JP2015213536A - Image processor and x-ray diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel art which suppresses artifacts due to movement of a subject before and after administration of a contrast medium in DSA (Digital Subtraction Angiography).SOLUTION: An image processor in one embodiment includes a selection part, a positional deviation calculation part and an image generation part. The selection part selects one of respective contrast image data (after administration of a contrast medium) or mask image (before administration of the contrast medium) as a positional deviation correction target when generating a DSA image, on the basis of selection input, an image processing condition or a photographing condition for the image processor. The positional deviation calculation part calculates a positional deviation having occurred due to movement of a subject before or after administration of the contrast medium between the contrast image data and the mask image data, on the basis of the contrast image data and the mask image data. The image generation part generates a DSA image by calculating each difference between each of the contrast image data and the mask image data, while shifting the object for correcting the positional deviation on the basis of the positional deviation.

Description

  Embodiments described herein relate generally to an image processing apparatus and an X-ray diagnostic apparatus.

  In recent years, DSA (Digital Subtraction Angiography) images have been used as data for grasping the blood vessel structure in a subject. A DSA image is obtained by, for example, imaging the same region of a subject with an X-ray diagnostic apparatus or the like in time series before and after administration of a contrast medium. Specifically, a plurality of difference images corresponding to each time phase obtained by subtracting the mask image from each time phase contrast image after contrast medium administration are DSA images.

  In addition, the said contrast image is the meaning of the image containing a contrast agent, and the said mask image is an image before contrast agent administration used as a reference | standard. The X-ray diagnostic apparatus detects the intensity of X-rays that have passed through the subject using, for example, a large number of detection elements arranged in a matrix, and reflects the amount of X-ray transmission for each detection element as the density of each pixel. This is an image diagnostic apparatus for generating a processed image.

As a technique for suppressing motion artifacts when a subject moves during imaging for generating a DSA image, for example, a technique called pixel shift described in Patent Document 1 is known. This technique suppresses body motion artifacts in the DSA image by shifting the mask image.
Shifting the contrast image has the same effect, but shifting the contrast image may cause loss of fine blood vessel information. Interpolation processing is generally applied during the shift, because this interpolation processing has the effect of reducing high-frequency signals. Therefore, when the blood vessel information is observed, the contrast image is not shifted by the motion correction.

  In addition, a technique called Functional Imaging has attracted attention in recent years. In Functional Imaging, a temporal change profile of contrast agent concentration is created for each pixel through a plurality of time-series DSA images, and each parameter for evaluating blood flow information is calculated based on this profile. For example, in a parameter called TTP (Time To Peak), the time phase DSA image in which the contrast agent concentration reaches the peak is calculated for each pixel.

JP 2003-250087 A

  Consider a case in which a subject moves during imaging for DSA images in Functional Imaging. In this case, even if a DSA image is generated by shifting the mask image using the method of Patent Document 1 to suppress body movement artifacts, the temporal change in contrast agent concentration at each same position in the subject is accurately calculated. Can not. This is because, for example, when the amount of movement of the subject P is different for each time phase of a plurality of contrast images, a change in contrast agent concentration over time can be created from data in different regions in the subject.

  For this reason, in DSA, a new technique for suppressing artifacts due to movement of the subject before and after contrast medium administration has been desired.

Hereinafter, several examples of the modes that the embodiments of the present invention can take will be described for each mode.
(1) In one embodiment, the image processing device includes mask image data that is image data of a subject before contrast medium administration and a plurality of time-series image data after contrast agent administration to the same subject. A DSA image is generated based on a plurality of contrast image data. The image processing apparatus includes a selection unit, a positional deviation calculation unit, and an image generation unit.
The selection unit selects one of a plurality of contrast image data or mask image data as a position shift correction target at the time of generating a DSA image based on a selection input to the image processing apparatus, an image processing condition, or an imaging condition.
The positional deviation calculation unit calculates a positional deviation caused by the movement of the subject before and after the contrast medium administration between the plurality of contrast image data and the mask image data based on the plurality of contrast image data and the mask image data. To do.
The image generation unit calculates each difference between the contrast image data and the mask image data while shifting the position shift correction target based on the position shift among the plurality of contrast image data or mask image data. Then, image data of a plurality of time-series DSA images is generated.

(2) In another embodiment, the image processing apparatus includes: mask image data that is image data of a subject before contrast medium administration; and a plurality of time-series image data after contrast medium administration for the same subject. A DSA image is generated based on a plurality of contrast image data. The image processing apparatus includes an image generation unit and a blood flow analysis unit.
The image generation unit generates image data of a plurality of time-sequential DSA images based on each difference between the contrast image data and the mask image data.
The blood flow analysis unit selects one of the plurality of DSA images as a reference time phase by analyzing the amount of arterial information included in the plurality of DSA images or by acquiring a selection input to the image processing apparatus. Further, the blood flow analysis unit minimizes the sum of squares of pixel values or the sum of absolute values of pixel values in a difference image between each time phase DSA image and a reference time phase DSA image. The shift amount for each time phase DSA image is calculated. Further, the blood flow analysis unit shifts the pixel position for each time phase based on the calculated shift amount, and contrasts for each pixel corresponding to the same position of the subject over a plurality of time-series DSA images. The time change of the agent concentration is calculated.

(3) In another embodiment, an X-ray diagnostic apparatus includes an X-ray imaging unit and the image processing apparatus according to (1) or (2).
The X-ray imaging unit detects X-rays transmitted through the subject before and after the contrast agent administration, thereby providing mask image data indicating an X-ray image before the contrast agent administration and a plurality of time series after the contrast agent administration. And a plurality of contrast image data respectively representing the X-ray images.
The image processing device generates image data of a plurality of DSA images based on the plurality of contrast image data and the mask image data.

(4) In another embodiment, the server displays at least one image diagnostic apparatus that generates mask image data and a plurality of contrast image data by imaging before and after contrast medium administration, and the transferred image data as an image. A server for a medical image archiving communication system connected to a display terminal, which includes an image archiving unit and the image processing apparatus according to (1) or (2).
The image storage unit stores mask image data and a plurality of contrast image data generated by the image diagnostic apparatus.
The image processing apparatus generates image data of a plurality of DSA images based on the plurality of contrast image data and mask image data acquired from the image storage unit, and transfers the image data of the DSA images to the display terminal.

