JP6203241B2 - Subject information acquisition apparatus, subject information acquisition method, and program - Google Patents

Description

  The present invention relates to a subject information acquisition apparatus, a subject information acquisition method, and a program. In particular, the present invention relates to a technique for acquiring subject information by transmitting an elastic wave to a subject and receiving a reflected wave reflected within the subject.

  In the ultrasonic diagnostic apparatus which is the object information acquisition apparatus, the spatial resolution in the depth direction when image data is formed by the pulse echo method is that the wavelength of the ultrasonic wave, which is an elastic wave, is λ, and the transmission wave number is n. It can be generally expressed as (nλ) / 2. For example, when two wavelengths of ultrasonic waves having a center frequency of 12 MHz are transmitted, the length is about 0.13 mm.

  The pulse echo method will be described. First, when an ultrasonic pulse is transmitted to the subject, the ultrasonic wave is reflected and returned according to the acoustic impedance difference in the subject. Next, the reflected wave is received, and image data is generated using the received signal of the reflected wave. Typically, an envelope of the waveform of the received signal is acquired, and the envelope is converted into a luminance value to generate image data. By displaying the obtained image, luminance information on the scanning line in the direction in which ultrasonic waves are transmitted and received can be obtained. By acquiring a plurality of pieces of luminance information on the scanning line, that is, by repeating transmission and reception of ultrasonic waves in a plurality of directions or positions within the subject, imaging within the subject becomes possible.

  As described above, the spatial resolution in the depth direction of about 0.13 mm can be realized by using the pulse echo method, but higher spatial resolution is required. For example, if the layer structure of the vascular wall of the carotid artery can be observed in more detail, it can be considered to contribute to early detection of arteriosclerosis and the like.

  As a technique for improving the spatial resolution in the depth direction, Non-Patent Document 1 applies a frequency domain interferometer method (FDI method: Frequency Domain Interferometry) and a Capon method, which is an adaptive signal processing, to create a layer of a blood vessel wall. The result of imaging the structure is shown. By applying the FDI method and the Capon method to the received signal, the spatial resolution in the depth direction (scanning line direction) can be further improved. However, it is assumed that there are a plurality of reflective layers in the range of signals in the depth direction (within the processing range) cut out for FDI processing. In addition, a plurality of reflected waves from adjacent reflective layers are highly likely to have high correlation. It is known that when an adaptive signal processing such as the Capon method is applied as it is to a plurality of reflected wave reception signals having high correlation, an unexpected operation such as cancellation of a desired signal is performed. By using the frequency averaging technique (frequency averaging technique), the influence of such a correlated wave (correlated interference wave) is reduced (suppressed), and the FDI method and the Capon method are applied to the received signal of the reflected wave. Applicable.

Hirofumi Taki, Kousuke Taki, Takuya Sakamoto, Makato Yamakawa, Tsuyoshi Shiina and Toru Sato: Conf Proc IEEE Eng Med Bio. 2010; 1: 5298-5301.

  However, when the FDI method and adaptive signal processing are applied to the received signal of the reflected wave, since the processing is performed for each scanning line, the degree of suppression of the correlation interference wave does not match between adjacent scanning lines. As a result, it has been found that there may be a portion where the continuity in the direction intersecting the scanning line is poor in the obtained image data.

  On the other hand, the spatial resolution in the direction intersecting with the scanning line changes depending on the convergence condition at the time of transmission and reception of elastic waves. In order to form an image without overlooking a minute reflector or the like existing in the observation region in the subject, the distance between the scanning lines (scanning line interval) is a direction intersecting the scanning lines in a general pulse echo method. Is set shorter than the spatial resolution. Therefore, when the FDI method and adaptive signal processing are not used, it is considered that the continuity between adjacent scanning lines does not become poor.

  That is, by using the FDI method and adaptive signal processing, the continuity in the direction intersecting the scanning line may be lower than that of a general image (an image generated by acquiring an envelope of a received signal). Arise. And the unique subject that visibility will fall if continuity becomes low arises. In view of the above problems, the present invention reduces the effect of image visibility degradation due to the difference in the degree of suppression of correlated interference waves for each scanning line when applying the FDI method and adaptive signal processing. Objective.

