JP2007144139A - X-ray computed tomography apparatus and image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray computed tomography apparatus etc. which detect blood flow delay information in CT perfusion and present it as visualizable information to easily specify an affected part presenting a symptom by vascular flow delay. <P>SOLUTION: An X-ray computed tomography apparatus calculates transfer functions h(t) using both a time-concentration curve Ca(t) for pixels of a cerebral artery and a time-concentration curve Ci(t) for pixels of cerebral tissues including capillary vessels and then calculates a delay time for each pixel of an object region from a time when an artery curve rises on the basis of the transfer functions. Further, the apparatus differently produces a visual color map showing time differences of blood flow conditions and provide it in a predetermined form by coloring pixels with a time delay from the other pixels without a time delay on the basis of the calculated delay time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is an X-ray computed tomography capable of executing a blood flow analysis method (hereinafter referred to as “CT perfusion”) using an X-ray computed tomography apparatus (hereinafter referred to as “X-ray CT apparatus”). The present invention relates to a photographing apparatus.

  An X-ray CT apparatus calculates (reconstructs) the X-ray absorption rate of a tissue such as an organ as an index called a CT value based on that of water based on the amount of X-rays received in the subject. An image (tomographic image) is obtained. In a normal X-ray CT examination using this X-ray CT apparatus, morphological information can be obtained from a simple CT image. In CT perfusion, dynamic information on blood flow around a lesion can be acquired by dynamic scanning using contrast CT and provided as visual information. In recent years, high-speed scanning by multi-slice CT has become possible, and the application range of dynamic scanning of contrast CT has been expanded more and more.

In CT perfusion, for example, there is a method called a CBP study for calculating an index related to blood flow dynamics of capillaries in brain tissue. In the CBP study, indexes such as CBP, CBV, MTT, and Err that quantitatively indicate the dynamics of “blood flow through capillaries” are obtained, and a map of these indexes is output. Index CBP and the like that quantitatively represent the blood flow dynamics of the capillaries in these brain tissues, together with information on the elapsed time since the onset of cerebral ischemia, pathological identification of ischemic cerebrovascular disorders, Expected to be useful information for evaluating the presence / absence of expansion, blood flow rate, and the like (see, for example, Patent Document 1).
JP 2003-116843 A

  However, in the conventional X-ray CT apparatus, it is impossible to detect information related to a delay (blood flow delay information) until the blood flow (or contrast medium) reaches the examination site in CT perfusion. Therefore, although the affected part that has developed due to a decrease in blood flow can be identified using the test result obtained by CT perfusion, the affected part that has developed due to a delay in blood flow cannot be identified.

  The present invention has been made in view of the above circumstances, and detects blood flow delay information in CT perfusion and presents it as information that can be visualized. An object of the present invention is to provide an X-ray computed tomography apparatus that can be easily specified.

  In order to achieve the above object, the present invention takes the following measures.

  According to a first aspect of the present invention, there is provided a data acquisition unit that acquires a plurality of time-series images relating to a region to be examined that has been injected with a contrast agent, and the arterial concentration change curve based on the plurality of images. An X-ray computed tomography apparatus comprising: a delay time calculation unit that calculates a delay time of a density change curve of a site to be inspected; and a map creation unit that creates a map image representing the distribution of the delay time It is.

  According to a second aspect of the present invention, there is provided a storage unit that stores a plurality of time-series images relating to a region to be examined that has been injected with a contrast agent, and the subject to be subjected to the concentration change curve of the artery based on the plurality of images. An image processing apparatus comprising: a delay time calculation unit that calculates a delay time of a density change curve of an examination region; and a map creation unit that creates a map image representing a distribution of the delay time.

  As described above, according to the present invention, the blood flow delay information is detected in CT perfusion, and presented as information that can be visualized, so that the affected part that has developed due to the blood flow delay can be easily identified. A tomographic apparatus or the like can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

  Embodiments of an X-ray CT apparatus according to the present invention will be described below with reference to the drawings. In the X-ray CT system, an X-ray tube and an X-ray detector are combined into one body, and a rotation / rotation (ROTATE / ROTATE) type that rotates around the subject, and a large number of detection elements are arrayed in a ring shape. There are various types such as a fixed / rotation (STATIONARY / ROTATE) type in which only the X-ray tube rotates around the subject, and the present invention can be applied to any type. Here, the rotation / rotation type that currently occupies the mainstream will be described.

