JP2014108292A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic device capable of performing speckle tracking by executing compression coding of volume data while suppressing deterioration of tracking accuracy.SOLUTION: An ultrasonic diagnostic device (1) comprises: transmitting and receiving means (2) that receives a reception signal; a volume data acquisition part (3) that generates volume data having positional information and intensity as one set, in real time, on the basis of the reception signal; and tracking means (4) that tracks speckle from the generated volume data. The tracking means (4) comprises: a speckle extraction part (41) that extracts the speckle and a speckle range showing a prescribed range including the speckle, from the generated volume data; and coding parts (42 and 44) that code intensity data in the extracted speckle range. The coding parts (42 and 44) code the intensity data in the speckle range by using a threshold value that decreases with the increasing distance from a position of the speckle.

Description

  The present invention relates to an ultrasonic diagnostic apparatus.

  An ultrasonic wave is incident on the measurement part of the subject, a reception signal reflected from the measurement part is received, volume data is generated based on the reception signal, and the measurement part is indicated based on this. An ultrasonic diagnostic apparatus that displays an image is used.

  As an example of an image showing the measured part, as disclosed in Non-Patent Document 1, there is an image showing a heart wall in a white spot shape. Patent Document 1 discloses an ultrasonic diagnostic apparatus capable of performing speckle tracking in which volume data of this image is subjected to pattern matching processing to track the movement of such speckles. In such an ultrasonic processing apparatus, the wall motion of the heart in the myocardial region that is the measurement target can be obtained by speckle tracking.

JP 2011-177494 A

“Latest Echo Echo Artida ™ Advanced Wall Motion Analysis Technology” [online], May 2008, Tetsuya Kawagishi, [November 22, 2012 search], Internet (http: // www. innervision.co.jp/suite/toshiba/supplement/0805/01cardiac_2/index.html)

  Incidentally, the volume data includes at least position information and signal strength information, and has a large amount of data. The pattern matching process is a process that requires a large amount of calculation. Therefore, in order to perform speckle tracking by performing pattern matching processing on volume data, it is necessary to use a large-scale circuit. On the other hand, although it is conceivable to perform speckle tracking after coding volume data with a threshold and compressing the data, the tracking accuracy may be greatly deteriorated.

  The present invention has been made to solve such problems, and provides an ultrasonic diagnostic apparatus capable of performing speckle tracking by compressing and encoding volume data while suppressing deterioration in tracking accuracy. is there.

The ultrasonic diagnostic apparatus of the present invention is
A transmitter / receiver for transmitting an ultrasonic wave to the measured part and receiving a reception signal from the measured part;
Based on the received signal, a volume data acquisition unit that generates volume data with a set of position information and intensity momentarily;
An ultrasonic diagnostic apparatus including tracking means for tracking speckles from generated volume data,
The tracking means includes
A speckle extraction unit that extracts a speckle and a speckle range that is a predetermined range including the speckle from the generated volume data;
An encoding unit that encodes the intensity data of the extracted speckle range,
The encoding unit encodes the intensity data in the speckle range using a threshold value that decreases as the distance from the speckle position increases.

  With such a configuration, volume data can be compressed by using a threshold value. Further, since the threshold value decreases as the distance from the speckle position increases, the volume data can be compressed while the speckle characteristics remain accurately. That is, speckle tracking can be performed by compressing the volume data while suppressing deterioration in tracking accuracy.

An arbitrary time point when the volume data acquisition unit generates volume data is a first time point, and a time point after a predetermined time has passed from the first time point is a second time point.
The speckle extraction unit extracts speckles and speckle ranges at the first time point,
The encoding unit encodes the intensity data of the speckle range at the first time point and the second time point to obtain first code data and second code data,
The tracking means includes an alignment unit,
The alignment unit may perform alignment based on the first code data and the second code data.

  Furthermore, the speckle range may be limited to the xy plane and the yz plane. The speckle range may be limited to an xyz space. Further, the intensity data of the volume data of the predetermined position information may be encoded.

  According to the present invention, it is possible to provide an ultrasonic diagnostic apparatus capable of performing speckle tracking by compressing and encoding volume data while suppressing deterioration in tracking accuracy.

