Ultrasound imaging device, ultrasound imaging method, ultrasound imaging system, and ultrasound imaging program

Abstract

[Problem] To provide an ultrasonic imaging device that generates a clear composite image of a transverse section of a specimen. [Solution] An ultrasonic imaging device 3 comprises: an ultrasonic receiver (351) that receives, via a probe disposed on the surface of a specimen, ultrasonic waves which are transmitted in two scan modes, namely, a first scan mode, and a second scan mode having a wider imaging range than the first scan mode, the ultrasonic waves being transmitted from the probe toward the interior of the specimen and being reflected in the interior of the specimen; a first fragment image generator (352) for generating, on the basis of the ultrasound waves, a first fragment image obtained by partially imaging the interior of the specimen in the first scan mode; a second fragment image generator (353) for generating, on the basis of the ultrasound waves, a second fragment image obtained by partially imaging the interior of the specimen in the second scan mode; and a cross-sectional image synthesizer (354) that generates a composite image of a cross-section of the specimen by non-uniformly synthesizing the first fragment image and the second fragment image.

Description

[Technical Field]

[0001] The present invention relates to an ultrasound imaging device, an ultrasound imaging method, an ultrasound imaging system, and an ultrasound imaging program for imaging the inside of a subject using ultrasound. [Background technology]

[0002] The quadriceps is a muscle in the thigh that controls movements such as lifting the thigh and extending the knee joint. The muscle mass of the quadriceps decreases significantly with aging, and this decrease in quadriceps is a factor in elderly people having difficulty walking and falling. Therefore, by understanding the muscle mass of the quadriceps, treatment for elderly people having difficulty walking and falling is carried out. To capture the entire cross section of the thigh, including the quadriceps, for example, CT (Computed Tomography) equipment or M An RI (Magnetic Resonance Imaging) device is used.

[0003] However, because CT and MRI devices are expensive and require a long time to perform imaging, simpler imaging techniques are desired. To address this, various techniques have been devised that use ultrasound to image a wide range of cross-sections of the human body.

[0004] For example, Patent Document 1 discloses a technique for imaging a cross section of a human body, such as the thigh, upper arm, or abdomen, using a probe that transmits and receives ultrasound waves. According to the technique of Patent Document 1, an operator continuously captures images while moving the probe along the cross section around the imaging target while maintaining an appropriate angle of the probe relative to the surface of the human body, and then combines the captured ultrasound images to obtain a panoramic composite image (hereinafter also simply referred to as a "composite image") capturing a wide range of images of the cross section related to the part of the imaging target.

[0005] FIG. 14 shows ultrasound images of a transverse section of the thigh taken in linear scan mode and sector scan mode according to the prior art.

[0006] When performing an examination using ultrasound imaging, a plurality of ultrasound scan modes are switched depending on the region of the subject, such as a linear scan mode, a sector scan mode, and a convex scan mode.

[0007] In linear scan mode, a band-like area extending from the ultrasound transmitting and receiving surface of the probe can be clearly imaged, as shown in Figure 14(a). Linear scan mode is primarily used for examining tissues located close to the surface of the human body. Continuous imaging of the thigh area using only linear scan mode results in a panoramic composite image of the cross section, as shown in Figure 14(b).

[0008] In sector scan mode, as shown in Figure 14(c), it is possible to image a fan-shaped area with a wider angular range than the strip-like area extending from the ultrasound transmitting and receiving surface of the probe. The sector scan mode is mainly used for examining tissues over a wide area, including parts of the human body far from the body surface. By continuously imaging the area around the thigh using only sector scan mode, a panoramic composite image of the cross section is obtained, as shown in Figure 14(d). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2017 / 010193 Summary of the Invention [Problem to be solved by the invention]

[0010] In the composite image of a thigh cross section taken only in sector scan mode shown in Figure 14(d), the entire thigh cross section and the intermuscular septum (area S surrounded by the dashed-dotted line) are clearly imaged, but noise appears inside the muscles, making the image unclear. In contrast, in the composite image of a thigh cross section taken only in linear scan mode shown in Figure 14(b), the inside of the muscles is clearly imaged, but the imaging range is narrow and the septum is not imaged. This is because if the outline of the internal tissue of the object extends perpendicularly from the surface of the object, the linear scan mode cannot clearly receive the ultrasound reflected by the outline. As such, both composite images taken only in linear scan mode and composite images taken only in sector scan mode have advantages and disadvantages.

[0011] SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasound imaging apparatus that generates clear composite images of cross sections of a subject. [Means for solving the problem]

[0012] The ultrasound imaging device according to the present invention is characterized by comprising an ultrasound receiving unit that receives ultrasound waves reflected from the interior of the subject by the probe, the ultrasound waves being transmitted from a probe placed on the surface of the subject toward the interior of the subject in two scan modes, namely a first scan mode and a second scan mode having a wider imaging range than the first scan mode; a first fragment image generating unit that generates, based on the ultrasound waves, a first fragment image that partially images the interior of the subject in the first scan mode; a second fragment image generating unit that generates, based on the ultrasound waves, a second fragment image that partially images the interior of the subject in the second scan mode; and a cross-sectional image synthesis unit that unevenly synthesizes the first fragment image and the second fragment image to generate a synthesized image of a cross section of the subject.

[0013] The ultrasound imaging method according to the present invention is characterized by comprising an ultrasound receiving step in which ultrasound waves are transmitted from a probe placed on the surface of a subject toward the interior of the subject in two scan modes, namely a first scan mode and a second scan mode having a wider imaging range than the first scan mode, and are received by the probe after being reflected from the interior of the subject; a first fragment image generating step in which, based on the ultrasound waves, a first fragment image is generated in the first scan mode, which partially images the interior of the subject; a second fragment image generating step in which, based on the ultrasound waves, a second fragment image is generated in the second scan mode, which partially images the interior of the subject; and a cross-sectional image synthesis step in which the first fragment image and the second fragment image are non-uniformly synthesized to generate a composite image of a cross section of the subject.

