JP2000148989A - Display parameter value setting method for medical image, medical image diagnostic device, and mri device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set display parameter values with which successive medical images can be displayed without giving any unnatural impression to a user. SOLUTION: The moving average value WW' of WW values of an object MR image to be set and an MR image present before it is calculated, the moving average value WW' of WW values of the object MR image and an MR image present behind it is calculated, and the mean value WW value of the moving average values WW' and WW'' in both the front and rear directions is set (ST5). When image pickup information on the MR image is Head/Axial, a WL value is not set, but when not, the moving average value WL' of the WL values of the object MR image and the MR image present before it is calculated, the moving average value WL'' of the WL values of the object image MR image and the MR image present behind it is calculated, and the mean WL value of the moving average values WL' and WL'' in both the front and rear directions is set (ST10).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a display parameter value of a medical image, a medical image diagnostic apparatus and an MRI apparatus, and more particularly, to a plurality of continuous medical images without giving an unnatural impression to a user. The present invention relates to a display parameter value setting method for a medical image, a medical image diagnostic apparatus, and an MRI apparatus capable of setting a display parameter value capable of displaying the image. In particular, MR (Magnetic Resonance) images and CT (Computed
Tomography) Image WW (WindowWidth) value or WL
Useful for setting (Window Level) values.

[0002]

2. Description of the Related Art Generally, when displaying medical images such as MR images and CT images, it is necessary to set display parameters such as WW values and WL values. Since the appearance of the image is completely different depending on the setting of the WW value and the WL value, each time the medical image is displayed, the user (operator or doctor) sets an appropriate WW value or WL value. However, since the setting of each image requires a large work load, the following prior art which supports the setting and reduces the work load is known. (1) As shown in FIG.
In advance, coefficient parameters Pww / PwL are stored in advance for each imaging region, and when the imaging region of the image to be displayed is designated,
The corresponding coefficient parameters Pww / PwL are read out from the coefficient parameter table 50, and using them, WW = Pww × S1 WL = PwL × S2 (S1, S2 are statistics obtained from MR images)
There is known a technique for calculating a W / WL value and automatically setting the WW / WL value. Note that S1 is, for example, the standard deviation of the pixel values of the MR image. S2 is, for example, the average value of the pixel values of the MR image. (2) Japanese Patent Application Laid-Open No. 9-299349 discloses FIGS.
As shown in FIG. 5, a series of tomographic images called a training series have WW / WL values appropriately set on a series of tomographic images called table series WW (X ′) and WL (X ′). The WW offset / WL offset calculated on the basis of the statistic (standard deviation / average) of the pixel values of the table curve WW
(X ′) and WL (X ′) are modified to output table curve W
WA (X ') and WLA (X') are created, and the slice position X '(lower part of the head) of each tomographic image of the series to be set is calculated using the output table curves WWA (X') and WLA (X '). A technology is disclosed that outputs a WW / WL value corresponding to (.

[0003]

In the above prior art (1), the coefficient parameters Pww, Pww
Since the WW / WL value is automatically set with wL, when displaying a plurality of consecutive medical images in order, the brightness and contrast tend to be discontinuous due to the variation of the WW / WL value set for each medical image, It is easy to give an unnatural impression to the user. In the prior art (2), WW / WL preset for a series of tomographic images of the training series is set.
WW of the tomographic image of the setting target series reflecting the value trend
Since the / WL value is set, the WW / WL value cannot be appropriately set depending on the state of the tomographic image of the series to be set, giving an unnatural impression to the user. Therefore, an object of the present invention is to provide a display parameter value setting method of a medical image capable of setting display parameter values capable of displaying a plurality of continuous medical images without giving an unnatural impression to a user, a medical image diagnostic apparatus, and an MRI. It is to provide a device.