The block diagram which shows an example of a structure of the X-ray diagnostic apparatus in 1st Embodiment. The schematic diagram which shows an example of the method of calculating the time change of contrast agent density | concentration for every pixel from the image data of a DSA image, and several examples of the blood flow analysis parameter calculated by the blood flow analysis part. FIG. 6 is a schematic explanatory diagram of a method for calculating a positional deviation between a mask image and a contrast image when Functional Imaging is not executed. FIG. 6 is a schematic diagram of a mask image and a contrast image when a positional shift amount is different for each time phase. FIG. 7 is a schematic explanatory diagram of a method for calculating a positional deviation between a mask image and a contrast image when Functional Imaging is executed. The flowchart which shows an example of operation | movement of the X-ray diagnostic apparatus of 1st Embodiment. The flowchart which shows an example of operation | movement of the X-ray diagnostic apparatus of 2nd Embodiment. FIG. 10 is a schematic diagram illustrating an example of an algorithm of an image processing apparatus that selects one reference image from DSA images of all time phases in the third embodiment. FIG. 10 is a schematic diagram illustrating an example of a method for defining a shift amount between a DSA image of each time phase and a DSA image of a reference time phase in the third embodiment. The schematic diagram which shows an example of the production | generation algorithm of the time change curve of the contrast agent density | concentration in 3rd Embodiment. The flowchart which shows an example of operation | movement of the X-ray diagnostic apparatus of 3rd Embodiment. The block diagram which shows an example of a structure of the image storage communication system in 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the first to third embodiments, an example in which the image processing apparatus of the present invention is mounted on an X-ray diagnostic apparatus will be described. In the fourth embodiment, the workstation of the image storage communication system (image processing server) An example in which an image processing apparatus is mounted will be described. In addition, in each figure, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

<First Embodiment>
FIG. 1 is a block diagram showing an example of the configuration of the X-ray diagnostic apparatus 10 according to the first embodiment. As shown in FIG. 1, the X-ray diagnostic apparatus 10 includes an operation unit 22, an image analysis device 24, a system control unit 26, a projection data storage unit 28, a projection data generation unit 30, and an X-ray detector 34. A C arm 36, a top plate 38, an aperture device 40, an X-ray tube 42, a high voltage generator 44, an aperture control mechanism 46, a top plate moving mechanism 48, a C arm operating mechanism 50, And a detector moving mechanism 54.

  Since the main feature of the X-ray diagnostic apparatus 10 is the function of the image analysis apparatus 24, the functions of the image analysis apparatus 24 will be described in detail after briefly describing the functions of the other components.

A subject P is placed on the top plate 38.
The C arm 36 is an arm that holds the X-ray tube 42, the diaphragm device 40, and the X-ray detector 34. By the C arm 36, the X-ray tube 42, the diaphragm device 40, and the X-ray detector 34 are arranged to face each other with the subject P interposed therebetween.

The high voltage generator 44 generates a high voltage and supplies the generated high voltage to the X-ray tube 42.
The X-ray tube 42 generates X-rays using the high voltage supplied from the high voltage generator 44.

  The diaphragm device 40 narrows the generated X-rays so as to be selectively irradiated to the imaging region of the subject P by sliding a plurality of diaphragm blades, for example.

  The aperture control mechanism 46 controls the X-ray irradiation range by adjusting the aperture of the aperture blades of the aperture device 40.

  The X-ray detector 34 converts, for example, the X-rays transmitted through the subject P into an electrical signal by using a large number of X-ray detection elements arranged in a matrix, and accumulates the accumulated electrical signal. To enter.

  The projection data generation unit 30 generates projection data of the imaging region using the electrical signal input from the X-ray detector 34 and stores the generated projection data in the projection data storage unit 28. The projection data is, for example, image data of an X-ray image in which each pixel has one pixel value, and each pixel value of the projection data reflects the X-ray transmittance of the imaging region of the subject.

  Here, as an example, the same region of the subject P (that is, the same region in the apparatus coordinate system of the X-ray diagnostic apparatus 10) when it is assumed that the subject P does not move on the top plate 38 is before and after contrast agent administration. The movement of the subject P is corrected after the imaging. An X-ray image at each time phase after administration of the contrast agent is referred to as a contrast image, and projection data of the contrast image is referred to as contrast image data. Further, an X-ray image before contrast medium administration used as a reference is referred to as a mask image, and projection data of the mask image is referred to as mask image data.

  The mask image may be an average image of a plurality of X-ray images before administration of the contrast agent, or may be one X-ray image taken at the instant of contrast agent administration (time t0). This is because the contrast agent does not reach the subject instantaneously after administration, and the pixel value at time t0 when the contrast agent is administered is equal to the pixel value before administration of the contrast agent.

  The operation unit 22 includes a monitor, a keyboard, operation buttons, and the like for the operator to input various commands such as shooting conditions, and transfers the input contents to the system control unit 26.

  The system control unit 26 controls the entire X-ray diagnostic apparatus 10 in setting of imaging conditions, imaging operation, and display processing.

Next, each component of the image analysis device 24 will be described.
The image analysis device 24 includes a system bus SB, a selection unit 24a, a positional deviation calculation unit 24b, an image generation unit 24c, a blood flow analysis unit 24d, and a GUI (Graphical User Interface) 24e.

  The system bus SB is a communication wiring that electrically connects the components of the image analysis device 24 to each other.

  The selection unit 24a, the positional deviation calculation unit 24b, and the image generation unit 24c generate DSA images in which artifacts due to movement of the subject P before and after contrast agent administration are suppressed.

  Specifically, the selection unit 24a shifts one of the plurality of contrast image data or mask image data at the time of DSA image generation based on the selection input to the image processing device 24, the image processing conditions, or the imaging conditions. Select as correction target.

  The positional deviation calculation unit 24b calculates a positional deviation caused by the movement of the subject P before and after the contrast agent administration between the contrast image data and the mask image data based on the acquired image data.

  The image generation unit 24c calculates each difference between the contrast image data and the mask image data while shifting the position shift correction target based on the position shift among the plurality of contrast image data or mask image data. Image data of a plurality of time-series DSA images is generated.

  The GUI 24e includes a monitor for the operator to input various commands, operation buttons, and the like, and accepts selection input and image processing condition input to the image processing device 24. The selection input to the image processing device 24 is an input for selecting one of a plurality of contrast image data or mask image data as a position shift correction target (shift target) when the DSA image is generated.

  When Functional Imaging is selected as the image processing condition, the blood flow analysis unit 24d calculates the value of the blood flow analysis parameter based on the image data of a plurality of time-series DSA images generated by the image generation unit 24c. To do. The blood flow analysis parameters will be described with reference to FIG.

  FIG. 2 is a schematic diagram illustrating an example of a method for calculating the temporal change in contrast agent concentration for each pixel from the image data of the DSA image, and several examples of blood flow analysis parameters calculated by the blood flow analysis unit 24d. is there. The upper part of FIG. 2 shows a DSA image of each time phase, and the lower part of FIG. 2 shows an example of a temporal change in contrast agent concentration focusing on one pixel.

  For example, by imaging with the X-ray diagnostic apparatus 10, for the same region of the same subject P, time t = 0 before contrast medium administration, time t = 1, 2, 3, 4, 5 after contrast medium administration Consider the case where the projection data generation unit 30 generates the projection data of 6 X-ray images in order.

  When motion correction is omitted, each difference image between each contrast image after administration of a contrast agent and a mask image at t = 0 is generated, thereby corresponding to t = 1, 2, 3, 4, 5 respectively. Image data of a frame DSA image is obtained (see the upper part of FIG. 2). In the upper part of FIG. 2, t = 1 is time phase 1 (Time Phase 1), and t = 2 is time phase 2 (Time Phase 2) (the same applies hereinafter).

  The DSA image as the difference image is generated, for example, by calculating a difference based on a natural logarithm for each pixel as in the following equation.

