JP2011115280A - Medical image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly and precisely obtain clinical physical quantities relating to an area to be monitored wider than a photographable area by a medical photographing device. <P>SOLUTION: A plurality of volume images obtained by photographing the area to be monitored wider than the photographable area by an MRI device 200 by dividing into multiple times are individually stored in a storing part 3. The image analyzing part 13 of a main processing part 1 executes the processing for obtaining the clinical physical quantities (vessel diameter, stenosis ratio or others) by analyzing one of the plurality of volume images for each of the plurality of volume images. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a medical imaging apparatus (diagnostic modality) such as a magnetic resonance diagnostic apparatus (hereinafter referred to as an MRI apparatus), an X-ray computed tomography apparatus (hereinafter referred to as a CT apparatus), an X-ray diagnostic apparatus, or an ultrasonic diagnostic apparatus. The medical image processing apparatus obtains a clinical physical quantity from the medical image captured by (1).

  Contrast-enhanced CTA (computed tomography angiography), contrast-enhanced MRA (magnetic resonance angiography), and non-contrast-enhanced MRA images are used for diagnosis of aneurysms and vascular stenosis. In order to support the above-described diagnosis, a technique for automatically analyzing the above-described medical image and obtaining a clinical physical quantity such as a stenosis rate of a blood vessel has been developed.

  By the way, in the case where the observation target for the diagnosis is a blood vessel of the whole body, the observation target region may be larger than the imageable region in the medical imaging apparatus. In this case, an image corresponding to the observation target region is generated by connecting a plurality of medical images obtained by imaging the observation target region in a plurality of times, and the image is analyzed. ing.

JP 2007-117669 A

  In an image generated by connecting a plurality of images, a connected distortion may occur in the vicinity of the boundary between the plurality of images. This connected distortion causes an error in the physical quantity obtained by analysis.

  Further, when each of the plurality of images is a three-dimensional image, for example, a technique called Volume Stitching is used to connect them. The processing using Volume Stitching takes a very long time, so the time required for diagnosis becomes long, and is not suitable for diagnosis in emergency or screening.

  The present invention has been made in view of such circumstances, and an object of the present invention is to quickly and accurately obtain a clinical physical quantity for an observation target area wider than an imageable area in a medical imaging apparatus. Is to make it possible.

  The medical image processing apparatus according to the first aspect of the present invention uses a medical imaging apparatus to divide a plurality of medical images obtained by imaging an observation target area that is wider than an imageable area of the medical imaging apparatus in multiple times. Storage means for storing, and analysis means for analyzing one of the plurality of medical images stored in the storage means to obtain a clinical physical quantity for each of the plurality of medical images; Equipped with.

  According to the present invention, it is possible to quickly and accurately obtain a clinical physical quantity for an observation target region that is wider than a region that can be imaged by a medical imaging apparatus.

1 is a block diagram of an image processing / display apparatus according to an embodiment of the present invention. The flowchart of the imaging region determination part in FIG. The figure which shows an example of the display image for setting an observation object area | region. The figure which shows the relationship between an effective area | region and an invalid length. The figure which shows the example of a setting of an imaging area and an effective area | region. The flowchart of the image analysis part in FIG. The flowchart of the display image generation part in FIG. The figure which shows an example of the area | region made into the object of analysis. The figure which shows an example of the display image which shows an analysis result. The figure which shows an example of the display image which shows an analysis result.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram of an image processing / display apparatus 100 according to this embodiment.

  The image processing / display apparatus 100 performs 3D image data (hereinafter referred to as volume data) acquired by the MRI apparatus 200 as a processing target and performs image processing for obtaining a clinical physical quantity. The image processing / display device 100 can be used to obtain various clinical physical quantities. Here, a description will be given of an apparatus that performs processing for measuring a stenosis rate of a blood vessel from an MRA image.

  The image processing / display device 100 includes a main processing unit 1, a communication unit 2, a storage unit 3, a display unit 4, and an operation unit 5.