[0014] The ultrasound imaging system according to the present invention is characterized by comprising a probe that transmits ultrasound waves from the surface of a subject toward the interior thereof and receives ultrasound waves reflected from the interior of the subject, and the ultrasound imaging device according to the present invention.

[0015] The ultrasound imaging program of the present invention is characterized by causing a computer to operate as an ultrasound receiving unit that receives ultrasound waves transmitted from a probe placed on the surface of a subject toward the interior of the subject in two scan modes, a first scan mode and a second scan mode having a wider imaging range than the first scan mode, and reflected from the interior of the subject, using the probe; a first fragment image generating unit that generates, based on the ultrasound waves, a first fragment image that partially images the interior of the subject using the first scan mode; a second fragment image generating unit that generates, based on the ultrasound waves, a second fragment image that partially images the interior of the subject using the second scan mode; and a cross-sectional image synthesis unit that unevenly synthesizes the first fragment image and the second fragment image to generate a composite image of a cross section of the subject. [Effects of the Invention]

[0016] According to the present invention, an ultrasonic imaging apparatus can be provided that generates a clear composite image of a cross section of a subject. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing the configuration of an ultrasound imaging system 1. FIG. [Figure 2] FIG. 2 is a block diagram showing the configuration of an ultrasound imaging device 3. [Figure 3] 3A and 3B are schematic diagrams for explaining a method of combining different types of fragment images performed by the ultrasound imaging apparatus according to the first embodiment. [Figure 4] 4 is a flowchart showing the processing procedure of the ultrasound imaging method according to the first embodiment. [Figure 5] 10 is a flowchart showing a detailed processing procedure of step S6A in the first embodiment. [Figure 6] 1 is an example of a panoramic composite image of a transverse section of a thigh generated by the ultrasound imaging method according to the first embodiment. [Figure 7] 10 is an example of a first intermediate composite image and a second intermediate composite image generated in an ultrasound imaging method according to a second embodiment. [Figure 8] FIG. 10 is a schematic diagram for explaining a weighted image synthesis method performed by an ultrasonic imaging apparatus according to a second embodiment. [Figure 9] FIG. 10 is a schematic diagram for explaining a weighted image synthesis method performed by an ultrasonic imaging apparatus according to a second embodiment. [Figure 10] 10 is an example of an image visualizing a weighting matrix calculated according to various weighting rules applied in the ultrasound imaging method according to the second embodiment. [Figure 11] 10 is a flowchart showing the processing procedure of an ultrasonic imaging method according to the second embodiment. [Figure 12] 10 is a flowchart showing a detailed processing procedure of step S6B in the second embodiment. [Figure 13] 10 is an example of a panoramic composite image of a transverse section of a thigh generated by the ultrasound imaging method according to the second embodiment. [Figure 14] 1A and 1B are ultrasound images of a transverse section of a thigh taken in a linear scan mode and a sector scan mode, respectively, according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, the same reference numerals will denote the same or similar components, and therefore, redundant descriptions of the same or similar components will be omitted. [First embodiment]

[0019] (Overall composition) 1 is a schematic diagram showing the configuration of an ultrasound imaging system 1. The ultrasound imaging system 1 includes a probe 2 and an ultrasound imaging device 3.

[0020] The probe 2 is a device that transmits ultrasonic waves from the surface of the subject 9 toward the interior of the subject 9 and receives ultrasonic waves reflected from the interior of the subject 9, and in this embodiment is configured so that the subject can hold and move it. An ultrasonic wave transmitting and receiving surface on which a plurality of ultrasonic vibrators are arranged in a row is provided at the lower end of the probe 2. Note that in this embodiment, the subject 9 is the thigh of a human body, but the biological part included in the subject 9 is not particularly limited.

[0021] In this embodiment, the probe 2 operates in both a linear scan mode (corresponding to the first scan mode described in the claims) for acquiring fragment images by linear scanning, and a sector scan mode (corresponding to the second scan mode described in the claims) for acquiring fragment images by sector scanning, which has a wider imaging range than linear scanning. A fragment image is an ultrasound image obtained by one imaging session in the linear scan mode or sector scan mode, and is equivalent to an image obtained by an ultrasound diagnostic device (ultrasound imaging device) with a general configuration.

[0022] When acquiring a panoramic composite image of a cross section of the subject 9, the subject places the ultrasound transmitting and receiving surface of the probe 2 in contact with the subject 9 and moves the probe 2 along the surface of the subject 9 (scanning the periphery of the thigh with the probe 2). During this movement, the probe 2 intermittently transmits ultrasound waves from the ultrasound transmitting and receiving surface toward the interior of the subject 9 while switching the scan mode between linear scan mode and sector scan mode at a predetermined cycle, and receives ultrasound waves reflected from the interior of the subject 9 at the ultrasound transmitting and receiving surface. As a result, the probe 2 outputs electrical signals (echo signals) indicating the received ultrasound waves for each of the linear scan mode and sector scan mode. Preferably, an angle sensor is attached to the probe 2, and information on the tilt angle of the probe 2 (for example, the tilt angle of the probe 2 from the vertical direction) is transmitted to the ultrasound imaging device 3 together with the echo signal.

[0023] The ultrasound imaging device 3 is connected to the probe 2 wirelessly, such as via WiFi (registered trademark). In this embodiment, the ultrasound imaging device 3 is configured, for example, as a tablet terminal, and has the function of generating a plurality of fragment images (a plurality of first fragment images and a plurality of second fragment images) for each of the linear scan mode and the sector scan mode based on the echo signals received from the probe 2, and further displaying a panoramic composite image of a cross section obtained by combining these fragment images.

