Abstract:
An ultrasonic Doppler diagnosis device having a velocity data interpolating section for generating interpolated velocity data for interpolating velocity data between two sound lines and two scanning lines, using the velocity data at the intersections. The velocity data interpolating section converts two scalar arrays of unsigned numeric data corresponding to a first and second numeric values to signed arrays of numeric data using a data converting section and generates the interpolated velocity data based on the converted signed array of numeric data, when a result of identification obtained from an identifying section indicates that one of the first and second numeric values has a positive velocity smaller than a first threshold value corresponding to a positive velocity, and the other of the first and second numeric values has a negative velocity greater than a second threshold value corresponding to a negative velocity.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims benefit of Japanese Application No. 2006-346271 filed in Japan on Dec. 22, 2006, and, No. 2007-245696 filed in Japan on Sep. 21, 2007, the contents of which are incorporated by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ultrasonic Doppler diagnosis device for measuring the velocity of a kinetic reflector such as a blood flow within a living body. 
     2. Description of the Related Art 
     An ultrasonic Doppler diagnosis device has been known for measuring a blood flow velocity within a living body, for example. When such an ultrasonic Doppler diagnosis device displays a two-dimensional Doppler view to represent spatial distribution of a velocity of a kinetic reflector such as a blood flow, the device passes a Doppler shift signal through an autocorrelator, obtains an average frequency from complex output data from the autocorrelator by an operation, and spatially interpolates the calculated average frequency for display. 
     However, there is a problem in that for frequency aliasing caused around a Nyquist frequency decided depending on a sampling frequency of a Doppler shift signal, a maximum value of a positive velocity (bright red) and a maximum value of a negative velocity (bright blue) are averaged, so that an average frequency is interpolated in incorrect data (a dark color with a velocity being approximately 0) where bright blue or bright red should be interpolated in the correct way. 
     In order to solve the problem as above, for example, Japanese Patent Laid-Open No. 2678124 proposes an ultrasonic Doppler diagnosis device to solve disadvantages of data interpolation due to frequency aliasing by obtaining complex interpolation data of each pixel between scanning lines and by operating velocity data from an argument of the complex interpolation data. 
     SUMMARY OF THE INVENTION 
     An ultrasonic Doppler diagnosis device according to the present invention comprises: ultrasonic transceiver means for emitting and scanning an ultrasonic wave and for transmitting and receiving the wave to a kinetic reflector; velocity data calculating means for extracting a Doppler shift signal using an ultrasonic signal from the kinetic reflector transmitted and received by the ultrasonic transceiver means, and for calculating velocity data at an intersection of a sound line and a scanning line of the kinetic reflector; velocity data interpolating means for interpolating the velocity data between the sound line and the scanning line and generating the interpolated velocity data; and color image generating means for generating a color flow mapping image of the kinetic reflector based on the velocity data and the interpolated velocity data, in which the velocity data interpolating means includes numeric value determining means for determining a plurality of values of the velocity data and the interpolated velocity data, and if a result of the determination is a pre-determined determination result based on the determination result of the numeric value determining means, the velocity data and the interpolated velocity data are converted to a first numeric value array to generate interpolated velocity data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram showing configuration of an ultrasonic Doppler diagnosis device according to a first embodiment of the present invention; 
         FIG. 2  is a block diagram showing configuration of an interpolation processing unit in  FIG. 1 ; 
         FIG. 3  is a block diagram showing configuration of first to third interpolation processing circuits in  FIG. 2 ; 
         FIG. 4  is a first illustrative drawing illustrating action of the interpolation processing unit in  FIG. 2 ; 
         FIG. 5  is a second illustrative drawing illustrating the action of the interpolation processing unit in  FIG. 2 ; 
         FIG. 6  is a drawing illustrating an example of color palette array representation of velocity data of the ultrasonic Doppler diagnosis device in  FIG. 1 ; 
         FIG. 7  is a drawing illustrating conversion of representation between the scalar array representation and the color palette array representation of the velocity data in  FIG. 6 ; 
         FIG. 8  is a drawing illustrating an example of scalar array representation of velocity data by the representation conversion in  FIG. 7 ; 
         FIG. 9  is a first illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 ; 
         FIG. 10  is a second illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 ; 
         FIG. 11  is a third illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 ; 
         FIG. 12  is a fourth illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 ; and 
         FIG. 13  is a fifth illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following will describe an embodiment of the present invention with reference to the drawings. 