In equation (1), i in (i, j) indicates what row of pixels as image coordinates, and j indicates what column of pixels. Further, DSA _n (i, j) on the left side of the expression (1) indicates the pixel value of the pixel in the i-th row and the j-th column in the DSA image in the n-th frame (n-th phase). Similarly, contrast _n (i, j) on the right side of equation (1) indicates the pixel value of the pixel in the i-th row and j-th column in the n-th frame contrast image. Similarly, mask (i, j) indicates the pixel value of the pixel in the i-th row and j-th column in the mask image. The above description is the same for the expressions (2) to (6) described later.

  The blood flow analysis unit 24d calculates the temporal change of the pixel value (from t = 1 to 5) for each pixel at the same position through the five-frame DSA image, thereby calculating the temporal change in the contrast agent concentration for each pixel. calculate. The lower part of FIG. 2 shows an example of temporal change in contrast agent concentration focusing on one pixel at the lower left of each DSA image (in this example, the number of pixels is 5 × 5). In the lower part of FIG. 2, the vertical axis indicates the contrast medium concentration (Intensity of Contrast Medium) normalized by the peak value, and the horizontal axis indicates the time phase (elapsed time t).

  More specifically, since the contrast agent has an X-ray absorption rate higher than that of the body tissue, the dose received by the X-ray detection element corresponding to the position where the contrast agent concentration is high is small, and the contrast agent is higher than the surrounding in the X-ray image Projected darkly. Since each pixel value of the DSA image is a difference from the pixel value at the same position in the mask image (before contrast agent administration), attention is paid to one pixel at the same position, and the time phase change of the pixel value of this pixel is encoded. Appropriate processing such as inversion is equivalent to a change in contrast agent concentration over time.

  The blood flow analysis unit 24d calculates, for example, the following blood flow analysis parameters for each pixel based on the temporal change in the contrast agent concentration calculated as described above.

  The first is TTP (Time To Peak), which indicates the time from the start of injection of the contrast agent to the peak.

  The second is MTT (Mean Transit Time), which is the time from the time when the contrast agent concentration rises to 50% of the peak value to the time when it passes the peak and falls to 50% of the peak value. Indicates the interval.

  Third is PH (Peak Height), which indicates the peak value of the contrast agent concentration (DSA value). In the example of the one pixel on the lower left, this corresponds to the value on the vertical axis in time phase 3. Note that the range of values on the vertical axis can be arbitrarily set according to, for example, the dynamic range.

  The fourth is AUC (Area Under Curve), which shows the time integration value of the contrast agent concentration (DSA value) from the first time phase to the last time phase of the DSA image. In the example of the one pixel on the lower left, it corresponds to the area of the region indicated by the diagonal line of the lower right broken line in the lower part of FIG.

  The above four are just a few examples of blood flow analysis parameters, and other blood flow analysis parameters may be calculated. The blood flow analysis unit 24d calculates blood flow analysis parameters by calculating the temporal change in contrast agent concentration in the same manner for all remaining pixels.

  The blood flow analysis unit 24d generates a parametric image based on, for example, TTP as the functional imaging and displays the parametric image on the GUI 24e. The parametric image here is a color image of a certain blood flow analysis parameter. For example, based on an arbitrarily determined color map such as red for pixels that reach TTP at time phase 1, yellow for pixels that reach TTP at time phase 2, and green for pixels that reach TTP at time phase 3. Thus, a chromatic color is assigned to each pixel. Thereby, TTP as a blood flow analysis parameter is displayed on the GUI 24e as a color image.

  Parametric images based on TTP are just one example of Functional Imaging. The blood flow analysis unit 24d can image other blood flow analysis parameters and display them on the GUI 24e according to the image processing conditions.

  Next, the principle of motion correction by the selection unit 24a, the positional deviation calculation unit 24b, and the image generation unit 24c will be described in the order of when Functional Imaging is not executed and when Functional Imaging is executed.

  FIG. 3 is a schematic explanatory diagram of a method for calculating a positional deviation between a mask image and a contrast image when Functional Imaging is not executed. Here, as an example, rectangular image coordinates (i, j) are defined as follows. That is, the vertical direction of the image is the i-th row and the horizontal direction of the image is the j-th column. In FIG. 3, only the mask image Imask is shown by a dotted line on the left side. On the right side of FIG. 3, the contrast image Icont is indicated by a solid line, and the shifted mask image Imask is indicated by a dotted line. In FIG. 3, for simplification, both the mask image Imask and the contrast image Icont are described with the number of pixels of 10 rows and 10 columns.

  First, when Functional Imaging is not executed, the positional deviation calculation unit 24b determines the degree of deviation (degree of divergence) between the nth frame contrast image and the mask image due to the movement of the subject P before and after the contrast agent administration. ) As MRn (Δi, Δj), and is calculated by the following equation.

  In the right side of equation (2), the first N corresponding to Σ related to i is the number of rows of the image, and the second N corresponding to Σ related to j is the number of columns of the image. In equation (2), Δi is the amount of positional deviation in the vertical direction of the image, and Δj is the amount of positional deviation in the horizontal direction of the image.

  In the equation (2), for example, consider a case where Δi = 2 and Δj = 1 as a provisional shift amount (provisional positional deviation). In this case, as shown on the right side of FIG. 3, for example, the pixel group in the first row of the mask image Imask becomes the pixel group in the third row, and the first pixel column of the mask image Imask is the second column. The difference calculation of equation (2) is executed while shifting the mask image so as to be the pixel group. Thereby, for the overlapping area of the mask image Imask and the contrast image Icont shown by the hatched area on the right side of FIG. 3, the sum of the squares of the logarithmic difference image pixel values of both images is calculated as MRn (Δi, Δj). Is done.

The positional deviation calculation unit 24b calculates Δi ₀ and Δj ₀ for minimizing MRn (Δi, Δj) for each time phase while changing Δi and Δj in equation (2). These Δi ₀ and Δj ₀ are the positional shift amounts in the vertical and horizontal directions between the contrast image of the nth frame and the mask image.
MRn (Δi, Δj) may not be the sum of the squares of the pixel values of the difference image, but may be the sum of the absolute values of the pixel values of the difference image, or the average value of the absolute values of the pixel values of the difference image. But you can. This also applies to the later-described equation (4).

After calculating the number of pairs of Δi ₀ and Δj _{0 corresponding to} the number of time phases of the contrast image, the position shift calculation unit 24b calculates the pixel value of each pixel of the DSA image subjected to motion correction by the following equation.

In equation (3), if n = 1 and i and j are calculated by the number of rows and columns of the image, the pixel values of all the pixels of the DSA image of the n = 1 frame are calculated. Similarly, the positional deviation calculation unit 24b generates image data of DSA images of all time phases.
When Functional Imaging is not executed, the difference calculation for DSA image generation is performed by shifting the mask image by the amount of positional deviation without shifting the contrast image as shown in the above equation (3) and the right side of FIG. Executed.

  Next, consider a case where Functional Imaging is executed. First, since the movement of the subject is not limited to one time, the amount of each positional deviation between the mask image and the contrast image of each time phase may differ for each time phase. Even in such a case, it is desirable that the time-varying curve of the contrast agent concentration calculated for each pixel is the time change of the contrast agent concentration at the same position in the subject.

