JP7348849B2 - Ultrasonic diagnostic device and three-dimensional image forming method - Google Patents

Description

The present invention relates to an ultrasonic diagnostic apparatus and a three-dimensional image forming method, and particularly to forming a three-dimensional image based on a plurality of volume data.

An ultrasound diagnostic device is a device that forms ultrasound images based on received information obtained by transmitting and receiving ultrasound waves to and from a living body. B-mode tomographic images showing tissue cross sections, three-dimensional images showing tissues three-dimensionally, and the like are known as ultrasound images. For example, a three-dimensional image is formed by volume rendering based on volume data obtained from a three-dimensional space inside a living body. Hereinafter, a three-dimensional image as a moving image will be referred to as a "4D image", and an operation mode for forming and displaying a 4D image will be referred to as a "4D mode". Further, a three-dimensional image as a still image is referred to as a "3D image", and an operation mode for forming and displaying a 3D image is referred to as a "3D mode".

In 4D mode, if the volume rate is low, the followability or responsiveness of the content of the 4D image during probe movement deteriorates. Therefore, the number of receiving beams (which can also be called the number of times of transmission and reception) per volume data is reduced. This increases the volume rate.

When observing a 3D image, which is a still image, in detail, the operation mode is switched from 4D mode to 3D mode. At that time, the transmission and reception sequence is changed. Specifically, the number of receiving beams per volume data is increased. By executing the 3D mode, a 3D image that is more detailed than each 3D image that makes up the 4D image is displayed. However, when switching from 4D mode to 3D mode, a time lag inevitably occurs due to changes in transmission and reception conditions. Normally, the 3D mode is executed for one scan, and after the execution, transmission and reception are stopped. Note that if the freeze button is turned on while the 4D mode is being executed, the last 3D image that made up the 4D image is displayed as a still image. The resolution of the 3D image is low, making it unsuitable for detailed observation.

Patent Document 1 discloses a technique for increasing the volume rate. However, this document does not disclose data processing linked to the freeze operation.

JP2008-79885A

An object of the present invention is to be able to display fine 3D images after execution of 4D mode without changing the transmission and reception sequence.

The ultrasound diagnostic apparatus according to the present disclosure acquires a volume data sequence by cyclically forming N (N is an integer of 2 or more) 2D receiving beam arrays having a spatially shifted relationship in a 4D mode. a transmitting/receiving means for forming a 4D image based on the volume data string in the 4D mode, and generating n temporally consecutive images ( (where n is an integer of 2 or more and N or less) volume data, and image forming means that forms a fine 3D image based on the volume data.

The three-dimensional image forming method according to the present disclosure provides a volume that is obtained by cyclically forming N (N is an integer of 2 or more) 2D receiving beam arrays that are spatially shifted in a 4D mode. A method for processing a data string, the method comprising: forming a 4D image consisting of a plurality of 3D images arranged in chronological order based on the volume data string in the 4D mode, and a freeze operation in the 4D mode; forming a fine 3D image that is finer than each of the 3D images based on n pieces of temporally consecutive volume data selected from the volume data string (where n is an integer between 2 and N); It is characterized by including the following.

According to the present disclosure, a fine 3D image can be displayed after execution of the 4D mode without changing the transmission/reception sequence.

FIG. 1 is a block diagram showing an ultrasonic diagnostic apparatus according to an embodiment. FIG. 3 illustrates the cyclical formation of N 2D receive beam arrays; FIG. 3 is a diagram for explaining formation of a 4D image and formation of a fine 3D image. FIG. 3 is a diagram showing volume rendering. FIG. 3 is a diagram illustrating interpolation processing during 4D image formation. FIG. 3 is a diagram illustrating interpolation processing when forming a fine 3D image. It is a flowchart showing the operation of the ultrasonic diagnostic apparatus. 3 is a flowchart showing a method for automatically setting N; It is a figure showing an example of a display. It is a flowchart which shows a modification.

Hereinafter, embodiments will be described based on the drawings.