The subject information acquisition device of the present invention is a subject information acquisition device that acquires information in a subject using elastic waves propagated from within the subject, and outputs the information from a plurality of conversion elements that have received the elastic waves. Envelope acquisition means for acquiring an envelope using a plurality of electrical signals, and frequency domain interferometry and frequency averaging using the plurality of electrical signals output from the plurality of conversion elements that have received the elastic waves FDI adaptive processing means for performing adaptive signal processing using a method, calculating power intensity at each position on a plurality of scanning lines, and obtaining power intensity distribution; and power intensity acquired by the FDI adaptive processing means Correction means for correcting the power intensity distribution so that fluctuations in power intensity between the adjacent scanning lines are reduced in the direction intersecting the scanning lines with respect to the distribution, and corrected by the correcting means Possess an image processing means for generating image data based on the force strength or the envelope, the said correction means, the number of power intensity to perform the correction process, to change the focusing condition of the transmission and reception of the acoustic wave It is characterized by that.

The subject information acquisition method of the present invention is a subject information acquisition method for acquiring information in a subject using elastic waves propagated from within the subject, and is output from a plurality of conversion elements that have received the elastic waves. An envelope acquisition step of acquiring an envelope using a plurality of electrical signals, and a frequency domain interferometry method and a frequency average using the plurality of electrical signals output from the plurality of conversion elements that have received the elastic wave FDI adaptive processing step of performing adaptive signal processing using a method, calculating power intensity at each position on a plurality of scanning lines, and acquiring a power intensity distribution; and power intensity acquired by the FDI adaptive processing step relative distribution, in a direction crossing the scanning lines, a correction step of performing correction processing to the power intensity distribution as fluctuations in signal strength between the adjacent scanning lines becomes smaller, the correction stearate Has an image processing step of generating image data based on the corrected power strength or the envelope by flop, said correction step, the number of power intensity to perform the correction processing, transmission and reception of the acoustic wave It is characterized by changing according to the focusing condition .

  According to the present invention, it is possible to reduce the influence of a decrease in the visibility of an image due to a difference in the degree of suppression of a correlated interference wave for each scanning line.

It is a schematic diagram which shows the system outline | summary of the subject information acquisition apparatus by this invention. It is a flowchart explaining the process inside a FDI adaptive process means. It is the figure which showed typically the position of a plurality of scanning lines. It is a figure which shows the effect of the correction process of 1st Embodiment. It is a plot of power intensity distribution by a 1st embodiment. It is a figure which shows the effect of the correction process of 2nd Embodiment. It is a figure which shows the effect of the correction process of 3rd Embodiment. It is a schematic diagram which shows the system outline | summary of 5th Embodiment.

  Embodiments of the present invention will be described with reference to the drawings. In the present invention, the elastic wave is typically an ultrasonic wave, and includes an elastic wave called a sound wave, an ultrasonic wave, and an acoustic wave. The subject information acquisition device of the present invention is a device that transmits elastic waves to a subject, receives reflected waves reflected inside the subject (reflected elastic waves), and acquires subject information as image data. Including. The acquired subject information is information reflecting the difference in acoustic impedance of the tissue inside the subject.

  (Configuration of the subject information acquisition apparatus of the present invention) The configuration of the subject information acquisition apparatus of the present invention and the processing contents when the FDI method and adaptive signal processing are used will be described with reference to FIGS. . FIG. 1 is a schematic diagram showing a system outline of a subject information acquiring apparatus to which the present invention can be applied. The subject information acquisition apparatus of this embodiment includes a probe 001 having a plurality of conversion elements 002, a receiving circuit 005, a transmitting circuit 003, a phasing addition means 006, an FDI adaptive processing means 007, a scanning line data memory 008, and a correction. Means 009, image processing means 010, and system control unit 004.

