JP4891577B2 - Medical image display device - Google Patents

Description

  The present invention relates to a medical image display apparatus.

  For example, in a magnetic resonance imaging apparatus (MRI apparatus) as a medical image generation apparatus, longitudinal relaxation enhancement (T1), transverse relaxation enhancement (T2), proton density, FLAIR, fat suppression, DWI, PWI, functional image (f-MRI), It is possible to take various images such as MR spectroscopy (MRS). Even with an X-ray computed tomography apparatus (X-ray CT), not only anatomical images of normal CT values but also multiple types of functional images such as blood flow may be captured. In many cases, the film is displayed in the same manner as the Schaukasten, but there are many apparatuses that capture and display an image of a composite modality of the same subject.

  Currently, when a doctor interprets an image, as shown in FIG. 7, a plurality of types of images related to the same part are displayed on a film or a monitor and observed while moving the viewpoint to each other corresponding to the same anatomical part. ing. On the other hand, instead of arranging them in separate positions, a method of comparing them in the same image in monochrome and color, etc. (fusion method) can be compared by X-ray CT, SPECT (Single Photon Emission Computed Tomography). ), PET (Positron Emission Computed Tomography) has been reported and has become common (see Non-Patent Documents 1 and 2), and MRI is a commercial product and free software for f-MRI and MRS. (See Non-Patent Document 3).

  In the current interpretation by “diagnosis by comparing a plurality of types of images side by side”, several types of arranged images are interpreted while moving the viewpoint, which causes eye fatigue and takes time to interpret. This is the same situation for a monitor of a display device instead of a film. In addition, when comparing images side by side, the viewpoint of the doctor moves, so it is difficult to make a diagnosis by comparing anatomical details. Dynamic display is also because the logical files are arranged in that order on the disk or display memory, and examples of sequential display on the same frame in the spatial slice direction and time axis direction are Although it is not created as an intentional function, it cannot be displayed in various orders. Although there is a multi-frame display, the frame order is the slice direction or the parameter direction.

  In addition, images to be compared often have anatomically different slice positions due to restrictions on imaging conditions and the like, and EPI and the like have a large image distortion and are difficult to compare compared to SE images and the like.

When simply picked up images to be displayed side by side, unless standardized, brightness and color are not constant depending on the object, and are difficult to compare objectively. In the case of MR, at present, it is said that the brightness information can be judged only at about three steps of white, gray, and black. In addition, in the fusion method, since the images overlap each other, the images to be superimposed are limited to those having a small spatial resolution or locality, and the entire contrast such as T1 enhancement and T2 enhancement routinely used in MRI has contrast. Depending on the images to be overlapped, such as certain images, the relationship may be difficult to understand. Up to two types of images can be discriminated before being overlapped. Also, it is not suitable for an image of a kind whose color is not common. The main prior art documents are as follows.
Ratib O. PET / CT image navigation and communication.Jnucl Med. Jan; 45 Suppl 1: 46S-55S. (2004) Joseph Hajnal, DJHawkes, Derek Hill, JV Hajnal.Medical Image Registration; CRC Press. Friston KJ, Ashburner J, Poline JB, Frith CD, Heather JD, Frackowiak RSJ.Spatial Registration and Normalization of Images Human Brain Mapping 2: 165-189 (1995)

  An object of the present invention is to improve image diagnosis efficiency in a medical image display apparatus.

The first aspect of the present invention includes a storage unit that stores data including multiple medical images of the same region of the subject generated by the MRI apparatus, while sequentially switching one by one the plurality of medical images screen And a plurality of medical images according to at least one different imaging parameter excluding a slice position or imaging time among a plurality of imaging parameters necessary for obtaining a medical image. The display unit includes different types of medical images captured and generated, or different types of medical images captured and generated using different types of pulse sequences, and different types of medical images and medical images having different slice positions. Is a display for switching a plurality of medical images having different imaging parameters or pulse sequences at substantially the same position on the screen, and a slice position. To provide a medical image display apparatus characterized by enabling switching display at substantially the same position on the screen a plurality of different medical images.

