JP2014151114A - Medical image diagnostic apparatus, medical image processor and medical image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical image diagnostic apparatus which allows a user to observe the same position of an organ by matching the position and orientation of the organ.SOLUTION: The medical image diagnostic apparatus includes: an imaging section for detecting radiation rays passing through an analyte to collect projection data; a detection section for detecting biological information periodically changing which is emitted from the analyte; a scanning control section for controlling the imaging section synchronously with the biological information; an image processing section for extracting at least two feature points from each piece of volume data acquired by processing the projection data, detecting an axis line connecting the two feature points and a direction vector starting from the axis line, converting coordinates of multiple pieces of volume data which continue with time so that reference coordinates of a portion of interest set on the axis line and the direction vector match each other and generating a cross sectional image passing through the reference coordinates of each piece of volume data; and a display section for displaying an image processed by the image processing section.

Description

  Embodiments described herein relate generally to a medical image diagnostic apparatus such as an X-ray CT apparatus, and more particularly to a medical image diagnostic apparatus capable of imaging a periodically changing organ such as a heart and displaying and observing a 4D image. The present invention relates to a medical image processing apparatus and a medical image processing method.

  Conventionally, when a moving organ such as the heart is imaged and a 4D image (moving image) is displayed and observed, since the patient coordinates are fixed with respect to the bed, the organ appears to move little by little. In other words, because the position and orientation of the organ changes little by time and phase, it is necessary to adjust the position and angle so that the volume of the organ looks the same for each volume when displaying it continuously as a movie. .

  However, it is troublesome to adjust the display position and angle for each volume. In addition, since the adjustment is performed manually, there is a problem that it is difficult to reproduce when a similar display is desired at a later date.

JP 2012-55392 A JP-A-3-251237

  The problem to be solved by the invention is to provide a medical image diagnostic apparatus, a medical image processing apparatus, and a medical image processing method that automatically match the positions and orientations of organs so that the same positions of the organs can be observed. is there.

  A medical image diagnostic apparatus according to an embodiment includes an imaging unit that detects radiation transmitted through a subject and collects projection data, a detection unit that detects biological information that changes periodically from the subject, and the detection A scan control unit that controls the imaging unit in synchronization with the biological information from the unit, and extracts at least two feature points from the volume data obtained by processing the projection data, and connects the two feature points Detecting an axis and a direction vector starting from the axis, and converting the coordinates of a plurality of time-sequential volume data so that the direction vector matches the reference coordinate of the target region set on the axis, An image processing unit that generates a cross-sectional image that passes through the reference coordinates of each volume data, and a display unit that displays an image processed by the image processing unit.

1 is a block diagram showing a medical image diagnostic apparatus according to an embodiment. Explanatory drawing which shows an example of the electrocardiogram waveform in one Embodiment. Explanatory drawing which shows the structure of the heart roughly. The flowchart explaining the process of the heart image in one Embodiment. Explanatory drawing which shows an example of the 3D image of the heart produced | generated in one Embodiment. Explanatory drawing which shows the reference | standard coordinate set to the volume in one Embodiment. Explanatory drawing which shows an example of the 3D image of the heart which made the cross-sectional position correspond to the reference coordinates in one embodiment, a cross-sectional image, and a continuous image. Explanatory drawing which shows an example of the continuous image of the cross-sectional image and 3D image of the heart when a cross-sectional position is fixed. The block diagram which shows the medical image diagnostic apparatus which concerns on 2nd Embodiment. Explanatory drawing which shows the feature point when the lung is image | photographed in 2nd Embodiment.

  Embodiments for carrying out the invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected about the same location.

(First embodiment)
FIG. 1 is a block diagram showing a medical image diagnostic apparatus according to an embodiment, and shows an X-ray CT apparatus (X-ray computed tomography apparatus) as an example. In FIG. 1, an X-ray CT apparatus 100 has a gantry 10, and a rotating frame 11 is provided in the gantry 10 and is rotated by a rotating mechanism (not shown). An X-ray tube 12 and an X-ray detector 13 are disposed in the rotating frame 11 so as to face each other. The central portion of the rotating frame 11 is open, and the opening is mounted on the top plate 14 of the bed. The placed subject 200 is inserted. In the following description, the subject 200 may be called a patient.