[0004]

According to a first aspect of the present invention, there is provided a medical image to be set which is designated from a plurality of continuous medical images, and a display parameter of a medical image existing in a forward direction thereof. Calculate the moving average of the values, calculate the moving average of the display parameter values of the medical image to be set and the medical image present in the backward direction, and average the moving average of both the front and rear directions, and calculate the average. Is set as a display parameter value of the medical image to be set, and a display parameter value setting method of the medical image is provided. In the medical image display parameter value setting method according to the first aspect, a forward moving average value reflecting a change in a display parameter value of a medical image existing in a forward direction from a medical image to be set is obtained. A backward moving average value reflecting a change in the display parameter value of the medical image existing in the backward direction from the image is calculated. However, since there is no medical image in the forward direction for the first medical image,
As the moving average value, for example, the display parameter value itself of the first medical image is adopted. Further, since there is no medical image in the backward direction with respect to the last medical image, for example, the display parameter value of the last medical image itself is used as the moving average value. Then, by averaging the moving average values in both the front and rear directions, it is possible to calculate a display parameter value that equally reflects a change in the display parameter value of the medical image existing before and after the MR image to be set, and It is possible to set display parameter values in which discontinuity with other medical images (especially images adjacent before and after) is sufficiently reduced. As a result, a plurality of continuous medical images can be displayed without giving an unnatural impression to the user (operating technician or doctor). In addition, since the display parameter value of the medical image to be displayed is reflected in the moving average value in both the front and rear directions, the display parameter value of the medical image to be displayed generally has the largest influence on the set value. Therefore, it is possible to calculate a setting value relatively faithful to the display parameter value predetermined on the user side for each medical image, and it is possible to sufficiently cope with the user's preference for the medical image.

According to a second aspect of the present invention, in the medical image display parameter value setting method having the above configuration, the medical image is an MR image or a CT image, and the display parameter value is a WW value or a WL value. A method for setting a display parameter value of a medical image is provided. In the method for setting display parameter values of a medical image according to the second aspect, since a WW value and a WL value are set for an MR image and a CT image, a plurality of continuous MR images can be obtained without giving an unnatural impression to the user. And a WW value and a WL value capable of displaying a CT image and a CT image can be set.

In a third aspect, the present invention provides a method for setting a display parameter value of a medical image having the above-described structure, wherein when the morphological change between the plurality of continuous medical images is large, W
Only the WW value among the W value and the WL value is set by the setting method according to claim 1, and when the morphological change between the plurality of medical images is small, both the WW value and the WL value are according to claim 1. A method for setting a display parameter value of a medical image, characterized by being set by a setting method, is provided. In the method for setting a display parameter value of a medical image according to the third aspect, M
When the morphological change between the R image and the CT image is large, the image quality deteriorates rather than smoothing the WL value in view of the fact that there is a physical meaning that the luminance and the contrast greatly change between the images. there's a possibility that. For this reason, only the WW value is set by the setting method according to the first aspect, without intentionally smoothing the WL value. On the other hand, when the morphological change between the MR image and the CT image is small, it is not physically meaningful to make a large difference in brightness or contrast between the images, and therefore both the WW value and the WL value are set to the first value. By setting using the setting method according to the above viewpoint, discontinuity of brightness and contrast between images is sufficiently reduced, and a plurality of continuous MR images and CT images can be formed without giving an unnatural impression to the user. Can be displayed.

According to a fourth aspect of the present invention, there is provided the medical image display parameter value setting method having the above-mentioned configuration, wherein the morphological change is applied to an MR image or a CT image whose head is an imaging part and whose imaging angle is axial. A display parameter value setting method of a medical image, wherein the setting is performed when the morphological change is small for another MR image or CT image. In the display parameter value setting method for a medical image according to the fourth aspect,
When the imaging region is the head and the imaging angle is axial, the setting is performed in the case where the morphological change is large in view of the fact that a large change in brightness and contrast between MR images and CT images has a physical meaning. . On the other hand, another MR image or C
In the case of a T image, it is determined that there is no physical meaning in providing a large difference in luminance and contrast between the MR image and the CT image, and setting is performed when the morphological change is small.

In a fifth aspect, the present invention provides a method for calculating a moving average value of a medical image to be set and a medical image existing in the forward direction from a plurality of continuous medical images. Moving average value calculating means, a backward moving average value calculating means for calculating a moving average value of the medical image to be set and a medical image present in the backward direction,
A medical image diagnostic apparatus, comprising: display parameter value setting means for averaging moving average values in both front and rear directions and setting the average value as a display parameter value of a medical image to be set. In the medical image diagnostic apparatus according to the fifth aspect, since the method for setting the display parameter value of the medical image according to the first aspect can be appropriately performed, a plurality of continuous medical image diagnostics can be performed without giving an unnatural impression to the user. Can be set to be able to display the MR image or CT image.