  In addition, to reconstruct one slice of tomographic image data, projection data for about 360 ° around the periphery of the subject is required, and projection data for 180 ° + view angle is also required in the half scan method. . The present invention can be applied to any reconstruction method.

  In addition, the mechanism for converting incident X-rays into electric charges is based on an indirect conversion type in which X-rays are converted into light by a phosphor such as a scintillator and the light is further converted into electric charges by a photoelectric conversion element such as a photodiode. The generation of electron-hole pairs in semiconductors and their transfer to the electrode, that is, the direct conversion type utilizing a photoconductive phenomenon, is the mainstream. Any of these methods may be employed as the X-ray detection element, but here, the former indirect conversion type will be described.

  In recent years, the so-called multi-tube X-ray computed tomography apparatus in which a plurality of pairs of X-ray tubes and X-ray detectors are mounted on a rotating frame has been commercialized, and the development of peripheral technologies has progressed. Yes. The present invention can be applied to both a conventional single-tube X-ray CT apparatus and a multi-tube X-ray computed tomography apparatus. Here, a single tube type will be described.

  FIG. 1 shows a block diagram of an X-ray CT apparatus 1 according to the present embodiment. As shown in the figure, the X-ray CT apparatus 1 includes a gantry 2 and an information processing unit 3. The gantry 2 is configured to collect projection data related to the subject P, and includes a slip ring 11, a gantry driving unit 12, an X-ray tube 13, an X-ray detector 15, a rotating frame 16, and a data collecting unit. 17. A non-contact data transmission device 18 is provided. The information processing unit 3 generates an X-ray CT image and various clinical information using the control by controlling the data collection operation in the gantry 2 and performing predetermined processing on the data collected in the gantry 2. , High voltage generator 19, preprocessing unit 20, memory unit 21, reconstruction unit 23, image processing unit 24, storage unit 25, control unit 27, display unit 29, input unit 31, blood flow information measurement unit 33, delay A time calculation unit 35, a map generation unit 37, and a transmission / reception unit 40 are provided.

  The gantry driving unit 12 drives the rotary frame 16 to rotate. By this rotational drive, the X-ray tube 13 and the X-ray detector 15 are rotated in a spiral manner around the body axis of the subject P while facing each other.

  The X-ray tube 13 is a vacuum tube that generates X-rays, and is provided on the rotating frame 16. The X-ray tube 13 is supplied with electric power (tube current, tube voltage) necessary for X-ray exposure from the high voltage generator 19 via the slip ring 11. The X-ray tube 13 exposes X-rays to the subject placed in the effective visual field region FOV by accelerating electrons by the supplied high voltage and colliding with the target.

  The X-ray detector 15 is a detector system that detects X-rays that have passed through the subject, and is attached to the rotating frame 16 in a direction facing the X-ray tube 13. The X-ray detector 15 is a single-slice type or multi-slice type detector, and a plurality of detection elements constituted by a combination of a scintillator and a photodiode are one-dimensional or two-dimensional depending on each type. Are arranged.

  The rotating frame 16 is a ring that is driven to rotate about the Z axis, and has the X-ray tube 13 and the X-ray detector 15 mounted thereon. A central portion of the rotating frame 16 is opened, and a subject P placed on a bed (not shown) is inserted into the opening.

  The data acquisition device 17 is generally called DAS (Data Acquisition System), converts a signal output from the detector 15 for each channel into a voltage signal, amplifies it, and converts it into a digital signal. This data (raw data) is taken into the information processing device 3 via the non-contact data transmission device 18.

  The high voltage generator 19 is a device that supplies electric power necessary for X-ray exposure to the X-ray tube 13 via the slip ring 11, and includes a high voltage transformer, a filament heating converter, a rectifier, and a high voltage. It consists of a switcher.

  The preprocessing unit 20 receives raw data from the data collection device 17 via the non-contact data transmission device 18 and executes sensitivity correction and X-ray intensity correction. The raw data for 360 degrees subjected to various corrections is temporarily stored in the storage unit 25. The raw data preprocessed by the preprocessing unit 20 is called “projection data”.