(1) Overview of Embodiment The ultrasonic diagnostic apparatus according to the embodiment includes a transmitting/receiving means and an image forming means. In the 4D mode, the transmitting/receiving means acquires a volume data sequence by cyclically forming N (where N is an integer of 2 or more) 2D receiving beam arrays having a spatially shifted relationship. The image forming means forms a 4D image based on the volume data string in the 4D mode, and when a freeze operation is performed in the 4D mode, the image forming means forms a 4D image based on the volume data string. A detailed 3D image is formed based on volume data (an integer greater than or equal to 2 and less than or equal to N).

A fine 3D image is created based on a plurality of temporally continuous volume data. The volume data is obtained by forming multiple 2D receive beam arrays with spatially offset relationships. In other words, a fine 3D image is created based on a plurality of volume data having spatially offset relationships. Therefore, the resolution of the fine 3D image is higher than the resolution of the individual 3D images that make up the 4D image. According to the above configuration, a fine 3D image can be quickly formed and displayed using the volume data string used in forming the 4D image without changing the transmission/reception sequence or the transmission/reception conditions after the freeze operation. According to the above configuration, there is also an advantage that additional transmission and reception associated with mode switching is not required.

It is desirable that n be equal to N, but if n is 2 or more, the above effects can be obtained. In the embodiment, the transmitting/receiving means includes a probe, a transmitting circuit, and a receiving circuit. The transmitting/receiving means may further include a transmitting/receiving control section. In the embodiment, the image forming means is constituted by a processor. Note that 2D means two dimensions, 3D means three dimensions, and 4D means four dimensions including time.

In an embodiment, the image forming means forms a fine 3D image based on N pieces of volume data including the latest volume data when transitioning to the frozen state.

Generally, immediately prior to a freeze operation, the contents of the 4D image are viewed for a period of time, during which the probe remains stationary. In such a stationary state, the latest volume data set (N volume data including the latest volume data) is acquired. The spatial distortion and temporal distortion included in the fine 3D image (the latest fine 3D image) created based on this is usually very small. The above configuration displays a fine 3D image of high quality and of most interest to the examiner immediately after the freeze operation.

In embodiments, the image forming means includes a 4D image forming means and a fine 3D image forming means. The 4D image forming means forms a 3D image sequence as a 4D image by individual rendering based on each volume data forming the volume data sequence. The fine 3D image forming means forms a fine 3D image by rendering based on a volume data set consisting of N pieces of volume data selected from the volume data string.

The fine 3D image is an image that is finer than each of the 3D images that make up the 4D image, that is, it is an image that has a higher resolution than each of the 3D images. Usually, the volume data string is stored in a ring buffer or the like. In the frozen state, the volume data set selected from the volume data string may be changed stepwise or continuously. That is, after freezing, a plurality of fine 3D images may be sequentially formed along the time axis. If temporal resolution is an issue in this case, a plurality of normal 3D images may be formed sequentially, as in the past.

In the embodiment, input means for specifying a numerical value to be given to N is provided. Generally, the resolution of a fine 3D image can be increased by increasing the value given to N, but the spatial distortion and temporal distortion included in the fine 3D image become larger. Therefore, it is desirable to determine the value given to N according to the probe rest period before the freeze operation. The numerical value to be given to n may be designated by input means. The value given to n may be changed after freezing.

In the embodiment, a determining means and a setting means are provided. The determining means determines the probe rest period based on the data string acquired before starting execution of the 4D mode. The setting means sets a numerical value to be given to N based on the probe rest period.

According to the above configuration, the value given to N can be optimized without causing any burden to the user. For example, in an ultrasound examination of a fetus, an examination using B mode is generally performed before an examination using 4D mode. A probe quiescent period may be determined based on data sequences acquired during B-mode execution. The value given to N may be set by multiplying the probe rest period by the volume rate.