     First Embodiment 
       FIGS. 1 to 13  relate to a first embodiment of the present invention.  FIG. 1  is a configuration diagram showing configuration of an ultrasonic Doppler diagnosis device.  FIG. 2  is a block diagram showing configuration of an interpolation processing unit in  FIG. 1 .  FIG. 3  is a block diagram showing configuration of first to third interpolation processing circuits in  FIG. 2 .  FIG. 4  is a first illustrative drawing illustrating action of the interpolation processing unit in  FIG. 2 .  FIG. 5  is a second illustrative drawing illustrating the action of the interpolation processing unit in  FIG. 2 .  FIG. 6  is a drawing illustrating an example of color palette array representation of velocity data of the ultrasonic Doppler diagnosis device in  FIG. 1 .  FIG. 7  is a drawing illustrating conversion of representation between the scalar array representation and the color palette array representation of the velocity data in  FIG. 6 .  FIG. 8  is a drawing illustrating an example of scalar array representation of velocity data by the representation conversion in  FIG. 7 .  FIG. 9  is a first illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 .  FIG. 10  is a second illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 .  FIG. 11  is a third illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 .  FIG. 12  is a fourth illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 .  FIG. 13  is a fifth illustrative drawing illustrating action of the first interpolation processing circuit in  FIG. 3 . 
     As shown in  FIG. 1 , an ultrasonic Doppler diagnosis device  1  according to the present embodiment includes a probe  2  for transmitting and receiving an ultrasonic wave to/from a living body (not shown). The probe  2  connects to a transceiver circuit  5  for transmitting an electric signal to the living body (not shown) in a pre-determined repeating cycle, and for receiving a received signal of the probe  2  that receives a reflected wave reflected by a kinetic reflector such as a blood flow within the living body. 
     The transceiver circuit  5  herein is configured to scan an ultrasonic pulse beam emitted from the probe  2  by mechanical or electrical angle deflection, for example, and to periodically scan a living body by the ultrasonic pulse beam or to stop the scan by a desired deflection angle. 
     The ultrasonic Doppler diagnosis device  1  further comprises a B-mode image generating circuit  7  for detecting a received signal received by the transceiver circuit  5  and generating a B-mode image, a Doppler image generating unit  6  for generating a Doppler image by color flow mapping (CFM), and a synthetic circuit  8  for displaying a synthesized image on a monitor, in which the synthesized image is produced by synthesization of the B-mode image and the Doppler image. 
     The Doppler image generating unit  6  includes a quadrature detection circuit  11  for assigning the received signal received by the transceiver circuit  5  to orthogonal coordinates. The quadrature detection circuit  11  connects to A/D converters  12  and  13  for converting an output of the quadrature detection circuit  11  to digital data. 
     The quadrature detection circuit  11  herein performs known quadrature detection processing on an inputted analog signal to output two signals that include only shift frequencies and have phases differing from each other by 90° to the A/D converters  12  and  13 . 
     The ultrasonic Doppler diagnosis device  1  also includes, in post-stages of the A/D converters  12  and  13 , memories  14  and  15  that store the converted digital data, MTI (Moving Target Indicator) filters  16  and  17  for removing a component that moves at a low velocity such as a living body from the digital data stored in the memories  14  and  15  using known processing, and for outputting I data (In Phase data) and Q data (Quadrature data) of a kinetic reflector, and an autocorrelation circuit  18  for performing complex autocorrelation processing on the I data and Q data from the MTI filters  16  and  17 . 
     The Doppler image generating unit  6  further comprises a velocity arithmetic circuit  19  for calculating the velocity of a blood flow, for example, from the processed signal subjected to the complex autocorrelation processing by the autocorrelation circuit  18 , an interpolation processing unit  20  for interpolating the velocity data calculated by the velocity arithmetic circuit  19 , and a DSC (digital scan converter)  21  for converting a value of the velocity data from the interpolation processing unit  20  to a brightness value depending on the velocity to output a Doppler color image to the synthetic circuit  8 . 
     The interpolation processing unit  20  is configured by three interpolation processing circuits, i.e., first to third interpolation processing circuits  20   a ,  20   b  and  20   c , as shown in  FIG. 2 . The interpolation processing unit  20  will be described later in detail. 
     Each of the first to third interpolation processing circuits  20   a ,  20   b  and  20   c  is configured by a data identifying unit  51 , a data converting unit  52 , a data interpolating unit  53 , a data reconverting unit  54  and four switches SW 1  to SW 4 , as shown in  FIG. 3 . The first to third interpolation processing circuits  20   a ,  20   b  and  20   c  will be described later in detail. 