 X-rays from the X-ray tube 12 are irradiated onto the subject 200, and the X-rays transmitted through the subject 200 are converted into electrical signals by the X-ray detector 13, and a data acquisition unit 15 called a DAS (data acquisition system). Are amplified and converted into digital data. The digital data is transmitted to the operation console 20 (described later) as projection data via the data transmission unit. The X-ray detector 13 has a large number of X-ray detection elements arranged in a matrix in the body axis direction (slice direction) and body width direction (channel direction) of the subject 200, and the detector arranged in the slice direction. Collect projection data for each column. The X-ray tube 12, the X-ray detector 13, and the data collection unit 15 constitute an imaging unit.

 The gantry 10 is provided with a gantry / bed control section 16 and a slip ring 17. The couchtop 14 can be moved back and forth to the opening of the gantry 10 by a couch driving unit 19 provided on the couch 18, and a driving signal is supplied to the couch driving unit 19 from the gantry / couch control unit 16. The couch 18 sends couch position information to the gantry / couch controller 16.

 The operation console 20 constitutes a computer system. The operation console 20 includes a preprocessing unit 21, and digital data from the data collection unit 15 is sent to the preprocessing unit 21 via the data transmission unit. The preprocessing unit 21 performs processing such as correction of signal intensity and correction of signal loss, and outputs projection data to the bus line 201.

 The system control unit 22 is connected to the bus line 201. A scan control unit 23 is connected to the system control unit 22, and an image processing unit 24, an image data storage unit 25, and the like are connected via a bus line 201. The scan control unit 23 is connected to the high voltage generation unit 26 and the gantry / bed control unit 16. Further, an input unit 27 having an operation unit and a display unit 28 are connected to the system control unit 22.

 The system control unit 22 functions as a host controller and controls the operation of each unit of the operation console 20. The scan control unit 23 also controls the gantry / bed control unit 16 and the high voltage generation unit 26 to control the X-ray irradiation amount and exposure timing when the subject 200 is scanned.

 The image processing unit 24 operates under the control of the system control unit 22, extracts a region of interest or an organ of interest from the volume data, and reconstructs 3D (three-dimensional) image data or the like. Further, the image processing unit 24 collects cardiac projection data over a plurality of heartbeats by, for example, an electrocardiographic reconstruction method, cuts out and reconstructs data of each heartbeat phase, and generates a 4D image. The image data storage unit 25 stores data such as tomographic images.

 The input unit 27 is connected to the system control unit 22 and can be operated by an operator (doctor, laboratory technician, etc.), and performs various settings for data processing. In addition, various information such as the patient's condition and examination method is input. Further, the input unit 27 is operated when setting the reference coordinates (described later) by the operator. The display unit 28 displays the image obtained by the image processing unit 24 or the image data stored in the image data storage unit 25.

 The high voltage generator 26 supplies electric power to the X-ray tube 12 via the slip ring 17 and supplies electric power (tube voltage and tube current) necessary for X-ray exposure. The X-ray tube 12 generates beam X-rays that spread in two directions: a slice direction parallel to the body axis direction of the subject 200 and a channel direction perpendicular thereto.

  The X-ray CT apparatus 100 is provided with, for example, an electrocardiograph (ECG) 30 in order to detect periodically changing biological information emitted from the subject 200. The electrocardiograph 30 constitutes a detection unit that detects biological information (electrocardiographic waveform) emitted from the subject 200. The electrocardiographic waveform data detected by the electrocardiograph 30 is supplied to the scan control unit 23. The electrocardiograph 30 may be incorporated as a component of the X-ray CT apparatus or may be configured as an external device.

    For example, in a cardiac examination in an X-ray CT apparatus, a specified heartbeat phase is scanned in synchronization with an electrocardiogram waveform as shown in FIG. 2 to reconstruct an image at the target heartbeat phase. FIG. 2 shows an example of an electrocardiogram waveform. As for the electrocardiogram waveform, P wave, Q wave, R wave, S wave, T wave, U wave appear in the period of one heartbeat period, R wave appears in the period when the heart is moving most, and the movement is relatively slow. U wave appears in the period. Therefore, in general, scanning (electrocardiographic synchronization scanning) is performed during a period of relatively slow movement while avoiding the R wave generation period.

  Next, an image processing method in the medical image diagnostic apparatus according to the embodiment will be described. In the following description, an example in which the heart is imaged as an organ image and a 4D image is displayed will be described.

  FIG. 3 is an explanatory diagram schematically showing the structure of the heart. The heart is composed of a right atrium, a left atrium, a right ventricle, and a left ventricle, and has four valves (a tricuspid valve, a pulmonary valve, a mitral valve, and an aortic valve) to prevent blood backflow. In addition, the upper part of the heart is called “the heart” and the lower part is called “the apex”. The arrows in FIG. 3 indicate the direction of blood flow.