  The transmission circuit 003 generates a transmission signal having a delay time and amplitude corresponding to the position of interest and the direction of interest in accordance with the control signal from the system control unit 004. This transmission signal is converted into an elastic wave by a plurality of conversion elements 002, and the elastic wave is transmitted into the subject. The elastic wave (reflected wave) reflected inside the subject 000 propagates through the subject, is received by the plurality of conversion elements 002, and is converted into a plurality of received signals (electric signals). The reception signal is input to the reception circuit 005. The receiving circuit 005 amplifies a plurality of received signals and converts them into a plurality of digital signals (digitized electrical signals). The digital signal output from the receiving circuit 005 is input to the phasing addition means 006. In the phasing addition means 006, delay processing is performed on a plurality of digital signals according to the direction and position in which the elastic wave is transmitted, and further addition, that is, phasing addition processing is executed. The signal subjected to the phasing addition processing is input to the FDI adaptive processing means 007.

  The frequency domain interferometer method (FDI method) is a method of estimating received power at a target position by decomposing a received signal for each frequency and changing the phase of the decomposed signal according to the target position. The amount of phase change can be determined in advance from the product of the distance from a certain reference position to the target position and the wave number corresponding to the frequency.

  The adaptive signal processing adaptively changes its processing parameter according to the received signal. The Capon method, which is one type of adaptive signal processing, is a method for processing a plurality of input signals so that power is minimized while the sensitivity related to the target position is fixed. In other words, the combination of the FDI method and adaptive signal processing is calculated according to the signal by adaptive signal processing instead of the predetermined phase change amount / weight for the received signal decomposed into each frequency component. The received power at the position of interest is estimated using the phase change amount / weight.

  Hereinafter, processing in the FDI adaptive processing unit 007 will be described with reference to FIG. The FDI adaptive processing unit 007 receives the signal subjected to phasing addition as an input signal (S200). A signal corresponding to the processing time, that is, a signal corresponding to the processing range is extracted from the signal (S201). The extracted signal is Fourier transformed and divided into components Xsk (Xs1, Xs2, Xs3,..., XsN) for each frequency (S202).

  On the other hand, a reference signal is input from the system control unit 004 (S203). This reference signal is subjected to Fourier transform and divided into frequency components Xrk (Xr1, Xr2, Xr3,..., XrN) (S204). The reference signal is a signal waveform of a reflected wave assumed to be returned from an interface (for example, a blood vessel wall) existing in the subject, and is stored in the system control unit 004. Then, the frequency components of the input signal and the reference signal are divided by each other, and whitening processing is performed (S205).

ここでＸｗｋ（ｋ＝１，２，・・・，Ｎ）はホワイトニング処理後の周波数ごとの成分、ηは安定化のための微小量、＊は複素共役を意味する。次に、ホワイトニング処理された各周波数成分からなるベクトルＸを用いて、相関行列Ｒを算出する（Ｓ２０６）。
Ｘ＝［ＸＷ１，ＸＷ２，・・・，ＸＷＮ］Ｔ
Ｒ＝ＸＸＴ＊
なおＴは転置を意味する。ここで相関行列ＲはＮ×Ｎのサイズを有する行列となる。
次に相関行列Ｒから部分行列を抽出し、それらを平均化する周波数平均法を適用する（Ｓ２０７）。

Here, Xwk (k = 1, 2,..., N) is a component for each frequency after whitening processing, η is a minute amount for stabilization, and * is a complex conjugate. Next, a correlation matrix R is calculated using a vector X composed of frequency components subjected to whitening processing (S206).
X = [XW1, XW2,..., XWN] T
R = XXX *
T means transposition. Here, the correlation matrix R is a matrix having a size of N × N.
Next, a frequency averaging method for extracting partial matrices from the correlation matrix R and averaging them is applied (S207).

Ｒｍｉｊ＝ＸＷ（ｉ＋ｍ−１）ＸＷ（ｊ＋ｍ−１）＊
Ｒ’は周波数平均相関行列、ＲｍはＲｍｉｊを要素に持つ相関行列Ｒの部分行列である。
このようにして周波数平均相関行列Ｒ’が算出される（Ｓ２０８）。

Rmij = XW (i + m−1) XW (j + m−1) *
R ′ is a frequency average correlation matrix, and Rm is a partial matrix of the correlation matrix R having Rmij as elements.
In this way, the frequency average correlation matrix R ′ is calculated (S208).