FIG. 4 is a schematic diagram of a mask image and a contrast image when the amount of positional deviation differs for each time phase. In FIG. 4, for the sake of simplification, consider a case where the subject P moves only in the horizontal direction with respect to the mask image taken at time t = 0. Here, as an example, Δj ₀ = −1 for a contrast image with t = 1, Δj ₀ = −2 for a contrast image with t = 2, and Δj ₀ = −3 for a contrast image with t = 3, and a contrast image with t = 4. Let us consider a case where Δj ₀ = −4.

  In this case, it is assumed that Q-POINT, which is defined as a specific position of the subject P such as the center of the right eyeball, is projected on the lower right pixel in the mask image. Q-POINT shifts one pixel to the left from the lower right pixel in the contrast image at t = 1, and shifts two pixels to the left from the lower right pixel in the contrast image at t = 2, and t = 3 The contrast image is shifted by 3 pixels to the left from the lower right pixel, and the contrast image at t = 4 is shifted by 4 pixels to the left from the lower right pixel.

  In this case, it is assumed that the DSA image of each time phase is generated by obtaining the difference between the mask image and the contrast image while shifting the mask image by a positional shift amount different for each time phase as in the prior art. In this case, the temporal change in the contrast agent concentration of each pixel of the DSA image in Functional Imaging reflects the contrast agent concentration in a different region of the subject, not the contrast agent concentration at the same position of the subject. The reason is as follows.

  Although the DSA image is not shown in FIG. 4, the lower leftmost pixel of the fourth phase DSA image obtained by the difference between the contrast image of t = 4 and the shifted mask image is the subject position of the Q-POINT. Reflect the contrast agent concentration. However, the lower leftmost pixel of the other phase DSA image reflects the contrast agent concentration in the region other than the Q-POINT of the subject. This is because the position of the contrast image in each time phase is fixed in the difference calculation at the time of DSA image generation, and the contrast image in which the lower left pixel is Q-POINT is only the contrast image of t = 4.

  On the contrary, in the difference calculation for generating all time phase DSA images, if the positions of the mask images that are commonly used at the time of generating any time phase DSA image are unified over all time phases, the above-described problem does not occur. That is, it is considered suitable for Functional Imaging to generate a DSA image of each time phase by difference calculation while fixing the mask image and shifting the contrast image for each time phase.

  Therefore, in the first embodiment, when Functional Imaging is executed, the position of the mask image is fixed to calculate the positional shift, and the contrast image is shifted in the difference calculation for DSA image generation.

  FIG. 5 is a schematic explanatory diagram of a method for calculating a positional deviation between a mask image and a contrast image when Functional Imaging is executed. The notation is the same as in FIG. 3, and only the mask image Imask is shown by a dotted line on the left side of FIG. On the right side of FIG. 5, the mask image Imask is indicated by a dotted line, and the shifted contrast image Icont is indicated by a solid line.

  When Functional Imaging is executed, the degree of deviation (degree of deviation) MRn (Δi, Δj) between the contrast image of the nth frame and the mask image is calculated by the following equation.

In the equation (4), for example, consider a case where Δi = 3 and Δj = 2. In this case, as shown on the right side of FIG. 5, each row of the contrast image Icont is shifted by 3 rows and each column is shifted by 2 rows, and the difference calculation of Expression (4) is executed. As described above, the positional deviation calculation unit 24b calculates Δi ₀ and Δj ₀ that minimize MRn (Δi, Δj) in the equation (4) for each time phase as the positional deviation amount.

After calculating the number of pairs of Δi ₀ and Δj _{0 corresponding to} the number of time phases of the contrast image, the position shift calculation unit 24b calculates the pixel value of each pixel of the DSA image subjected to motion correction by the following equation.

  Note that in the formulas (2) and (4), only vertical and horizontal shifts are taken into account for the sake of simplification of description, but in reality, the positional deviation may be calculated with the influence of rotation.

Further, in Expressions (2) and (4), the positional deviations Δi ₀ and Δj ₀ are determined for the entire image, but this is only an example. The positional deviations Δi ₀ and Δj ₀ may be calculated by focusing on the pixel group in the region of interest. For example, if the region of interest is the 21st row to the 40th row and the 31st column to the 50th column, the sum total from the 21st row to the 40th row is calculated in the Σ at the beginning of the equation (2) and the second The positional deviations Δi ₀ and Δj ₀ may be determined by calculating the sum total from the 31st column to the 50th column in Σ. Thereby, the load of position shift calculation can be reduced.

When Δi ₀ and Δj ₀ are decimal numbers, interpolation processing or the like may be used in the difference calculation in equation (3). For example, when Δi ₀ = 0.2 and Δj ₀ = 0.2, the logarithmic difference is executed between the pixel value of the 10th row and the 10th column of the contrast image. This is the pixel value in the 9.8th row and the 9.8th column. That is, in the numerator in the logarithm of the expression (3), the image coordinates of the mask image are not integers.

In such a case, the numerator of equation (3) is calculated by interpolation processing. As a first example, four pixels of (9, 9), (9, 10), (10, 9), (10, 10) in the vicinity of the 9.8th row and the 9.8th column in the mask image It may be a simple average value. As a second example, the pixel values of these four pixels may be weighted average values. The weighting here is theoretically the pixel value in the 9.8th row and the 9.8th column of the mask image, so that the weight in the 10th row is larger than that in the 9th row. This is to increase the weight in the 10th column rather than the 9th column. When Δi ₀ and Δj ₀ are decimal numbers, the same applies to equation (5).

In the above description, a pair of Δi ₀ and Δj ₀ is calculated for the number n of time phases of the contrast image. However, if the subject P is moved only once, the entire time phase of the contrast image is obtained. , Uniform Δi ₀ and Δj ₀ may be calculated and used. Alternatively, .DELTA.i from 1:00 phase first at 10 time phases eyes _0, calculates .DELTA.j _0, .DELTA.i 0 at 20 time phases counted from 11:00 phase _eyes, to separately calculate the .DELTA.j _0, for each phase group when successive One positional deviation may be identified.

  FIG. 6 is a flowchart illustrating an example of the operation of the X-ray diagnostic apparatus 10 according to the first embodiment. Hereinafter, the operation of the X-ray diagnostic apparatus 10 will be described according to the step numbers in the flowchart shown in FIG.

  [Step S1] The system control unit 26 (see FIG. 1) determines the contrast agent based on some imaging conditions such as the imaging region, tube current, tube voltage, and X-ray pulse width input via the operation unit 22. Set all imaging conditions at each time phase before and after administration. Thereafter, the process proceeds to step S2.

  [Step S2] Before and after contrast medium administration, time-series X-ray image projection data is generated for the same region of the subject P by a known operation. Specifically, the high voltage generator 44 supplies a high voltage to the X-ray tube 42 according to the control of the system control unit 26, and the X-ray tube 42 generates X-rays. The irradiation range is controlled.