  In one embodiment, an organ characteristic point, for example, in the heart, an axis Y connecting the mitral valve and the apex is detected, and four chambers (right atrium, left atrium, right ventricle, left ventricle) start from one point of the axis Y. An axis X (direction vector) indicating the direction of the right ventricle is detected in a cross section passing through. Further, reference coordinates indicating the position of the target region to be observed are set, and the display position and direction are adjusted and displayed for all volumes so that the reference coordinates of the position to be observed and the direction vector X coincide.

  The image processing method will be described below with reference to the flowchart of FIG. FIG. 4 is a flowchart for explaining processing of a heart image when a heart is imaged.

  First, in step S1, a contrast medium is injected into the subject 200, and in the next step S2, the scan control unit 23 controls the gantry / bed control unit 16 to perform an electrocardiographic synchronization scan. In the electrocardiogram synchronous scan, scanning is performed using an electrocardiogram waveform (FIG. 2) from the electrocardiograph 30.

  In the next step S3, the image processing unit 24 reconstructs images at a plurality of heartbeat phases. In step S <b> 4, the image processing unit 24 captures all the reconstructed images of a plurality of heartbeat phases, and displays the volume data on the display unit 28. FIG. 5 shows an example of a 3D image 30 based on heart volume data. In FIG. 5, for easy understanding, the heart is shown in a simplified manner, images from the mitral valve to the apex are schematically shown, and images of the right ventricle 31 and the left ventricle 32 are shown.

  Next, the image processing unit 24 detects the position of the mitral valve, which is a feature point, in step S5, and detects the position of the apex, which is another feature point, in step S6. In step S7, a cardiac axis Y (see FIG. 5) that is an axis connecting the mitral valve and the apex is determined, and in the next step S8, a short-axis image is created. The short axis image is an image of a cross section cut from a direction orthogonal to the axis Y.

  In step S9, the image processing unit 24 detects the right ventricular direction vector X based on the short-axis image. The direction vector X is an axis indicating the direction of the right ventricle in a cross section passing from one point of the cardiac axis Y to four chambers (right atrium, left atrium, right ventricle, left ventricle). The direction vector X defines the direction of the heart and indicates that the direction indicated by the vector X is right.

  Further, in step S10, the image processing unit 24 creates an arbitrary cross-sectional image, for example, a four-chamber display cross-sectional image or a two-chamber display cross-sectional image. The four-chamber display cross-sectional image is a cross-sectional image orthogonal to the cardiac axis Y and crossing the four chambers (right atrium, left atrium, right ventricle, left ventricle). The two-chamber display cross-sectional image is a cross-sectional view in which the left ventricle and the left atrium are cut in the vertical direction in a direction parallel to the cardiac axis Y. Since the left ventricle is a part that pumps blood to the aorta, the two-chamber display cross-sectional image is an important image for diagnosis. An instruction to create the four-chamber display cross-sectional image or the two-chamber display cross-sectional image is made by the operator operating the input unit 27. In step S11, in response to the operator's operation of the input unit 27, reference coordinates are set in order to determine the cross-sectional position. For example, the reference coordinates are set in a portion where there is an infarction or a portion where there is a possibility of infarction. FIG. 6 is an explanatory diagram showing the reference coordinates set for the volume.

  FIG. 6 shows the head volume obtained by, for example, an electrocardiogram synchronous scan, and the cardiac axis Y and the right ventricular direction vector X correspond to FIG. For example, when there is an infarction on the heart axis Y of the heart, the distance between the mitral valve and the apex is L1, and the position of the infarction is 30% of the distance L1 from the mitral valve, the cross-sectional position (α · L1 ) To set the reference coordinate P.

  The ratio α is (0 <α <1), and α = 0.3 when the position of the infarct is 30% of the distance L1 from the mitral valve. The position (point P) at a distance α · L1 from the position of the mitral valve, which is a feature point, is the reference coordinate for moving image display. In FIG. 6, a cross-sectional position that crosses the reference coordinate P and is parallel to the direction vector X is indicated by A.

  The image processing unit 24 determines the heart axis Y based on the feature points (mitral valve and apex) for all other volume data in the same manner in steps S5 to S9, and detects the direction vector X. To do.

  Next, in step S <b> 12, the image processing unit 24 continuously displays a 3D image in time series in accordance with an operator instruction from the input unit 27 and displays a moving image. At this time, the image processing unit 24 adjusts each volume data by moving / rotating the vector coordinates so that the reference coordinates set in step S11 coincide with the vector X, and successively 3D images based on the plurality of adjusted volume data. A 4D image (moving image) is displayed on the display unit 28.