     Next, action of the present embodiment configured as described in the above will be described. The ultrasonic Doppler diagnosis device  1  according to the present embodiment transmits an ultrasonic pulse from the transceiver circuit  5  via the probe  2  in a pre-determined repeating cycle, and receives a reflected wave emitted from the transceiver circuit  5  and reflected by a kinetic reflector such as a blood flow. 
     The reflected wave received by the transceiver circuit  5  is further detected by the quadrature detection circuit  11 . A Doppler shift signal detected by the quadrature detection circuit  11  is digitized by the A/D converters  12  and  13  and stored in the memories  14  and  15 . 
     Then, I data (In Phase data) and Q data (Quadrature data) of a kinetic reflector are extracted from the Doppler shift signal stored in the memories  14  and  15  by the MTI filters  16  and  17 , and sent to the autocorrelation circuit  18 . The autocorrelation circuit  18  obtains an argument from the I data and Q data, and outputs calculated argument data to the velocity arithmetic circuit  19 . The velocity arithmetic circuit  19  calculates velocity data of a kinetic reflector such as a blood flow from the argument data, and outputs the calculated velocity data to the interpolation processing unit  20 . 
     The interpolation processing unit  20  performs interpolation processing on the velocity data, as described later. An output from the interpolation processing unit  20  is converted to two-dimensional coordinates by the DSC  21 , synthesized with a B-mode image from the B-mode image generating circuit  7  by the synthetic circuit  8 , and displayed on a monitor  3 . 
     The interpolation processing unit  20  will be described herein. Suppose that velocity data at intersections where sound lines and scanning lines intersect are x 00 , x 01 , x 10  and x 11 , as shown in  FIG. 4 . First, the interpolation processing unit  20  calculates velocity data u 0  at a position (coordinates) between the intersections from velocity data: x 00  of an intersection (sound line position, scanning line position) (Line, Point) and velocity data: x 01  of an intersection (sound line position, scanning line position)=(Line, Point+1) in the first interpolation processing circuit  20   a  by the first to third interpolation processing circuit  20   a ,  20   b  and  20   c  (see  FIG. 2 ) by performing interpolation operation using the following equation (1) by interpolation processing, as shown in  FIG. 5 .
 
 u 0=(1−α)× x 00+α× x 01= x 00+α×( x 01− x 00)  (1)
 
     Similarly, the second interpolation processing circuit  20   b  calculates velocity data u 1  at a position (coordinates) between the intersections from velocity data: x 10  of an intersection (sound line position, scanning line position)=(Line+1, Point) and velocity data: x 11  of an intersection (sound line position, scanning line position)=(Line+1, Point+1) by performing interpolation operation using the following equation (2) by interpolation processing.
 
 u 1=(1−α)× x 10+α× x 11= x 10+α×( x 11− x 10)  (2)
 
     Then, the third interpolation processing circuit  20   c  performs interpolation processing on the velocity data u 0  and the velocity data u 1 , and calculates velocity data v 0  between the velocity data u 0  and the velocity data u 1  by performing interpolation operation using the following equation (3):
 
 v 0=(1−β)× u 0+β× u 1= x 00+β×( u 1− u 0)  (3)
 
     In the above equations, α is a correction coefficient at a sound line position and β is a correction coefficient at a scanning line position. 
     As described in the above, the velocity arithmetic circuit  19  calculates velocity data of a kinetic reflector such as a blood flow from argument data. Conceptually describing, if complex vectors P 1  and P 2  including I data and Q data of a kinetic reflector are as shown in  FIG. 6 , velocity data k 1  and k 2  are calculated from arguments φ 1  and φ 2  of the respective complex vectors P 1  and P 2 . 
     Specifically, according to standard ultrasonic Doppler display, if a blood flow gets close at an intersection (sound line position, scanning line position), velocity data is represented in red; if a blood flow gets away, velocity data is represented in blue; and a level of the velocity is represented by brightness, as shown in  FIG. 7 . Meanwhile, argument data contains sign information indicating positive or negative in the highest-order bit of the data, so that argument data in a red region is represented correspondently to 0 to +π in the brightness: dark to bright, while argument data in a blue region is represented correspondently to 0 to −π in brightness: dark to bright. 
     Hereinafter, such an array of signed numeric data (a left array in  FIG. 7 ) is referred to as a color palette array. 