  The X-ray detector 34 detects X-rays that have passed through the subject P, converts them into electrical signals, and inputs them to the projection data generation unit 30. The projection data generation unit 30 generates projection data of an X-ray image from the input electrical signal and stores it in the projection data storage unit 28.

  In this way, before and after contrast medium administration, the subject P is the same so that the luminance of each pixel becomes the luminance according to the dose received for each X-ray detection element (not shown) of the X-ray detector 34. Multi-phase projection data is generated for the region. That is, image data of the mask image before administration of the contrast agent and image data of a plurality of time-series contrast images after administration of the contrast agent are generated and stored in the projection data storage unit 28.

  Note that a plurality of X-ray images after contrast medium administration are required so as to correspond to a plurality of time phases, but only one X-ray image before contrast medium administration may be provided. Thereafter, the process proceeds to step S3.

  [Step S3] When it is instructed by the operator's input to perform motion correction of the subject P in the DSA image via the GUI 24e (see FIG. 1) of the image processing device 24, the process proceeds to Step S5. Otherwise, the process proceeds to step S4.

[Step S4] The image generation unit 24c acquires mask image data and contrast image data of each time phase from the projection data storage unit 28. The image generation unit 24c generates and stores the image data of the DSA image of each time phase based on the logarithmic difference based on the equation (1) without executing the motion correction. The image generation unit 24c inputs the image data of the DSA image at each time phase to the GUI 24e, and the GUI 24e displays each DSA image.
If it is selected in step S3 that the motion correction is not performed, the process ends here.

  [Step S5] If execution of Functional Imaging is selected by the operator's input via the GUI 24e, the process proceeds to Step S8. Otherwise, the process proceeds to step S6.

  [Step S6] Since Functional Imaging is not executed as the image processing condition, the selection unit 24a selects a mask image as a position shift correction target, and inputs the selection result to the position shift calculation unit 24b.

The positional deviation calculation unit 24 b acquires the mask image data and the contrast image data of each time phase from the projection data storage unit 28. Since the position shift correction target is a mask image, the position shift calculation unit 24b defines Δi ₀ and Δj that define the position shift between the contrast image data and the mask image data so as to minimize the above-described equation (2). ₀ is calculated and stored for each time phase (see FIG. 3). The positional deviation calculation unit 24b inputs Δi ₀ and Δj ₀ to the image generation unit 24c.

The image generation unit 24c calculates the logarithmic difference between each contrast image and the mask image while shifting the mask image as a position shift correction target based on Δi ₀ , Δj ₀ and Equation (3). Thereby, the image generation unit 24c generates a plurality of time-series image data (motion corrected) corresponding to each time phase of the contrast image.
Thereafter, the process proceeds to step S7.

  [Step S7] The image generation unit 24c inputs the image data of the DSA image of each time phase after the motion correction generated in Step S6 to the GUI 24e, and the GUI 24e displays each DSA image. If Functional Imaging is not executed, the process ends.

  [Step S8] Since Functional Imaging is executed as an image processing condition, the selection unit 24a selects each contrast image as a position shift correction target, and inputs the selection result to the position shift calculation unit 24b.

The positional deviation calculation unit 24 b acquires the mask image data and the contrast image data of each time phase from the projection data storage unit 28. Since the positional deviation correction target is each contrast image, the positional deviation calculation unit 24b defines Δi ₀ , which defines the positional deviation between the contrast image data and the mask image data so as to minimize the above-described equation (4). Δj ₀ is calculated and stored for each time phase (see FIG. 5). The positional deviation calculation unit 24b inputs Δi ₀ and Δj ₀ to the image generation unit 24c.

The image generation unit 24c calculates the logarithmic difference between each contrast image and the mask image while shifting each contrast image as a position shift correction target based on Δi ₀ , Δj ₀ and Equation (5). Thereby, the image generation unit 24c generates a plurality of time-series image data (motion corrected) corresponding to each time phase of the contrast image.
Thereafter, the process proceeds to step S9.

[Step S9] The image generation unit 24c inputs the image data of the DSA image of each time phase after the motion correction generated in step S8 to the blood flow analysis unit 24d (see FIG. 1).
As described above, the blood flow analysis unit 24d calculates and stores a temporal change curve of the contrast agent concentration for each pixel at the same position in the time-series DSA image (see FIG. 2).
Thereafter, the process proceeds to step S10.
[Step S10] The blood flow analysis unit 24d calculates the blood flow analysis parameter described above for each pixel based on the temporal change in the contrast agent concentration calculated in step S9. Thereafter, the process proceeds to step S11.

  [Step S11] The blood flow analysis unit 24d generates a blood flow analysis result such as a parametric image based on TTP as Functional Imaging, and displays the blood flow analysis result on the GUI 24e.

  The above is the description of the operation of the X-ray diagnostic apparatus 10 of the first embodiment. Hereinafter, the difference between the prior art and the first embodiment will be described.

  In the prior art (pixel shift), when the contrast image is shifted, blood vessel information in the DSA image is blurred. Therefore, when performing the difference calculation for generating the DSA image, the body movement artifact is suppressed by shifting the mask image. . However, in the above method, as described with reference to FIG. 4, when the temporal change of the contrast agent concentration is calculated for each pixel at the same position as the DSA image, the contrast agent concentration in a different region of the subject is reflected.

Therefore, in the first embodiment, when Functional Imaging is executed as an image processing condition, a positional shift that minimizes the expression (4) is set for each time phase on the premise that the contrast image is shifted in the difference calculation for DSA image generation. Is calculated. Then, the image generation unit 24c shifts the contrast image in accordance with the positional deviation amount for each time phase, and fixes the mask image over all time phases, and executes the difference calculation of Expression (5). A motion-corrected DSA image is generated (step S8).
In the case of the DSA image generated in this way, if the temporal change of the pixel value is calculated for each pixel at the same position over the entire temporal phase, the temporal change of the contrast agent concentration in the same region of the subject can be accurately obtained. It is done.

  In the first embodiment, as a result of accurately obtaining the temporal change of the contrast agent concentration in the same region in the subject, each blood flow analysis parameter of Functional Imaging is also accurately calculated (step S10). Therefore, the accuracy of Functional Imaging can be improved as compared with the prior art. Thus, the result of displaying the blood flow analysis result with high accuracy (step S11) and the accuracy of the image diagnosis can be improved.

  Further, in the first embodiment, when Functional Imaging is not executed, body motion artifacts are suppressed by shifting the mask image when executing the difference calculation for DSA image generation.

  As described above, according to the first embodiment, artifacts due to the movement of the subject before and after the contrast agent administration can be appropriately suppressed according to, for example, image processing conditions by a method different from the conventional method.

  In the first embodiment, the selection unit 24a automatically sets one of the mask image and the contrast image as a position misalignment correction target (a shift target in the difference calculation at the time of DSA image generation) according to the image processing conditions. An example to choose was described. The embodiment of the present invention is not limited to such an aspect.

  For example, in step S5, it may be configured to select which of the mask image and the contrast image is to be subjected to position shift correction (shift target) by an operator input via the GUI 24e. Alternatively, as in the second embodiment, the selection unit 24a may select one of the mask image and the contrast image as a position shift correction target (shift target) according to the shooting conditions.