In an embodiment, the N 2D receive beam arrays include a first 2D receive beam array, a second 2D receive beam array, a third 2D receive beam array, and a fourth 2D receive beam array. include. The second 2D receive beam array is offset in the first scanning direction with respect to the first 2D receive beam array. The third 2D receive beam array is offset in a second scan direction intersecting the first scan direction with respect to the first 2D receive beam array. The fourth 2D receive beam array is offset in the first scan direction and the second scan direction with respect to the first 2D receive beam array. When the reception beam pitch in the first scanning direction is larger than the reception beam pitch in the second scanning direction, the first scanning direction may be preferentially selected as the direction in which the 2D reception beam array is shifted.

In the embodiment, display processing means is provided for displaying the numerical value given to n when displaying the fine 3D image. According to this configuration, the conditions for forming a fine 3D image can be checked when observing the fine 3D image. If n is different from N, the numerical value given to N may also be displayed.

The three-dimensional image forming method according to the embodiment includes a volume obtained by cyclically forming N (N is an integer of 2 or more) 2D receiving beam arrays that are spatially shifted in a 4D mode. It is a method of processing data columns. The method includes a first step and a second step. In the first step, a 4D image consisting of a plurality of 3D images arranged in chronological order is formed in 4D mode based on the volume data sequence. In the second step, when a freeze operation is performed in the 4D mode, each volume data is A fine 3D image that is finer than a 3D image is formed.

The above method can be implemented as a hardware function or as a software function. In the latter case, a program for executing the above method is installed in the information processing device via a network or via a portable storage medium. The concept of an information processing device includes a computer, an ultrasonic diagnostic device, an image processing device, and the like.

(2) Details of Embodiment FIG. 1 shows an ultrasonic diagnostic apparatus according to an embodiment as a block diagram. This ultrasonic diagnostic apparatus is installed in a medical institution such as a hospital, and forms an ultrasonic image by transmitting and receiving ultrasonic waves to and from a living body. The organ to be diagnosed is, for example, a fetus within the mother's body. Other diagnostic targets include the liver, kidneys, breasts, etc. Ultrasonic diagnostic equipment has many operating modes. FIG. 1 shows configurations related to B mode and 4D mode.

B mode is a mode for forming and displaying a tomographic image representing a tissue cross section. A real-time tomographic image as a moving image is composed of a plurality of tomographic images arranged on the time axis. To form these tomographic images, one-dimensional scanning of the ultrasound beam is repeatedly performed. One beam scanning plane is formed by one one-dimensional scanning of the ultrasonic beam. The beam scan plane is a two-dimensional data acquisition area. In the process of executing B mode, when a freeze operation is performed to stop transmission and reception, a tomographic image is displayed as a still image.

The 4D mode is a mode for forming and displaying a three-dimensional image (4D image) as a moving image. A 4D image is composed of a plurality of 3D images arranged on the time axis. To form these 3D images, two-dimensional scanning of the ultrasound beam is performed repeatedly. One three-dimensional data acquisition area is formed by one two-dimensional ultrasound beam scan. In 4D mode, the volume rate is typically increased. In other words, the number of receiving beams formed when acquiring one piece of volume data is reduced.

As will be described in detail later, in the embodiment, when a freeze operation is performed during the execution process of the 4D mode, a fine 3D image is formed and displayed as a still image based on the volume data sequence obtained so far. be done. A fine 3D image is an image that has a relatively higher resolution than the individual regular 3D images that make up the 4D image.

In FIG. 1, a 3D probe 10 has a two-dimensional vibrating element array. The ultrasonic beam is two-dimensionally scanned by the two-dimensional transducer array. In FIG. 1, the first scanning direction is the θ direction, and the second scanning direction is the φ direction. The depth direction is the r direction. The 3D probe 10 is held by the examiner, and the wave transmitting/receiving surface of the 3D probe 10 is brought into contact with the surface of the living body.