  For the image processing / display device 100, for example, a general-purpose computer device can be used as basic hardware. The main processing unit 1 can be realized by causing a processor mounted on the computer apparatus to execute an image display processing program. The image display processing program may be preinstalled in the computer device, or may be recorded on a removable recording medium such as a magnetic disk, a magneto-optical disk, an optical disk, or a semiconductor memory, or via a network. The image display processing program may be distributed and the image display processing program may be appropriately installed in the computer device. As the communication unit 2, the storage unit 3, and the display unit 4, a communication device, a storage device, and a display device that are built in the computer apparatus can be used. That is, the communication unit 2 can use a LAN interface circuit, for example. The storage unit 3 can use a semiconductor memory or a hard disk. The display unit 4 can use a liquid crystal display or a CRT (cathode-ray tube). As the operation unit 5, various operation devices such as an input device such as a keyboard and a pointing device such as a mouse can be used. As the communication unit 2, the storage unit 3, the display unit 4, and the operation unit 5, a communication device, a storage device, a display device, and an operation device that are externally attached to the computer apparatus may be used. The communication unit 2 and the display unit 4 are not included in the image processing / display device 100, and a device separate from the image processing / display device 100 may be connected to the image processing / display device 100 and used. .

  The main processing unit 1 includes an imaging region determination unit 11, a medical image management unit 12, an image analysis unit 13, and a display image generation unit 14.

  The imaging area determination unit 11 determines an imaging area for acquiring volume data suitable for accurately measuring the stenosis rate by the MRI apparatus 200. And in order to implement | achieve such a process, the imaging area determination part 11 contains the effective area | region calculation part 11a and the imaging area calculation part 11b.

  The effective area calculation unit 11a calculates an effective area in the volume image. The volume image refers to a three-dimensional image represented by volume data acquired by one imaging. The effective region refers to an effective region for measuring the stenosis rate.

  The imaging area calculation unit 11b calculates a plurality of imaging areas such that the entire observation target area is covered by a plurality of effective areas. The observation target region refers to a region that is a target for observing a lesion related to blood vessel stenosis, and is also a region that is a target for measuring a stenosis rate. The imaging area refers to an area that is a target for one imaging operation of the MRI apparatus 200.

  The medical image management unit 12 acquires volume data from the MRI apparatus 200 and stores it in the storage unit 3. The medical image management unit 12 manages volume data stored in the storage unit 3.

  The image analysis unit 13 determines a portion that may be a lesion (hereinafter referred to as a lesion portion), and analyzes the volume image in order to measure the stenosis rate. In order to realize such processing, the image analysis unit 13 includes a blood vessel core line extraction unit 13a and a lesion determination unit 13b.

  The blood vessel core line extraction unit 13a extracts a blood vessel core line (hereinafter referred to as a blood vessel core line) and a contour (hereinafter referred to as a blood vessel contour) depicted in the volume image.

  The lesion determination unit 13b performs determination of the lesion site and measurement of the stenosis rate using the blood vessel core line and the blood vessel contour.

  The display image generation unit 14 generates a display image that represents the result of the analysis by the image analysis unit 13 together with the volume image.

  In addition, each said part in the main process part 1 may be implement | achieved based on a single program, and may be implement | achieved by several programs. The above-described units in the main processing unit 1 can be partially or entirely realized by hardware such as a logic circuit. Each of the above-described units can also be realized by combining hardware and software control.

  The communication unit 2 communicates various information with the MRI apparatus 200. The information communicated by the communication unit 2 includes imaging area information for instructing an imaging area and volume data.

  The storage unit 3 stores various types of information. The information stored in the storage unit 3 includes volume data acquired from the MRI apparatus 200 and analysis information indicating a result of analysis in the main control unit 1.

  The display unit 4 displays various images under the control of the main processing unit 1. The image displayed by the display unit 4 includes the above display image.

  The operation unit 5 inputs various instructions from the operator.

  Next, the operation of the image processing / display apparatus 100 configured as described above will be described.

  FIG. 2 is a flowchart of the imaging area determination unit 11.

  In step Sa1, the imaging region determination unit 11 sets an observation target region. The setting of the observation target area is performed according to an instruction from the operator, for example. Specifically, for example, the imaging region determination unit 11 causes the display unit 4 to display a positioning image Im1 and a rectangular frame F1 as illustrated in FIG. Then, the imaging area determination unit 11 changes the size and position of the rectangular frame F1 according to the change operation by the user, and sets an area corresponding to the area covered by the rectangular frame F1 when the user performs the confirmation operation as an observation target area Set as. Accordingly, the operator changes the rectangular frame F1 so as to match the region where the lesion is desired to be observed, and then performs the confirmation operation.

