases that cannot be detected by traditional ultrasound. In three-dimensional ultrasound elastography, a simple scanning method is linear scanning (see the published patent for details: a scanning device and method for three-dimensional ultrasound elastography, publication number: CN102908166A), this scanning method is By fixing the ultrasonic probe on a linear slide rail with a position sensor, moving the probe along the slide rail to scan and collect signals and record the position of the probe.

Because it is difficult for the human hand to control the uniform movement of the probe, the collected signal will be denser in some positions and sparse in other positions, and usually there will be a signal at a certain position before compression but no signal after compression. situation. When calculating the elastic image, if only the two nearest neighbor signals in the two sets of signal sequences collected before compression and after compression are used as matching signals, the calculation result is not very accurate.

Therefore, in linear scanning 3D ultrasound elastography, a reasonable and effective RF signal estimation method is needed if more accurate elastic images are to be obtained.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and provide a method for estimating RF signals in three-dimensional ultrasonic elastography based on linear scanning, which can be used to solve the matching problem of signals before and after compression, and make the imaging effect better.

The purpose of the present invention is achieved through the following technical solutions:

The RF signal estimation method in the three-dimensional ultrasound elastography based on linear scanning comprises the steps in the following sequence:

1) Obtain the position of the RF signal to be estimated from the RF signal sequence obtained by scanning the linear moving probe;

2) Take the distance-weighted average of the two RF signal amplitudes closest to the RF signal to be estimated as its amplitude, take the phase of the RF signal closest to the RF signal to be estimated as its phase, and use its amplitude and phase to calculate the target estimated RF signal.

Described step 2) specifically comprises the following steps:

a. The position of the RF signal to be estimated is x, and the two RF signals RF(a) and RF(b) closest to x are taken, where a and b indicate the position of the signal, a<x<b;

b. Perform Hilbert transform on RF(a), obtain its amplitude amp(a) and its phase ang(a), perform Hilbert transform on RF(b), obtain its amplitude amp(b) and its phase ang(b );

Taking the distance-weighted average of the magnitudes of the two is $A=\frac{b-x}{b-a}.\mathrm{amp}\left(a\right)+\frac{x-a}{b-a}.\mathrm{amp}\left(b\right);$

Take the phase of the closest to x among the two as φ=ang(i), i=a or b;

The signal to be estimated is calculated using the formula RF(x)=A·cos(φ).

In step 1), the RF signal sequence is a pre-compressed RF signal sequence or a compressed RF signal sequence.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The method of the invention is simple and applicable, can estimate the signal at any position between two adjacent signals, and can effectively solve the problem of inhomogeneous collected signals caused by changes in the moving speed of the probe during the linear scanning process. In addition, the weighted average of amplitude and distance can make the signal to be estimated closer to the real information.

Description of drawings

Fig. 1 is the flow chart of the RF signal estimation method in the three-dimensional ultrasound elastography based on linear scanning according to the present invention;

Fig. 2 is the processing schematic diagram of the method described in Fig. 1;

Fig. 3 is two RF signals of adjacent positions of the method described in Fig. 1 and the RF signal to be estimated between these two signals;

Fig. 4 is a three-dimensional ultrasonic elastic image obtained by the method described in Fig. 1 .

detailed description

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

As shown in Figures 1, 2, and 3, the RF signal estimation method in 3D ultrasound elastography based on linear scanning includes the following sequential steps:

1) Obtain the position x of the RF signal to be estimated from the RF signal sequence scanned by the linear moving probe, wherein the RF signal sequence is the RF signal sequence before compression or the RF signal sequence after compression;

2) As shown in Figure 3, a, the position of the RF signal to be estimated is x, take the two RF signals RF(a) and RF(b) closest to x, where a and b indicate the position of the signal, a<x< b;

b. Perform Hilbert transform on RF(a), obtain its amplitude amp(a) and its phase ang(a), perform Hilbert transform on RF(b), obtain its amplitude amp(b) and its phase ang(b );

Taking the distance-weighted average of the magnitudes of the two is $A=\frac{b-x}{b-a}.\mathrm{amp}\left(a\right)+\frac{x-a}{b-a}.\mathrm{amp}\left(b\right);$

Take the phase of the closest to x among the two as φ=ang(i), i=a or b;

The signal to be estimated is calculated using the formula RF(x)=A·cos(φ).

Since each signal frame contains many signals, in order to estimate a frame of signals, each signal must be estimated separately, and the estimation method of each signal is the same, repeating steps 1) and 2) until the complete signal at x is estimated One frame of signal, and finally get the final three-dimensional ultrasonic elastic image, as shown in Figure 4, the image is clearly visible, which effectively solves the problem of signal mismatch between before and after compression caused by the difficulty in keeping the probe moving uniformly.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (3)

1. RF signal estimation method in the three-dimensional ultrasound elastography based on linear scanning, it is characterized in that: comprise the step of following order: 1) Obtain the position of the RF signal to be estimated from the RF signal sequence obtained by scanning the linear moving probe; 2) Take the distance-weighted average of the two RF signal amplitudes closest to the RF signal to be estimated as its amplitude, take the phase of the RF signal closest to the RF signal to be estimated as its phase, and use its amplitude and phase to calculate the target estimated RF signal. 2. RF signal estimation method in the three-dimensional ultrasonic elastography based on linear scanning according to claim 1, is characterized in that: described step 2) specifically comprises the following steps: a. The position of the RF signal to be estimated is x, and the two RF signals RF(a) and RF(b) closest to x are taken, where a and b indicate the position of the signal, a<x<b; b. Perform Hilbert transform on RF(a), obtain its amplitude amp(a) and its phase ang(a), perform Hilbert transform on RF(b), obtain its amplitude amp(b) and its phase ang(b ); Taking the distance-weighted average of the magnitudes of the two is Take the phase of the closest to x among the two as φ=ang(i), i=a or b; The signal to be estimated is calculated using the formula RF(x)=A·cos(φ). 3. RF signal estimation method in the three-dimensional ultrasonic elastography based on linear scan according to claim 1, is characterized in that: in step 1), described RF signal sequence is the RF signal sequence before compression or RF after compression signal sequence.