When scanning the ultrasonic beam, various electronic scanning methods can be employed. As electronic scanning methods, electronic sector scanning methods, electronic linear scanning methods, etc. are known. For example, when the electronic sector scanning method is applied to both the first scanning direction and the second scanning direction, a pyramid-shaped three-dimensional data acquisition area 12 is formed as shown in FIG. By repeatedly performing two-dimensional electronic scanning of the ultrasound beam, a plurality of volume data are sequentially acquired from the three-dimensional data acquisition area 12. They constitute a volume data sequence.

Parallel reception technology is used to obtain volume data. That is, a receive beam group 16 consisting of a plurality of receive beams is simultaneously formed for one transmit beam 14. For example, 4 receive beams or 16 receive beams are formed simultaneously. This makes it possible to increase the volume rate.

The three-dimensional data acquisition region 12 may be formed by mechanically scanning a one-dimensional transducer array. For example, in a 3D probe having a cylindrical transmitting/receiving wave surface, electronic convex scanning is applied in the first scanning direction (long axis direction, circular arc direction), and electronic linear scanning is applied in the second scanning direction (short axis direction). Good too. A 3D probe inserted into a body cavity may also be utilized.

The transmitting circuit 17 is an electronic circuit that functions as a transmitting beamformer. The transmission circuit 17 supplies a plurality of transmission signals to the two-dimensional transducer array during transmission. As a result, ultrasonic waves are emitted from the two-dimensional transducer array into the living body, and a transmission beam is formed. The receiving circuit 18 is an electronic circuit that functions as a receiving beamformer. During reception, when the reflection from within the living body is received by the two-dimensional transducer array, a plurality of reception signals are outputted from there to the reception circuit 18. In the receiving circuit 18, a plurality of received signals are delayed and added, thereby generating beam data. When using parallel reception technology, multiple pieces of beam data are generated per transmission/reception.

Generally, one volume data is made up of a plurality of frame data, and one frame data is made up of a plurality of beam data. One beam data is composed of a plurality of echo data arranged in the depth direction. A transmit beamformer and multiple receive sub-beamformers may be provided within the 3D probe. In that case, the receiving circuit 18 functions as a main beamformer. The 3D probe 10 can also be used in B mode. In that case, one-dimensional scanning of the ultrasound beam is repeatedly performed in the 3D probe 10. As a result, a beam scanning surface is repeatedly formed.

The operations of the transmitter circuit 17 and the receiver circuit 18 are controlled by a transmitter/receiver controller 20 . The operation of the transmission/reception control section 20 is controlled by the main control section 22. In the embodiment, a specific subsequence is repeatedly executed under the control of the transmission/reception control unit 20 in the 4D mode. Per execution of the subsequence, N 2D receive beam arrays with spatially offset relationships are formed. This will be explained in detail later. N is an integer greater than or equal to 2, and in an embodiment, N is 4. Note that the spatially shifted relationship means a relationship in which the receiving beams do not overlap.

In the configuration example shown in FIG. 1, a cine memory 24 is provided after the receiving circuit 18. The cine memory 24 is a ring buffer that temporarily stores volume data acquired at each time in the 4D mode. The cine memory 24 stores a volume data sequence over a certain period of time. The unit of writing in the cine memory 24 is echo data, beam data, frame data, or volume data. During or after reading from the cine memory 24, a coordinate transformation is applied to each echo data. For example, a conversion from an rθφ coordinate system to an xyz coordinate system is performed. Coordinate transformation may be performed during the writing process to the cine memory 24.

Note that in the B mode, the cine memory 24 stores a plurality of frame data over a certain period of time. A cine memory for 4D mode and a cine memory for B mode may be provided separately. In the embodiment, the cine memory 24 is provided between the receiving circuit 18 and the plurality of image forming sections 28, 30, 34, but the cine memory 24 is provided in parallel with the plurality of image forming sections 28, 30, 34. may be provided.