[0024] The ultrasound imaging device 3 is not particularly limited as long as it is a device capable of displaying images, and can be configured as a general-purpose personal computer, a smartphone, etc. Furthermore, the method of connecting the probe 2 and the ultrasound imaging device 3 is not particularly limited, and a wired connection may be used.

[0025] (Functions of ultrasound imaging device) 2 is a block diagram showing the configuration of the ultrasound imaging device 3. The ultrasound imaging device 3 includes, as hardware components, a display 31, an input device 32, an auxiliary storage device 33, a communication interface unit (I / F unit) 34, and a display interface unit (I / F unit) 36.

[0026] The display 31 can be configured, for example, as a liquid crystal display, a plasma display, an organic EL display, etc. The display 31 may be configured as a device separate from the ultrasound imaging device 3.

[0027] The input device 32 is a touch panel provided on the surface of the display 31. The subject can perform input operations on the image displayed on the display 31 via the input device 32.

[0028] The auxiliary storage device 33 is a non-volatile storage device that stores an operating system (OS), various control programs, data generated by the programs, and the like, and is configured, for example, by an eMMC (embedded multi media card) or an SSD (solid state drive). An ultrasound imaging program P is stored in the auxiliary storage device 33. The ultrasound imaging program P may be installed in the ultrasound imaging device 3 via a network such as the Internet. Alternatively, the ultrasound imaging program P may be installed in the ultrasound imaging device 3 by having the ultrasound imaging device 3 read a computer-readable, non-transitory, tangible recording medium, such as an SD card, on which the ultrasound imaging program P is recorded.

[0029] The communication interface unit 34 transmits and receives data to and from external devices, and in this embodiment demodulates signals received from the probe 2, modulates control signals to be transmitted to the probe 2, and so on.

[0030] The display interface unit 36 ​​displays various image data generated by the calculation processing of the ultrasound imaging device 3 on the display 31 by expanding the images into VRAM, and displays, for example, composite images generated by the signal processing unit 35 described later on the display 31.

[0031] Although not shown, the ultrasound imaging device 3 further includes, as other hardware components, a processor such as a CPU that processes data, and a memory (main storage device) that the processor uses as a working area for data processing.

[0032] The ultrasound imaging device 3 also includes a signal processing unit 35 as a software configuration. The signal processing unit 35 is a functional block realized by the processor executing the ultrasound imaging program P, and has a function of processing echo signals received from the probe 2 and displaying a composite image of a cross section of the subject 9 on the display 31 so that the subject, a doctor, an imaging technician, and the like can easily understand the condition of the subject 9. To realize this function, the signal processing unit 35 includes an ultrasound receiving unit 351, a first fragment image generating unit 352, a second fragment image generating unit 353, and a cross-sectional image combining unit 354. The signal processing unit 35 may also be realized in hardware by a logic circuit formed on an integrated circuit.

[0033] The ultrasonic receiver 351 generates a transmission signal by delaying a signal having a frequency in the ultrasonic range and outputs the transmission signal to a control device (not shown) built into the probe 2. The control device drives the probe 2 based on the received transmission signal. The ultrasonic receiver 351 can control the drive method and beam shape of the probe 2 by controlling the delay. The ultrasonic receiver 351 also receives a reception signal from the probe 2. The ultrasonic receiver 351 performs processing such as analog-to-digital conversion on the input reception signal, and outputs the processed reception signal to a first fragment image generator 352 when driven in linear scan mode and to a second fragment image generator 353 when driven in sector scan mode. While the probe 2 is moved along the surface of the subject 9, the ultrasonic receiver 351 repeatedly outputs a transmission signal at regular time intervals for both linear scan mode and sector scan mode, and acquires a reception signal of the ultrasound received by the probe 2 each time a transmission signal is output.

[0034] The function of the ultrasonic receiving unit 351 may be provided in a control device that controls the probe 2. In this case, the control device may be connected to the ultrasonic imaging device 3, or the ultrasonic images may be stored in the control device and transmitted to the ultrasonic imaging device 3 via a recording medium.

[0035] The first fragment image generating unit 352 and the second fragment image generating unit 353 each generate fragment images of a portion of the imaging target by image conversion processing according to the drive method of the probe 2, based on the reception signal output by the ultrasound receiving unit 351. In this embodiment, the first fragment image generating unit 352 generates fragment images (first fragment images) in a linear scan mode, and the second fragment image generating unit 353 generates fragment images (second fragment images) in a sector scan mode. While the probe 2 is moved along the surface of the subject 9, the first fragment image generating unit 352 and the second fragment image generating unit 353 each generate a plurality of fragment images (a plurality of first fragment images and a plurality of second fragment images) obtained by capturing a cross section of the subject 9 from various directions, based on the reception signal repeatedly input from the ultrasound receiving unit 351, together with angle information (tilt angle information) of the probe 2 with respect to the surface of the subject 9 when the fragment images were acquired.

[0036] That is, in this embodiment, at a certain tilt angle of the probe 2 relative to the surface of the subject 9, a pair of fragmentary images, a first fragmentary image in linear scan mode and a second fragmentary image in sector scan mode, is generated, and while the probe 2 is continuously moved along the surface of the subject 9, a plurality of such pairs of fragmentary images are generated for each tilt angle of the probe 2 together with information on the tilt angle of the probe 2. The number of pairs of fragmentary images generated varies depending on the transmission and reception time and transmission and reception cycle of ultrasound waves by the probe 2. Illustratively, one pair of fragmentary images, a first fragmentary image and a second fragmentary image, is generated approximately every 125 msec.

