Information processing device, information processing system, information processing method, and computer program

Abstract

To automatically detect NURD existing in a tomographic image.SOLUTION: An information processor for generating a frame image using line data indicating reflection waves with respect to signal waves transmitted at predetermined intervals from an imaging core rotating in a probe to the outside of the probe comprises a control section that compares a phase of a reflection wave with a phase of a reflection wave received at timing adjacent to timing of receiving the reflection wave, the reflection waves indicated by the line data, to calculate a phase change between the reflection waves along the imaging core's direction of rotation and, on the basis of the phase change, detects an image defect caused by rotational distortion of the imaging core.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an information processing device, an information processing system, an information processing method, and a computer program. [Background technology]

[0002] Patent Document 1 describes a technique for processing IVUS (intravascular ultrasound) images. "IVUS" is an abbreviation for Intravascular Ultrasound. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-504834 A Summary of the Invention [Problem to be solved by the invention]

[0004] In imaging diagnostic catheters such as IVUS and OFDI (optical coherence tomography), the torque generated at the drive unit at the base end is not transmitted to the sensor unit at the tip, and image defects due to rotational unevenness called NURD may occur. "OFDI" is an abbreviation for Optical Frequency Domain Imaging. "NURD" is an abbreviation for Non-uniform Rotational Distortion. If a doctor or other surgeon cannot recognize such NURD, there is a possibility that the procedure will be performed with a misidentification of the location and extent of the lesion.

[0005] An objective of the present disclosure is to automatically detect NURD present in tomographic images. [Means for solving the problem]

[0006] An information processing device according to one aspect of the present disclosure generates a frame image using line data indicating a reflected wave of a signal wave transmitted from an imaging core rotating within a probe toward the outside of the probe at a predetermined time interval, and includes a control unit that calculates a change in the phase of the reflected wave along the rotation direction of the imaging core by comparing the phase of the reflected wave indicated by the line data with the phase of a reflected wave received at a timing adjacent to the timing at which the reflected wave was received, and detects image defects caused by uneven rotation of the imaging core based on the change in phase.

[0007] In one embodiment, the control unit detects as the image defect a portion of the image corresponding to the line data in a range in which the phase change of the reflected wave along the rotation direction of the imaging core falls below a predetermined value.

[0008] In one embodiment, the control unit further detects image defects caused by uneven rotation of the imaging core based on a change in amplitude of the reflected wave along the rotation direction of the imaging core.

[0009] In one embodiment, the control unit detects as the image defect a portion of the image corresponding to the line data in a range where the change in phase of the reflected wave along the rotation direction of the imaging core is below the predetermined value and the change in amplitude of the reflected wave along the rotation direction of the imaging core is below another predetermined value.

[0010] In one embodiment, when an image defect caused by rotational unevenness of the imaging core is detected, the control unit generates the frame image using the line data acquired while there is no rotational unevenness.

[0011] In one embodiment, when the control unit detects an image defect caused by rotational unevenness of the imaging core, it enlarges a portion of the frame image generated using the line data acquired when there is no rotational unevenness along the rotational direction of the imaging core to generate the frame image.

[0012] In one embodiment, the control unit causes a display unit to display the generated frame image.

[0013] In one embodiment, the signal wave is an ultrasonic wave or a light wave.

[0014] An information processing system according to one aspect of the present disclosure includes the information processing device according to any one of claims 1 to 8 and a probe having the imaging core.

[0015] An information processing method of an information processing device according to one aspect of the present disclosure generates a frame image using line data indicating a reflected wave of a signal wave transmitted from an imaging core rotating inside a probe toward the outside of the probe at a predetermined time interval, wherein a control unit calculates a change in the phase of the reflected wave along the rotation direction of the imaging core by comparing the phase of the reflected wave indicated by the line data with the phase of a reflected wave received at a timing adjacent to the timing at which the reflected wave was received, and detects image defects caused by uneven rotation of the imaging core based on the change in phase.