  According to the present invention, it is possible to improve the efficiency of image diagnosis in a medical image display apparatus.

Embodiments of the present invention will be described below with reference to the drawings.
A medical image display apparatus according to this embodiment shown in FIG. 1 includes an MRI apparatus (magnetic resonance imaging apparatus), an X-ray CT apparatus (X-ray computer tomography apparatus), an ultrasonic diagnostic apparatus, and a SPECT apparatus (single photon emission). A computer tomography apparatus), a PET apparatus (positron emission tomography apparatus), and a so-called viewer related to display of medical images generated by a medical image generation apparatus such as an endoscope. The medical image display apparatus according to the present embodiment is connected to an image database such as a PACS, an image generation apparatus such as an MRI apparatus or an X-ray CT through the communication unit 7, and a plurality of images to be interpreted from the image database or the image generation apparatus. Receive medical image data. The medical image data is typically a tomographic image or a projection image, but includes multi-sectional tomographic images and volume data expressed in voxels. The image storage unit 2 stores a plurality of medical images. The plurality of medical images differ in at least one of the subject, imaging parameters, slice position (imaging position), and imaging time (or imaging time). If the imaging parameters are MRI (magnetic resonance imaging), the type of imaging procedure (pulse sequence), the echo time TE, the repetition time TR, the width and amplitude of the RF pulse in the imaging procedure, the gradient magnetic field pulse Width and amplitude are included.

  The data of the plurality of medical images stored in the image storage unit 2 includes data of a plurality of different types of medical images relating to the same part of the subject generated by the same type of image generation device. The data of a plurality of medical images stored in the image storage unit 2 includes the current medical image of the same part of the subject generated at different times by the same or the same type of image generating device and the past two weeks ago, etc. The medical image data of is included. In addition, the data of the plurality of medical images stored in the image storage unit 2 includes reference images (standard images) related to subjects other than the subject and subjects such as a standard phantom.

  Here, for convenience of explanation, a vertical relaxation emphasized image, a lateral relaxation emphasized image, and a proton density image by the MRI apparatus related to the same part related to the same subject will be described as examples of display target images.

  The medical image display apparatus according to the present embodiment, along with the communication unit 7 and the image storage unit 2, the control unit 1 serving as the center of the entire apparatus, the image display unit 3, the input unit 4, and processing to be described later And a display control unit 6 that controls the image display unit 3 so that an image processed by the image processing unit 5 is displayed on the image display unit 3 as described later.

  The image processing unit 5 aligns the anatomical position among the plurality of display target images, and aligns the image size and the slice direction as necessary. And a pixel value correction unit 9 for reducing variations in pixel values due to imaging parameters, a map creation unit 10 for creating a map whose pixel value is a ratio or difference between a display target image and a reference image related to the same part, a region of interest ( ROI processing unit 11 for generating a graphic or the like representing a change between medical images regarding a pixel value in the ROI) or a ratio or difference between the pixel value and the standard pixel value of the part, and display from multi-sectional tomographic images and volume data The slicing processing unit 12 reconstructs a tomographic image as a target image. The reference image is typically an image captured in the past regarding the same subject, or a standard image regarding a normal or abnormal case processed statistically. A standard image is created for each disease.

Hereinafter, main functions and display procedures of the medical image display apparatus according to the present embodiment will be described.
(1) Image display function (display control unit 6)
As shown in FIG. 2, the display control unit 6 displays three types of MRI images related to the same part and the same slice of the same subject as a plurality of display target images stored in the image storage unit 2. The display position of the section 3 on the screen is substantially fixed, and the page 3 is displayed while being sequentially switched at a certain time interval so as to turn the page. By switching and displaying the display target image at the same position on the screen of the image display unit 3 (with the center of the image coincident with a specific position on the screen) and matching the anatomical position between the images, The same part is displayed at the same position on the screen. Therefore, when interpreting an image while paying attention to a specific part of the subject, the interpretation doctor displays the shadow on the multiple types of display target images with the viewpoint fixed at a specific position on the screen. You can figure out what will be done.