[0037] The cross-sectional image synthesis unit 354 non-uniformly synthesizes the plurality of first fragment images generated by the first fragment image generation unit 352 and the plurality of second fragment images generated by the second fragment image generation unit 353. In this specification, the terms "cross section" and "transverse section" are concepts that include not only cross sections of a cross section, but also partial cross sections.

[0038] The composite image of the cross section of the subject 9 generated by the cross-sectional image synthesis unit 354 is input to the display interface unit 36. The display interface unit 36 ​​expands the data of the composite image in a VRAM, thereby displaying the composite image on the display 31.

[0039] Hereinafter, a specific description will be given of an example in which the cross-sectional image synthesis unit 354 non-uniformly synthesizes the first fragmentary images and the second fragmentary images in the first embodiment.

[0040] In the first embodiment, first, by a method described later with reference to the schematic diagram of Fig. 3, a process of non-uniformly combining a first fragment image acquired in linear scan mode and a second fragment image acquired in sector scan mode is performed for each tilt angle of the probe 2, thereby generating a plurality of intermediate composite images 43. Information on the tilt angle of the probe 2 is associated with the intermediate composite images 43.

[0041] Next, the multiple intermediate composite images 43 generated for each tilt angle of the probe 2 are rotated and combined based on the tilt angle of the probe 2 to generate a panoramic composite image in which a wide range of cross-sections of the subject 9 are captured.

[0042] (Composition of different types of fragment images) FIG. 3 is a schematic diagram for explaining a method of combining different types of fragment images performed by the ultrasound imaging apparatus according to the first embodiment.

[0043] Fig. 3(a) shows the first image fragment 41 and the second image fragment 42 before synthesis. In the first embodiment, as shown in Fig. 3(a), the area of ​​the second image fragment 42 acquired in the sector scan mode that corresponds to the first image fragment 41 (area R surrounded by a dashed line) is replaced with the first image fragment 41 acquired in the linear scan mode, thereby partially superimposing the first image fragment 41 on the second image fragment 42 and synthesizing them to generate an intermediate synthesized image 43.

[0044] 3(b) shows an intermediate composite image 43 at a certain angle of the probe 2. In the intermediate composite image 43, the first fragmentary image 41 is placed in the foreground in the region R surrounded by the dashed line, and the inside of the muscle is clearly visible. In addition, the second fragmentary image 42 remains in the region S surrounded by the dashed line, and the septum is clearly visible.

[0045] This makes it possible to generate a clear composite image of the cross section of the thigh of the subject 9, taking advantage of the advantages of both the linear scan mode and the sector scan mode.

[0046] In the intermediate composite image 43 shown in Fig. 3(b), image processing for noise removal may be further performed on the areas 51 surrounded by two-dot chain lines located on both sides of the area R surrounded by the dashed line. This can further improve the clarity of the panoramic composite image generated in the subsequent process.

[0047] (Processing Procedure) FIG. 4 is a flowchart showing the processing procedure of the ultrasound imaging method according to the first embodiment.

[0048] In step S1, the ultrasonic receiving unit 351 (control device) drives the probe 2 in the linear scan mode, and the probe 2 transmits ultrasonic waves in the linear scan mode from the surface of the subject 9 toward the inside of the subject 9. As a result, the probe 2 receives ultrasonic waves reflected inside the subject 9, and an echo signal corresponding to the linear scan mode is output from the probe 2.

[0049] In step S2, the ultrasound receiving unit 351 performs processing such as analog-to-digital conversion on the input reception signal, and outputs the processed reception signal to the first fragment image generating unit 352. The first fragment image generating unit 352 generates a first fragment image 41 in linear scan mode. In this embodiment, the first fragment image generating unit 352 generates a first fragment image 41 every time an echo signal is output from the probe 2.

[0050] In step S3, similarly to step S1, the ultrasonic wave receiving unit 351 drives the probe 2 in the sector scan mode, and the probe 2 outputs an echo signal corresponding to the sector scan mode.

[0051] In step S4, similarly to step S2, the second fragment image generating unit 353 generates the second fragment image 42 in the sector scan mode every time an echo signal is output from the probe 2.

[0052] Steps S1 to S4 are repeated until the scan of the probe 2 is completed. As a result, a plurality of first fragment images 41 corresponding to a plurality of different positions on the surface of the subject 9 are generated for each tilt angle of the probe 2. Similarly, a plurality of second fragment images 42 corresponding to a plurality of different positions on the surface of the subject 9 are generated for each tilt angle of the probe 2.

[0053] When the scan of the probe 2 is completed (Yes in step S5), in step S6A (image synthesis step), the cross-sectional image synthesis unit 354 generates a composite image of the cross section of the subject 9 by unevenly synthesizing multiple first fragment images and multiple second fragment images.

[0054] Thereafter, in step S7 (display step), a panoramic composite image of the cross section of the subject 9 is displayed on the display 31.

[0055] 5 is a flowchart showing the detailed processing procedure of step S6A in the first embodiment. Step S6A includes steps S6A-1 to S6A-3.

[0056] First, in step S6A-1, the cross-sectional image synthesis unit 354 generates an intermediate composite image 43 for each tilt angle of the probe 2. The cross-sectional image synthesis unit 354 generates the intermediate composite image 43 by partially superimposing and synthesizing the first fragment image 41 on the second fragment image 42 using the synthesis method described with reference to FIG.

[0057] Step S6A-1 is repeated until generation of intermediate composite images 43 for all probe tilt angles is completed (Yes in step S6A-2). As a result, a plurality of intermediate composite images 43 are generated for each tilt angle of probe 2.

[0058] Next, in step S6A-3, the cross-sectional image synthesis unit 354 rotates and synthesizes the multiple intermediate synthetic images 43 based on the tilt angle of the probe 2. This generates a panoramic composite image of the transverse section of the subject 9. An example of a panoramic composite image of the transverse section of the thigh generated by the ultrasound imaging method according to the first embodiment is shown in FIG.