[0016] A computer program according to one aspect of the present disclosure causes a computer to execute a process of generating a frame image using line data indicating a reflected wave of a signal wave transmitted from an imaging core rotating within a probe toward the outside of the probe at a predetermined time interval, the computer program causes a computer to execute a process of calculating a change in the phase of the reflected wave along the rotation direction of the imaging core by comparing a phase of the reflected wave indicated by the line data with a phase of a reflected wave received at a timing adjacent to the timing at which the reflected wave was received, and a process of detecting an image defect caused by uneven rotation of the imaging core based on the change in phase. Effect of the Invention

[0017] According to the present disclosure, NURD present in a tomographic image can be automatically detected. [Brief description of the drawings]

[0018] [Figure 1] 1 is a perspective view of a diagnosis support system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a perspective view of a probe and a drive unit according to an embodiment of the present disclosure; [Diagram 3] 1 is a block diagram showing a configuration of a diagnosis support device according to an embodiment of the present disclosure. [Figure 4A] 1 is a diagram showing an example in which an IVUS image is acquired by a diagnosis support device according to an embodiment of the present disclosure. [Figure 4B] 1 is a diagram showing an example in which an IVUS image is acquired by a diagnosis support device according to an embodiment of the present disclosure. [Figure 4C] 1 is a diagram showing an example in which an IVUS image is acquired by a diagnosis support device according to an embodiment of the present disclosure. [Figure 4D] 1 is a diagram showing an example in which an IVUS image is acquired by a diagnosis support device according to an embodiment of the present disclosure. [Figure 4E] 1 is a diagram showing an example in which an IVUS image is acquired by a diagnosis support device according to an embodiment of the present disclosure. [Diagram 5] 1A to 1C are diagrams illustrating a detection principle of NURD by a diagnosis support device according to an embodiment of the present disclosure. [Figure 6] 1A to 1C are diagrams illustrating a process of correcting a tomographic image including NURD by a diagnosis support device according to an embodiment of the present disclosure. [Figure 7] 5 is a flowchart illustrating an operation of the diagnosis support device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0020] (System Configuration) 1 is a perspective view of a diagnosis support system 10 serving as an information processing system according to this embodiment. The diagnosis support system 10 includes a diagnosis support device 11 serving as an information processing device, a cable 12, a drive unit 13, a keyboard 14, a pointing device 15, and a display 16.

[0021] In this embodiment, the diagnosis support device 11 is a dedicated computer specialized for image diagnosis, but it may be a general-purpose computer such as a PC, a WS, or a tablet terminal. "PC" is an abbreviation for Personal Computer. "WS" is an abbreviation for Work Station.

[0022] The cable 12 is used to connect the diagnosis support device 11 and the drive unit 13 to transmit and receive information.

[0023] The drive unit 13 is a device that is connected to a probe 20 (described later) and drives the probe 20. The drive unit 13 is also called an MDU. "MDU" is an abbreviation for Motor Drive Unit. The probe 20 is applied to IVUS. The probe 20 is also called an IVUS catheter or an imaging diagnostic catheter. Details of the drive unit 13 and the probe 20 will be described later with reference to FIG. 2.

[0024] The keyboard 14, the pointing device 15, and the display 16 are connected to the diagnostic support device 11 via any cable or wirelessly. The display 16 as a display unit is, for example, an LCD, an organic EL display, or an HMD. "LCD" is an abbreviation for Liquid Crystal Display. "EL" is an abbreviation for Electro Luminescence. "HMD" is an abbreviation for Head-Mounted Display.

[0025] The diagnosis support system 10 further includes, as options, a connection terminal 17 and a cart unit 18. The connection terminal 17 is used to connect the diagnosis support device 11 to an external device. The connection terminal 17 is, for example, a USB terminal. "USB" is an abbreviation for Universal Serial Bus. The external device is, for example, a recording medium such as a magnetic disk drive, a magneto-optical disk drive, or an optical disk drive.

[0026] The cart unit 18 is a cart with casters for mobility. The diagnostic support device 11, the cable 12, and the drive unit 13 are installed in the cart body of the cart unit 18. The keyboard 14, the pointing device 15, and the display 16 are installed on the top table of the cart unit 18.

[0027] In this embodiment, an example is described in which the detection target of NURD is an IVUS image generated by reflected waves of ultrasonic waves. However, the detection target of NURD may be, for example, an OFDI image generated by reflected waves of light waves instead of an IVUS image.

[0028] 2 is a perspective view of the probe 20 according to this embodiment and the drive unit 13. The probe 20 includes a drive shaft 21, a hub 22, a sheath 23, an outer tube 24, an ultrasonic transducer 25, and a relay connector .

[0029] The drive shaft 21 passes through a sheath 23 inserted into a body cavity of a living body and an outer tube 24 connected to the base end of the sheath 23, and extends to the inside of a hub 22 provided at the base end of the probe 20. The drive shaft 21 has an ultrasonic transducer 25 at its tip as an imaging core that transmits and receives signals, and is rotatably provided within the sheath 23 and outer tube 24. A relay connector 26 connects the sheath 23 and outer tube 24.