  Display conditions such as an image display area in the screen and an image switching time interval are preset and manually adjusted via the input unit 4 as necessary. If necessary depending on the conditions of the displayed image, the alignment processing unit 8 performs anatomical alignment between the display target images two-dimensionally or three-dimensionally, and corrects the size and shape.

  As shown in FIG. 2, images may be switched in accordance with the shooting parameters within a single screen area (single frame), or the screen may be divided into a plurality of screen elements (multi-frame) as shown in FIG. It is possible to divide and display a plurality of images with different slice positions or shooting times on a plurality of screen elements, and switch the images according to the shooting parameters in each screen region. Further, as shown in FIG. 3 (b), the image is switched in accordance with the imaging parameter within the single frame, and then the slice position or the imaging time is moved, and the image is switched in accordance with the imaging parameter at the slice position or the imaging time. It may be repeated.

The display function by the display control unit 6 has the following modes.
a) As a function related to the display transition (transition), a mode in which the current display target image is switched while fading in and out, and a next display target image from the currently displayed display target image. There is a mode that switches instantaneously. In the fade-in / fade-out mode, comparison between images before and after switching becomes easier than in the mode in which switching is performed instantaneously.

b) There is a manual mode that manually triggers the timing of display transition, and an auto animation mode in which display target images are automatically switched one after another at a rate of 1 to 30 frames per second as in animation, and this is repeated many times. is there. When the auto animation mode is selected, it is possible to check the repeated comparison by repeating it periodically. The rate can be adjusted manually. Instantaneous and fade-in / fading-out variation can be selected.

c) Mapping process (map creation unit 10)
This is a function for creating a map comprising a ratio or difference between a display target image and a reference image for the same part, and can be displayed instead of the original display target image (also referred to as an absolute value image). The reference image is stored in advance in the image storage unit 2 or is acquired from an external standard image database via the Internet line. The reference image is a past image relating to the same subject, a standard image relating to the same case relating to the same part, or a normal standard image relating to the same part. The database can be compared not only with normal persons but also with databases created for each specific disease. In the future, it is possible to expand to Computer Aided Diagnosis (CAD).

d) Region of interest processing (ROI processing unit 11)
A change in the pixel value in the region of interest (ROI) set on the display target image or map or the derived value thereof is created as a graphic by an appropriate operation of the input unit 4 (FIGS. 5A and 5B). )reference). The figure can be displayed instead of the original display target image (absolute value image) or map. The derived values are typically the pixel value average, standard deviation (SD), and skewness of a plurality of pixels in the ROI. When the display target image is selected due to a difference in shooting parameters, the relationship between the shooting parameter and the pixel value is expressed, and when the display target image is selected due to a difference in shooting time, the temporal change in the pixel value (Lesion progress) is expressed. In addition, when an organ is divided and an ROI is set for each divided region, a change in pixel value or a derived value between the divided regions is created. Examples of division include a liver area, a lung area, a cerebral blood vessel dominating area, and an innervating function.

Next, an image display procedure will be described.
This will be described with reference to the flowchart of FIG. As a display target image (interpretation target image), for example, a longitudinal relaxation emphasized image, a lateral relaxation emphasized image, and a proton density image with different imaging parameters relating to the same part of the same subject collected by the MRI apparatus are transmitted via the communication device 7. Supplied and stored in the storage unit 2 composed of a magnetic disk or a large-capacity semiconductor memory (S11).

  The stored display target image is processed by the image processing unit 5 based on the control information that is given on the spot by the interpretation doctor or is given in advance and stored. If necessary, the standard image in the standard database is referred to based on the control information, and alignment between images and pixel value (luminance) correction are performed (S12).