[0059] When combining the multiple intermediate composite images 43, the cross-sectional image combining unit 354 can determine the positions at which to superimpose the multiple intermediate composite images 43 by detecting and matching feature amounts between regions included in each of the multiple intermediate composite images 43. At this time, it is preferable that the cross-sectional image combining unit 354 rotates the intermediate composite images 43 based on the angle detected by the angle sensor of the probe 2, and performs matching based on the rotated intermediate composite images 43. In this way, the rotation angle of each intermediate composite image 43 can be accurately corrected, and the superimposition positions of the intermediate composite images 43 can be determined with higher accuracy.

[0060] Well-known techniques can be applied to the process of generating one panoramic composite image by rotating and combining multiple intermediate composite images 43. In this embodiment, for example, the multiple intermediate composite images 43 are combined using feature point matching between the respective intermediate composite images 43.

[0061] In this method, feature points are detected from the first and second intermediate composite images. Then, the feature points of the first and second intermediate composite images are matched to calculate the homogeneous transformation matrix of the first and second intermediate composite images. Specifically, the second intermediate composite image is rotated clockwise by θ with respect to the first intermediate composite image, and is rotated by t in the x-axis direction. x , t in the y-axis direction y If the feature points of the first and second intermediate composite images match when they are translated by a factor of 1, the homogeneous transformation matrix R that moves the coordinate system of the second intermediate composite image to match the first intermediate composite image is

number

number

[0062] The homogeneous transformation matrix R is calculated for two intermediate composite images that are adjacent in the generation order, up to the n-1th intermediate composite image and the nth intermediate composite image. The homogeneous transformation matrix from the k+1 (1≦k≦n-1)th intermediate composite image to the kth intermediate composite image is calculated as R. k Then, the homogeneous transformation matrix from the k+1th intermediate composite image to the 1st intermediate composite image is R1R2…Rk The coordinate system of the first intermediate composite image is called the world coordinate system, and the coordinates of all intermediate composite images can be calculated by calculating a homogeneous transformation matrix to the world coordinate system for all intermediate composite images. After that, a single panoramic composite image is generated by blending the pixels of all intermediate composite images.

[0063] (Summary) As described above, in the first embodiment, the first fragment image acquired in the linear scan mode and the second fragment image acquired in the sector scan mode are non-uniformly synthesized, thereby making it possible to generate a clear synthesized image of the cross section of the human body, which is the subject 9, by taking advantage of the advantages of both the linear scan mode and the sector scan mode. [Second embodiment]

[0064] Hereinafter, a specific description will be given of an example in which the cross-sectional image synthesis unit 354 non-uniformly synthesizes the first fragmentary images and the second fragmentary images in the second embodiment.

[0065] In the second embodiment, first, a first intermediate composite image 45 is generated by rotating and combining a plurality of first fragment images acquired in linear scan mode, which are generated for each tilt angle of the probe 2, based on the tilt angle of the probe 2. Similarly, for second fragment images acquired in sector scan mode, a second intermediate composite image 46 is generated by rotating and combining a plurality of second fragment images generated for each tilt angle of the probe 2 based on the tilt angle of the probe 2. Examples of the first intermediate composite image 45 and the second intermediate composite image 46 generated in the ultrasound imaging method according to the second embodiment are shown in FIGS. 7( a) and 7(b). Both the first intermediate composite image 45 and the second intermediate composite image 46 are panoramic composite images in which a cross section of the subject 9 is captured over a wide range.

[0066] Next, the first intermediate composite image 45 and the second intermediate composite image 46 are weighted and combined using a method described below with reference to the schematic diagrams of Figures 8 to 10 to generate a panoramic composite image in which the first fragmentary images and the second fragmentary images are unevenly combined.

[0067] (Composition of fragment images of the same type) The cross-sectional image synthesis unit 354 generates a first intermediate composite image 45 by rotating and synthesizing a plurality of first fragment images, which have been generated for each tilt angle of the probe 2, based on the tilt angle of the probe 2. Similarly, the cross-sectional image synthesis unit 354 generates a second intermediate composite image 46 by rotating and synthesizing a plurality of second fragment images, which have been generated for each tilt angle of the probe 2, based on the tilt angle of the probe 2.

[0068] When generating the first intermediate composite image 45 and the second intermediate composite image 46, the cross-sectional image synthesis unit 354 can determine the positions at which to superimpose the multiple fragment images by detecting and matching feature amounts between regions included in each of the multiple fragment images. At this time, it is preferable that the cross-sectional image synthesis unit 354 rotates the fragment images based on the detected angle obtained from the angle sensor of the probe 2, and performs matching based on the rotated fragment images. In this way, the rotation angle of each fragment image can be accurately corrected, and the superimposition positions of the fragment images can be determined with higher accuracy.

[0069] Well-known techniques can be applied to the process of generating a single intermediate composite image by rotating and combining a plurality of image fragments. In this embodiment, a plurality of image fragments are combined, for example, by using feature point matching between the image fragments. As the feature point matching method was described above in the first embodiment using an intermediate composite image as an example, a detailed description thereof will be omitted in this embodiment.

[0070] (weighted synthesis) 8 to 10 are schematic diagrams for explaining a weighted image synthesis method performed by the ultrasonic imaging apparatus according to the second embodiment.

[0071] In the second embodiment, intermediate composite images 45, 46 generated in the linear scan mode and the sector scan mode are composited by applying a weighting rule. This makes it possible to generate a clear composite image of a cross section of a human body, which is a subject 9, by taking advantage of the advantages of both the linear scan mode and the sector scan mode. Note that, as the weighting rule, for example, both or at least one of a weighting according to depth and a weighting according to tilt angle, as exemplified below, can be applied. When both a weighting according to depth and a weighting according to tilt angle are applied, it is preferable to apply a weighting according to tilt angle stronger than a weighting according to depth.