In a sixth aspect, the present invention provides a WW / WL value acquiring means for acquiring at least one of a WW value and a WL value of a plurality of continuous MR images, and a WW / WL value acquiring means designated from the plurality of MR images. Forward moving average value calculating means for calculating a moving average value of the WW value or the WL value of the MR image to be set and the MR image existing in the forward direction, and the MR image to be set and the backward direction thereof A moving average value calculating means for calculating a WW value or a WL value of an MR image existing in the medical image, a moving average value in both the front and rear directions, and averaging the average value to obtain a WW value or a WL value of the medical image to be set.
M comprising WW / WL value setting means for setting as a value, and MR image display means for displaying an MR image on a screen according to the set WW value or WL value.
An RI device is provided. In the MRI apparatus according to the sixth aspect, since the MR image is displayed by performing the method for setting the display parameter value of the medical image according to the second aspect, the MRI apparatus does not give an unnatural impression to the user and is continuously displayed. A plurality of MR images can be displayed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited by this. FIG. 1 is a block diagram showing an MRI apparatus according to one embodiment of the present invention. This M
The RI device 100 includes an imaging device 1, a processing device 2, a storage device 3, a display device 4, and an input device 5. The imaging device 1 scans the subject K and passes obtained scan data to the processing device 2. The processing device 2
A data acquisition unit 2a for acquiring scan data from the imaging device 1, an image data generation unit 2b for generating image data of an MR image from the scan data, a WW value, WL
A WW / WL value setting unit 2c for setting a value. The storage device 3 stores the scan data, the image data, and the like. The display device 4 includes the MR
Displays images and various information. The input device 5 receives information input by an operator.

FIG. 2 is a flowchart showing a process for setting a WW value and a WL value by the WW / WL value setting section 2c. In step ST1, WW values and WL values for a plurality of continuous MR images are read from the storage device 3. The continuous MR images are, for example, a group of multi-slice images taken at regular intervals along the spine of the subject. For convenience of explanation, W of N consecutive MR images
WW1, WW2, ..., WWi, ..., WWN-1, WWN
, WLi,..., WLN−
1, WLN. In step ST2, the MR to be set
The image identification number i is initialized to 1.

In step ST3, when N ≧ i ≧ 2,
The moving average value WW′i of the WW values of the MR image corresponding to the identification number i and the MR image existing in the forward direction than the MR image,
It is calculated by equation (1). (Equation 1) When N ≧ i ≧ 3, equation (1) is transformed into equation (2). (Equation 2) When i = 1, there is no MR image in the forward direction, so WW′i = WW1. (A) to (f) of FIG.
, When N = 6, the moving average values WW′1, WW′2,.
The weight α ′ of each MR image is shown for each WW′N. From FIG. 3, it is understood that the weight α ′ is larger as the position is closer to the MR image to be set.

In step ST4, when 1 ≦ i ≦ N−1, the moving average WW ″ i of the WW values of the MR image corresponding to the identification number i and the MR images existing behind the MR image.
Is calculated by Expression (3). (Equation 3) When 1 ≦ i ≦ N−2, equation (3) is transformed into equation (4). (Equation 4) When i = N, there is no MR image in the backward direction, so WW′i = WWN. (A) to (f) of FIG.
, When N = 6, the moving average values WW "1, WW" 2,.
The weight α ″ of each MR image is shown for each WW ″ N. From FIG. 4, it can be seen that the weight α ″ is larger as the MR image is closer to the MR image to be set.

In step ST5, an average WW value = Ave {WWi} obtained by averaging the moving average values in both the forward and backward directions is calculated by the equation (5) and set as the WW value of the MR image corresponding to the identification number i. Here, i is 1 ≦ i ≦ N. (Equation 5) When 3 ≦ i ≦ N−2 and N ≧ 5, the above (Equation 5) is transformed into the following (Equation 6). (Equation 6) 5A to 5F, when N = 6, the average WW value =
The weight α of each MR image is shown for each of Ave {WW1}, Ave {WW2}, ..., Ave {WWN}. From FIG. 5, the weight α increases as the MR image approaches the MR image to be set, and the M
It can be seen that the weight α decreases as the distance from the R image increases and decreases (the WW value of each MR image is reflected in the average WW value as the MR image approaches the MR image to be set).