[0030] The hub 22, the drive shaft 21, and the ultrasonic transducer 25 are connected to each other so that they can integrally move forward and backward in the axial direction of the probe 20. Therefore, for example, when the hub 22 is pushed toward the distal end, the drive shaft 21 and the ultrasonic transducer 25 move toward the distal end inside the sheath 23. For example, when the hub 22 is pulled toward the proximal end, the drive shaft 21 and the ultrasonic transducer 25 move toward the proximal end inside the sheath 23 as shown by the arrow in FIG.

[0031] The drive unit 13 includes a scanner unit 31, a slide unit 32, and a bottom cover 33. The scanner unit 31 is connected to the diagnosis support device 11 via a cable 12.

[0032] The scanner unit 31 includes a probe connection section 34 that connects to the probe 20, and a scanner motor 35 that is a drive source for rotating the drive shaft 21. The probe connection section 34 is detachably connected to the probe 20 via a socket 36 of a hub 22 provided at the base end of the probe 20. Inside the hub 22, the base end of the drive shaft 21 is rotatably supported, and the rotational force of the scanner motor 35 is transmitted to the drive shaft 21. In addition, signals are transmitted and received between the drive shaft 21 and the diagnosis support device 11 via a cable 12. In the diagnosis support device 11, tomographic images of the biological lumen are generated and image processing is performed based on the signal transmitted from the drive shaft 21.

[0033] The slide unit 32 carries the scanner unit 31 so as to be movable forward and backward, and is mechanically and electrically connected to the scanner unit 31. The slide unit 32 includes a probe clamp portion 37, a slide motor 38, and a group of switches 39.

[0034] The probe clamp portion 37 is provided at a position closer to the tip side than the probe connection portion 34 and coaxial therewith, and supports the probe 20 connected to the probe connection portion 34 .

[0035] The slide motor 38 is a drive source that generates a driving force in the axial direction of the probe 20. The scanner unit 31 moves forward and backward when driven by the slide motor 38, and accordingly the drive shaft 21 moves forward and backward in the axial direction of the probe 20. The slide motor 38 is, for example, a servo motor.

[0036] The group of switches 39 includes, for example, a forward switch and a pullback switch that are pressed when moving the scanner unit 31 forward or backward, and a scan switch that is pressed when starting and ending image drawing. The group of switches 39 is not limited to the examples given here, and various switches may be included in the group of switches 39 as necessary.

[0037] When the forward switch is pressed, the slide motor 38 rotates forward. In response, the scanner unit 31 moves forward. As a result, the hub 22 connected to the probe connection portion 34 of the scanner unit 31 is pushed toward the tip side. The drive shaft 21 and the ultrasonic transducer 25 move toward the tip side inside the sheath 23. On the other hand, when the pullback switch is pressed, the slide motor 38 rotates in the reverse direction. In response, the scanner unit 31 moves backward. As a result, the hub 22 connected to the probe connection portion 34 is swept toward the base end side. The drive shaft 21 and the ultrasonic transducer 25 move toward the base end side inside the sheath 23.

[0038] When the scan switch is pressed, image drawing begins, and the scanner motor 35 and slide motor 38 are driven to move the scanner unit 31 backward. A user such as an operator connects the probe 20 to the scanner unit 31 in advance, so that when image drawing begins, the drive shaft 21 moves axially toward the base end while rotating about the central axis of the probe 20. When the scan switch is pressed again, the scanner motor 35 and slide motor 38 stop, and image drawing ends.

[0039] The bottom cover 33 covers the bottom surface of the slide unit 32 and the entire periphery of the side surface on the bottom surface side, and is freely movable toward and away from the bottom surface of the slide unit 32 .

[0040] 3 is a diagram showing the configuration of the diagnosis support device 11 according to this embodiment. The diagnosis support device 11 includes components such as a control unit 41, a storage unit 42, a communication unit 43, an input unit 44, and an output unit 45.

[0041] The control unit 41 is one or more processors. The processor is a general-purpose processor such as a CPU or a GPU, or a dedicated processor specialized for a specific process. "CPU" is an abbreviation for Central Processing Unit. "GPU" is an abbreviation for Graphics Processing Unit. The control unit 41 may include one or more dedicated circuits, or one or more processors in the control unit 41 may be replaced with one or more dedicated circuits. The dedicated circuits are, for example, FPGAs or ASICs. "FPGA" is an abbreviation for Field-Programmable Gate Array. "ASIC" is an abbreviation for Application Specific Integrated Circuit. The control unit 41 executes information processing related to the operation of the diagnosis support device 11 while controlling each part of the diagnosis support system 10 including the diagnosis support device 11.