  Next, the constraint vector C is input (S209). The constraint vector C is a vector that changes according to the position r within the processing range, and is defined by the following equation.

C = [exp (jk1r), exp (jk2r),..., Exp (jk (N−M + 1)
r)]
The power intensity distribution P (r) within the processing range is calculated using the frequency average correlation matrix R ′ and the constraint vector C (S210).

η’Ｅは逆行列算出を安定させるために加算した対角行列である。

η′E is a diagonal matrix added to stabilize the inverse matrix calculation.

  As described above, the FDI adaptive processing unit 007 performs the FDI method and adaptive signal processing (here, the Capon method is used) with the signal subjected to phasing and addition as an input signal, and outputs a power intensity distribution. In the present invention, the acquired power intensity distribution indicates subject information reflecting a difference in acoustic impedance of tissues inside the subject.

  The output power intensity distribution is stored in the scanning line data memory 008. In this way, the received signal is processed for one elastic wave transmission, and the power intensity distribution for one scanning line is calculated and stored. By repeating this operation, the power intensity distributions of the plurality of scanning lines are stored in the scanning line data memory 008.

  Using the power intensity distributions of the plurality of scanning lines output from the scanning line data memory 008 as input, the correcting means 009 continues the power intensity distribution in the direction intersecting the scanning lines (typically, the direction perpendicular to the scanning lines). Correction is performed so that increases. That is, the correction unit 009 performs a correction process in which the fluctuation in power intensity between adjacent scanning lines is reduced in the direction intersecting the scanning lines. The image processing unit 010 performs various image processing such as edge enhancement and contrast adjustment in accordance with instructions from the system control unit 004 according to instructions from the power intensity distributions of the plurality of scanning lines that have been subjected to such correction, and luminance data (image Data). The image display unit 011 displays the input luminance data as an image. The image display unit 011 may be provided separately from the subject information acquisition apparatus of the present invention.

  The concept of the operation in the correction unit 009 will be described with reference to FIG. FIG. 3 is a diagram schematically showing the power intensity distribution on the scanning lines 301A to 301F. White circles on the scanning line indicate the power intensity at each position. As described above, generally, the spatial resolution in the direction intersecting the scanning lines (lateral direction in FIG. 3) is larger (longer) than the distance between the scanning lines. That is, the distribution of power intensity (for example, 302) in the direction intersecting with the scanning line changes gently. However, when the FDI method and adaptive signal processing are used, the degree of suppression of correlated interference waves differs from scan line to scan line, so the continuity of power intensity in the direction intersecting the scan line may be low. The correction unit 009 corrects the power intensity arranged in the direction intersecting the scanning line so that the fluctuation of the power intensity between the adjacent scanning lines is reduced, thereby improving the continuity.

  Thus, by increasing the continuity in the direction intersecting the scanning line, when using the FDI method and adaptive signal processing, not only the spatial resolution in the scanning line direction is improved, but also the visibility of the image is reduced. And a more stable and highly visible image can be obtained.

  In addition, the number of scanning lines to be corrected (that is, the number of power intensities to be corrected) is preferably changed according to the focusing condition at the time of transmission and reception of elastic waves. By performing the correction according to the present invention, the resolution in the direction intersecting the scanning line is lowered, so that the larger the number of scanning lines to be corrected, the better.

  Here, the spatial resolution in the direction crossing the scanning line varies depending on the focusing condition of the elastic wave. When the wavelength of the elastic wave is λ, the opening width of the plurality of conversion elements is D, and the distance in the depth direction (scanning line direction) is z, the convergence width can be expressed by 1.22 (λ / D) z. That is, the spatial resolution in the direction intersecting the scanning line is determined by the wavelength λ, the aperture width D, and the distance z in the depth direction.

  Therefore, in the present invention, when the spatial resolution determined by this focusing condition (setting condition of wavelength λ, aperture width D, depth direction distance z) is changed, it is preferable to change the number of power intensities to be corrected. Specifically, it is preferable that the number of power intensities to be corrected is a number in a range not more than twice the spatial resolution in the direction intersecting the scanning line. More preferably, the number of power intensities to be corrected is a number in a range equal to or lower than the spatial resolution in the direction crossing the scanning line.