  In the case of MRI, it is possible to collect a plurality of types of images while the subject is lying on the bed. Therefore, as long as the anatomical alignment is determined, the position correction is a position associated with the image data. This can be done relatively easily based on the information (S13). Note that position correction is almost unnecessary if images of the same subject collected in the same examination are to be displayed, but if slices are different, it is necessary to perform slicing. In addition, when matching the same image with past image data, it is necessary to select a reference image and three-dimensionally match the shape with the reference image in consideration of the slice angle and parallel movement. If there is no deformation in the same subject, only the affine transformation considered to be a rigid body is sufficient. If the deformation from the reference image is large even for the same subject, and if it is not the same subject, non-rigid transformation is required. Minimize the amount of control information that people give whenever possible. If the operation form is decided, it is set in the file in advance and it can be controlled just by referring to it.

  Normalization processing using a linear function (y = ax + b, where, x: input pixel value, y: output pixel value) to suppress pixel value fluctuations between images due to gain variations and shooting parameter differences Yes (S14). The determination method of a and b may be calculated from a given image or a certain statistically calculated value may be used. In the case of MRI, if the acquisition conditions such as hardware and reception gain are kept constant, there will not be much variation between examinations, but if the same device is used in other cases, or if images from different devices are used, some pixel values will be used. Normalization is required.

  The display target image that has undergone processing such as necessary position correction and deformation is transferred to the display memory of the display control unit 6, and display of the display control unit 6 is started (S16). Initially, the display target image is intermittently displayed in an initial animation. This is displayed under the control of the interpretation doctor or from preset control information in accordance with imaging parameter designation, display transition mode, display (switching) speed, and presence / absence of fade-in / fade-out. Of these, it is possible to change and display the setting at any time according to the judgment of the interpretation doctor. For example, speed is done with a mouse, software or hardware dial. It also has a function of switching to an arbitrary image by the operation of the interpretation doctor. It is important to be able to control without looking away from the image. You can also make a hard copy of the image at any time. In the case of spatial multi-slice, the parameter type can be switched synchronously in all slices. In addition, multi-slice display in the time axis direction can be selected for various parameter images collected in different time axis directions.

  Further, the display switching rule can be changed not only to the imaging parameters but also to the slice direction, the time axis direction, and the like, or any combination thereof. As an example of combination, as shown in FIG. 3B, images with different shooting parameters are sequentially switched and displayed, and then the slice position is moved, and an image at that position with different shooting parameters is displayed. Switch in order and display. The interpretation direction can be arbitrarily designated by the interpretation doctor. Furthermore, not only the configuration of the present embodiment, but also known time-series dynamic acquisition images and fusion display of different parameter images can be arbitrarily selected and combined.

  While the images having different shooting parameters are being switched and displayed, the switching rules such as the time direction and the slice direction can be changed to other rules. 6 types of switching rules for shooting parameters, time, and slice position can be changed without changing the viewpoint from the image by using the button keys shown in FIG. 6A or the joystick shown in FIG. It is possible. This function facilitates the diagnostic action of the interpretation doctor.

  By appropriate operation of the input unit 4, the display of images and maps can be changed to the display of statistical processing results (S15). When the region of interest (ROI) is set at an arbitrary location on the image, the statistical value is calculated by the ROI processing unit 11 from the pixel value of the display target image or map in the ROI, either numerically or as shown in FIG. As shown in FIG. 5B, a graphic is displayed. Each time the ROI is reset, it switches in real time. A hard copy of the graphic display results can be taken at any time.

  One of the points of this embodiment is a standard image database reference function. There are data levels by subject, normal, and disease. By comparing with a certain standard image, the normal / abnormal level can be quantitatively diagnosed. This is not particularly necessary in the absolute value display mode in which the original pixel value of the image is displayed (normalization information is necessary). However, a standard image is required when creating a map. As a reference comparison method, for example, a map of pixel value ratios between the standard image and the image to be interpreted is created.