[0042] The storage unit 42 is one or more semiconductor memories, one or more magnetic memories, one or more optical memories, or a combination of at least two of these. The semiconductor memory is, for example, a RAM or a ROM. "RAM" is an abbreviation for Random Access Memory. "ROM" is an abbreviation for Read Only Memory. The RAM is, for example, an SRAM or a DRAM. "SRAM" is an abbreviation for Static Random Access Memory. "DRAM" is an abbreviation for Dynamic Random Access Memory. The ROM is, for example, an EEPROM. "EEPROM" is an abbreviation for Electrically Erasable Programmable Read Only Memory. The storage unit 42 functions, for example, as a main storage device, an auxiliary storage device, or a cache memory. The storage unit 42 stores information used in the operation of the diagnosis support device 11 and information obtained by the operation of the diagnosis support device 11.

[0043] The communication unit 43 is one or more communication interfaces. The communication interface is a wired LAN interface, a wireless LAN interface, or an image diagnosis interface that receives and A / D converts IVUS signals. "LAN" is an abbreviation for Local Area Network. "A / D" is an abbreviation for Analog to Digital. The communication unit 43 receives information used in the operation of the diagnostic support device 11, and transmits information obtained by the operation of the diagnostic support device 11. In this embodiment, the drive unit 13 is connected to the image diagnosis interface included in the communication unit 43.

[0044] The input unit 44 is one or more input interfaces. The input interface is, for example, a USB interface or an HDMI (registered trademark) interface. "HDMI (registered trademark)" is an abbreviation for High-Definition Multimedia Interface. The input unit 44 accepts an operation to input information used for the operation of the diagnostic support device 11. In this embodiment, the keyboard 14 and the pointing device 15 are connected to a USB interface included in the input unit 44, but the keyboard 14 and the pointing device 15 may also be connected to a wireless LAN interface included in the communication unit 43.

[0045] The output unit 45 is one or more output interfaces. The output interface is, for example, a USB interface or an HDMI (registered trademark) interface. The output unit 45 outputs information obtained by the operation of the diagnostic support device 11. In this embodiment, the display 16 serving as a display unit is connected to the HDMI (registered trademark) interface included in the output unit 45.

[0046] The functions of the diagnostic support device 11 are realized by executing a diagnostic support program (computer program) according to this embodiment on a processor included in the control unit 41. That is, the functions of the diagnostic support device 11 are realized by software. The diagnostic support program is a program for making a computer execute processing of steps included in the operation of the diagnostic support device 11, thereby making the computer realize functions corresponding to the processing of the steps. That is, the diagnostic support program is a program for making a computer function as the diagnostic support device 11.

[0047] The program may be recorded on a computer-readable recording medium. The computer-readable recording medium may be, for example, a magnetic recording device, an optical disk, a magneto-optical recording medium, or a semiconductor memory. The program may be distributed, for example, by selling, transferring, or lending a portable recording medium such as a DVD or CD-ROM on which the program is recorded. "DVD" is an abbreviation for Digital Versatile Disc. "CD-ROM" is an abbreviation for Compact Disc Read Only Memory. The program may be distributed by being stored in the storage of a server and transferred from the server to other computers via a network. The program may be provided as a program product.

[0048] A computer temporarily stores a program recorded on a portable recording medium or a program transferred from a server in a main storage device. Then, the computer reads the program stored in the main storage device with a processor and executes processing according to the read program with the processor. The computer may read the program directly from a portable recording medium and execute processing according to the program. The computer may execute processing according to the received program each time a program is transferred from the server to the computer. Processing may be executed by a so-called ASP-type service that realizes functions only by execution instructions and result acquisition without transferring a program from the server to the computer. "ASP" is an abbreviation for Application Service Provider. Programs include information used for processing by a computer and equivalent to a program. For example, data that is not a direct command to a computer but has the property of defining computer processing corresponds to "something equivalent to a program."

[0049] A part or all of the functions of the diagnosis support device 11 may be realized by a dedicated circuit included in the control unit 41. That is, a part or all of the functions of the diagnosis support device 11 may be realized by hardware. Furthermore, the diagnosis support device 11 may be realized by a single information processing device, or may be realized by cooperation of multiple information processing devices.

[0050] (IVUS image acquisition) 4A to 4E are diagrams showing an example in which an IVUS image is acquired by the diagnosis support device 11 according to this embodiment.

[0051] As described above, during IVUS imaging, the drive shaft 21 rotates around the central axis of the probe 20 and is pulled back to the base end side where the drive unit 13 is located in accordance with the retraction of the scanner unit 31. The ultrasound transducer 25 provided at the tip of the drive shaft 21 moves towards the base end side of the probe 20 while rotating around the central axis of the probe 20 in conjunction with the drive shaft 21, while transmitting and receiving ultrasound signals inside biological tissue such as blood vessels.