Although the Capon method has been described here, the present invention can also be applied to other adaptive signal processing that requires the frequency averaging method to suppress the influence of correlated interference waves, the MUSIC method, the ESPRIT method, and the like. it can.
Hereinafter, embodiments of the subject information acquiring apparatus according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
In the first embodiment of the present invention, a mode in which processing is performed using the system shown in FIG. 1 will be described. Since the operation of the system is the same as described above, a description thereof will be omitted, and the operation of the correction unit 009 will be described.

  The correction unit 009 according to the present embodiment performs correction processing on the input power intensity distribution of the plurality of scanning lines. Signals indicating L scanning lines each having K-point power intensity information, which are input to the correction unit 009, are expressed as follows.

Y1 [s], Y2 [s],..., YL [s] (s = 1, 2,..., K)
Each electric power intensity has a positional relationship as shown in FIG.

  The correction unit 009 first performs correction processing to reduce the fluctuation of the power intensity distribution between adjacent scanning lines in the direction intersecting with the scanning line. First, the power intensity in the direction intersecting with the scanning line (for example, Y1 [5], Y2 [5], Y3 [5]. In the present embodiment, a correction process represented by the following equation is performed to obtain a new power intensity Yk ′. Hi is a coefficient set separately.

図４は本実施形態の補正手段による補正処理の効果を示す図である。縦軸は深さ方向（走査線方向）の距離を示し、横軸は、走査線と交差する方向の距離を示す。図４（Ａ）〜（Ｃ）は全て、豚大腿動脈からの反射波を受信して大腿動脈の血管壁を画像化した結果である。図４（Ｃ）は受信信号を包絡線検波することにより豚大腿動脈を画像化した結果（所謂Ｂモード像）である。図４中の４０１、４０２で示した位置がそれぞれ大腿動脈の血管壁である。図４（Ａ）は受信信号にＦＤＩ法及びＣａｐｏｎ法を適用した結果である。
走査線方向（画像の上下方向）の空間分解能が向上しているが、走査線ごとに相関性の抑圧の程度が異なるため、走査線と交差する方向（画像の左右方向）に連続性が乏しい部分が存在することが分かる。

FIG. 4 is a diagram showing the effect of the correction process by the correction means of this embodiment. The vertical axis represents the distance in the depth direction (scanning line direction), and the horizontal axis represents the distance in the direction intersecting the scanning line. FIGS. 4A to 4C are all the results of receiving the reflected wave from the porcine femoral artery and imaging the femoral artery blood vessel wall. FIG. 4C shows a result (so-called B-mode image) obtained by imaging the porcine femoral artery by performing envelope detection on the received signal. The positions indicated by 401 and 402 in FIG. 4 are the blood vessel walls of the femoral artery. FIG. 4A shows the result of applying the FDI method and Capon method to the received signal.
Although the spatial resolution in the scanning line direction (up and down direction of the image) has been improved, the degree of suppression of correlation differs for each scanning line, so the continuity is poor in the direction intersecting the scanning line (the left and right direction of the image) You can see that there is a part.

  FIG. 4B shows the result of correction processing using the coefficients h0 = h1 = h2 = h3 = h4 = 1 and w = 5 in the correction means of this embodiment. The spatial resolution in the scanning line direction (the vertical direction of the image) is higher than that in FIG. 4C, and the continuity in the direction intersecting the scanning line (the horizontal direction in the image) is higher than that in FIG. It can be seen that it has improved.

  FIG. 5 is a plot of the power intensity distribution of one scanning line (up and down direction of the image) in the image of FIG. Each plot shows a B-mode image (501) obtained by envelope detection, a result of applying the FDI method and the Capon method (502), and a processing result (503) according to the present embodiment. As can be seen from FIG. 5, even in the result of applying the present invention, the resolution in the scanning line direction is higher than that of a general B-mode image.

  As described above, according to the present embodiment, the FDI method and the Capon method are applied to improve the spatial resolution in the scanning line direction and to provide stable image data with high continuity in the direction intersecting the scanning line. be able to.