  The reconstruction unit 23 is equipped with a plurality of kinds of reconstruction methods, and reconstructs image data by the reconstruction method selected by the operator. The multiple types of reconstruction methods include, for example, a fan beam reconstruction method (also referred to as a fan beam convolution back projection method), and a reconstruction method when a projection ray intersects obliquely with respect to the reconstruction surface. Feldkamp method, Feldkamp method as an approximate image reconstruction method in which convolution is considered as a fan projection beam, and backprojection is processed along the ray at the time of scanning, assuming that the cone angle is small As a method for suppressing the cone angle error, a cone beam reconstruction method for correcting projection data in accordance with the ray angle with respect to the reconstruction surface is included.

  The image processing unit 24 performs image processing for display such as window conversion and RGB processing on the reconstructed image data generated by the reconstructing unit 23, and outputs the image processing to the display unit 29. Further, the image processing unit 24 generates a so-called pseudo three-dimensional image such as a tomographic image of an arbitrary cross section, a projection image from an arbitrary direction, or a three-dimensional surface image based on an instruction from the operator, and outputs the generated image to the display unit 29.

  The storage unit 25 stores image data such as raw data, projection data, scanogram data, tomographic image data, a program for an inspection plan, and the like. The storage unit 25 stores a dedicated program for executing blood flow information measurement processing, delay time calculation processing, delay map creation processing, and the like, which will be described later.

  The control unit 27 performs overall control of the X-ray CT apparatus 1 in scan processing, signal processing, image generation processing, image display processing, and the like. For example, in the scan process, the control unit 27 stores a scan condition such as a slice thickness that is input in advance in the memory unit 21 and automatically selects a scan condition that is automatically selected based on a patient ID or the like (or in manual mode) Based on the scanning conditions set directly from the unit 31), the feeding amount in the body axis direction, the feeding speed, the X-ray tube 13 and the X-rays of the high voltage generator 19, the bed driving unit 12, and the bed top plate a. The rotational speed, rotational pitch, and X-ray exposure timing of the detector 15 are controlled, and an X-ray cone beam or X-ray fan beam is exposed from multiple directions to a desired imaging region of the subject. Data collection (scanning) processing of the line CT image is performed.

  The display unit 29 is an output device that displays CT images such as a computer tomographic image, a scanogram image, blood flow information (CBP, CBV, MTT, a delay map described later) input from the image processing unit 24. In the present embodiment, the CT image is defined as “an image generated based on each CT value in the imaging region acquired by the X-ray computed tomography apparatus”. Here, the CT value represents an X-ray absorption coefficient of a substance as a relative value from a reference substance (for example, water). The display unit 29 displays a scan plan screen and the like realized by a planning assistance system (not shown).

  The input unit 31 includes a keyboard, various switches, a mouse, and the like, and can input various scan conditions such as a slice thickness and the number of slices through an operator.

  The blood flow information measurement unit 33 executes blood flow information measurement processing represented by a CBP study. This blood flow information measurement process will be described in detail later.

  Based on the blood flow information generated by the blood flow information measurement unit 33, the delay time calculation unit 35 performs a time series change curve (arterial curve) of pixels corresponding to an artery and a time series change of pixels corresponding to a region to be examined. The transfer function of both is calculated from the curve (curved part curve). Further, the delay time calculation unit 35 calculates the delay time of the inspected part curve from the calculated transfer function for the arterial curve. These transfer function and delay time calculation processing will be described in detail later.

  Based on the calculated delay time, the map generation unit 37 generates a delay map that visualizes a time axis direction shift (delay) between the artery and the site to be examined. The generation of the delay map will also be described in detail later.

  The transmission / reception unit 40 transmits / receives image data, patient information, and the like to / from other devices via the network N. In particular, the transmission / reception unit 40 receives information (patient information, diagnosis part, etc.) related to imaging of the subject from an RIS (Radiology Information System) connected to the network N.

(Blood flow information measurement process)
Next, blood flow information measurement processing using a CBP study as an example will be described. In the CBP study, indexes of CBP, CBV, MTT, and Err that quantitatively indicate the dynamics of “blood flow through capillaries” in brain tissue are obtained, and a map of these indexes is output. The definition of each index is as follows.

CBP: Unit volume and blood flow per unit time in capillaries of brain tissue [ml / 100 ml / min]
CBV: Blood volume per unit volume in brain tissue [ml / 100ml]
MTT: Average blood passage time in capillaries [sec]
Err: An index of the residual deviation of the actual measurement value from the analysis model. Depending on the degree of this index, it is possible to analyze the discriminating between the dominating tissue and the non-dominating tissue of the cerebral artery.