[0052] FIG. 4A shows a schematic diagram of a plane perpendicular to the central axis of the probe 20, passing through the position where the ultrasonic transducer 25 is present. The ultrasonic transducer 25 transmits ultrasonic pulse waves radially while rotating at a uniform speed around the central axis of the probe 20 in the living tissue, receives reflected waves of the pulse waves from each direction, and generates a reception signal. That is, the ultrasonic transducer 25 as an imaging core transmits ultrasonic waves as signal waves at predetermined time intervals toward the outside of the probe while rotating within the probe, receives the reflected waves, and generates a reception signal. FIG. 4A to FIG. 4E show an example in which the ultrasonic transducer 25 transmits 512 pulse waves at equal intervals while rotating 360 degrees, and generates a reception signal of the reflected waves from each direction. Thus, each direction in which ultrasonic pulses are transmitted around the entire circumference of the ultrasonic transducer 25 is called a line (scanning line), and data indicating the reflected waves of ultrasonic waves in each line is called line data.

[0053] FIG. 4B shows an example of acquiring a luminance image by performing luminance conversion on the received signal of the reflected wave in each line. As shown in FIG. 4B, the received signal of each line is converted into a detection waveform indicating its amplitude, and then a logarithmic conversion is performed. Then, in order to associate the signal strength with the luminance in the image, a luminance conversion is performed. The control unit 41 of the diagnosis support device 11 constructs luminance data for one line by, for example, assigning 256 grayscale colors according to the strength of the reflected signal. The horizontal axis of each diagram in FIG. 4B indicates time. The vertical axis of the received signal, detection waveform, and logarithmic conversion indicates signal strength. The speed at which the ultrasonic wave travels is constant. Therefore, the time from transmitting the ultrasonic wave to receiving the reflected wave is proportional to the distance between the ultrasonic transducer 25 and the object that reflected the ultrasonic wave. Therefore, the line data obtained by the processing in FIG. 4B indicates the strength of the reflected signal according to the distance from the ultrasonic transducer 25 by the luminance of the image.

[0054] FIG. 4C is an example in which the line data of each of lines 1 to 512, which have been subjected to brightness conversion, are stacked and displayed. By converting this image into polar coordinates, a cross-sectional image of biological tissue as shown in FIG. 4D is acquired. One cross-sectional image is generated from 512 pieces of line data acquired while the ultrasonic transducer 25 rotates 360 degrees around the central axis of the probe 20. Such one cross-sectional image is called a frame image, and the data is called frame data. The position of each pixel included in the frame image related to the IVUS image is specified by the distance R from the ultrasonic transducer 25 and the rotation angle θ from the reference angle of the ultrasonic transducer 25. The rotation angle θ is determined corresponding to the line number n (n=1 to 512).

[0055] As described above, the IVUS image is acquired while the ultrasonic transducer 25 is pulled back toward the base end side of the probe 20. Therefore, as shown in FIG. 4E, when the ultrasonic transducer 25 moves in the blood vessel, the imaging catheter (probe 20) is swept (pulled back) in the blood vessel long axis direction to acquire continuous frame data. Here, the ultrasonic transducer 25 acquires frame data one by one while moving. Therefore, the long axis direction of the blood vessel in the continuously acquired multiple frame data corresponds to the time direction. Hereinafter, the two orthogonal directions in the same frame image are referred to as spatial directions to distinguish from the time direction. In FIG. 4E, the x direction and the y direction correspond to the spatial direction. The z direction corresponds to the time direction. Note that, in FIG. 4A to FIG. 4E, an example in which the number of line data acquired per one rotation of the probe 20 is 512 has been described, but the number of line data is not limited to 512, and may be, for example, 256 or 1024.

[0056] (Example of operation) The control unit 41 of the diagnosis support device 11 compares the phase of the reflected wave of the ultrasound indicated by the line data with the phase of the reflected wave received at the timing adjacent to the timing at which the reflected wave was received. As a result, the control unit 41 calculates the change in phase of the reflected wave along the rotation direction of the imaging core. Based on the change in phase, the control unit 41 detects image defects caused by uneven rotation of the imaging core. This allows the diagnosis support device 11 to automatically detect NURD present in a given tomographic image.