  Note that the correction processing of the correction unit in this embodiment operates as an FIR filter that performs smoothing on the power intensity distribution in the direction crossing the scanning line. As long as the coefficient has the performance as a smoothing filter, the same effect can be obtained even if the coefficient is uniform (rectangular) or other coefficients such as triangular, trapezoidal, and Gaussian. I can do it.

(Second Embodiment)
Also in the second embodiment of the present invention, a specific mode for performing processing using the system shown in FIG. 1 will be described. Since the operation of the system is the same as described above, a description thereof will be omitted, and the operation of the correction unit 009 will be described. The correction unit 009 according to the present embodiment performs a correction process represented by the following expression on the input power intensity distribution of the plurality of scanning lines.

図６は本実施形態の一例として、本実施形態の補正手段において［ａ１，ａ２，ａ３，ａ４，ａ５，ａ６］＝［１，０，０．６３３４，０，０．０５５７，０］，［ｂ０，ｂ１，ｂ２，ｂ３，ｂ４，ｂ５］＝［０．０５２８，０．２６３９，０．５２７９，０．２６３９，０．０５２８］の係数を用いて処理した結果である。図６より、走査線方向（画像の上下方向）の空間分解能は一般的なＢモード画像（図４（Ｃ））よりも高く、走査線と交差する方向（画像の左右方向）の連続性が図４（Ａ）よりも高まり、視認性が向上していることが分かる。

FIG. 6 shows, as an example of this embodiment, [a1, a2, a3, a4, a5, a6] = [1, 0, 0.6334, 0, 0.0557, 0], [ b0, b1, b2, b3, b4, b5] = [0.0528, 0.2639, 0.5279, 0.2639, 0.0528]. From FIG. 6, the spatial resolution in the scanning line direction (the vertical direction of the image) is higher than that of a general B-mode image (FIG. 4C), and the continuity in the direction crossing the scanning line (the horizontal direction of the image) is high. It can be seen that the visibility is improved as compared with FIG. 4A.

  As described above, according to the present embodiment, the FDI method and the Capon method are applied to improve the spatial resolution in the scanning line direction and provide stable image data with high continuity in the direction intersecting the scanning line. can do. Note that the correction processing in the correction unit 009 of this embodiment operates as an IIR filter that performs smoothing on the power intensity distribution in the direction intersecting the scanning line, and the coefficient has performance as a smoothing filter. If this is the case, the same effect can be obtained with other coefficients. As described above, by using the IIR filter in the correction process, it is possible to realize a more preferable filter characteristic and perform the correction process even with a small calculation load (the number of coefficients used in the calculation is small).

(Third embodiment)
Also in the third embodiment of the present invention, a mode in which processing is performed using the system shown in FIG. 1 will be described. Since the operation of the system is the same as described above, a description thereof will be omitted, and the operation of the correction unit 009 will be described.

  The correction means 009 according to this embodiment receives power intensity distributions of a plurality of scanning lines, and then receives power intensity in a direction intersecting the scanning lines (for example, Y1 [5], Y2 [5], Y3 [5],... Extract NX). The NX power intensities are rearranged in order of intensity. When NX is an even number, the NX / 2 + 1th power intensity is output, and when NX is an odd number, correction processing is performed to output the (NX + 1) / 2th power intensity. .

FIG. 7 shows the result of the correction processing performed with NX = 3 in the correction means of this embodiment.
The spatial resolution in the scanning line direction (the vertical direction of the image) is higher than that of a general B-mode image (FIG. 4C), and the continuity in the direction intersecting the scanning line (the horizontal direction of the image) is as shown in FIG. ) And the visibility is improved.

  As described above, according to the present embodiment, the FDI method and the Capon method are applied to improve the spatial resolution in the scanning line direction and provide a stable image with high continuity in the direction intersecting the scanning line. be able to. Note that the correction processing in the correction means in this embodiment operates as a median filter for the power distribution in the direction intersecting the scanning line, and a correction effect for smoothing is obtained.

(Fourth embodiment)
In the fourth embodiment according to the present invention, a mode in which processing is performed using the system shown in FIG. 1 will be described. Since the operation of the system is the same as described above, a description thereof will be omitted, and the operation of the correction unit 009 will be described.