  That is, the reference coordinate P is set based on any one (for example, the head) volume. In addition, by applying the ratio α obtained previously to the distance between the feature points on the axis Y in all other volumes, the reference coordinates are set for all the volumes so that the respective reference coordinates and direction vectors coincide. Convert all volume coordinates to.

  FIG. 7A is a diagram continuously showing 3D images of the heart that change at times T1 to T5. FIG. 7B shows a continuous image of the cross-sectional images obtained by matching the cross-sectional position A with the reference coordinates P of each 3D image of FIG. 7A and cutting at each cross-sectional position A. The cross-sectional position A in FIG. 7B corresponds to the cross-sectional position A in FIG.

  As shown in FIG. 7A, the heart pulsates in the cardiac cycle to circulate blood by contraction and expansion of the ventricles. Therefore, even if the position and orientation of the organ (heart) change little by little for each time phase / phase, the cross-sectional image of FIG. 7B can be obtained by matching the reference coordinates P of each volume with the direction vector X. Since the infarcted part is always displayed on the display, the diagnosis can be facilitated.

  FIG. 8 shows an example of a continuous image of cross-sectional images when the cross-sectional position is fixed in the 3D image of the heart. FIG. 8 (a) continuously shows 3D images of the heart changing from time T1 to T5, and FIG. 8 (b) sets the cross-sectional position B to the fixed position of each 3D image in FIG. 8 (a). The continuous image of a cross-sectional image is shown.

  As shown in FIG. 8B, when the cross-sectional position B is fixed, the infarct portion may not be displayed in the cross-sectional image when the position or orientation of the organ (heart) changes for each time phase / phase. Yes, it takes time to diagnose.

  As described above, in one embodiment, for each volume of 4D data, by setting the reference coordinate P and displaying a cross-sectional image, it is possible to always display an image of a site of interest (for example, an infarct portion).

(Second Embodiment)
Next, a medical image diagnostic apparatus according to the second embodiment will be described. In the second embodiment, a respiratory synchronization scan is executed to process a captured image of an organ (eg, lung).

  FIG. 9 is a block diagram of the second embodiment. In FIG. 9, a respiratory detector 40 is provided instead of the electrocardiograph 30 in FIG. 1, and scanning is performed in accordance with the patient's breathing. The respiration detector 40 constitutes a detection unit that detects biological information (breathing data) that changes periodically from the subject 200. Since other configurations are the same as those in FIG. 1, description thereof is omitted.

  In other words, the respiration detector 40 generates respiration data generated by the subject 200 and detects when the patient inhales or exhales. As a detection method, for example, there is a method of measuring the swelling of the chest (chest thickness) when the patient exercises a breathing exercise. Or you may measure the flow volume and flow velocity of respiration. The respiration data from the respiration detector 40 is supplied to the scan control unit 23, and for example, in the examination of the chest, the scan is performed in respiration synchronization.

  FIG. 10 is an explanatory diagram showing feature points when a lung is imaged for a chest examination. When the lungs are imaged, feature points are detected based on one of the volumes (for example, the head). As feature points, for example, the top (P1) of the lung and the top (P2) of the diaphragm are detected, and an axis Y connecting the feature points P1 and P2 is determined. A short axis image (cross-sectional image) in a direction orthogonal to the axis Y is created, and a lung direction vector is detected.

  Then, an arbitrary cross-sectional image is created, a region of interest (for example, a portion having a nodule C) is determined from the image, and reference coordinates are set. For example, when the distance between the feature points P1 and P2 is L2, and the position of the nodule is 30% of the distance L2 from the feature point P1, the reference coordinate P is set to the cross-sectional position (α · L2). . That is, the position of the distance α · L2 from the position of the feature point P1 becomes the reference coordinate P for moving image display.

  Further, the ratio α previously obtained is applied to the distance between the feature points on the axis Y in all other volumes, and the coordinates are converted so that the reference coordinates and the direction vectors coincide for all the volumes.

  Also in the second embodiment, by matching the cross-sectional position to the reference coordinates, even when the 3D image is continuously displayed, even when the size of the organ (lung) changes due to the patient's breathing, Since the attention site (nodule) of the cross-sectional image is always displayed, diagnosis can be facilitated.

  In addition to the lung, examples of organs that change due to breathing include, for example, vocal cords. Even in such organs, it is possible to display an image of a site of interest by obtaining feature points and axis lines and setting reference coordinates. it can.