[0057] Fig. 5 illustrates an example in which the diagnosis support device 11 detects NURD. In Fig. 5, 51 is an IVUS image in which no NURD is present. 52 is an IVUS image in which an image defect caused by NURD is present. 53 is a waveform of a received signal in three lines of the IVUS image 51 in which no NURD is present. 54 is a waveform of a received signal in three lines of the IVUS image 52 in which NURD is present.

[0058] When an ultrasonic wave passes through an object boundary surface, the phase and amplitude change due to the difference in acoustic impedance between the objects, and the waveform may even be inverted. In particular, since the presence or absence of plaque and the arrangement of tissues are not uniform within a living body, it is common for the phase and amplitude of the wave to differ for each line of the image. Similarly, when other types of waves, such as light waves, pass through an object boundary surface, the phase and amplitude of the wave change. In FIG. 5, in an IVUS image 51 in which NURD is not present, the phase changes randomly (53).

[0059] On the other hand, NURD occurs when the imaging core, which should rotate at a constant rotation speed, does not rotate at a constant speed, but stops rotating or changes its rotation speed, resulting in uneven rotation of the imaging core. Even while the imaging core is stopped, the imaging core transmits signal waves toward the outside of the probe at predetermined time intervals, receives the reflected waves, and generates a received signal. Therefore, in an IVUS image 52 in which NURD exists, there is no phase change in the line data before and after a certain line, or the change is extremely small (54). As for the amplitude, it changes randomly in an IVUS image 51 in which NURD does not exist (53), but there is no change before and after the line, or the change is extremely small (54), in an IVUS image 52 in which NURD exists.

[0060] The diagnostic support device 11 focuses on such a property and calculates the phase and amplitude differences in the waveforms of the received signals for line data acquired by the IVUS imaging diagnostic catheter. The diagnostic support device 11 detects, as NURD portions, the portions where the phase and amplitude of the reflected waves do not change or change only slightly.

[0061] When NURD is detected, the diagnostic support device 11 adjusts the line width of the IVUS image including NURD, processes it to be equivalent to a normal image, and displays it on the display 16 as a display unit. When NURD occurs, there is a period when the rotation of the imaging core stops, but in the period when it does not stop, the imaging core often rotates at a constant speed faster than normal. In addition, regardless of whether the rotation of the imaging core stops or not, the imaging core transmits a signal wave toward the outside of the probe at a predetermined time interval, receives the reflected wave, and generates a received signal. Therefore, the diagnostic support device 11 corrects the IVUS image by shrinking the part where NURD occurs in the IVUS image caused by NURD along the rotation direction of the imaging core and enlarging the part where NURD occurs along the rotation direction.

[0062] FIG. 6 illustrates an example in which the diagnostic support device 11 corrects NURD. In an IVUS image 52, 61 indicates a portion where NURD occurs. The diagnostic support device 11 generates an IVUS image 64 by enlarging a portion 62 where NURD does not occur in the IVUS image 52 along the rotation direction of the imaging core and reducing a portion 63 where NURD occurs. Even if the rotation of the imaging core stops temporarily, the imaging core often rotates at a constant speed during rotation. Therefore, an IVUS image 64 generated by enlarging the portion 62 where NURD does not occur appropriately shows the structure of the imaging target such as biological tissue.

[0063] The operation of the diagnosis support system 10 according to this embodiment will be described with reference to Fig. 7. The operation of the diagnosis support device 11 described with reference to Fig. 7 corresponds to the information processing method according to this embodiment. The operation of each step in Fig. 7 is executed under the control of the control unit 41. Note that, although an example in which an IVUS image is used as a tomographic image is described in this embodiment, images acquired by other imaging devices such as an OCT / OFDI device may also be used. "OCT" is an abbreviation for Optical Coherence Tomography.

[0064] 6 begins, the user fits the probe 20 into the probe connection portion 34 and the probe clamp portion 37 of the drive unit 13, and connects and fixes the probe 20 to the drive unit 13. The probe 20 is then inserted to a target site in a blood vessel. The diagnosis support system 10 starts capturing an IVUS image by pulling back the ultrasound transducer 25 while rotating it around the central axis of the probe 20.

[0065] In step S11, the control unit 41 acquires line data indicating reflected waves in response to signal waves transmitted from an imaging core (ultrasonic transducer 25) rotating within the probe 20 toward the outside of the probe 20 at predetermined time intervals.