[0072] Fig. 8 is a schematic diagram for explaining weighting according to depth. Fig. 8(a) shows an image obtained by cutting out a second fragmentary image 42 acquired in sector scan mode from the surface of the subject 9 in the depth direction. Fig. 8(b) shows a first fragmentary image 41 acquired in linear scan mode. The upper direction in the figure corresponds to a shallower region from the surface inside the subject 9, and the lower direction corresponds to a deeper region from the surface.

[0073] In the depth-dependent weighting, the proportion of the first intermediate composite image 45 obtained by the linear scan mode is increased for shallow regions from the surface inside the subject 9, and the proportion of the second intermediate composite image 46 obtained by the sector scan mode is increased for deep regions from the surface, and the first intermediate composite image 45 and the second intermediate composite image 46 are weighted and combined.

[0074] One reason for increasing the contribution of the linear scan mode in the shallow region from the surface is that the influence of noise is small in the shallow region, and the inside of the muscle is clearly imaged, as shown by reference numeral 52 in the fragment image of Figure 8(b). One reason for increasing the contribution of the sector scan mode in the deep region from the surface is that ultrasonic echoes are attenuated in the linear scan mode in the deep region, as shown by reference numeral 53 in the fragment image of Figure 8(b). Figure 8(c) shows an example of a visualized image of a weighting matrix calculated using such weighting rules.

[0075] In the image in Figure 8(c), white indicates strong weighting by linear scan mode, black indicates strong weighting by sector scan mode, and multiple shades of gray indicate intermediate weighting. The degree of black gradually increases from shallow to deep regions, indicating a gradual increase in weighting by sector scan mode.

[0076] 9 is a schematic diagram for explaining weighting according to the tilt angle of the probe, showing an example of the correspondence relationship between the tilt angle of the probe 2 and the thigh. Note that the composite image of the thigh cross section used to illustrate the correspondence relationship is a composite image obtained only in sector scan mode according to the prior art.

[0077] For ease of explanation, assuming that the thigh of a human body is measured in a sitting or supine position, the anterior of the thigh corresponds to an inclination angle of probe 2 of approximately 0 degrees. Similarly, the medial and lateral sides of the thigh correspond to an inclination angle of probe 2 of approximately ±90 degrees.

[0078] The weighting according to the tilt angle of the probe is such that the proportion of the first intermediate composite image 45 obtained by the linear scan mode is higher for tilt angles around 0 degrees, and the proportion of the second intermediate composite image 46 obtained by the sector scan mode is higher for tilt angles around ±90 degrees, and the first intermediate composite image 45 and the second intermediate composite image 46 are weighted and combined.

[0079] One reason for increasing the contribution of the linear scan mode near a tilt angle of 0° is that the septum is unlikely to be included in the captured ultrasound image at a tilt angle of 0°. One reason for increasing the contribution of the sector scan mode near tilt angles of ±90° is that it is desirable to include the septum in the captured ultrasound image. At tilt angles of ±90°, the outline of the septum and the ultrasound waves emitted from probe 2 gradually become substantially parallel, and the ultrasound waves reflected by the septum cannot be clearly received in the linear scan mode.

[0080] Figure 10 shows an example of an image visualizing a weighting matrix calculated using such a weighting rule. Figure 10(a) is an image visualizing a weighting matrix that takes into account only the depth, Figure 10(b) is an image visualizing a weighting matrix that takes into account only the tilt angle of the probe, and Figure 10(c) is an image visualizing a weighting matrix that takes into account both the depth and tilt angle.

[0081] In the image shown in Figure 10, white indicates strong weighting by linear scan mode, black indicates strong weighting by sector scan mode, and multiple gray shades indicate weighting to an intermediate level between these. For example, referring to the image in Figure 10(a), it can be seen that the degree of shading does not change at the same depth even when the tilt angle changes from near 0 degrees to near ±90 degrees. Also, referring to the image in Figure 10(b), it can be seen that the degree of black gradually increases as the tilt angle changes from near 0 degrees to near ±90 degrees, indicating a gradual increase in weighting by sector scan mode.

[0082] (Processing Procedure) Fig. 11 is a flowchart showing the processing procedure of an ultrasound imaging method according to the second embodiment. In the flowchart shown in Fig. 11, the overall processing procedure is similar to that of the flowchart shown in Fig. 4, but step S6A for generating a composite image of cross sections is replaced with step S6B.

[0083] 12 is a flowchart showing the detailed processing procedure of step S6B in the second embodiment. Step S6B includes steps S6B-1 to S6B-3.

[0084] First, in step S6B-1, the cross-sectional image synthesis unit 354 generates a first intermediate composite image 45 synthesized only with fragment images related to the linear scan mode by rotating and synthesizing a plurality of first fragment images 41 acquired in the linear scan mode based on the tilt angle of the probe 2. At this point, the first intermediate composite image 45 is a panoramic composite image in which a cross section of the subject 9 is imaged over a wide range.

[0085] In step S6B-2, similarly to step S6B-1, the cross-sectional image synthesis unit 354 generates a second intermediate composite image 46 synthesized only with the fragment images related to the sector scan mode by rotating and synthesizing the plurality of second fragment images 42 acquired in the sector scan mode based on the tilt angle of the probe 2. At this point, the second intermediate composite image 46 is also a panoramic composite image in which the cross section of the subject 9 is imaged over a wide range.