1 is a configuration diagram of an ultrasonic diagnostic apparatus according to an embodiment. It is explanatory drawing for demonstrating the extraction method of a speckle and the compression encoding of a speckle range. It is a mimetic diagram about an example of a speckle range speckle range in the 1st time. It is a figure which shows an example of a threshold value. It is explanatory drawing for demonstrating the compression encoding of the speckle range in a 2nd time. It is a schematic diagram about an example of the speckle range in a 2nd time. It is explanatory drawing for demonstrating a three-dimensional collective tracking system. It is a figure which shows an example of a speckle range.

(First embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. First, the configuration of the invention according to the first embodiment will be described with reference to FIG. FIG. 1 schematically shows a configuration of an ultrasonic diagnostic apparatus 1 connected to the information terminal 7.

  The ultrasonic diagnostic apparatus 1 is an ultrasonic diagnostic apparatus that can perform speckle tracking based on a reception signal obtained by transmitting / receiving ultrasonic waves to / from a measurement portion of a subject. As shown in FIG. 1, the ultrasound diagnostic apparatus 1 includes a transmission / reception unit 2, a volume data acquisition unit 3, a tracking unit 4, a control unit 5, and a storage unit 6.

  The transmission / reception means 2 includes a transmission unit 21, a probe 22, and a reception unit 23. The transmission / reception unit 2 functions as a transmission / reception unit that transmits ultrasonic waves to the measurement target and receives a signal reflected from the measurement target. Specifically, the transmission unit 21 receives a control signal from the control unit 5 to be described later, and appropriately supplies an electrical signal for causing the probe 22 to generate an ultrasonic wave. The probe 22 transmits the signal to the part to be measured and receives the signal reflected from the part to be measured. The receiving unit 23 receives a control signal from the control unit 5 to be described later, appropriately performs amplification processing and addition processing on the signal received by the probe 22, and outputs a reception signal.

  The volume data acquisition unit 3 generates volume data from the reception signal from the reception unit 23. Here, the obtained volume data includes at least data on position information and received signal strength.

  The tracking means 4 functions as means for tracking speckles from the generated volume data. The tracking means 4 includes a speckle extraction unit 41, a first compression encoding unit 42, a buffer 43, a second compression encoding unit 44, and an alignment unit 45.

  The speckle extraction unit 41 extracts a speckle range that is a predetermined range including speckles and speckles from the generated volume data.

  The first compression encoding unit 42 and the second compression encoding unit 44 encode the extracted speckle range intensity data using a threshold value that decreases as the speckle range moves away from the speckle position. Here, assuming that an arbitrary time point at which volume data is generated by the volume data acquisition unit is a first time point, and a time point after a predetermined time has elapsed from the first time point is a second time point, the first compression encoding unit 42 The intensity data in the speckle range at is encoded to obtain first code data. In addition, the second compression encoding unit 44 encodes the intensity data of the speckle range at the second time point to acquire the second code data.

  The buffer 43 temporarily stores the first code data and outputs it to the alignment unit 45 at an appropriate timing. The alignment unit 45 performs alignment based on the first code data and the second code data.

  The control unit 5 includes an arithmetic processing unit, a temporary storage unit, and the like (not shown). Further, the control unit 5 outputs a control signal for controlling the transmission unit 21 and the reception unit 23 according to a control program (described later) stored in the storage unit 6 as necessary.

  The storage unit 6 stores a control program for controlling the transmission unit 21 and the reception unit 23 of the ultrasonic diagnostic apparatus 1 and data on the speckle tracking result.

  The information terminal 7 is connected to the control unit 5 through an interface. The information terminal 7 is a personal computer including an input device such as a keyboard and a mouse (not shown) and an output device such as a liquid crystal display and a printer. The information terminal 7 receives a signal related to data on the speckle tracking result, and outputs the signal with an output device. As a result, the operator of the ultrasonic diagnostic apparatus 1 can check the speckle tracking result.

(Operation method)
Subsequently, the operation of the ultrasonic diagnostic apparatus 1 will be described with reference to FIG. 1 and FIGS. 2 to 6. Hereinafter, as an example, a case where speckle tracking is performed using a two-dimensional synthesis tracking method will be described. The two-dimensional synthesis tracking method is, for example, a method of obtaining a position change of speckles in two planes of an xz plane and a yz plane and obtaining a position change in the xyz space from the position change in these two planes. In the following, the operation for obtaining the speckle position change in the xz plane will be described first.