  In step Sa2, the imaging region determination unit 11 sets an invalid length. The invalid length refers to the length from the end of an area that is not suitable for measurement of the stenosis rate (hereinafter referred to as an invalid area) because the image distortion is large at the end of the once imaging area in the MRI apparatus 200. . That is, in the MRI apparatus 200, the image is distorted due to the influence of the magnetic field distortion at the end of the imaging region, and there is a possibility that an invalid region that is not suitable for the measurement of the stenosis ratio may be generated. Many MRI apparatuses 200 have a function of correcting image distortion due to magnetic field distortion, but it is difficult to completely eliminate image distortion. That is, an area where the image distortion is sufficiently corrected and an area where the image distortion cannot be corrected are generated, and the latter area becomes an invalid area. The invalid length is a value for specifying the size of such an invalid area. In this embodiment, the invalid length is set individually for the invalid lengths L1 and L2 for the static magnetic field direction and the direction orthogonal to the static magnetic field direction, respectively. The invalid length may be set according to an instruction from the operator, or may be automatically set in consideration of the performance of the MRI apparatus 200. However, the size of the invalid area varies depending on the model difference or individual difference in the performance of the MRI apparatus 200, and how much distortion is allowed may vary depending on the user. Therefore, the invalid length is typically set according to an instruction from the operator. However, it is more convenient if both the invalid length setting according to the operator's specification and the automatic invalid length setting can be selectively executed according to the operator's request. In order to reduce the measurement error of the stenosis rate, it is desirable to set the invalid length larger.

  In step Sa3, the imaging area determination unit 11 calculates an effective area in consideration of the invalid lengths L1 and L2. Specifically, as shown in FIG. 4, the imaging region determination unit 11 calculates the effective region R1 as a region excluding the invalid region at the end of the imageable region R2 in the MRI apparatus 200. Note that the imageable area refers to the maximum imaging area in one imaging in the MRI apparatus 200.

  In step Sa4, the imaging region determination unit 11 calculates a plurality of imaging regions in which all of the observation target region is filled with the effective region. Specifically, for example, the imaging area determination unit 11 calculates imaging areas R3-1, R3-2, R3-3, R3-4, and R3-5 as shown in FIG. In the example of FIG. 5, the effective areas of the imaging areas R3-1 to R3-5 are R4-1 to R4-5. Of these effective regions R4-1 to R4-5, adjacent ones partially overlap each other. Then, all of the observation target area is filled with the effective areas R4-1 to R4-5.

  In step Sa5, the imaging region determination unit 11 transmits imaging region information indicating the imaging region determined as described above to the MRI apparatus 200 via the communication unit 2. Then, the imaging area determination unit 11 ends the process shown in FIG.

  When receiving the imaging area information transmitted from the image processing / display apparatus 100 as described above, the MRI apparatus 200 individually performs volume imaging regarding each of the plurality of imaging areas indicated by the imaging area information. Thus, the MRI apparatus 200 performs volume imaging a plurality of times and acquires a plurality of volume data.

  Therefore, the image processing / display apparatus 100 acquires a plurality of volume data acquired by the MRI apparatus 200 in this way from the MRI apparatus 200 by the medical image management unit 12. Communication at this time may be requested from the MRI apparatus 200 to the image processing / display apparatus 100, or may be requested from the image processing / display apparatus 100 to the MRI apparatus 200. Then, the medical image management unit 12 stores a plurality of volume data acquired from the MRI apparatus 200 in the storage unit 3.

  At an arbitrary timing, the image analysis unit 13 starts analysis processing for the volume image represented by the volume data stored in the storage unit 3 as described above. The timing for starting the analysis processing may be, for example, immediately after acquisition of a plurality of volume data is completed, at a predetermined time, or when execution is instructed by an operator.

  FIG. 6 is a flowchart of the image analysis unit 13. Note that the flowchart of FIG. 6 illustrates processing performed with one inspection as a processing target.

  In the loop from step Sb1 to step Sb5, the image analysis unit 13 repeats the processing from step Sb2 to step Sb4 while increasing the variable P by 1 from 1 to n. Note that the variable n is the number of imaging regions in the examination to be processed. That is, when imaging is performed for the imaging region set as shown in FIG. 5, the variable n is “5”.

  In step Sb2, the image analysis unit 13 reads the Pth image as the current analysis target. Specifically, the image analysis unit 13 reads volume data regarding the image related to the P-th imaging region among the plurality of volume images related to the examination to be processed from the storage unit 3.