In step ST6, header information relating to the MR image corresponding to the identification number i is read. Step S
At T7, referring to the header information, the imaging information of the MR image is displayed.
Head / Axial (the imaging part is the head and the imaging angle is axial)
Is determined. Step S if Head / Axial
Proceed to T11, and if not Head / Axial (for example, Head / Sag
The process proceeds to step ST8 (if ital or Spine / Coronal). In other words, in the case of Head / Axial, in view of the fact that the morphological change between MR images is large and the luminance and contrast largely change, there is a physical meaning, and if the WL value is smoothed, the image quality will deteriorate instead. there's a possibility that. Therefore, the WL value is not intentionally smoothed. On the other hand, in cases other than Head / Axial, since the morphological change between MR images is small and it is not physically meaningful to make a large difference in luminance or contrast, both the WW value and the WL value are smoothed. Proceed to processing.

In step ST8, when N ≧ i ≧ 2,
The moving average WL ′ of the WL values of the MR image corresponding to the identification number i and the MR image existing in the forward direction than the MR image
It is calculated by Expression (7). (Equation 7) When N ≧ i ≧ 3, Equation (7) is transformed into Equation (8). (Equation 8) When i = 1, there is no MR image in the forward direction, so WL'i = WL1. Moving average WL ”1,
Weight β ′ of each MR image in WL ”2,..., WL” N
Is the same as the weight α ′ shown in FIGS. 3A to 3F.

In step ST9, when 1 ≦ i ≦ N−1, the moving average WL ″ of the WL values of the MR image corresponding to the identification number i and the MR images existing behind the MR image.
Is calculated by Expression (9). (Equation 9) When 1 ≦ i ≦ N−2, the above equation (9) becomes the following equation (10).
It is transformed like the expression. (Equation 10) When i = N, there is no MR image in the backward direction, so WL'i = WLN. Moving average value WL "1, W
The weight β ″ of each MR image in L ″ 2,.
The weights α ″ shown in FIGS. 4A to 4F are the same.

In step ST10, an average WL value Ave {WLi} obtained by averaging the moving average values in both the forward and backward directions is expressed by (Equation 1).
It is calculated by the equation 1) and set as the WL value of the MR image corresponding to the identification number i. Here, i is 1 ≦ i ≦ N. (Equation 11) When 3 ≦ i ≦ N−2 and N ≧ 5, the above (Equation 11) is
It is transformed as shown in (Equation 12). (Equation 12) Average WL value Ave {WL1}, Ave {WL2}, ..., Ave W
The weight β of each MR image in LN｝ is the same as the weight α shown in FIGS. 5A to 5F. That is,
The weight β increases as the position approaches the MR image to be set, and decreases as the position moves forward and backward from the MR image to be set (the WL value of each MR image increases as the position approaches the MR image to be set. Is reflected in).

At step ST11, it is determined whether or not the identification number i = N. When i = N, it is determined that the setting of the WW value (and WL value) has been completed for all the MR images, and the WW / WL value setting process ends. When i = N, the WW value (or WL) has not been set. MR to set value)
It is determined that an image remains, and the process proceeds to step ST12.
In step ST12, 1 is added to the identification number i, and the process returns to step ST3.

Returning to FIG. 1, when a user (operating technician or doctor) instructs to display the plurality of MR images via the input device 5, the WW / WL set by the WW / WL value setting processing is set. Each MR image is sequentially displayed on the display device 4 by the value.

According to the MRI apparatus 100 described above, the WW values of the MR images in both the front and rear directions when viewed from the MR image to be set,
Since the moving averages of the WL values are calculated, and the averages of the moving averages are set as the WW value and the WL value, the discontinuity between the MR images can be sufficiently reduced. Also,
Since the WW value and WL value of each MR image are more strongly reflected on the set value as they approach the MR image to be set, the WW value and the WW value relatively faithful to the WW value and WL value predetermined on the user side are set. The WL value can be set, and it is possible to sufficiently cope with the user's preference for the MR image.