[0086] Next, in step S6B-3, the cross-sectional image composition unit 354 weight-composes the first intermediate composite image 45 and the second intermediate composite image 46 using the composition method applying weighting described with reference to FIGS. 8 to 10. In this embodiment, as weighting rules, for example, weighting according to depth and weighting according to tilt angle, as shown in FIG. 10(c), are applied. As a result, a panoramic composite image of the cross section of the subject 9 is generated in which the first fragmentary images and the second fragmentary images are non-uniformly combined. FIG. 13 shows an example of a panoramic composite image of the cross section of the thigh generated by the ultrasound imaging method according to the second embodiment.

[0087] (Summary) As described above, in the second embodiment, intermediate composite images generated in the linear scan mode and the sector scan mode are combined by applying a weighting rule to the intermediate composite images generated in the linear scan mode and the sector scan mode, respectively. This makes it possible to generate a clear composite image of the cross section of the human body, which is the subject 9, by taking advantage of the advantages of both the linear scan mode and the sector scan mode. [Other forms]

[0088] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-described embodiments.

[0089] In the above embodiment, in order to obtain fragment images corresponding to a plurality of different positions on the surface of the subject 9, ultrasonic waves are transmitted intermittently from the probe 2 while the probe 2 is moved along the surface of the subject 9, but the manner in which the fragment images are obtained is not limited to this. For example, a plurality of probes 2 may be placed on the subject 9, and ultrasonic waves may be transmitted from each probe 2 simultaneously.

[0090] In the above embodiment, the probe 2 operates in both the linear scan mode and the sector scan mode, but the drive mode of the probe 2 is not limited to this. The probe 2 may also operate in the convex scan mode instead of the sector scan mode. That is, the probe 2 may also operate in both the linear scan mode and the convex scan mode.

[0091] In the first embodiment described above, in step S6A-1, the cross-sectional image synthesis unit 354 generates the intermediate composite image 43 by partially superimposing the first fragment image 41 on the second fragment image 42 using the synthesis method described with reference to Fig. 3, but the manner of generating the intermediate composite image 43 is not limited to this. When partially superimposing the first fragment image 41 on the second fragment image 42 and synthesizing them, the cross-sectional image synthesis unit 354 may apply the weighting rules described with reference to Figs. 8 to 10.

[0092] In the first embodiment described above, in step S6A-3, the cross-sectional image synthesis unit 354 generates a panoramic composite image of a cross section of the subject 9 by rotating and synthesizing the plurality of intermediate composite images 43 based on the tilt angle of the probe 2, but the manner in which the panoramic composite image is generated is not limited to this. When rotating and synthesizing the plurality of intermediate composite images 43 based on the tilt angle of the probe 2, the cross-sectional image synthesis unit 354 may apply the weighting rules described with reference to FIGS. 8 to 10. [Industrial Applicability]

[0093] The present invention is applicable to both medical and non-medical applications, but is particularly suitable for applications in which non-medical subjects visualize and check the condition of their own muscles on a daily basis. [Explanation of symbols]

[0094] 1. Ultrasound imaging system 2 probes 3. Ultrasound imaging device 9. Subject 31 Display 32 Input Devices 33 Auxiliary storage device 34 Communication interface section 35 Signal Processing Section 36 Display interface section 41 First fragment image 42 Second fragment image 43 Intermediate composite image 45 First intermediate composite image 46 Second intermediate composite image 351 Ultrasonic receiver 352 First fragment image generation unit 353 Second Fragment Image Generation Unit 354 Cross-sectional image synthesis unit

Claims

1. An ultrasonic receiving unit that receives ultrasonic waves reflected from the inside of the subject, which are transmitted from a probe placed on the surface of the subject toward the inside of the subject in two scan modes, namely a first scan mode and a second scan mode having a wider imaging range than the first scan mode, with the probe; a first fragment image generating unit that generates a first fragment image by capturing a partial image of the inside of the subject in the first scan mode based on the ultrasound; a second fragment image generating unit that generates second fragment images obtained by capturing partial images of the inside of the subject in the second scan mode based on the ultrasound; a cross-sectional image synthesis unit that synthesizes the first fragment images and the second fragment images non-uniformly to generate a synthesized image of the cross section of the subject; Equipped with The cross-sectional image synthesis unit generating a plurality of intermediate composite images by replacing regions of the second fragment images corresponding to the first fragment images with the first fragment images for each tilt angle of the probe; an ultrasonic imaging apparatus that generates a composite image of the cross section of the subject by combining the plurality of intermediate composite images generated for each of the tilt angles of the probe based on the tilt angle of the probe.

2. The cross-sectional image synthesis unit 2. The ultrasound imaging device of claim 1, wherein when generating a plurality of intermediate composite images by replacing an area of ​​the second fragment image corresponding to the first fragment image with the first fragment image for each tilt angle of the probe, the first fragment image and the second fragment image are combined using a weighted combination based on at least one of a weight based on a depth from the surface of the subject and a weight based on the tilt angle of the probe, thereby generating the plurality of intermediate composite images for each tilt angle of the probe.

3. The cross-sectional image synthesis unit 3. The ultrasound imaging device according to claim 1, wherein when a plurality of intermediate composite images generated by replacing a region of the second fragment image corresponding to the first fragment image with the first fragment image for each of the tilt angles of the probe are synthesized based on the tilt angle of the probe, the plurality of intermediate composite images are synthesized by weighting synthesis based on at least one of weighting based on a depth from the surface of the subject and weighting based on the tilt angle of the probe to generate a composite image of the cross section of the subject.