<Second Embodiment>
In the second embodiment, as an example of the shooting condition, one of the mask image and the contrast image is selected as a position shift correction target (shift target) according to the type of the shooting program. The hardware configuration and other points of the X-ray diagnostic apparatus 10 are the same as those in the first embodiment.

  FIG. 7 is a flowchart illustrating an example of the operation of the X-ray diagnostic apparatus 10 according to the second embodiment. Hereinafter, the operation of the X-ray diagnostic apparatus 10 of the second embodiment will be described according to the step numbers of the flowchart shown in FIG.

  [Step S21] The system control unit 26 (see FIG. 1) performs before and after contrast medium administration based on imaging conditions such as the imaging region, tube current, tube voltage, and X-ray pulse width input via the operation unit 22. Sets all shooting conditions for each time phase in. This shooting condition includes selection of a shooting program.

For example, in an imaging program based on blood flow analysis such as Functional Imaging, the imaging conditions such as the imaging interval of each contrast image are controlled by the system so that the temporal change in contrast agent concentration for each pixel of the DSA image can be obtained accurately. It is set appropriately by the unit 26. Specifically, a temporal resolution is prioritized over a spatial resolution, and a program that captures, for example, 512 × 512 [pixel ² ], 15 [fps] is configured.

On the other hand, in an imaging program that does not assume blood flow analysis, the system control unit 26 appropriately sets imaging conditions that allow a DSA image with sufficient resolution to be obtained. More specifically, a spatial resolution is given priority over a temporal resolution, and a program that shoots at, for example, 1024 × 1024 [pixel ² ], 7.5 [fps] is configured. Thereafter, the process proceeds to step S22.

  [Steps S22 to S24] Steps S2 to S4 are the same as steps S2 to S4 of FIG.

  [Step S25] The selection unit 24a acquires the mask image data and the contrast image data from the projection data storage unit 28, and determines the type of the shooting program used when shooting these images, for example, from the incidental information of the image data. Note that the selection unit 24 a may acquire information about the type of the shooting program from the system control unit 26.

  When the mask image data and the contrast image data are those captured in step S22 by an imaging program based on blood flow analysis, the selection unit 24e shifts the processing of the image processing device 24 to step S28. Otherwise, the process proceeds to step S26.

  [Steps S26 to S31] Steps S6 to S11 of FIG. 6 of the first embodiment are the same as those of FIG.

  The above is the description of the operation of the X-ray diagnostic apparatus 10 of the second embodiment. Thus, also in 2nd Embodiment, the effect similar to 1st Embodiment is acquired.

<Third Embodiment>
In the first embodiment and the second embodiment, the example in which the motion correction method is selected according to the image processing function and the shooting program has been described. On the other hand, in the motion correction of the third embodiment, a DSA image is generated by shifting the mask image based on the equations (2) and (3) regardless of the conditions. In that case, the temporal change of the pixel value of the pixel at the same position of the DSA image over the entire time phase does not become the temporal change of the contrast agent concentration at the same position of the subject as described in FIG.

  Therefore, when Functional Imaging is executed, the image processing apparatus 24 according to the third embodiment applies motion correction to the DSA image generated by shifting the mask image, so that the same region of the subject can be detected. The time change of the contrast agent concentration is acquired.

  Specifically, for example, one DSA image on which most arteries are projected is selected as the reference time phase. Next, a shift amount that minimizes the summed pixel value of the difference image between the DSA image of the other time phase and the DSA image of the reference time phase is calculated for each time phase as a positional deviation amount. Based on the positional shift amount for each time phase calculated in this way and the DSA image, the temporal change in contrast agent concentration is calculated for each same region of the subject. This will be described in more detail below.

  FIG. 8 is a schematic diagram illustrating an example of an algorithm of the image processing device 24 that selects one reference time phase DSA image from all time phase DSA images in the third embodiment. FIG. 8 shows a schematic diagram of five DSA images generated based on the equations (2) and (3) of the first embodiment in order from the left. The leftmost is the DSA image of time phase 1, the right neighbor is the DSA image of time phase 10, the right neighbor is the DSA image of time phase 20, and the right neighbor is the DSA image of time phase 30 The rightmost is a DSA image of time phase 40. Since it becomes complicated, the DSA image of the time phase in the middle is omitted.

  Here, as an example, the blood flow analysis unit 24d selects one DSA image at a time phase in which the main trunk artery appears most strongly. As the selection algorithm, for example, the blood flow analysis unit 24d sets a determination area JUD that is a common position in each DSA image. The determination area JUD is indicated by a one-dot chain line in FIG. In the schematic diagram of the DSA image at each time phase in FIG. 8, the artery is indicated by a solid line and the vein is indicated by a dotted line.

  As a determination region JUD setting method, the blood flow analysis unit 24d performs, for example, a segmentation process for extracting each tissue region of a human body from a mask image that is a generation source of a DSA image, and then based on the result of the segmentation process. An estimated arterial region is determined. The segmentation process can be performed by image processing such as template matching with a mask image based on a standard human tissue model including the shape and size of the skull.

  Next, the blood flow analysis unit 24d determines the running direction of blood in the estimated artery region of the mask image based on the human tissue model, and sets the distal side of the artery as the determination region JUD.

  Next, the blood flow analysis unit 24d calculates a total value of all the pixel values of the determination area JUD of the DSA image for each time phase. Then, the blood flow analysis unit 24d selects, for example, the earliest time phase at which the total pixel value of the determination region JUD exceeds the threshold as the reference time phase. Alternatively, the earliest time phase at which the total pixel value of the determination area JUD becomes the maximum value or the time phase at which the sum value becomes the maximum value may be selected as the reference time phase. Note that the average pixel value of the determination area JUD may be used instead of the summed pixel value of the determination area JUD.

  When the imaging region is the head, the blood flow analysis unit 24d determines, for example, the top of the head based on the human tissue model, and the first time when the change in the pixel value near the top of the DSA image is equal to or greater than a predetermined value. A phase may be selected as a reference time phase.

  Further, when selecting the reference time phase, a configuration may be adopted in which DSA images of all time phases are displayed on the GUI 24e and are selected by a user input to the GUI 24e. Alternatively, DSA images of all time phases may be displayed on the GUI 24e, and after the user sets the determination area JUD via the GUI 24e, the blood flow analysis unit 24d may select the reference time phase by threshold processing or the like as described above. .

FIG. 9 is a schematic diagram illustrating an example of a method for defining the shift amount between each time phase DSA image and the reference time phase DSA image DSAcr in the third embodiment. The left side of FIG. 9 shows the DSA image DSAcr of the reference time phase, and the right side of FIG. 9 shows the DSA image DSAcr of the reference time phase by a solid line and the DSA image DSA ₁ of the time phase ₁ by a broken line. On the right side of FIG. 9, the overlapping area between the DSA image DSAcr in the reference time phase and the DSA image DSA ₁ in the time phase 1 is indicated by a hatching area.

  The blood flow analysis unit 24d calculates the shift amount between the DSA image of each time phase other than the reference time phase and the DSA image DSAcr of the reference time phase according to the following equations.