[0066] In step S12, the control unit 41 calculates the change in phase of the reflected wave along the rotation direction of the imaging core by comparing the phase of the reflected wave indicated by the line data with the phase of the reflected wave received at the timing adjacent to the timing at which the reflected wave was received. As described above, the position of each pixel included in the frame image related to the IVUS image is specified by the distance R from the ultrasonic transducer 25 and the rotation angle θ from the reference angle of the ultrasonic transducer 25 (see FIG. 4A). The rotation angle θ is determined according to the line number n (n=1 to 512). Of the 512 lines, the signal f of the nth line is n (t) is expressed in complex notation as follows: f n (t)=R n (τ)e i φ n( τ ) (1) however, R n (t)=v τ=v(t-nT) (2) τ=t-nT (3) t: time, v: speed of sound, T: period of one line Here, the complex conjugate of the signals on lines n and (n-1) is calculated by the following equation (4). f n (τ)*f n-1 -1 (τ)=Rn (τ)e i φ n( τ ) *R n-1 (τ)e i φ n-1( τ ) =R n '(τ)e i( φ n( τ )- φ n-1( τ )) (4) f n (τ)*f n-1 -1 (τ) angle(f n (τ)*f n-1 -1 (τ))=φ n (τ)-φ n-1 (τ) corresponds to the phase difference between the nth and (n-1)th lines. Then, f n By calculating (τ) as a matrix of τ and n, the phase difference between adjacent lines can be calculated for all lines constituting one IVUS image.

[0067] In step S13, the control unit 41 calculates the change in the amplitude of the reflected wave along the rotation direction of the imaging core. Specifically, the control unit 41 calculates the difference in amplitude between adjacent lines for all lines constituting one IVUS image. The control unit 41 may skip the process of step S13.

[0068] In step S14, the control unit 41 detects image defects caused by uneven rotation of the imaging core based on the change in phase of the reflected wave along the rotation direction of the imaging core. As described above, in a portion where NURD occurs, there is no phase change in the line data before and after the line, or the change is extremely small. Therefore, the control unit 41 detects as an image defect a portion of the image corresponding to the line data in a range where the change in phase of the reflected wave along the rotation direction of the imaging core falls below a predetermined value. In this way, the diagnosis support device 11 can detect image defects by focusing on the change in phase of the reflected wave.

[0069] As described above, the amplitude changes randomly in an IVUS image in which NURD does not exist, but there is no change before and after the line in an IVUS image in which NURD exists, or the change is very small. Therefore, when the change in amplitude is calculated in step S13, the control unit 41 can detect an image defect caused by uneven rotation of the imaging core based on not only the change in phase of the reflected wave along the rotation direction of the imaging core, but also the change in amplitude. For example, the control unit 41 may detect, as an image defect, a portion of the image corresponding to line data in a range in which the change in phase of the reflected wave falls below a predetermined value and the change in amplitude falls below another predetermined value. Based on not only the change in phase but also the change in amplitude, the diagnosis support device 11 can detect the image defect more accurately.

[0070] In step S15, when an image defect caused by the rotational unevenness of the imaging core is detected in step S14, the control unit 41 generates a frame image using line data acquired while there is no rotational unevenness. Specifically, when an image defect caused by the rotational unevenness of the imaging core is detected, the control unit 41 may generate a frame image by enlarging a portion of the frame image generated using line data acquired while there is no rotational unevenness along the rotational direction of the imaging core. Note that, when generating a frame image, the control unit 41 may reduce and use a portion of the frame image generated using line data acquired while there is rotational unevenness. Through these processes, the generated frame image appropriately represents the structure of the imaging target such as biological tissue.

[0071] In step S16, the control unit 41 displays the frame image generated in step S15 on the display 16 as a display unit. Therefore, the surgeon can check the structure of the imaging target such as biological tissue by checking the image displayed on the display 16.

[0072] As described above, the diagnostic support device 11 generates a frame image using line data indicating reflected waves of ultrasonic waves transmitted from the ultrasonic transducer 25 as an imaging core rotating inside the probe 20 toward the outside of the probe 20 at a predetermined time interval. Here, the control unit 41 of the diagnostic support device 11 calculates the change in phase of the reflected wave along the rotation direction of the imaging core by comparing the phase of the reflected wave indicated by the line data with the phase of the reflected wave received at the timing adjacent to the timing at which the reflected wave was received. Furthermore, the control unit 41 detects image defects caused by uneven rotation of the imaging core based on the change in phase. Therefore, according to this embodiment, it is possible to automatically detect NURD present in a tomographic image.

[0073] In this embodiment, an example has been described in which an IVUS device transmits ultrasonic waves as signal waves from an imaging core to acquire an IVUS image, but an OFDI / OCT device may transmit light waves as signal waves to acquire an image.