  In the CBP study, a contrast agent having no cerebral vascular permeability, such as an iodine contrast agent, is used as a tracer. The iodine contrast agent is injected from the cubital vein by an injector, for example. The iodine contrast agent intravenously injected by the injector flows from the cerebral artery via the heart and lungs. Then, it flows out from the cerebral artery to the cerebral vein through the capillaries in the brain tissue. At this time, a contrast agent having no cerebral vascular permeability, for example, an iodinated contrast agent, passes through the capillary in normal brain tissue without leaking out of the blood vessel.

  The blood flow information measuring unit 33 continuously acquires the state of the contrast agent passing by dynamic CT, and from the continuous image, the temporal concentration curve Ca (t) of the pixels on the cerebral artery, and the brain tissue including the capillaries The time density curve Ci (t) of the upper pixel and the time density curve Csss (t) of the pixel on the cerebral vein are measured. In the CBP study, the blood concentration of the contrast agent is established between the time curve Ca (t) of the blood concentration of the cerebral blood vessels close to the brain tissue and the time curve Ci (t) of the blood concentration of the capillaries. The ideal relationship is an analysis model, that is, when a contrast medium is injected from a blood vessel just before entering the brain tissue, the time density curve in the brain tissue unit volume (1 pixel) including the capillaries has a vertical rise and is slightly It will fall with a gradient of. The transfer function can be approximated by a rectangular function (box-MTTF method: box-Modulation Transfer Function method). In addition, using the cerebral artery blood time concentration curve Ca (t) as an input function and the brain tissue time concentration curve Ci (t) as an output function, the characteristics of the process of passing through capillaries are solved by solving Equation 1 below. It can be obtained as an obtained transfer function.

(Delay time calculation process)
Next, the delay time calculation process executed in the delay time calculation unit 35 will be described. In this embodiment, it is assumed that the arterial curve Ca (t) acquired in the CBP study, each inspected part curve Ci (t), and the transfer function h (t) between them have the relationship shown in (Equation 1). To do.

Further, since the input image is sampled at discrete time, when (Equation 1) is discretized at sampling time Δt, (Equation 2) is obtained.

Since (Equation 2) is a simultaneous equation for the transfer function h, it is possible to identify the transfer function h by solving this equation. However, due to clinical problems, each of the arterial curves Ca (t) is not necessarily Imaging is not always performed before the inspected portion curve Ci (t).

Therefore, assuming that the arterial matrix Mc in (Equation 2) is a block-circulant type, and modeling the positional deviation in the time axis direction between the arterial curve Ca (t) and each inspected part curve Ci (t), ( Equation 3)

  Next, the transfer function h (t) is identified by solving the simultaneous equations of (Equation 3). There are various methods for solving simultaneous equations. When the singular value decomposition method (SVD method) generally used for solving simultaneous equations of real problems is used, for example, FIG. The transfer function having the shape shown in FIG. 2B (example in which the inspected curve is ahead of the arterial curve) is calculated. In the case of the example shown in FIG. 2A, the time at which the peak of the transfer function is given is the deviation in the time axis direction between the arterial curve Ca (t) and each inspected part curve Ci (t). Can be used as the delay time of each pixel to be inspected.

A method for calculating the time at which the peak of the transfer function h is given, that is, the delay time will be described below. The transfer function h (n) analyzed by the block-circulant SVD method has a continuous transfer function starting point (0, h (0)) and ending point (N-1, h (N-1)). Is modeled as circulating. For this reason, as shown in FIG. 2B, when the contrast agent reaches the region to be examined earlier than the artery, the peak of the transfer function that originally exists in the negative direction of the time axis is the end point side (n = N−1 ). Therefore, the data that has come to the end point side is returned in the negative direction of the time axis. Clinically, the possible difference in the contrast agent arrival time between the arterial and the region to be examined is 10 seconds at the maximum, and M data for 10 seconds on the end point side is moved in the negative direction of the time axis as shown in Equation 4 below.