In the B mode, the tomographic image forming unit 28 generates a plurality of tomographic image data (a plurality of display frame data) based on a plurality of chronologically ordered frame data (a plurality of received frame data) read out from the cine memory 24. It is something that generates. These tomographic image data are sent to the display processing section 36. A digital scan converter (DSC) may be provided as the tomographic image forming section 28. In the tomographic image forming unit 28, tomographic image data may be formed based on surface data cut out from the volume data. As described later, tomographic image data may be formed based on surface data cut out from a volume data set consisting of N pieces of volume data. The plurality of tomographic image data in chronological order are sent to the display 37 via the display processing section 36. In the B mode, a real-time tomographic image is displayed as a moving image on the display 37 based on a plurality of tomographic image data.

The 4D image forming unit 30 forms a plurality of 3D image data based on a plurality of volume data sequentially read from the cine memory 24 in the 4D mode. Specifically, 3D image data is formed by volume rendering based on individual volume data. 4D image data is composed of a plurality of pieces of 3D image data arranged in chronological order. Other three-dimensional image processing methods such as surface rendering may be applied instead of volume rendering. A plurality of 3D image data generated in the 4D image forming section 30 is sent to the display device 37 via the display processing section 36. A 4D image is displayed as a moving image on the display 37 based on a plurality of 3D image data in chronological order.

The fine 3D image forming section forms fine 3D image data when a freeze operation is performed in 4D mode. Specifically, the fine 3D image forming unit forms fine 3D image data by volume rendering on N pieces of temporally consecutive volume data stored in the cine memory. The N volume data are obtained by forming N 2D receive beam arrays that have a spatially shifted relationship.Simply put, the N volume data have a temporally shifted relationship. At the same time, they are in a spatially shifted relationship. By subjecting all of them to volume rendering, it is possible to generate fine 3D image data with a higher resolution than normal 3D image data. The fine 3D image data is sent to the display 37 via the display processing section 36. The fine 3D image is displayed on the display 37 as a still image.

At the time of the freeze operation, transmission and reception stop, and writing of new data to the cine memory 24 stops. After the freeze operation, first the latest definition 3D image based on the latest volume data set is displayed. The latest volume data set is composed of N pieces of volume data consecutive in time, including the latest volume data acquired last. Thereafter, by retracing the time phase of reading the volume data set from the volume data string on the cine memory, it is also possible to sequentially display fine 3D images along the time axis. Volume data sets acquired during the probe movement process typically contain many temporal and spatial distortions. Therefore, in such a case, a normal 3D image forming the 4D image may be displayed instead of the fine 3D image.

A compositing section 32 may be provided between the cine memory 24 and the fine 3D image. The combining unit 32 spatially combines N pieces of volume data to generate combined volume data. If N volume data on the cine memory 24 can be referenced in parallel, there is no need to provide the combining section 32.

The main control unit 22 controls each element shown in FIG. An operation panel 38 is connected to the main control section 22 . The operation panel 38 is an input device that includes switches, buttons, trackballs, keyboards, and the like. The operation panel 38 is also provided with a freeze switch. Using the operation panel 38, the user specifies a numerical value to be given to N (and n, which will be described later). Note that the display 37 is composed of a liquid crystal display, an organic EL display, or the like.

A portion indicated by the reference numeral 40 is constituted by a processor. The processor is, for example, a CPU that executes a program. A processor may be composed of multiple devices. The cine memory 24 is composed of, for example, a semiconductor memory.

In FIG. 2 a subsequence 39 in 4D mode is shown. The transmission and reception sequence corresponds to the repetition of subsequence 39. In the embodiment, one execution of subsequence 39 sequentially forms four 2D receive beam arrays 40, 42, 44, 46. They have a spatially offset relationship.

I will explain in detail. The first 2D receiving beam array 40 is composed of a plurality of receiving beams 48 arranged in the θ direction and the φ direction. The pitch in the θ direction is Δθ, and the pitch in the φ direction is Δφ. Grid 54 shows the arrangement of a plurality of receive beams that make up first 2D receive beam array 40 . The first 2D receive beam array 40 is generated by multiple times of transmission and reception. In the process, for example, 16 receive beams 52A are simultaneously formed for each transmit beam 50A. In the illustrated example, 16 two-dimensionally arranged receiving beams 52A are formed simultaneously. A plurality of one-dimensionally arranged receive beams may be formed simultaneously. Four reception beams may be formed for one transmission beam 50A.