  The correction unit 009 according to this embodiment receives power intensity distributions of a plurality of scanning lines, and then inputs power intensity in a direction intersecting the scanning lines (for example, Y1 [5], Y2 [5], Y3 [5],... Extract NX). A low-pass filter that applies a Fourier transform to the NX power intensity distributions and does not pass a frequency band higher than a predetermined frequency is applied.

  By applying this low-pass filter, the high frequency component can be cut in the direction intersecting the scanning line. That is, fluctuations in power intensity between adjacent scanning lines can be reduced in the direction intersecting the scanning lines.

  As described above, according to the present embodiment, as in the first to third embodiments, the FDI method and the Capon method are applied, the spatial resolution in the scanning line direction is improved, and the continuity in the direction intersecting the scanning line is further improved. Can provide a high and stable image.

(Fifth embodiment)
The present embodiment is characterized by having switching means for switching the input destination of the signal subjected to phasing addition. FIG. 8 is a system schematic diagram according to the fifth embodiment of the present invention. The description will focus on parts different from the first to fourth embodiments.

  The subject information acquisition apparatus of the present embodiment further includes a switching unit 701 and an envelope acquisition unit 702 in addition to the components described in FIG. The steps up to the point where the elastic wave is transmitted and received and the phasing addition processing is performed are the same as those in the first to fourth embodiments. In the present embodiment, the signal subjected to the phasing addition processing by the phasing addition means 006 is input to the switching means 701. The switching unit 701 outputs the input signal to the envelope acquisition unit 702 or the FDI adaptive processing unit 007 in accordance with an instruction from the system control unit 004.

  First, an operation when the switching unit 701 outputs a signal subjected to the phasing addition processing only to the envelope acquisition unit 702 will be described. The envelope acquisition unit 702 acquires the envelope of the input signal and outputs it to the scanning line data memory 008 as envelope data. Both the scanning line data memory 008 and the correction unit 009 pass the envelope data directly to the next unit, and finally inputs the envelope data to the image processing unit 010. The image processing unit 010 performs various image processing such as edge enhancement and contrast adjustment in accordance with instructions from the system control unit 004, and outputs luminance data (image data). The image display unit 011 displays the input luminance data as an image.

  Next, an operation when the switching unit 701 outputs a signal subjected to the phasing addition processing only to the FDI adaptive processing unit 007 will be described. In this case, the FDI adaptive processing unit 007, the scanning line data memory 008, and the correcting unit 009 perform correction processing for improving continuity in the direction in which the scanning lines are adjacent, as in the first to fourth embodiments.

  As described above, the correction unit 009 is not operated for the envelope data, and the correction unit 009 is operated for the power intensity distribution processed by the FDI adaptive processing unit 007, so that the power intensity distribution becomes continuous. Control is performed so that the correction is made. However, in the present embodiment, the envelope acquisition unit 702 and the image processing unit 010 may be connected. In this case, the envelope data is input to the image processing unit as it is.

  The system according to this embodiment may be set so that the system control unit 004 issues an instruction to the switching unit 701 according to, for example, an explicit instruction from the apparatus operator or an imaging mode selected by the operator. With such a setting, when importance is attached to the spatial resolution in the depth direction (for example, when measuring the thickness of the carotid artery blood vessel wall) or a conventional B-mode image (acquired using envelope detection) It is possible to cope with the case of comparing with (image).

  Further, in response to an instruction from the system control unit 004, an FDI method and adaptive signal processing in which a B-mode image that already has continuity is not subjected to correction processing more than necessary and there is a portion with poor continuity. Correction processing can be performed on image data to which the above are applied.

(Sixth embodiment)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. To be executed.