  In step Sb3, the image analysis unit 13 extracts the blood vessel core line and the blood vessel contour for the blood vessel drawn in the volume image (hereinafter referred to as an analysis target image) read out as described above. Specifically, for example, the image analysis unit 13 first sets a start point in the analysis target image in accordance with an operator's designation. At this time, the operator designates the start point for the blood vessel lumen depicted in the analysis target image. The image analysis unit 13 extracts the blood vessel core line and the blood vessel contour from the above starting point. For example, “Onno Wink, Wiro J. Niessen,“ Fast Delineation and Visualization of Vessel in 3-D Angiographic Images ”, IEEE Trans. Med. Imag., Vol. 19, No. 4, 2000” A well-known technique as shown in FIG.

  In step Sb4, the image analysis unit 13 uses the blood vessel core line and the blood vessel contour extracted as described above to determine a lesion site and measure the stenosis rate of the blood vessel at that site. For the processing here, for example, a well-known technique as disclosed in JP-A-2005-198708 can be applied. Specifically, a plurality of minimum blood vessel diameters are detected from a plurality of blood vessel shape data obtained by collecting blood vessel core lines and blood vessel contours. Next, a minimum diameter curve is generated from the plurality of detected minimum blood vessel diameters. Further, a plurality of regions having a small blood vessel diameter in this minimum diameter curve are obtained for each branch of each blood vessel and set as a stenosis site. Then, a place where a stenosis site exists is set as a lesion site. For each of the lesions determined in this way, the stenosis rate is measured using the ratio between the blood vessel diameter and the normal blood vessel diameters before and after that. Then, the image analysis unit 13 stores the lesion information representing the lesion site and the stenosis rate information representing the stenosis rate in the storage unit 3 in association with the volume image used for obtaining the lesion information.

  However, the image analysis unit 13 performs the process of step Sb4 only on the effective region of the analysis target image. Here, the process of step Sb4 may be performed on the entire effective area. However, as shown in FIG. 5, when a part of a plurality of effective areas overlaps, the process of step Sb4 is performed twice for the overlapping areas, which is inefficient. Therefore, if the process of step Sb4 is performed only on the regions R5-1 to R5-5 as shown in FIG. 8, for example, selected from the effective regions R4-1 to R4-5 so as not to overlap each other, More efficient.

  If the processing of steps Sb2 to Sb4 is completed with the volume image relating to the nth imaging region as the analysis target image and the processing of the loop of step Sb1 to step Sb5 is completed, it has been acquired for the examination to be processed. The analysis for each of the plurality of volume images has been completed. Therefore, in this case, the image analysis unit 13 ends the process shown in FIG.

  At an arbitrary timing, the display image generation unit 14 starts an analysis result display process for displaying the result of the analysis process performed as described above. The timing for starting the analysis result display process may be, for example, immediately after the above analysis process is completed or when an execution instruction is given by the operator.

  FIG. 7 is a flowchart of the display image generation unit 14.

  In step Sc1, the display image generation unit 14 generates a display image and outputs it to the display unit 4 for display.

  FIG. 9 is a diagram illustrating an example of a display image.

  The display image shown in FIG. 9 includes a blood vessel image Im2, an enlarged image Im3, a stenosis rate presentation image Im4, marks M1, M2, M3, and a frame F2.

  The blood vessel image Im2 is an image in which enlarged images of the regions R5-1 to R5-5 of each of the plurality of volume images are displayed side by side. In the blood vessel image Im2, processing for connecting blood vessels at the boundaries of a plurality of enlarged images is not performed.

  The marks M1 and M2 are shown superimposed on the blood vessel image Im2, and represent a lesion site.

  The mark M3 is shown superimposed on the blood vessel image Im2, and represents a lesion site that is a target of detailed display.

  A frame F2 is shown superimposed on the blood vessel image Im2, and represents a range corresponding to the enlarged image Im3.

  The enlarged image Im3 is an image obtained by performing MIP (maximum intensity projection) processing or SVR (shaded volume rendering) processing on one volume image including a lesion indicated by the mark M3. The enlarged image Im3 is displayed in an enlarged manner than the blood vessel image Im2.

  The stenosis rate presentation image Im4 is an image in which the stenosis rate measured for the lesion site indicated by the mark M3 is represented by characters.

  In step Sc2 and step Sc3, the display image generation unit 14 waits for an operator to give an instruction to change the observation location or to end the display. At this time, if a plurality of lesion sites have been determined and the operator wants to observe a lesion site different from that already displayed in the display image, the operator instructs to change the observation site to that lesion site. To do. If the instruction is given, the display image generation unit 14 proceeds from step Sc2 to step Sc3.