  In this case, when the target object data is close to normal, it becomes close to 1. Since there is some statistical variation in the data, the average value (P value) of the pixel values is displayed together with the graph of the average value of the ratio and the standard deviation SD. When the doctor assumes certain disease data, the target disease is selected by the interpretation doctor and its statistical distance is tested. Using multiple parameters and referring to the database stored in the computer, the target case with the closest Mahalanobis distance is selected. The Mahalanobis distance is a scale that represents the degree of similarity in the multidimensional feature space. Suspicious cases are presented with statistical accuracy in descending order of likelihood. This is a CAD function. The Mahalanobis distance between multidimensional vectors, which is the theory used in pattern recognition, is used for quantifying the comparison results between indexes with the database. Considering heterogeneous parameters as vectors, measurement parameter vectors can be used as they are for analyzing the relationship with the database. However, if necessary, the database and comparison data can be used for principal component analysis (PCA) or independent component analysis (ICA). It is more efficient to carry out common preprocessing such as reducing the number of parameters and increasing the independence between parameter vectors by performing dimensional compression using the above.

  In creating a map using a standard image, anatomical alignment between the target image of the subject and the standard image is important. The alignment is performed either by matching with the form of a standard database or by matching standard data with individual subject data. The greater the spatial resolution, the smaller the meaning of detail matching, since individual differences can be ignored. Matching with standard data has begun to be actually performed in nuclear medicine using SPECT and PET, but it has been successful to some extent because the spatial resolution is so small that it does not cause individual differences.

  The level of the database is a single device unit, the same model of the manufacturer, the same modality as a whole, between different modalities if there are common parameters, and the size of the subject is the same subject unit, hospital unit, local government, It is assumed to be domestic, and ultimately to the world level. Accessed via LAN or INTERNET.

  As described above, the display method of the present embodiment is an effective display method for MRI that collects and observes imaging parameters such as T1 weighting, T2 weighting, and proton density on a daily basis. Therefore, the MRI image has been described as an example. The display of various other modalities such as X-ray CT, ultrasound, SPECT, PET, and endoscope, or a combination image thereof, and not limited to medical images, This is applied to the same part image display of different parameters such as temperature distribution, CT value, and elastic distribution.

According to this embodiment, at least one of the following effects 1 to 4 can be achieved.
1. Multiple types of images taken with various methods for the same part are displayed at the same position on the screen, like page turning, so that the viewpoint remains on the screen position of the part of interest, depending on the difference in the imaging method. Changes in details are difficult to overlook. Thereby, it is possible to improve the diagnosis efficiency and ability by the doctor and reduce fatigue.

2. Displayed as a ratio or difference from the normal value and, if necessary, the results of a superior difference test that is numerically statistically analyzed, it is possible to make a quantitative diagnosis rather than qualitative. Since it can be compared with a reference image created for each specific disease, the possibility of the disease can be numerically grasped, so that an objective diagnosis is possible. Deployment to Computer Aided Diagnosis is also possible.

4). Rather than the vague qualitative data of conventional gray scale information, it is possible to numerically compare with standard images created for each specific disease, so the possibility of disease can also be grasped numerically. Contribute to progress. As a result, medical malpractice problems are reduced, the degree of satisfaction of the subject is improved, and medical costs are reduced. As a result, medical treatment based on diagnostic treatment data using images, evidence-based medicine (EBM), will advance.