  FIG. 2 schematically shows a speckle extraction method and a compression encoding method at the first time point. FIG. 3 shows an example of the speckle range on the xz plane. FIG. 4 shows an example of the threshold value. FIG. 5 schematically shows a compression encoding method at the second time point. FIG. 6 shows a movement candidate range on the xz plane.

  In response to the control signal from the control unit 5, the transmission / reception means 2 receives the reception signal reflected from the measurement target part of the subject.

  Next, the volume data acquisition unit 3 generates volume data from moment to moment based on the received reception signal. The volume data here includes three-dimensional orthogonal coordinate data indicating the position of the speckle in the xyz space, and luminance data corresponding to the intensity data of the signal. The luminance data here is composed of, for example, 256 levels of data often used as luminance data, that is, 8-bit data.

  Next, the speckle extraction unit 41 extracts speckles. For example, as shown in FIG. 2, a portion that is higher than an arbitrary luminance value and that shows a maximum value in the vicinity thereof is selected and extracted as speckle. Here, the extracted speckle is defined as an extracted speckle.

この数式１により、輝度値Ｓ（i）が閾値Ａ（i）を上回ると「０」と符号化し、輝度値Ｓ（i）が閾値と同じ、又は、閾値Ａ（i）を下回ると「１」と符号化して圧縮符号化して、圧縮符号値ａ１、ａ２、…、ａ２４を得る。例えば、図２に示すように、スペックル範囲に含まれるＳ１１〜Ｓ１４について圧縮符号化して、１、１、１、０と圧縮符号値ａ１１〜ａ１４を得る。 Next, the first compression encoding unit 42 compresses and encodes the intensity data of the speckle range at the first time point using the threshold value based on the position data of the extracted speckles to obtain the first code data on the xz plane. Can do. For example, as shown in FIG. 3, the speckle range Sz is a pixel excluding the extracted speckle Sa out of a total of 25 points of 5 rows and 5 columns centered on the position of the extracted speckle Sa on the xz plane, that is, S1. , S2,..., S24. The luminance value S (i) corresponding to the intensity data is a luminance value at a distance i from the extracted speckle. The threshold value A (i) is a function having the distance i from the extracted speckle as a variable. Here, i is a function having at least the z coordinate value as a variable. The threshold value A (i) is a value that decreases as the distance from the speckle position increases. As the threshold A (i), for example, a function that shows a maximum value at a position where the distance i becomes 0, that is, a position of the extracted speckle, and decreases as the distance i increases can be used. As shown in FIG. 4, on the xz plane, the threshold value decreases as the distance from the extracted speckle position increases. As a function indicating the threshold A (i), for example, a Gaussian function, a triangle function, or a step function may be used. Compression encoding is performed using Equation 1 below.

According to Equation 1, when the luminance value S (i) exceeds the threshold value A (i), it is encoded as “0”, and when the luminance value S (i) is equal to the threshold value or falls below the threshold value A (i), “1”. ”And compression encoding to obtain compression code values a1, a2,..., A24. For example, as shown in FIG. 2, compression encoding is performed on S11 to S14 included in the speckle range to obtain 1, 1, 1, 0 and compression code values a11 to a14.

  Here, the compression code values a11 to a14 are two-stage data composed of “0” and “1”. That is, luminance data that is 256-stage data is converted into 2-stage code data by encoding. That is, it is possible to compress the volume data and obtain the first code data on the xz plane having a data capacity of 1/8 of the volume data. The obtained first code data of the xz plane is sent to the buffer 43.

  The buffer 43 temporarily stores the first code data on the xz plane and sends it to the alignment unit 45 according to the timing.