  According to at least one embodiment described above, the reference point is created by obtaining the feature point of the volume, and the same reference point of each volume is made to coincide, so that the same organ in each time phase / phase is obtained. The position can be observed. Therefore, diagnosis becomes easy. The same image set can always be adjusted and displayed in the same way, and can be reproduced even if it is desired to display the same image at a later date.

  In addition, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

100: Medical diagnostic imaging apparatus (X-ray CT apparatus)
DESCRIPTION OF SYMBOLS 10 ... Gantry 11 ... Rotating plate 12 ... X-ray tube 13 ... X-ray detector 14 ... Top plate 15 ... Data collection part 16 ... Base and bed control part 18 ... Bed 20 ... Operation console 21 ... Pre-processing part 22 ... System control Unit 23 ... Scan control unit 24 ... Image processing unit 25 ... Image data storage unit 26 ... High pressure generation unit 27 ... Input unit 28 ... Display unit 30 ... Electrocardiograph 40 ... Respiration detector P ... Reference coordinates

Claims (14)

An imaging unit that detects radiation transmitted through the subject and collects projection data; and
A detection unit for detecting periodically changing biological information emitted by the subject;
A scan control unit that controls the imaging unit in synchronization with the biological information from the detection unit;
At least two feature points are extracted from the volume data obtained by processing the projection data, an axis connecting the two feature points and a direction vector starting from the axis are detected, and the attention set on the axis An image processing unit that converts the coordinates of a plurality of volume data that are temporally continuous so that the reference coordinates of a part and the direction vector match, and generates a cross-sectional image that passes through the reference coordinates of each volume data;
A display unit for displaying an image processed by the image processing unit;
A medical image diagnostic apparatus comprising:   The medical image diagnostic apparatus according to claim 1, wherein the image processing unit creates an arbitrary cross-sectional image of the volume for setting the reference coordinates of the site of interest and displays the image on the display unit.   The medical image diagnostic apparatus according to claim 1, wherein the image processing unit detects the direction vector by creating a short-axis image across the axis of the volume data.   The medical image processing apparatus according to claim 1, wherein the image processing unit creates a continuous three-dimensional image based on a plurality of temporally continuous volumes, and outputs and displays the cross-sectional image passing through the reference coordinates on the display unit. Diagnostic imaging device.   The detection unit includes an electrocardiograph that detects a motion of the heart of the subject, and the scan control unit performs control so that the heart is imaged by an electrocardiographic synchronization scan based on an output of the electrocardiograph. The medical image diagnostic apparatus according to claim 1.   The detection unit includes a respiration detector that detects a respiration state of the subject, and the scan control unit controls to capture an organ by a respiration synchronization scan based on the respiration data of the subject. The medical image diagnostic apparatus according to 1. Obtaining projection data of the subject imaged by the imaging unit, extracting at least two feature points from the volume data obtained by processing the projection data, and starting from the axis line connecting the two feature points and the axis line Detecting the direction vector, and converting the coordinates of a plurality of temporally continuous volume data so that the direction vector matches the reference coordinate of the target region set on the axis, and the reference of each volume data An image processing unit for generating a cross-sectional image passing through the coordinates;
A display unit for displaying an image processed by the image processing unit;
A medical image processing apparatus comprising:   The medical image processing apparatus according to claim 7, wherein the image processing unit creates an arbitrary cross-sectional image of the volume for setting reference coordinates of the site of interest and displays the image on the display unit.   The medical image processing apparatus according to claim 7, wherein the image processing unit detects the direction vector by creating a short-axis image across the axis of the volume data.   The medical image processing apparatus according to claim 7, wherein the image processing unit creates a continuous three-dimensional image based on a plurality of temporally continuous volumes, and outputs and displays the cross-sectional image passing through the reference coordinates on the display unit. Image processing device. Obtain the projection data of the subject imaged by the imaging unit,
Extracting at least two feature points of the volume data obtained by processing the projection data, detecting an axis connecting the two feature points and a direction vector starting from the axis;
The coordinates of a plurality of volume data that are temporally continuous are converted so that the direction vector coincides with the reference coordinates of the region of interest set on the axis,
A cross-sectional image passing through the reference coordinates of each volume data is generated,
A medical image processing method for displaying the generated cross-sectional image on a display unit.   The medical image processing method according to claim 11, wherein an arbitrary cross-sectional image of the volume is created and set on the display unit for setting the reference coordinates of the attention site.   The medical image processing method according to claim 11, wherein the direction vector is detected by creating a short-axis image crossing the axis of the volume data.   The medical image processing method according to claim 11, wherein a continuous three-dimensional image is created based on a plurality of temporally continuous volumes, and is output and displayed on the display unit together with a cross-sectional image passing through the reference coordinates.

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