[0074] The present disclosure is not limited to the above-described embodiments. For example, multiple blocks shown in the block diagram may be integrated, or one block may be divided. Multiple steps shown in the flowchart may be executed in parallel or in a different order, depending on the processing capacity of the device executing each step, or as necessary, instead of being executed in chronological order as described. Other modifications are possible without departing from the spirit of the present disclosure. [Explanation of symbols]

[0075] 10 Diagnostic Support System 11 Diagnostic support devices 12 Cable 13 Drive unit 14 Keyboard 15 Pointing Devices 16 Display 17 Connection terminal 18 Cart Unit 20 Probe 21 Drive shaft 22 Hub 23 Sheath 24 Outer tube 25 Ultrasonic transducer 26 Relay connector 31 Scanner unit 32 Slide unit 33 Bottom cover 34 Probe connection 35 Scanner motor 36 Outlet 37 Probe clamp part 38 Slide motor 39 Switches 41 Control section 42 Storage section 43 Communications Department 44 Input section 45 Output section

Claims

1. An information processing device that generates a frame image using line data indicating a reflected wave of a signal wave transmitted from an imaging core rotating inside a probe toward an outside of the probe at a predetermined time interval, comprising: Calculating a change in the phase of the reflected wave along the rotation direction of the imaging core by comparing a phase of the reflected wave indicated by the line data with a phase of a reflected wave received at a timing adjacent to the timing at which the reflected wave was received; Based on the change in phase, an image defect caused by uneven rotation of the imaging core is detected. A control unit is provided, When an image defect caused by rotational unevenness of the imaging core is detected, the control unit enlarges, along the rotational direction of the imaging core, a portion of the frame image generated using the line data acquired while there is no rotational unevenness, and reduces, along the rotational direction of the imaging core, a portion of the frame image generated using the line data acquired while there is rotational unevenness, thereby generating the frame image. Information processing device.

2. The information processing device according to claim 1 , wherein the control unit detects as the image defect a portion of the image corresponding to the line data in a range in which a change in phase of the reflected wave along the rotation direction of the imaging core falls below a predetermined value.

3. The information processing device according to claim 2 , wherein the control unit further detects image defects caused by uneven rotation of the imaging core based on a change in amplitude of the reflected wave along the rotation direction of the imaging core.

4. The information processing device described in claim 3, wherein the control unit detects as the image defect a portion of the image corresponding to the line data in a range where the change in phase of the reflected wave along the rotation direction of the imaging core falls below the predetermined value and the change in amplitude of the reflected wave along the rotation direction of the imaging core falls below another predetermined value.

5. The information processing apparatus according to claim 1 , wherein the control unit causes the generated frame image to be displayed on a display unit.

6. The information processing apparatus according to claim 1 , wherein the signal wave is an ultrasonic wave or a light wave.

7. An information processing device according to any one of claims 1 to 6, A probe having the imaging core; An information processing system comprising:

8. 1. An information processing method of an information processing device including a control unit, which generates a frame image using line data indicating a reflected wave of a signal wave transmitted from an imaging core rotating inside a probe toward an outside of the probe at a predetermined time interval, The control unit: Calculating a change in the phase of the reflected wave along the rotation direction of the imaging core by comparing a phase of the reflected wave indicated by the line data with a phase of a reflected wave received at a timing adjacent to the timing at which the reflected wave was received; Detecting an image defect caused by uneven rotation of the imaging core based on the change in phase; Including, When an image defect caused by rotational unevenness of the imaging core is detected, the control unit enlarges, along the rotational direction of the imaging core, a portion of the frame image generated using the line data acquired while there is no rotational unevenness, and reduces, along the rotational direction of the imaging core, a portion of the frame image generated using the line data acquired while there is rotational unevenness, thereby generating the frame image. Information processing methods.

9. A computer program for causing a computer to execute a process of generating a frame image using line data indicating a reflected wave in response to a signal wave transmitted from an imaging core rotating within a probe toward an outside of the probe at a predetermined time interval, the computer program comprising: A process of calculating a change in the phase of the reflected wave along the rotation direction of the imaging core by comparing a phase of the reflected wave indicated by the line data with a phase of a reflected wave received at a timing adjacent to the timing at which the reflected wave was received; A process for detecting an image defect caused by a rotation irregularity of the imaging core based on the change in the phase; a process of generating the frame image by enlarging, in a rotation direction of the imaging core, a portion of the frame image generated using the line data acquired while there is no rotation unevenness, and shrinking, in a rotation direction of the imaging core, a portion of the frame image generated using the line data acquired while there is rotation unevenness, to generate the frame image, when an image defect caused by rotation unevenness of the imaging core is detected; A computer program that causes a computer to execute the following:

Images