In Equation (6), N is the number of rows and columns of the DSA image, and n is the time phase. That is, for DSA images DSA ₁ time phase 1, (6) of the left side and is MR ₁ (.DELTA.i, .DELTA.j) .DELTA.i that minimizes, .DELTA.j is, the row direction of the DSA images DSA ₁ time phase 1 , The shift amounts Δi ₁ and Δj ₁ in the column direction are calculated.
For the phase 2 DSA image DSA ₂ , Δi and Δj that minimize MR ₂ (Δi, Δj), which is the left side of equation (6), are the row direction and column of the phase 2 DSA image DSA _1. Calculated as the respective shift amounts Δi ₂ and Δj _{2 in the} direction. The same applies to other time phases.

  Note that MRn (Δi, Δj) in equation (6) is not the sum of the squares of the pixel values of the difference image as described above, but may be the sum of the absolute values of the pixel values of the difference image, It may be an average value of absolute values of pixel values.

FIG. 10 is a schematic diagram illustrating an example of an algorithm for generating a time change curve of a contrast agent concentration according to the third embodiment. The upper side of FIG. 10 is a schematic diagram of each DSA image of time phases 1, 10, 20, 30, and 40 similar to FIG. 8. Here, as an example, the case where time phase 20 is selected as the reference time phase is shown. Think.
The lower side of FIG. 10 corresponds to the same subject area as the pixel in the third row and the third column of the DSA image DSAcr of the reference time phase based on the shift amount for each time phase calculated by the equation (6). It is a time change curve of the pixel value of a pixel. That is, the lower side of FIG. 10 is a time change curve of the contrast agent concentration in the same subject region.

As an example, the shift amount of time phase 1 is Δi ₁ = 2 and Δj ₁ = 2, the shift amount of time phase 10 is Δi ₁₀ = 1, Δj ₁₀ = 1, and the shift amount of time phase 30 is It is assumed that Δi ₃₀ = −1, Δj ₃₀ = −1, and the shift amount of the time phase 40 is Δi ₄₀ = −2, Δj ₄₀ = −2. In this case, since there is no shift amount for the DSA image DSAcr in the reference time phase, the pixel value of the pixel in the third row and the third column is plotted as the contrast agent concentration at the time of the time phase 20.

In the DSA image DSA1 in the time phase 1, the pixel corresponding to the same subject area as the pixel in the third row and the third column of the DSA image DSAcr in the reference time phase is a pixel in the 3 + Δi _first row and the 3 + Δj _first column. The pixel value of this pixel is plotted as the contrast agent concentration of time phase 1. The same applies to other time phase images. The blood flow analysis unit 24d calculates the time change curve of the contrast agent concentration obtained in this way for each pixel in the reference time phase.
The larger the shift amount, the smaller the overlapping area between the DSA image of the reference time phase and the DSA image of the other time phase, so the number of contrast agent concentration time change curves is smaller than the number of pixels of one DSA image. ("Duplicate" here means that it corresponds to the same region of the subject P).

  Here, as an example, the time change curve of the contrast agent concentration is obtained up to the time phase 40 when only the vein is projected in the DSA image of FIG. 8, but this is only an example. In the DSA image, a configuration in which a time change curve of the contrast agent concentration is obtained up to a time phase in which the amount of arterial projection is somewhat large may be used.

  FIG. 11 is a flowchart illustrating an example of the operation of the X-ray diagnostic apparatus 10 according to the third embodiment. Hereinafter, the operation of the X-ray diagnostic apparatus 10 of the third embodiment will be described in accordance with the step numbers of the flowchart shown in FIG.

  [Steps S41 to S44] Steps S41 to S44 are the same as steps S1 to S4 in FIG. 6 of the first embodiment.

  [Step S45] When step S45 is reached, execution of motion correction is selected in step S43. Therefore, the image generation unit 24c (see FIG. 1) generates and stores a DSA image by shifting the mask image based on the equations (2) and (3) regardless of the conditions. Thereafter, the process proceeds to step S46.

  [Step S46] When it is selected by the operator's input to execute Functional Imaging via the GUI 24e, the process proceeds to Step S47. Otherwise, the process proceeds to step S48.

  [Step S47] The GUI 24e displays the DSA image generated in step S45. If Functional Imaging is not executed, this is the end.

[Step S48] The blood flow analysis unit 24d acquires image data of DSA images of all time phases from the image generation unit 24c. Next, the blood flow analysis unit 24d selects a reference time phase DSA image by a method such as setting a determination region JUD and performing threshold processing. This selection method has been described with reference to FIG. 8, and may be selected by a user's selection input.
Thereafter, the process proceeds to step S49.

  [Step S49] As described with reference to FIG. 9, the blood flow analysis unit 24d sets the shift amount between the DSA image of each time phase other than the reference time phase and the DSA image DSAcr of the reference time phase based on the equation (6). Respectively. Thereafter, the process proceeds to step S50.

  [Step S50] As described with reference to FIG. 10, the blood flow analysis unit 24d, based on each shift amount obtained in Step S49, pixels corresponding to the same subject region over each time phase of the DSA image. A time change curve of the contrast agent concentration is calculated for each time. Thereafter, the process proceeds to step S51.

  [Steps S51 to S52] Steps S51 and S52 are the same as steps S10 and S11 of FIG.

  The above is the description of the operation of the X-ray diagnostic apparatus 10 of the third embodiment. Thus, also in 3rd Embodiment, the effect similar to 1st Embodiment is acquired.

<Fourth Embodiment>
FIG. 12 is a block diagram illustrating an example of a configuration of a picture archiving communication system (PACS: Picture Archiving and Communication Systems) 200 according to the fourth embodiment.

  As shown in FIG. 12, in the image storage communication system 200, a plurality of display terminals 300, a workstation 400, and a plurality of modalities such as the X-ray diagnostic apparatus 10 and the magnetic resonance imaging apparatus 500 are connected via a network cable NC. Are connected to each other.

  The X-ray diagnostic apparatus 10 and the magnetic resonance imaging 500 transfer medical image data generated by imaging to the workstation 400 as, for example, a DICOM type file via the network cable NC. The image data is stored as, for example, a DICOM type file, and the incidental information of the file includes information for specifying a patient as a subject, imaging conditions, and the like. DICOM is a network standard “Digital Imaging and Communications in Medicine”.

  The display terminal 300 includes an input unit 304 and a monitor 308. The operator can transfer the image data stored in the server 300 to the monitor 308 via the network cable NC via the input unit 304 and display the image data on the monitor 308.

  In addition, the operator causes the image processing apparatus 24 in the server 300 to perform image processing on the image data stored in the server 300 via the input unit 304, and similarly monitors the image 308 after the image processing. Can be displayed.

  The workstation 400 provides an image processing function as an example here. Note that the workstation in this specification is constructed with higher performance than a personal computer for general use, for example, in order to carry out highly specialized work with high processing load such as scientific calculation. Is the meaning of the computer.

  The workstation 400 includes a CPU (Central Processor Unit) 402, a communication unit 404, an image storage unit 406, an operation unit 408, and the image processing apparatus 24 according to the first to third embodiments via a system bus 430. It is an interconnected configuration.