The second 2D receiving beam array 42 is composed of a plurality of receiving beams 56 arranged in the θ direction and the φ direction. The receive beam array in the second 2D receive beam array 42 is the same as the array in the first 2D receive beam array 40 (see grid 54), but is shifted from each other by Δθ1 in the θ direction. The two arrays match in the φ direction. For example, Δθ1 is Δθ/2. Also in the process of generating the second 2D receive beam array 42, 16 receive beams 52B are simultaneously formed for each transmit beam 50B.

The third 2D receiving beam array 44 is composed of a plurality of receiving beams 58 arranged in the θ direction and the φ direction. The receive beam array in the third 2D receive beam array 44 is the same as the array in the first 2D receive beam array 40 (see grid 54), but is shifted from each other by Δφ1 in the φ direction. The two arrays match in the θ direction. For example, Δφ1 is Δφ/2. Also in the process of generating the third 2D receive beam array 44, 16 receive beams 52C are simultaneously formed for each transmit beam 50C.

The fourth 2D receiving beam array 46 is composed of a plurality of receiving beams 60 arranged in the θ direction and the φ direction. The receive beam array in the fourth 2D receive beam array 46 is the same as the array in the first 2D receive beam array 40 (see grid 54), but they are shifted from each other by Δθ1 in the θ direction, and are φ It is shifted by Δφ1 in the direction. Also in the process of generating the fourth 2D receive beam array 46, 16 receive beams 52D are simultaneously formed for each transmit beam 50D.

A composite beam array 62 is constructed by spatially combining the four 2D receive beam arrays 40, 42, 44, and 46. Combined beam array 62 has four times the beam density relative to the individual 2D receive beam arrays 40, 42, 44, 46. The composite beam array 62 corresponds to the volume data set described above.

FIG. 3 shows the stored contents of the cine memory 24 in the 4D mode. t indicates the time axis. The volume data string 67 is composed of a plurality of volume data starting with the latest volume data Cm. Here, the volume data Am is obtained by forming the m-th first 2D receiving beam array. The volume data Bm is obtained by forming the mth second 2D receive beam array. The volume data Cm is obtained by forming the mth third 2D receive beam array. Volume data Dm-1 is obtained by forming the m-1th fourth 2D receive beam array.

In the 4D mode, one 3D image 66 is formed for each volume data, and a 4D image as a moving image is constructed by continuously displaying them. When a freeze operation is performed in the 4D mode, transmission and reception are stopped at that point, and new volume data is no longer written to the cine memory 24. At the time of the freeze operation, four volume data Dm-1, Am, Bm, Cm, ie, the latest volume data set 68, are read out, and a fine 3D image 70 is formed by volume rendering based on them. It will be displayed as a still image. Usually, the 4D image is gazed at by the examiner just before the freeze operation, and in that state the 3D probe is in a stationary state or a state close to it. For example, during the period indicated by the reference numeral 71, the 3D probe can be considered to be stationary. A fine 3D image is created based on a plurality of temporally consecutive volume data acquired during such a period.

Immediately after the freeze operation, a fine 4D image is created based on the latest volume data set and displayed. Thereafter, the volume data set to be read is changed as necessary. For example, a fine 3D image is formed based on the volume data set 68A of one unit before, and a fine 3D image is formed based on the volume data set 68B of two units before. At the user's selection, a normal 3D image may be played instead of the fine 3D image.

FIG. 4 schematically shows volume rendering. A plurality of lines of sight are set for the volume data 72, and pixel values are calculated for each line of sight. Each pixel value is projected onto screen 78. In FIG. 4, one line of sight R1 emerging from the viewpoint 74 is shown. A plurality of sample points are set within the volume data 72 on the line of sight R1. An interpolated value is calculated for each sample point by referring to a plurality of surrounding echo values. For each line of sight R1, the pixel value of the pixel P1 corresponding to the line of sight R1 is calculated using all or part of a plurality of interpolated values from the first interpolated value Q1 to the last interpolated value Qi. When a three-dimensional region of interest is set within the volume data 72, volume rendering is applied to the inside of the three-dimensional region of interest.