  Next, the time n = n_max that gives the maximum value of the transfer function h (n) (n = −M, −M + 1,..., −1,0,1... N−M−1) is calculated. , Interpolating 3 points (n_max-1, h (n_max-1)), (n_max, h (n_max)), (n_max + 1, h (n_max + 1)) including 2 points before and after that with a quadratic function The time when the maximum value of the interpolated curve is given is set as the delay time.

  In this way, by calculating the entire inspected image using the same arterial curve, calculating the relative delay time of blood flow arrival of each pixel when the contrast agent arrival time to the artery is 0 Is possible. Furthermore, it is possible to display as a map by generating an image having a delay time for each pixel as a pixel value.

  The delay time calculation process according to the present embodiment has been described above, but various modifications can be made without being limited to the above contents. For example, in the present embodiment, the delay time calculation method when the block-circulant SVD method is used for the transfer function identification method has been described. However, the transfer function identification method is not limited to the block-circulant SVD method. Further, without using the transfer function identification method, the delay time may be calculated from the difference between the rise time of the arterial curve and the rise time of the examination site curve.

  Further, in the above example, when the contrast medium reaches the region to be inspected earlier than the artery, the data wrapping around to the end point side according to the equation (4) is moved in the negative direction of the time axis. However, without being bound by this, for example, for the position (pixel) where the contrast agent reaches the examination region earlier than the artery and the negative delay time is obtained, the delay map is not actively generated. The delay time (or pixel value) may be set to 0, or a predetermined color indicating that the delay time is negative may be assigned.

  Furthermore, the delay time image is not limited to two dimensions, and when the input time-series image is three-dimensional, the delay time image may be displayed in three dimensions. In such a case, the blood flow information measurement process and the delay time calculation process are executed for each voxel.

(Delay map generation process reflecting delay time)
Next, a delay map generation process reflecting the delay time will be described. This processing is performed for a pixel in which a delay has occurred (for example, a pixel in which the calculated delay time exceeds a predetermined threshold), and a pixel in which no delay has occurred in the pixel (for example, the calculated delay time has a predetermined A delay map is generated by creating a blood flow map to which a color different from that of a pixel not exceeding the threshold value is assigned.

  FIG. 3A shows an example of a blood flow map obtained by blood flow information measurement processing. FIG. 4 shows an example of a delay map corresponding to the blood flow map in FIG. 3A. As can be seen from a comparison between FIG. 3A and FIG. 4, in the delay map, different colors are assigned to the portions where the delay time is generated. Therefore, the observer can easily visually grasp which part is slower in blood flow than the surroundings by observing the delay map. In addition, by assigning different colors according to the delay time, it is possible to grasp the delay time based on the color.

  The delay map can be displayed simultaneously with the blood flow map or selectively with the blood flow map. Further, for example, as shown in FIG. 5, a fusion image of a delay map C and CTA (Computed Tomographic Angiography) may be displayed. In particular, when displayed as a fused image, it is possible to visually recognize the upstream artery of the site to be inspected that may cause a delay. In any display form, it is preferable that the delay map is displayed so that it can be determined which information corresponds to which blood flow map.

(Operation)
Next, the operation of the X-ray CT apparatus 1 when performing CT perfusion will be described. In the present embodiment, for the sake of concrete explanation, a case where a CBP and a delay map corresponding to the CBP are generated using a predetermined region in the brain as a site to be inspected is taken as an example. However, the present invention is not limited to this, blood flow information other than CBP may be adopted, and the region to be examined may be other than the intracerebral region.

  FIG. 6 is a flowchart showing a flow of processing executed by the X-ray CT apparatus 1 in CT perfusion. As shown in the figure, first, a contrast agent having no cerebral vascular permeability as a tracer, for example, an iodine contrast agent, is injected from the elbow vein by, for example, an injector (step S1). The iodine contrast agent intravenously injected by the injector flows from the cerebral artery via the heart and lungs. Then, it flows out from the cerebral artery to the cerebral vein through the capillaries in the brain tissue. At this time, the iodine contrast medium passes (inflows) without leaking out of the blood vessel in the capillary blood vessels in normal brain tissue. On the other hand, in the capillaries in abnormal brain tissue, the contrast medium leaks out of the blood vessels. Further, in a region where vascular stenosis or the like exists in the inflow route, the iodine contrast medium passes with a delay compared to a region where stenosis does not exist in the inflow route.