について、圧縮符号化を行う。つまり、この例では、移動可能範囲Ｃｚ、つまり、Ｓ７、Ｓ８、Ｓ９、Ｓ１２、Ｓａ、Ｓ１３、Ｓ１６、Ｓ１７、Ｓ１８のそれぞれ移動候補位置について圧縮符号化を行う。これにより、第２符号データを得る。これにより、それぞれの移動候補位置の計９点について、それぞれｂ１、ｂ２、…、ｂ２４を有する第２符号データを得ることができる。例えば、図５に示すように、移動候補位置をＳａとした場合、第２時点におけるスペックル範囲に含まれるＳ１１〜Ｓ１４について圧縮符号化して、１、１、１、０と圧縮符号値ｂ１１〜ｂ１４を得る。 The second compression encoding unit 44 compresses and encodes the intensity data of the range in which the extracted speckle can be moved from the first time point to the second time point (speckle range at the second time point) using a threshold value. The range in which the extracted speckle can move in advance from the first time point to the second time point may be, for example, a range having a luminance value exceeding a certain reference value. Here, as shown in FIG. 6, the movable range Cz here includes a total of nine points in three rows and three columns centering on the position of the speckle on the xz plane, and in detail, S7, S8, Let S9, S12, Sa, S13, S16, S17, and S18. Unlike the first compression encoding unit 42, the second compression encoding unit 44 uses a total of nine pieces of position data in place of the extracted speckles to determine the speckle range (movement candidate range) at the second time point. The intensity data is compression encoded using a threshold value. The threshold value A (j) is a function that uses the distance j from the movement candidate position as a variable instead of the extracted speckle. Compression encoding is performed using Equation 2 below.

Is compressed and encoded. That is, in this example, compression encoding is performed for each of the movable range Cz, that is, each of the movement candidate positions S7, S8, S9, S12, Sa, S13, S16, S17, and S18. As a result, second code data is obtained. Thereby, the second code data having b1, b2,..., B24 can be obtained for a total of nine points of the respective movement candidate positions. For example, as illustrated in FIG. 5, when the movement candidate position is Sa, compression encoding is performed on S11 to S14 included in the speckle range at the second time point, and 1, 1, 1, 0 and the compression code value b11 b14 is obtained.

この排他的論理和の和Ｋが最少となる第２符号データの移動候補位置を、第２時点におけるスペックルの移動位置と判定する。これにより、ｘｚ平面上の第２時点におけるスペックルの移動位置を求めることができる。同様に、上記した手順を行うことによって、ｙｚ平面上の第２時点におけるスペックルの移動位置を求めることができる。また、ｙｚ平面上及びｘｚ平面上の第２時点におけるスペックルの移動位置から、第１時点から第２時点におけるスペックルの移動位置の変化を求めることができる。このスペックル移動位置変化を繰り返し求めることで、スペックルトラッキングを行うことができる。圧縮符号化したデータを用いることで、ボリュームデータの時間経過に従う量の変動やノイズが生じても、ロバスト性を保持してスペックルトラッキングを行うことができる。スペックルトラッキングの結果は、制御部５を介して情報端末７の出力装置に出力され、操作者に確認される。 The alignment unit 45 can perform, for example, correlation processing on the first code data and the second code data, and performs alignment. First, the following formula 3 is used to obtain the sum K of exclusive OR at each point between the first code data and the second code data at each movement candidate position.

The movement candidate position of the second code data that minimizes the exclusive OR sum K is determined as the speckle movement position at the second time point. Thereby, the speckle movement position at the second time point on the xz plane can be obtained. Similarly, the speckle movement position at the second time point on the yz plane can be obtained by performing the above-described procedure. Further, the change in the speckle movement position from the first time point to the second time point can be obtained from the speckle movement position at the second time point on the yz plane and the xz plane. Speckle tracking can be performed by repeatedly obtaining this speckle movement position change. By using the compression-encoded data, speckle tracking can be performed while maintaining robustness even if fluctuations in the amount of volume data and noise occur with the passage of time. The result of the speckle tracking is output to the output device of the information terminal 7 via the control unit 5 and confirmed by the operator.

  As described above, according to the present invention, volume data can be compressed by using a threshold value. Further, since the threshold value decreases as the distance from the speckle position increases, the volume data can be compressed while the speckle characteristics remain accurately. That is, speckle tracking can be performed by compressing the volume data while suppressing deterioration in tracking accuracy. Thereby, speckle tracking can be performed in real time. Further, even if a small circuit is used, a sufficient processing speed can be secured and speckle tracking can be performed. Furthermore, with the miniaturization of the circuit, the power consumption of the ultrasonic diagnostic apparatus can be reduced. On the other hand, since compression-coded data is used, it has robustness against fluctuations in volume and noise over time of volume data.