4. An ultrasonic receiving unit that receives ultrasonic waves reflected from the inside of the subject by the probe, the ultrasonic waves being transmitted from a probe placed on the surface of the subject toward the inside of the subject in two scan modes, a first scan mode and a second scan mode having a wider imaging range than the first scan mode, and that are received by the probe; a first fragment image generating unit that generates a first fragment image by capturing a partial image of the inside of the subject in the first scan mode based on the ultrasound; a second fragment image generating unit that generates second fragment images obtained by capturing partial images of the inside of the subject in the second scan mode based on the ultrasound; a cross-sectional image synthesis unit that synthesizes the first fragment images and the second fragment images non-uniformly to generate a synthesized image of the cross section of the subject; Equipped with The cross-sectional image synthesis unit synthesizing the plurality of first fragment images generated for each tilt angle of the probe based on the tilt angle of the probe to generate a first intermediate composite image; synthesizing the second fragment images generated for each tilt angle of the probe based on the tilt angle of the probe to generate a second intermediate composite image; an ultrasound imaging device that generates a composite image of the cross section of the subject by combining the first intermediate composite image and the second intermediate composite image using weighting based on at least one of weighting based on the depth from the surface of the subject and weighting based on the tilt angle of the probe.

5. the first scan mode is a linear scan mode; The ultrasonic imaging apparatus according to claim 1 , wherein the second scan mode is a sector scan mode or a convex scan mode.

6. an ultrasonic wave receiving step of transmitting ultrasonic waves from a probe placed on a surface of a subject toward the interior of the subject in two scan modes, a first scan mode and a second scan mode having a wider imaging range than the first scan mode, and receiving, by the probe, ultrasonic waves reflected from the interior of the subject; a first fragment image generating step of generating a first fragment image obtained by imaging a part of the inside of the subject in the first scan mode based on the ultrasound; a second fragment image generating step of generating a second fragment image obtained by partially imaging the inside of the subject in the second scan mode based on the ultrasound; a cross-sectional image synthesis step of non-uniformly synthesizing the first fragment image and the second fragment image to generate a synthetic image of the cross section of the subject; Including, The cross-sectional image synthesis step includes: generating a plurality of intermediate composite images by replacing regions of the second fragment images corresponding to the first fragment images with the first fragment images for each tilt angle of the probe; an ultrasound imaging method for generating a composite image of the cross section of the subject by combining the intermediate composite images generated for each of the tilt angles of the probe based on the tilt angle of the probe.

7. An ultrasound receiving step in which ultrasound waves are transmitted from a probe placed on the surface of a subject toward the interior of the subject in two scan modes, a first scan mode and a second scan mode having a wider imaging range than the first scan mode, and are received by the probe after being reflected from the interior of the subject; a first fragment image generating step of generating a first fragment image obtained by imaging a part of the inside of the subject in the first scan mode based on the ultrasound; a second fragment image generating step of generating a second fragment image obtained by partially imaging the inside of the subject in the second scan mode based on the ultrasound; a cross-sectional image synthesis step of non-uniformly synthesizing the first fragment image and the second fragment image to generate a synthetic image of the cross section of the subject; Including, The cross-sectional image synthesis step includes: synthesizing the plurality of first fragment images generated for each tilt angle of the probe based on the tilt angle of the probe to generate a first intermediate composite image; synthesizing the second fragment images generated for each tilt angle of the probe based on the tilt angle of the probe to generate a second intermediate composite image; an ultrasound imaging method for generating a composite image of the cross section of the subject by combining the first intermediate composite image and the second intermediate composite image using a weighted combination based on at least one of a weighting based on a depth from the surface of the subject and a weighting based on a tilt angle of the probe.

8. a probe that transmits ultrasonic waves from a surface of a subject toward the inside of the subject and receives ultrasonic waves reflected from the inside of the subject; The ultrasonic imaging device according to any one of claims 1 to 5, An ultrasound imaging system comprising:

9. an ultrasonic wave receiving unit that receives, by the probe, ultrasonic waves that are transmitted from a probe placed on the surface of a subject toward the interior of the subject in two scan modes, i.e., a first scan mode and a second scan mode having a wider imaging range than the first scan mode, and that are reflected from the interior of the subject; a first fragment image generating unit that generates a first fragment image obtained by partially capturing an image of the inside of the subject in the first scan mode based on the ultrasound; a second fragment image generating unit that generates second fragment images obtained by partially capturing an image of the inside of the subject in the second scan mode based on the ultrasound; a cross-sectional image synthesis unit that non-uniformly synthesizes the first fragment images and the second fragment images to generate a composite image of the cross section of the subject; generating a plurality of intermediate composite images by replacing regions of the second fragment images corresponding to the first fragment images with the first fragment images for each tilt angle of the probe; a plurality of intermediate composite images generated for each of the tilt angles of the probe are combined based on the tilt angle of the probe to generate a composite image of the cross section of the subject; cross-sectional image synthesis unit, an ultrasound imaging program that causes a computer to operate as a

10. An ultrasonic receiving unit that receives ultrasonic waves reflected from the inside of the subject, which are transmitted from a probe placed on the surface of the subject toward the inside of the subject in two scan modes, namely a first scan mode and a second scan mode having a wider imaging range than the first scan mode, by the probe; a first fragment image generating unit that generates a first fragment image obtained by partially capturing an image of the inside of the subject in the first scan mode based on the ultrasound; a second fragment image generating unit that generates second fragment images obtained by partially capturing an image of the inside of the subject in the second scan mode based on the ultrasound; a cross-sectional image synthesis unit that non-uniformly synthesizes the first fragment images and the second fragment images to generate a composite image of the cross section of the subject; synthesizing the plurality of first fragment images generated for each tilt angle of the probe based on the tilt angle of the probe to generate a first intermediate composite image; synthesizing the second fragment images generated for each tilt angle of the probe based on the tilt angle of the probe to generate a second intermediate composite image; generating a composite image of the cross section of the subject by combining the first intermediate composite image and the second intermediate composite image using a weighting combination based on at least one of a weighting based on a depth from the surface of the subject and a weighting based on a tilt angle of the probe; cross-sectional image synthesis unit, an ultrasound imaging program that causes a computer to operate as a

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