  Next, the control unit 27 executes dynamic CT to collect data for visualizing the passage of the contrast agent injected into the subject, and performs a predetermined process to generate a continuous image. (Step S2). The blood flow information measurement unit 33 executes a CBP study using the generated continuous image, thereby at least a time density curve Ca (t) of a cerebral artery pixel and a time density curve of a brain tissue pixel including a capillary blood vessel. Ci (t) is measured (step S3).

  Next, the delay time calculation unit 35 uses the measured time density curve Ca (t) of the cerebral artery pixel and the time density curve Ci (t) of the pixel of the brain tissue including the capillary blood vessel to transfer function h ( t) is calculated, and based on the time when the peak of the transfer function h (t) is given, the delay time for each pixel of the region to be inspected with respect to the rise time of the arterial curve is calculated (step S4).

  Next, the control unit 27 determines whether or not the calculated delay time exceeds a predetermined threshold (step S5), and when determining that the calculated delay time does not exceed the threshold, the map generation unit 37 A blood flow information map (CBP in this case) is generated (step S6). On the other hand, when the control unit 27 determines that the predetermined threshold value is not exceeded, the map generation unit 37 generates a delay map by assigning a color corresponding to the delay time to the pixel in which the delay time has occurred ( Step S6 '). The threshold value used as a reference in step S5 is automatically set by an initial condition or a manual operation, but can be changed to an arbitrary value by a predetermined operation from the input unit 31.

  Next, the display unit 29 displays the generated blood flow information map (CBP, delay map) in a predetermined form (step S7).

  According to the configuration described above, the following effects can be obtained.

  According to the X-ray CT apparatus according to the present embodiment, the transfer function h is obtained using both the time density curve Ca (t) of the cerebral artery pixel and the time density curve Ci (t) of the pixel of the brain tissue including the capillary blood vessel. (t) is calculated, and based on this, the delay time for each pixel of the region to be inspected is calculated based on the rise time of the arterial curve. Also, based on the calculated delay time, a color map that visualizes the time difference of the blood inflow situation is created by assigning a color different from that of the pixel where the delay time has occurred to the pixel where the delay time has occurred. Present it in a predetermined form. Therefore, an observer such as a doctor can easily identify an affected part that has developed due to a delay in blood flow in the region to be examined and its vicinity by observing the presented color map.

  Further, according to the X-ray CT apparatus according to the present embodiment, a color corresponding to the calculated delay time can be assigned to each pixel. Therefore, an observer such as a doctor can provide a delay map in which the delay time can be intuitively grasped by color.

  Further, according to the X-ray CT apparatus according to the present embodiment, transmission is performed using both the time density curve Ca (t) of the cerebral artery pixel and the time density curve Ci (t) of the brain tissue pixel including the capillary. In identifying the function h (t), for example, a block-circulant SVD method is used. With this method, based on the time when the peak of the transfer function h (t) is given, it is possible to relatively easily calculate the delay time for each pixel of the site to be examined with reference to the rise time of the arterial curve.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage.

  For example, each of the blood flow information measurement process, the delay time calculation process, and the delay map generation process reflecting the delay time described in the present embodiment is a time series related to the site to be examined that has been collected in advance and into which the contrast medium has been injected. By using a plurality of images, the image processing apparatus can execute the images. It can also be realized by installing a program for executing each process in a computer such as a workstation and developing the program on a memory. At this time, a program capable of causing the computer to execute the technique is stored in a recording medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory. It can also be distributed.

  In addition, various inventions can be formed by appropriately combining a plurality of constituent elements 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.

  As described above, according to the present invention, the blood flow delay information is detected in CT perfusion, and presented as information that can be visualized, so that the affected part that has developed due to the blood flow delay can be easily identified. A tomographic apparatus or the like can be realized.