  Next, speckle tracking by the two-dimensional synthesis tracking method has been described. Hereinafter, a method called a three-dimensional batch tracking method will be described. FIG. 7 is an explanatory diagram for explaining the three-dimensional collective tracking method. As shown in FIG. 7, the three-dimensional collective tracking method is a method for obtaining a change in position by performing correlation processing in a lump in the xyz space. Here, if the number of pixels on one side of the speckle range and the movement candidate range is M, the number N for calculating the sum K of exclusive OR is M × M × M−1. On the other hand, in the speckle tracking by the two-dimensional synthesis tracking method, the number N for calculating the sum K of exclusive OR is M × M−1. For example, if M is 5, the number N is 24 in speckle tracking by the two-dimensional synthetic tracking method, while the number N is 124 in speckle tracking by the three-dimensional collective tracking method. Although the amount of computation increases compared to the above-described two-dimensional synthesis tracking method, the volume data is compressed and encoded, so after sufficiently ensuring the computation processing speed required for speckle tracking, Tracking accuracy can be increased.

  Note that the intensity data of the volume data of the predetermined position information may be encoded. For example, as shown in FIG. 8, out of a total of 81 points of 9 rows and 9 columns centering on the position of the extracted speckle Sa on the xz plane, the volume data is thinned out every other piece and compressed and encoded. Also good. That is, as shown in FIG. 8, the speckle range in this example may be a total of 24 points of S1, S2,.

  In the present embodiment, as an example, an ultrasonic diagnostic apparatus including one tracking unit has been described. However, an ultrasonic diagnosis apparatus including a large number of tracking units 4 depending on the number of speckles to be extracted and the size of the speckle range. A sonic diagnostic apparatus may be used. Thereby, speckle tracking can be performed for a large number of speckles. Further, the second compression encoding unit 44 may be provided more than the first compression encoding unit 42 and may be connected in parallel. With such an ultrasonic diagnostic apparatus, it is possible to perform calculation at a higher processing speed and suppress speckle tracking while suppressing deterioration in tracking accuracy.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

1 ultrasonic diagnostic apparatus, 2 transmission / reception means, 3 volume data acquisition unit,
4 tracking means, 5 control unit, 6 storage unit, 7 information terminal,
21 transmitting unit, 22 probe, 23 receiving unit,
41 speckle extraction unit, 42 first compression encoding unit, 43 buffer,
44 2nd compression encoding part, 45 Position alignment part

Claims (5)

A transmitter / receiver for transmitting an ultrasonic wave to the measured part and receiving a reception signal from the measured part;
Based on the received signal, a volume data acquisition unit that generates volume data with a set of position information and intensity momentarily;
An ultrasonic diagnostic apparatus including tracking means for tracking speckles from generated volume data,
The tracking means includes
A speckle extraction unit that extracts a speckle and a speckle range that is a predetermined range including the speckle from the generated volume data;
An encoding unit that encodes the intensity data of the extracted speckle range,
The ultrasonic diagnostic apparatus, wherein the encoding unit encodes the intensity data in the speckle range using a threshold value that decreases as the distance from the speckle position increases. An arbitrary time point when the volume data acquisition unit generates volume data is a first time point, and a time point after a predetermined time has passed from the first time point is a second time point.
The speckle extraction unit extracts speckles and speckle ranges at the first time point,
The encoding unit encodes the intensity data of the speckle range at the first time point and the second time point to obtain first code data and second code data,
The tracking means includes an alignment unit,
The ultrasonic diagnostic apparatus according to claim 1, wherein the alignment unit performs alignment based on the first code data and the second code data.   The ultrasonic diagnostic apparatus according to claim 1, wherein the speckle range is limited to an xy plane and a yz plane.   The ultrasonic diagnostic apparatus according to claim 1, wherein the speckle range is limited to an xyz space.   The ultrasonic diagnostic apparatus according to claim 1, wherein intensity data of volume data of predetermined position information is encoded.

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