  The CPU 402 controls each part of the workstation 400 via the system bus 430 and performs system control thereof.

  The communication unit 404 corresponds to a network interface such as an Ethernet (registered trademark) card. The communication unit 404 performs communication such as data transmission / reception between each modality and the display terminal 300 and the workstation 400 under the control of the CPU 402.

  The image storage unit 406 stores image data transferred from modalities such as the X-ray diagnostic apparatus 10 and the magnetic resonance imaging 500 as image data of the original image. Therefore, the workstation 400 may be regarded as an image server or an image processing server. For example, a server is a computer that provides its own functions and data to a client computer in a computer network, and is a superordinate concept of a workstation.

  The image processing device 24 acquires, for example, mask image data and contrast image data stored in the image storage unit 406, and generates and displays DSA images and DSA images as in the first to third embodiments. To perform blood flow analysis based on.

  The operation unit 408 includes a keyboard, a monitor, and the like that accept a user's direct instruction input to the workstation 400.

  The user can select that the workstation 400 (the image processing apparatus 24 thereof) functions in the same manner as in the first embodiment via the operation unit 408.

  Alternatively, the user can select that the workstation 400 (the image processing apparatus 24) functions via the operation unit 408 in the same manner as in the second embodiment.

  Alternatively, the user can select the function of the workstation 400 (the image processing apparatus 24) via the operation unit 408 in the same manner as in the third embodiment.

  Therefore, also in 4th Embodiment, the effect similar to 1st-3rd embodiment can be acquired. According to each embodiment described above, in DSA, artifacts due to the movement of the subject before and after contrast agent administration can be suppressed by a technique different from the conventional technique.

<Supplementary items of the embodiment>
[1] In the first to third embodiments, an example in which the image processing apparatus 24 is mounted on the X-ray diagnostic apparatus 10 will be described. In the fourth embodiment, the image processing apparatus is installed in the workstation 400 of the image storage communication system 200. An example in which 24 is mounted has been described. The embodiment of the present invention is not limited to such an aspect. The image processing device 24 is mounted on other diagnostic imaging apparatuses such as an X-ray computed tomography apparatus (X-ray CT) and a magnetic resonance imaging apparatus that can take blood flow images before and after contrast medium administration. May be.

[2] A correspondence relationship between the terms of the claims and the embodiment will be described. In addition, the correspondence shown below is one interpretation shown for reference, and does not limit the present invention.
The function of the GUI 24e that includes a monitor (not shown) that displays information for selecting a position shift correction target (shift target) and that accepts a position shift correction target selection input is an example of an input unit described in the claims.

  [3] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

10: X-ray diagnostic device, 24: Image processing device,
24a: selection unit, 24b: position shift calculation unit, 24c: image generation unit,
24d: blood flow analysis unit, 24e: GUI,
200: Image storage communication system, 400: Workstation

Claims (10)

A DSA image is obtained based on mask image data that is image data of a subject before administration of a contrast agent and a plurality of contrast image data that is a plurality of time-series image data after administration of the contrast agent for the same subject. An image processing device to generate,
A selection unit that selects one of a plurality of the contrast image data or the mask image data as a position shift correction target when generating the DSA image based on a selection input to the image processing apparatus, an image processing condition, or an imaging condition; ,
A positional deviation caused by the movement of the subject before and after contrast medium administration is calculated between the plurality of contrast image data and the mask image data based on the plurality of contrast image data and the mask image data. A positional deviation calculation unit;
By calculating each difference between each of the contrast image data and the mask image data while shifting the position shift correction target based on the position shift among a plurality of the contrast image data or the mask image data. An image processing apparatus comprising: an image generation unit configured to generate image data of a plurality of time-sequential DSA images. The image processing apparatus according to claim 1.
A monitor that displays information for selecting the position shift correction target, and further includes an input unit that receives a selection input of the position shift correction target;
When the input unit receives the selection input to the image processing apparatus, the selection unit selects the position shift correction target based on the selection input. The image processing apparatus according to claim 1.
The image processing apparatus, wherein the selection unit selects the misalignment correction target based on a shooting program as the shooting condition used for shooting the mask image data and the plurality of contrast image data. The image processing apparatus according to claim 1.
When the image processing apparatus executes Functional Imaging as the image processing condition, the selection unit selects a plurality of the contrast image data as the position shift correction target. The image processing apparatus according to claim 4.
An image processing apparatus, further comprising: a blood flow analysis unit that calculates a temporal change in contrast agent concentration for each pixel at the same position between the plurality of time-series DSA images as the functional imaging. The image processing apparatus according to claim 1.
When the selection unit selects the mask image data as the position shift correction target, the position shift calculation unit calculates a difference between the mask image data shifted in position by an arbitrary temporary shift amount and the contrast image data. In the image data, a process of calculating the provisional shift amount that minimizes the sum of squares of pixel values or the sum of absolute values of pixel values as the positional deviation is performed on the contrast image data of each time phase, respectively. An image processing apparatus characterized by being executed. The image processing apparatus according to claim 1.
When the selection unit selects a plurality of the contrast image data as the position shift correction target, the position shift calculation unit includes the contrast image data shifted by an arbitrary provisional shift amount, the mask image data, In the difference image data, the process of calculating the provisional shift amount that minimizes the sum of squares of pixel values or the sum of absolute values of pixel values as the positional deviation is performed on the contrast image data of each time phase. Each of the image processing devices is executed. A DSA image is obtained based on mask image data that is image data of a subject before administration of a contrast agent and a plurality of contrast image data that is a plurality of time-series image data after administration of the contrast agent for the same subject. An image processing device to generate,
An image generation unit configured to generate image data of the plurality of DSA images in a time series based on each difference between each of the contrast image data and the mask image data;
Analyzing the amount of arterial information included in the plurality of DSA images, or obtaining a selection input to the image processing device, thereby selecting one of the plurality of DSA images as a reference time phase, In the difference image between the DSA image and the DSA image in the reference time phase, the sum of squares of pixel values or the sum of absolute values of pixel values is minimized with respect to the DSA image of each time phase. A contrast agent for each pixel corresponding to the same position of the subject over a plurality of time-series DSA images while calculating the shift amount and shifting the pixel position for each time phase based on the shift amount An image processing apparatus comprising: a blood flow analysis unit that calculates a temporal change in concentration. The image processing apparatus according to claim 8.
The blood flow analysis unit sets a common determination region for a plurality of time-sequential DSA images, and executes threshold processing for the summed pixel values of the determination region for each DSA image. An image processing apparatus, wherein one DSA image whose information amount is a predetermined amount or more is selected as the reference time phase. By detecting X-rays transmitted through the subject before and after contrast medium administration, the mask image data indicating the X-ray image before contrast medium administration and a plurality of time-series X-ray images after contrast medium administration are obtained. An X-ray imaging unit that generates a plurality of contrast image data respectively shown;
The image processing apparatus according to any one of claims 1 to 9, wherein image data of the plurality of DSA images is generated based on the plurality of contrast image data and the mask image data. X-ray diagnostic equipment.