In the above-described MRI apparatus 100, the moving average value in the forward or backward direction is calculated by using the first or last M
The calculation was performed using the WW values and WL values of all the MR images from the R image to the MR image to be set.
The calculation may be performed using only the WW value and the WL value of a predetermined number (for example, five) of MR images viewed from the images. In this case, the arithmetic processing can be simplified and each moving average value can be calculated more quickly.

[0023]

According to the medical image display parameter value setting method, the medical image diagnostic apparatus and the MRI apparatus of the present invention,
The moving average of the display parameters (WW value and WL value) of the medical image in the forward and backward directions as viewed from the medical image (MR image or CT image) to be set is calculated, and the moving average in both the front and rear directions is averaged. Is set as a display parameter value, so that discontinuity of image characteristics (luminance and contrast) when medical images are sequentially displayed can be sufficiently reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an MRI apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a WW / WL value setting process by the MRI apparatus of FIG. 1;

FIG. 3 is an explanatory diagram showing weights of each MR image in a moving average value in a forward direction.

FIG. 4 is an explanatory diagram showing weights of each MR image in a backward moving average value.

FIG. 5 is an explanatory diagram showing a weight of each MR image in an average value of a moving average value in a forward direction and a moving average value in a backward direction.

FIG. 6 is an explanatory diagram showing a coefficient parameter table used in a conventional WW / WL value setting method.

FIG. 7 is an explanatory diagram of an output WW table curve.

FIG. 8 is an explanatory diagram of an output WL table curve.

[Explanation of symbols]

 Reference Signs List 100 MRI apparatus 2 Processing unit 2a Data acquisition unit 2b Image data generation unit 2c WW / WL value setting unit 4 Display device 5 Input device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C093 AA26 CA01 CA21 DA04 FD20 FF30 FF31 FH02 4C096 AB01 AB50 DC30 DE02 5B057 AA07 BA03 BA28 BA29 CA02 CA06 CB02 CB06 CE05 CE12 CE15 CF01 CF03 CF05 DB02 DB05 DB08 DC19

Claims (6)

[Claims] 1. A moving average value of display parameter values of a designated medical image to be set and a medical image existing in front of the designated medical image among a plurality of continuous medical images, and Calculate the moving average value of the display parameter values of the image and the medical image existing in the backward direction, average the moving average values of the front and rear directions, and set the average value as the display parameter value of the medical image to be set. A method for setting a display parameter value of a medical image, comprising: 2. The method for setting a display parameter value of a medical image according to claim 1, wherein the medical image is an MR image or a CT image, and the display parameter value is a WW value or a WL value. A method for setting display parameters for medical images. 3. The medical image display parameter value setting method according to claim 2, wherein only the WW value of the WW value and the WL value is charged when the morphological change between the plurality of consecutive medical images is large. Set by the setting method according to item 1,
If the morphological change between the plurality of medical images is small, W
A method for setting a display parameter value of a medical image, wherein both the W value and the WL value are set by the setting method according to claim 1. 4. The medical image display parameter value setting method according to claim 3, wherein the morphological change is large for an MR image or a CT image whose imaging region is a head and whose imaging angle is axial. Performing a setting when the morphological change is small with respect to another MR image or CT image. 5. A forward moving average value calculating means for calculating a moving average value of a designated medical image to be set from a plurality of continuous medical images and a medical image existing in a forward direction thereof, and A backward moving average value calculating means for calculating a moving average value of the medical image to be set and a medical image existing in the backward direction, and averaging the moving average values in both the front and rear directions to obtain the average value of the medical image to be set. A medical image diagnostic apparatus, comprising: display parameter value setting means for setting as a display parameter value of an image. 6. A WW / WL value acquiring means for acquiring at least one of a WW value and a WL value of a plurality of continuous MR images, and an MR image to be set which is designated from among the plurality of MR images, and Means for calculating a moving average of the WW value or the WL value of the MR image existing in the forward direction, and the WW value of the MR image to be set and the MR image existing in the backward direction. Or W
Backward moving average value calculating means for calculating the L value, and WW / W for averaging the moving average values in both the forward and backward directions and setting the average value as a WW value or a WL value of the medical image to be set.
An MRI apparatus comprising: an L value setting unit; and an MR image display unit that displays an MR image on a screen based on the set WW value or WL value.