FIG. 1 shows a block diagram of an X-ray CT apparatus 1 according to the present embodiment. FIG. 2A is a diagram illustrating an example of a transfer function when the block-circulant SVD method is used. FIG. 2B is a diagram illustrating an example of a transfer function when the block-circulant SVD method is used. FIG. 3 shows an example of a blood flow map obtained by the blood flow information measurement process. FIG. 3B shows an example of a blood flow map obtained by the blood flow information measurement process. FIG. 3 shows an example of a blood flow map obtained by the blood flow information measurement process. FIG. 4 shows an example of a delay map corresponding to the blood flow map of FIG. 3A. FIG. 5 shows a fusion image of the delay map and the computed tomographic angiography. FIG. 6 is a flowchart showing a flow of processing executed by the X-ray CT apparatus 1 in CT perfusion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... X-ray CT apparatus, 2 ... Mount, 3 ... Information processing part, 11 ... Slip ring, 12 ... Mount drive part, 13 ... X-ray tube, 15 ... X-ray detector, 16 ... Rotating frame, 17 ... Data Collection unit 18 ... Non-contact data transmission device 18 ... High voltage generator 20 ... Pre-processing unit 21 ... Memory unit 23 ... Reconstruction unit 25 ... Storage unit 27 ... Control unit 29 ... Display unit DESCRIPTION OF SYMBOLS 31 ... Input part, 33 ... Blood flow information measurement, 35 ... Delay time calculation part, 37 ... Map generation part, 40 ... Transmission / reception part

Claims (16)

A data acquisition unit for acquiring a plurality of time-series images relating to a region to be examined injected with a contrast agent;
A delay time calculation unit for calculating a delay time of the concentration change curve of the region to be examined with respect to the concentration change curve of the artery based on the plurality of images;
A map creation unit for creating a map image representing the distribution of the delay time;
An X-ray computed tomography apparatus comprising:   The delay time calculation unit uses a block-circulant SVD method to calculate a transfer function of the time concentration curve of the region to be examined with respect to the time concentration curve of the artery, and based on the peak time of the transfer function, The X-ray computed tomography apparatus according to claim 1, wherein the delay time is calculated.   The delay time calculating unit calculates the delay time based on a time difference between a rise time of the concentration change curve of the artery and a rise time of the concentration change curve of the examination site. The X-ray computed tomography apparatus described.   The said map creation unit creates the color map by which the time difference of the blood inflow situation was visually recognized by allocating the color according to the said delay time. X-ray computed tomography apparatus. The map creation unit
When the contrast agent reaches the region to be examined earlier than the artery, the concentration change curve of the region to be examined is moved in the negative direction of the time axis,
Creating a two-dimensional map image representing a delay time distribution based on the concentration change curve of the inspected site after the movement;
The X-ray computed tomography apparatus according to any one of claims 1 to 4, wherein:   The map creating unit replaces the delay time from the calculated value to another value when the contrast medium reaches the region to be examined earlier than the artery. The X-ray computed tomography apparatus as described in any one of Claims.   The X-ray computed tomography apparatus according to any one of claims 1 to 6, further comprising a display unit that displays the two-dimensional map image simultaneously or selectively with a blood flow map.   The X-ray computed tomography apparatus according to claim 1, further comprising a display unit that displays a fusion image of the two-dimensional map image and the computed tomographic angiography. A storage unit for storing a plurality of time-series images related to a region to be examined into which a contrast medium has been injected;
A delay time calculation unit for calculating a delay time of the concentration change curve of the region to be examined with respect to the concentration change curve of the artery based on the plurality of images;
A map creation unit for creating a map image representing the distribution of the delay time;
An image processing apparatus comprising:   The delay time calculation unit uses a block-circulant SVD method to calculate a transfer function of the time concentration curve of the region to be examined with respect to the time concentration curve of the artery, and based on the peak time of the transfer function, The image processing apparatus according to claim 9, wherein the delay time is calculated.   The delay time calculation unit calculates the delay time based on a time difference between a rise time of the concentration change curve of the artery and a rise time of the concentration change curve of the examination site. The image processing apparatus described.   The said map creation unit creates the color map by which the time difference of the blood inflow situation was visually recognized by assigning the color according to the said delay time. Image processing device. The map creation unit
When the contrast agent reaches the region to be examined earlier than the artery, the concentration change curve of the region to be examined is moved in the negative direction of the time axis,
The image processing apparatus according to any one of claims 9 to 11, wherein a two-dimensional map image representing a delay time distribution is created based on a density change curve of the examination site after the movement.   The map creating unit replaces the delay time from the calculated value to another value when the contrast agent reaches the region to be examined earlier than the artery. The image processing apparatus according to claim 1.   The image processing apparatus according to claim 9, further comprising a display unit that displays the two-dimensional map image simultaneously or selectively with a blood flow map.   The image processing apparatus according to claim 9, further comprising a display unit that displays a fusion image of the two-dimensional map image and the computed tomographic angiography.

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