  In the above-described embodiment, the image of the same part has been described. However, any image including the same part may be used. For example, images having different slice thicknesses may be used as long as the images include the same part.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

FIG. 1 is a diagram showing a configuration of an image display apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing image switching rules by the display control unit of FIG. FIG. 3 is a diagram showing another image switching rule by the display control unit of FIG. FIG. 4 is a diagram showing a flow of processing of the entire image display by the control unit of FIG. FIG. 5 is a diagram showing a display example of a processing result by the ROI processing unit of FIG. FIG. 6 is a diagram showing an operation device for selecting an image switching rule installed in the input unit of FIG. FIG. 7 shows an example of a conventional image display screen.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Control part, 2 ... Image memory | storage part, 3 ... Image display part, 4 ... Input part, 5 ... Image processing part, 6 ... Display control part, 7 ... Position alignment processing part, 9 ... Pixel value correction part, 10 ... Map creation unit, 11... ROI processing unit, 12... Slicing processing unit.

Claims (21)

A storage unit for the same region of the subject for storing data including multiple medical images generated by the MRI apparatus,
A display unit that displays the medical images at substantially the same position on the screen while switching one by one one after another,
The plurality of medical images may be different types of medical images captured and generated by at least one different imaging parameter excluding a slice position or imaging time among a plurality of imaging parameters necessary for obtaining a medical image, or different types of medical images. Including different types of medical images captured and generated in a pulse sequence, and different types of medical images and medical images having different slice positions,
The display unit
Enabling switching display of a plurality of medical images having different imaging parameters or pulse sequences at substantially the same position on the screen, and switching display of a plurality of medical images having different slice positions at substantially the same position on the screen. A medical image display device characterized by the above.   The medical image display apparatus according to claim 1, wherein the display unit switches and displays the image centers of the plurality of medical images in accordance with a specific position on the screen.   The medical image display device according to claim 1, wherein the display unit switches and displays anatomical positions of the plurality of medical images together.   The medical image display apparatus according to claim 1, wherein the plurality of medical images include medical images collected at different times.   The medical image display apparatus according to claim 1, wherein the display unit switches and displays the plurality of medical images while fading in and out.   The medical image display apparatus according to claim 1, wherein the display unit aligns the plurality of medical images.   The medical image display apparatus according to claim 1, further comprising a map creation unit that creates a map having a pixel value as a ratio or difference between each of the medical images and a reference image related to the part.   The medical image display apparatus according to claim 7, wherein the reference image is a past image related to the part of the subject. The medical image display apparatus according to claim 7 , wherein the reference image is a standard image regarding the part that has been statistically processed. The medical image display apparatus according to claim 7, wherein the map creation unit eliminates or reduces a shift between the medical image and the reference image by deformation.   The medical image display device according to claim 7, wherein the standard image is provided for each disease.   The medical image display apparatus according to claim 1, wherein the display unit switches the medical images at a constant time interval.   The medical region according to claim 1, further comprising a region-of-interest processing unit that generates a graphic representing a change between the medical images related to a pixel value included in a region of interest in the medical image or a ratio or difference between the pixel value and a standard value. Image display device. The medical image display apparatus according to claim 1, wherein the plurality of medical images having different imaging parameters or pulse sequences include a longitudinal relaxation enhanced image, a lateral relaxation enhanced image, and a proton density image obtained by an MRI apparatus. The slice position in the different medical images, medical image display apparatus according to claim 1, wherein the slice position location is included tomographic image differs.   The medical image display device according to claim 1, wherein the plurality of medical images include an image by an X-ray CT apparatus, an image by an ultrasonic diagnostic apparatus, an image by a SPECT apparatus, an image by a PET apparatus, or an endoscopic image. Wherein the plurality of medical images, medical image display apparatus according to claim 6, wherein the positional information of the medical image position correction on the basis of performed.   The medical image display apparatus according to claim 1, wherein the plurality of medical images are images that have been subjected to normalization processing. The medical image display apparatus according to claim 1, wherein the display unit displays a calculation result obtained by statistically processing pixel values in a region of interest set in the plurality of medical images. The medical image display apparatus according to claim 1, further comprising an operation unit for changing the switching display direction .   The medical image display apparatus according to claim 1, wherein the medical images are images having different slice thicknesses including the same part.

Images