  In step Sc <b> 4, the display image generation unit 14 generates a display image in which another designated lesion site is a target for detailed display, and outputs the display image to the display unit 4 for display, thereby updating the display image.

  FIG. 10 is a diagram illustrating an example of the display image after the change.

  The display image shown in FIG. 10 includes a blood vessel image Im2, an enlarged image Im5, a stenosis rate presentation image Im6, marks M1, M2, M4, and a frame F3.

  That is, the enlarged image Im3 is changed to the enlarged image Im5 and the stenosis rate presentation image Im4 is changed to the stenosis rate presentation image Im6 in accordance with the change of the observation target from the lesion portion indicated by the mark M1 to the lesion location indicated by the mark M2. The mark M3 is updated to the mark M4, and the frame F2 is updated to the frame F3.

  If the display end instruction is given in the standby state of step Sc2 and step Sc3, the display image generation unit 14 ends the process shown in FIG.

  As described above, according to the image processing / display apparatus 100, image analysis is performed individually for each volume image. For this reason, it is possible to perform a highly accurate analysis based on an image with no connected distortion. That is, in the above embodiment, the blood vessel diameter and the stenosis rate can be measured with high accuracy.

  In the image processing / display apparatus 100, the determination of the lesion site is performed in the image analysis processing, but since this is performed based on the blood vessel diameter measured with high accuracy as described above, the determination accuracy is also improved. can do.

  In addition, since the image processing / display apparatus 100 analyzes only a part of the effective area with small distortion in the volume image, it is possible to perform analysis with higher accuracy.

  Since the image processing / display apparatus 100 does not perform processing for connecting a plurality of volume images, the load on the main processing unit 1 is reduced and the time required for analysis processing is reduced. For this reason, the image processing / display apparatus 100 can promptly present the analysis result, and is useful for diagnosis in an emergency or screening.

  This embodiment can be variously modified as follows.

  Instead of determining the lesion location, it is also possible to only measure clinical physical quantities as reference information or statistical information for the doctor to make the determination.

  Presentation of the analysis result to the user may be performed by another device. Accordingly, the function of outputting the analysis result to such another apparatus may be provided, and the function of displaying the analysis result may be omitted.

  The display image representing the analysis result may not include an image representing the entire observation target region such as the blood vessel image Im2.

  Only when the time available for the analysis process can be secured sufficiently, an image obtained by connecting a plurality of volume images using Volume Stitching or the like instead of the blood vessel image Im2 in FIGS. May be included.

  The functions of the image processing / display device may be incorporated in a medical imaging apparatus such as an MRI apparatus, CT apparatus, X-ray diagnostic apparatus, or ultrasonic diagnostic apparatus.

  The present invention can be applied for analysis of any lesion other than vascular stenosis.

  The present invention is applicable for analysis of medical images captured by a medical imaging apparatus other than an MRI apparatus such as a CT apparatus, an X-ray diagnostic apparatus, or an ultrasonic diagnostic apparatus.

  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 constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Main processing part, 2 ... Communication part, 3 ... Memory | storage part, 4 ... Display part, 5 ... Operation part, 11 ... Imaging area determination part, 11a ... Effective area calculation part, 11b ... Imaging area calculation part, 12 ... Medical Image management unit, 13 ... image analysis unit, 13a ... blood vessel core line extraction unit, 13b ... lesion determination unit, 14 ... display image generation unit, 100 ... image processing / display device, 200 ... magnetic resonance imaging device (MRI device).

Claims (5)

Storage means for storing a plurality of medical images obtained by dividing a plurality of observation target areas that are larger than an imageable area of the medical imaging apparatus by a medical imaging apparatus in multiple times;
Analyzing means for analyzing one of the plurality of medical images stored in the storage means and obtaining a clinical physical quantity for each of the plurality of medical images. A medical image processing apparatus.   The medical image according to claim 1, further comprising: a generating unit that generates a display image representing the physical quantity obtained by the analyzing unit in association with the medical image analyzed to obtain the physical quantity. Processing equipment.   The medical image processing apparatus according to claim 2, further comprising display means for displaying the display image generated by the generation means.   The medical image processing apparatus according to claim 1, wherein the analysis unit analyzes only a part of the effective region in the medical image.   The medical image processing apparatus according to claim 4, further comprising a setting unit that sets the effective area in accordance with an instruction from an operator.

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