     On the other hand, the velocity arithmetic circuit  19  does not handle the highest-order bit as a sign contrary to the argument data containing a sign, but as a numeric value to calculate velocity data. Specifically, if argument data is −π/2 (in a blue region), for example, then a highest-order bit indicating a sign is “1” so that velocity data as numeric value data containing a sign is “−63”, while velocity data considering a sign as a part of a numeric value is “191”. If argument data is +π/2 (in a red region), then a highest-order bit indicating a sign is “0” so that velocity data as numeric value data containing a sign is “+63”, while velocity data considering a sign as a part of a numeric value is “63”. Argument data is represented as an array of unsigned numeric data (hereinafter, a scalar array) as shown in a right side in  FIG. 7  based on unsigned numeric data being velocity data considering a sign as a part of a numeric value. The velocity arithmetic circuit  19  handles unsigned numeric data of the scalar array as velocity data. 
     The complex vectors P 1  and P 2  based on the scalar array are shown in  FIG. 8 . In  FIG. 8 , arguments (φ 1 , φ 2 ) of the complex vectors P 1  and P 2  shown in  FIG. 6  are represented as arguments (−(π−φ 1 ), π−φ 2 ). 
     Hereinafter, a numeric value representing velocity data considering a sign as a part of a numeric value (unsigned numeric data) is underlined. Meanwhile, a numeric value representing numeric value data containing a sign (signed numeric data) is attached with a sign (+ or −). 
     As shown in  FIG. 9 , if one of two velocity data is a value of 233 within “192 to 255 (+π/2 to +π): darker blue side”, for example, and the other is a value of 43 within “0 to 63 (−π to π/2): darker red side”, for example, in a scalar array, then when the first interpolation processing circuit  20   a  of the interpolation processing unit  20  performs interpolation processing on the two velocity data, a value of 131 is calculated as a result of the interpolation. The result is different from a result of interpolation based on the original vector operation, as shown in  FIGS. 10 and 11 . 
     The above description is not limited to the first interpolation processing circuit  20   a , but the second and third interpolation processing circuits  20   b  and  20   c  also act similarly. Hereinafter, the first interpolation processing circuit  20   a  will be described as an example. 
     According to the present embodiment, as shown in  FIG. 9 , the first interpolation processing circuit  20   a  judges whether or not one of velocity data of two inputted scalar arrays is a value of “192 to 255 (+π/2 to +π): darker blue side” and the other is a value of “0 to 63 (−π to −π/2): darker red side” by the data identifying unit  51  (see  FIG. 3 ). 
     If the circuit  20   a  judges one is a value of “192 to 255 (+π/2 to +π): darker blue side” and the other is a value of “0 to 63 (−π to −π/2): darker red side”, the data identifying unit  51  (see  FIG. 3 ) controls the switches SW 1  to SW 4  (see  FIG. 3 ) to convert two scalar arrays of velocity data to color palette arrays of velocity data by the data converting unit  52  (see  FIG. 3 ), and outputs the result to the data interpolating unit  53  (see  FIG. 3 ). In that case, the data interpolating unit  53  interpolates the velocity data based on vector operation on complex spaces in the color palette arrays, as shown in  FIGS. 12 and 13 . Then, based on the velocity data interpolated in the data interpolating unit  53 , the data reconverting unit  54  (see  FIG. 3 ) reversely converts the velocity data from the color palette arrays to scalar arrays to output the result as an interpolation processing result of the first interpolation processing circuit  20   a.    
     Otherwise, if the circuit  20   a  judges that one is not a value of “192 to 255 (+π/2 to +π): darker blue side”, and the other is not a value of “0 to 63 (−π to −π/2): darker red side”, then the data identifying unit  51  (see  FIG. 3 ) outputs two scalar arrays of velocity data to the data interpolating unit  53  (see  FIG. 3 ) without causing the data converting unit  52  (see  FIG. 3 ) to perform conversion processing. In that case, the data interpolating unit  53  interpolates the velocity data based on vector operation on complex spaces in the scalar arrays to output the result as an interpolation processing result of the first interpolation processing circuit  20   a , as shown in  FIGS. 12 and 13 , for example. 
     As described in the above, according to the present embodiment, after the data identifying unit  51  determines a value of velocity data, the data converting unit  52 , the data interpolating unit  53  and the data reconverting unit  54  switch between vector operation on a complex space based on a scalar array and vector operation on the complex space based on a color palette array to execute interpolation processing. As such, according to the present embodiment, aliasing disadvantages in interpolation processing on velocity data can be surely solved using an interpolating circuit of known and simple conventional circuit configuration through simple numeric value determination processing. 
     The present invention is not limited to the above embodiment, but various changes or modifications are possible without departing from the scope of the present invention. 
     Having described the preferred embodiments of the invention referring to the accompanying drawings, it should be understood that the present invention is not limited to those precise embodiments and various changes and modifications thereof could be made by one skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims.