JP2004159983A - X-ray ct apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus providing a perfusion image in a short period of time. <P>SOLUTION: This X-ray CT apparatus is provided with an injection means 10 injecting contrast media into an imaging object, imaging means 2, 4 and 6 taking a tomographic image of the imaging object parallel with the injection of the contrast media, a creation means 60 creating a perfusion image based on the tomographic image simultaneously and parallel with the imaging and a display means 68 displaying the perfusion image. The perfusion image is a color image expressing two-dimensional distribution of CBF (Cerebral Blood Flow), CBV (Cerebral Blood Volume) and MTT (Mean Transit Time), respectively. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray CT (Computed Tomography) apparatus, and more particularly, to an X-ray CT apparatus that performs imaging using a contrast agent.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when a tomographic image is captured by an X-ray CT apparatus, a contrast agent is injected into an imaging target as needed (for example, see Patent Literature 1).
[0003]
[Patent Document 1]
JP-A-10-286252 (page 3-4, FIG. 3-5).
[0004]
[Problems to be solved by the invention]
When an image representing the perfusion state of blood, that is, a perfusion image, is created from a tomographic image of the brain captured using a contrast agent, a plurality of tomographic images captured over a predetermined period of time are post-processed. , It takes a considerable time from the start of photographing to obtaining a perfusion image. Since the perfusion image is mainly used for diagnosing cerebral infarction, it is desired to obtain the image in as short a time as possible.
[0005]
Therefore, an object of the present invention is to realize an X-ray CT apparatus in which the time required to obtain a perfusion image is short.
[0006]
[Means for Solving the Problems]
The present invention for solving the above-mentioned problems includes an injection unit that injects a contrast agent into an imaging target, an imaging unit that captures a tomographic image of the imaging target in parallel with the injection of the contrast agent, An X-ray CT apparatus comprising: a creation unit for creating a perfusion image based on the tomographic image; and a display unit for displaying the perfusion image.
[0007]
According to the present invention, since a perfusion image is created concurrently with photographing, the time required to obtain a perfusion image can be reduced. It is preferable that the perfusion image is an image showing a two-dimensional distribution of CBF, from the viewpoint of diagnosing cerebral infarction based on CBF. It is preferable that the perfusion image is an image showing a two-dimensional distribution of CBV from the viewpoint of performing a cerebral infarction diagnosis based on CBV. It is preferable that the perfusion image is an image showing a two-dimensional distribution of MTT in terms of diagnosing cerebral infarction based on MTT. It is preferable that the perfusion image is an image showing a two-dimensional distribution of CBF, CBV and MTT, respectively, from the viewpoint of performing a cerebral infarction diagnosis based on CBF, CBV and MTT.
[0008]
It is preferable that the perfusion image is a color image in order to improve the manifestation of cerebral infarction. It is preferable that the display means also displays a tomographic image in order to easily grasp the condition of the affected part. It is preferable that the photographing means performs continuous photographing in terms of increasing the time resolution.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiment. FIG. 1 shows a block diagram of the X-ray CT apparatus. This device is an example of an embodiment of the present invention. The configuration of the present apparatus shows an example of an embodiment relating to the apparatus of the present invention.
[0010]
As shown in FIG. 1, the present apparatus includes a scanning gantry 2, an imaging table 4, an operation console 6, and a contrast agent injection device 10. The portion including the scanning gantry 2, the imaging table 4, and the operation console 6 is an example of an embodiment of the imaging means in the present invention.
[0011]
The scanning gantry 2 has an X-ray tube 20. An X-ray (not shown) emitted from the X-ray tube 20 is shaped into a fan-shaped X-ray beam (beam) by a collimator 22, and is applied to an X-ray detector 24. You.
[0012]
The X-ray detector 24 has a plurality of detection elements arranged in an array in the direction of expansion of the fan-shaped X-ray beam. The configuration of the X-ray detector 24 will be described later. The X-ray tube 20, collimator 22, and X-ray detector 24 constitute an X-ray irradiation / detection device. The X-ray irradiation / detection device will be described later.
[0013]
A data acquisition unit 26 is connected to the X-ray detector 24. The data collection unit 26 collects detection signals of the individual detection elements of the X-ray detector 24 as digital data.
[0014]
The irradiation of X-rays from the X-ray tube 20 is controlled by an X-ray controller 28. The illustration of the connection relationship between the X-ray tube 20 and the X-ray controller 28 is omitted. The collimator 22 is controlled by a collimator controller 30. The illustration of the connection relationship between the collimator 22 and the collimator controller 30 is omitted.
[0015]
The components from the X-ray tube 20 to the collimator controller 30 are mounted on the rotating unit 34 of the scanning gantry 2. The rotation of the rotation unit 34 is controlled by a rotation controller 36. The illustration of the connection relationship between the rotation unit 34 and the rotation controller 36 is omitted.
[0016]
The imaging table 4 carries in and out an imaging target (patient) (not shown) into and out of the X-ray irradiation space of the scanning gantry 2. The relationship between the object and the X-ray irradiation space will be described later.
[0017]
The contrast agent injection device 10 is configured to inject a contrast agent into an object on the imaging table 4. The injection of the contrast agent is performed by, for example, intravenous injection or the like. The contrast agent injection device 10 is an example of an embodiment of an injection unit in the present invention.
[0018]
The operation console 6 has a data processing device 60. The data processing device 60 is configured by, for example, a computer. The data processing device 60 is connected to a control interface (interface) 62. The scanning gantry 2, the imaging table 4, and the contrast agent injection device 10 are connected to the control interface 62. The data processing device 60 controls the scanning gantry 2, the imaging table 4, and the contrast agent injection device 10 through the control interface 62.
[0019]
The data acquisition unit 26, X-ray controller 28, collimator controller 30, and rotation controller 36 in the scanning gantry 2 are controlled through a control interface 62. It should be noted that illustration of individual connections between these units and the control interface 62 is omitted.
[0020]
A data collection buffer 64 is also connected to the data processing device 60. The data collection buffer 26 is connected to the data collection unit 26 of the scanning gantry 2. The data collected by the data collection unit 26 is input to the data processing device 60 through the data collection buffer 64.
[0021]
The data processing device 60 performs image reconstruction using transmission X-ray data of a plurality of views collected through the data collection buffer 64. For image reconstruction, for example, a filtered back projection method or the like is used.
[0022]
The storage device 66 is also connected to the data processing device 60. The storage device 66 stores various data, programs, and the like. When the data processing device 60 executes the program stored in the storage device 66, various types of data processing related to the execution of imaging are performed. The creation of the perfusion image is also performed by the data processing device 60. The data processing device 60 is an example of an embodiment of a creating unit according to the present invention.
[0023]
A display device 68 and an operation device 70 are also connected to the data processing device 60. The display device 68 displays a reconstructed image output from the data processing device 60 and other information. The display device 68 is an example of an embodiment of a display unit in the present invention.
[0024]
The operation device 70 is operated by a user and inputs various instructions and information to the data processing device 60. The user uses the display device 68 and the operation device 70 to interactively operate the present device.
[0025]
FIG. 2 shows a schematic configuration of the X-ray detector 24. As shown in the figure, the X-ray detector 24 is a multi-channel (channel) X-ray detector in which a plurality of detection elements 24 (i) are arranged in an array. The plurality of detection elements 24 (i) form an X-ray incident surface curved in a cylindrical concave shape as a whole. i is a channel number, for example, i = 1 to 1000.
[0026]
The detection element 24 (i) is configured by, for example, a combination of a scintillator and a photodiode. The present invention is not limited to this, and may be, for example, a semiconductor detection element using cadmium tellurium (CdTe) or an ionization chamber type detection element using Xe gas (gas).
[0027]
FIG. 3 shows the mutual relationship between the X-ray tube 20, the collimator 22, and the X-ray detector 24 in the X-ray irradiation / detection device. 3A is a diagram illustrating a state when viewed from the front of the scanning gantry 2, and FIG. 3B is a diagram illustrating a state when viewed from the side. As shown in the figure, the X-rays radiated from the X-ray tube 20 are shaped into a fan-shaped X-ray beam 400 by the collimator 22 and irradiated to the X-ray detector 24.
[0028]
FIG. 3A shows the spread of the fan-shaped X-ray beam 400. The spreading direction of the X-ray beam 400 coincides with the channel arrangement direction in the X-ray detector 24. (B) shows the thickness of the X-ray beam 400.
[0029]
With the body axis intersecting the fan surface of the X-ray beam 400, for example, as shown in FIG. 4, the object 8 placed on the imaging table 4 is carried into the X-ray irradiation space. The scanning gantry 2 has a cylindrical structure including an X-ray irradiation / detection device inside.
[0030]
The X-ray irradiation space is formed in a space inside the cylindrical structure of the scanning gantry 2. An image of the object 8 sliced by the X-ray beam 400 is projected on the X-ray detector 24. The X-ray detector 24 detects X-rays transmitted through the subject 8. The thickness of the X-ray beam 400 irradiating the target 8 is adjusted by the aperture of the collimator 22.
[0031]
The X-ray irradiation / detection device including the X-ray tube 20, the collimator 22, and the X-ray detector 24 can continuously rotate (scan) around the body axis of the object 8 while maintaining their mutual relationship. It is.
[0032]
FIG. 5 shows a flow chart of the operation of the present apparatus. As shown in the drawing, in step 501, a preliminary scan is performed. As a result, a tomographic image of the contrast-enhanced portion is captured. Next, in step 503, tomographic image display is performed. Thus, a tomographic image is displayed on the display device 68.
[0033]
Next, in step 505, a region of interest (ROI) setting is performed. The ROI setting is performed by the user. The user sets ROIa and ROIv for the tomographic image displayed on the display device 68, for example, as shown in FIG. ROIa is set to a portion where an artery exists, and ROIv is set to a portion where a vein exists.
[0034]
Next, in Step 507, a contrast agent injection is performed. The contrast agent injection is performed by the contrast agent injection device 10. Next, in step 509, a contrast agent arrival waiting is performed. FIG. 7 shows a flowchart of the operation of waiting for the arrival of the contrast agent. As shown in the figure, in step 591, a monitoring scan is performed. The monitoring scan is a scan for monitoring the arrival of the contrast agent. The monitoring scan is performed on a part to be contrast-enhanced. The monitoring scan is performed in the same manner as ordinary tomographic imaging.
[0035]
For the tomographic image obtained by the monitoring scan, in step 593, the CT value in the ROIa is binarized in a range of 150 ± ε. The value of ε is, for example, 50. Next, in step 595, labeling is performed on the binarized portion. Next, in step 597, it is determined whether or not each label has a portion corresponding to a blood vessel having a diameter of 2 to 3 mm, that is, a circular region. The data processing of these steps 593 to 597 is performed by the data processing device 60.
[0036]
If the determination is No, the process returns to step 591 to repeat the above operation. While the determination is No, the operations of steps 591 to 597 are repeated. Thus, the arrival of the contrast agent is waited.
[0037]
When the determination is Yes, a cine scan is performed in step 511. Cine scan is to sequentially generate tomographic images while continuously performing scans. As a result, an image with a high temporal resolution can be obtained.
[0038]
Next, in step 513, a perfusion image is created. The perfusion image is created from time-series tomographic images sequentially obtained by cine scan. The creation of the perfusion image is performed by the data processing device 60 as follows.
[0039]
That is, when creating a perfusion image, first, a time intensity curve of the ROIa, ROIv, and other parts of the pixel (pixel) is obtained from the time-series tomographic image.
[0040]
The time intensity curve is a change over time in the signal intensity of a pixel as shown in FIG. 8, for example. Such a curve is obtained for each pixel of ROIa, ROIv, and other parts. Each curve reflects the blood flow state at each pixel.
[0041]
The perfusion image is created based on those time intensity curves by a predetermined algorithm (algorithm) that applies the principle of Flick.
[0042]
There are three types of images to be created. That is, a CBF (cerebral flow) image, a CBV (cerebral blood volume) image, and an MTT (mean transit time) image. Each of these images shows a two-dimensional distribution of CBF, CBV and MTT.
[0043]
Next, at step 515, a perfusion image is displayed. The display of the perfusion image is performed by the display device 68. Thus, as shown in FIG. 9, for example, a CBF image, a CBV image, and an MTT image are displayed side by side with a tomographic image obtained by cine scan.
[0044]
The tomographic image is a cine image, and shows the spread state of the contrast agent in the imaging slice in real time. Thereby, the condition of the affected part can be easily grasped.
[0045]
The CBF image, the CBV image, and the MTT image show changes in the two-dimensional distribution of the CBF, CBV, and MTT, respectively, in real time. The CBF image, the CBV image, and the MTT image are displayed as color images. Thereby, the manifestation of cerebral infarction is improved.
[0046]
As described above, since the CBF image, the CBV image, and the MTT image are created and displayed in real time simultaneously with the contrast imaging, a perfusion image can be obtained in a short time after the start of the imaging.
[0047]
Note that as the perfusion image, only one or two of the CBF image, the CBV image, and the MTT image may be created. However, to facilitate the diagnosis of cerebral infarction, it is preferable to create all three types of images.
[0048]
【The invention's effect】
As described above in detail, according to the present invention, an X-ray CT apparatus in which the time required to obtain a perfusion image is short is realized.
[Brief description of the drawings]
FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of an X-ray detector.
FIG. 3 is a schematic diagram of an X-ray irradiation / detection device.
FIG. 4 is a schematic diagram of an X-ray irradiation / detection device.
FIG. 5 is a flowchart showing an operation of the apparatus according to the embodiment of the present invention;
FIG. 6 is a diagram showing ROI setting.
FIG. 7 is a detailed flowchart showing a part of the operation of the apparatus according to the embodiment of the present invention;
FIG. 8 is a diagram showing a time intensity curve.
FIG. 9 is a diagram illustrating a display method of a perfusion image.
[Explanation of symbols]
2 Scanning gantry 20 X-ray tube 22 Collimator 24 X-ray detector 26 Data collection unit 28 X-ray controller 30 Collimator controller 34 Rotation unit 36 Rotation controller 4 Imaging table 6 Operation console 60 Data processing device 62 Control interface 64 Data collection buffer 66 Storage Device 68 Display device 70 Operating device 8 Target 10 Contrast injection device

Claims (8)

Injection means for injecting a contrast agent into an object to be imaged,
Imaging means for capturing a tomographic image of a target to be captured in parallel with the injection of the contrast agent,
Creating means for creating a perfusion image based on the tomographic image concurrently with imaging;
Display means for displaying the perfusion image,
An X-ray CT apparatus comprising: The perfusion image is an image showing a two-dimensional distribution of CBF.
The X-ray CT apparatus according to claim 1, wherein: The perfusion image is an image showing a two-dimensional distribution of CBV.
The X-ray CT apparatus according to claim 1, wherein: The perfusion image is an image showing a two-dimensional distribution of MTT,
The X-ray CT apparatus according to claim 1, wherein: The perfusion image is an image showing a two-dimensional distribution of CBF, CBV and MTT, respectively.
The X-ray CT apparatus according to claim 1, wherein: The perfusion image is a color image,
The X-ray CT apparatus according to any one of claims 1 to 5, wherein: The display means also displays a tomographic image,
The X-ray CT apparatus according to any one of claims 1 to 6, wherein: The photographing means performs continuous photographing;
The X-ray CT apparatus according to any one of claims 1 to 7, wherein:

Images