000 object 001 probe 002 conversion element 003 transmission circuit 004 system control unit 005 reception circuit 006 phasing addition means 007 FDI adaptive processing means 008 scanning line data memory 009 correction means 010 image processing means 011 image display systems 301A to 301F scanning Line 701 Switching means 702 Envelope acquisition means

Claims (16)

A subject information acquisition device that acquires information in a subject using elastic waves propagated from within the subject,
An envelope acquisition means for acquiring an envelope using a plurality of electrical signals output from a plurality of conversion elements that have received the elastic wave;
Frequency domain interferometry and adaptive signal processing using frequency averaging are performed using the plurality of electrical signals output from the plurality of transducers that have received the elastic wave, and at each position on a plurality of scanning lines. FDI adaptive processing means for calculating the power intensity of and acquiring the power intensity distribution;
For the power intensity distribution acquired by the FDI adaptive processing means, correction processing is performed on the power intensity distribution so that the fluctuation of the power intensity between the adjacent scanning lines is reduced in the direction intersecting the scanning line. Correction means;
Image processing means for generating image data based on the power intensity corrected by the correction means or the envelope; and
Have
The object information acquisition apparatus according to claim 1, wherein the correction unit changes the number of power intensities to be subjected to the correction process according to a focusing condition of the elastic wave transmission / reception.   The object information acquiring apparatus according to claim 1, wherein the number of power intensities for performing the correction processing is a number in a range that is not more than twice a spatial resolution in a direction intersecting the scanning line.   The object information acquiring apparatus according to claim 2, wherein the number of power intensities for performing the correction processing is a number in a range equal to or lower than a spatial resolution in a direction intersecting the scanning line.   The object information acquiring apparatus according to claim 1, further comprising a phasing addition unit configured to perform phasing addition of the plurality of electric signals.   5. The subject according to claim 4, further comprising switching means for switching so that an output of the phasing addition means is input to either the envelope acquisition means or the FDI adaptive processing means. Information acquisition device.   6. The subject according to claim 5, further comprising a switching selection unit that selects which of the envelope acquisition unit and the FDI adaptive processing unit the output of the phasing addition unit is input to. Information acquisition device.   7. The correction unit according to claim 1, wherein a smoothing filter, a median filter, or a low-pass filter is applied to the power intensity distribution in a direction crossing the scanning line as the correction process. 2. The subject information acquisition apparatus according to item 1.   The object information acquiring apparatus according to claim 1, wherein the FDI adaptive processing unit performs processing by a Capon method, a MUSIC method, or an ESPRIT method.   The object information acquiring apparatus according to claim 1, further comprising the plurality of conversion elements. A subject information acquisition method for acquiring information in a subject using elastic waves propagated from within the subject,
An envelope acquisition step of acquiring an envelope using a plurality of electrical signals output from a plurality of conversion elements that have received the elastic wave;
Frequency domain interferometry and adaptive signal processing using frequency averaging are performed using the plurality of electrical signals output from the plurality of transducers that have received the elastic wave, and at each position on a plurality of scanning lines. FDI adaptive processing step for calculating the power intensity of the power and obtaining the power intensity distribution;
The power intensity distribution acquired by the FDI adaptive processing step is corrected for the power intensity distribution so that the fluctuation of the power intensity between the adjacent scan lines is reduced in the direction crossing the scan line. A correction step;
An image processing step of generating image data based on the power intensity corrected by the correction step or the envelope; and
Have
In the correction step, the number of power intensities to be subjected to the correction process is changed according to a focusing condition for transmitting / receiving the elastic wave.   The object information acquiring method according to claim 10, wherein the number of power intensities for performing the correction processing is a number in a range equal to or less than twice a spatial resolution in a direction intersecting the scanning line.   The object information acquisition method according to claim 11, wherein the number of power intensities to be subjected to the correction processing is a number in a range equal to or lower than a spatial resolution in a direction intersecting the scanning line.   The object information acquiring method according to claim 10, further comprising a phasing addition step of phasing and adding the plurality of electrical signals.   14. In the correction step, as the correction process, a process based on a smoothing filter, a median filter, or a low-pass filter is applied to a power intensity distribution in a direction intersecting with the scanning line. The subject information acquisition method according to any one of the above.   The object information acquisition method according to claim 10, wherein the FDI adaptive processing step performs processing by a Capon method, a MUSIC method, or an ESPRIT method.   The program for making a computer perform each step of the subject information acquisition method of any one of Claims 10 thru | or 15.

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