5 and 6 schematically show calculation of interpolated values. In reality, interpolated values are calculated in a three-dimensional space, but FIGS. 5 and 6 show the calculation of interpolated values in a two-dimensional space. FIG. 5 shows calculation of interpolation values when forming a normal 3D image. Reference numeral 48a indicates an echo value. FIG. 6 shows the calculation of interpolation values when forming a fine 3D image. Numerals 48a, 56a, 58a, and 60a indicate four echo values generated by forming four 2D receive beam arrays.

In FIG. 5, the interpolated value Q3 is obtained by linear interpolation calculation based on the surrounding echo values A1, B1, C1, and D1. In FIG. 6, the interpolated value Q3 is obtained by linear interpolation calculation based on the surrounding echo values A2, B2, C2, and D2. The data density in the volume data shown in FIG. 6 is higher than the data density in the volume data shown in FIG. Therefore, according to the embodiment, a detailed 3D image with high resolution can be formed.

FIG. 7 shows an example of operation in 4D mode. FIG. 7 also shows a three-dimensional image forming method according to the embodiment. In S10, N is set. For example, a numerical value to be given to N is specified by the inspector. N is an integer of 2 or more. It is desirable to select the value given to N depending on the probe rest period immediately before the freeze operation.

In S12, a counter k is initialized. In S14, a k-th receive beam array is formed. As a result, one piece of volume data is acquired. In S16, it is determined whether a freeze operation has been performed. If it is determined that there has been no freeze operation, volume rendering is performed in S18 based on the current volume data, that is, the latest volume data. This generates a 3D image, which is displayed in S20. A 4D image is displayed by sequentially displaying a plurality of 3D images.

In S22, it is determined whether k has reached N. If k has not reached N, 1 is added to k and a new k is set in S24. After that, the steps after S14 are executed again. If it is determined in S22 that k has reached N, k is initialized in S12, and then the steps from S14 onwards are executed again.

If it is determined in S16 that a freeze operation has been performed, volume rendering is performed in S26 based on the latest volume data set consisting of N volume data including the latest volume data, thereby forming a fine 3D image. Ru. At S28, the fine 3D image is displayed as a still image. In S30, it is determined whether or not the freeze has been released, and if it is determined that the freeze has not been released, the display of the fine 3D image is maintained. If it is determined in S30 that the freeze has been released, it is determined in S32 whether or not to continue the 4D mode, and if the 4D mode is to be continued, the steps from S12 onwards are executed.

FIG. 8 shows an example of a method for automatically setting N. In S40, an ultrasonic examination is performed in B mode. When the freeze operation is performed in the B mode, the probe rest period before the freeze operation is determined in S44. When performing an ultrasonic examination in the 4D mode in S42, N is set in S46 based on the probe rest period determined in S44, prior to or at an initial stage thereof. Ultrasonic examination using 4D mode is performed based on the set N.

At S44, the probe stationary period may be determined using an interframe correlation calculation. Specifically, after freezing, the latest frame is used as the reference frame, past frames are sequentially selected in reverse order on the time axis, the correlation value is calculated between the reference frame and the past frames, and the correlation value is calculated from the reference frame. The period until the value exceeds the threshold may be determined as the probe rest period. Further, in S46, N may be calculated by multiplying the probe rest period by the volume rate.

A display example is shown in FIG. Display image 84 includes a fine 3D image 86. Information 88 is displayed near it. The information 88 indicates the numerical value given to N. Note that the following numerical value given to n may be displayed together with or in place of the numerical value given to N.

A modified example is shown in FIG. Steps that are the same as those shown in FIG. 7 are given the same step numbers, and their explanations will be omitted. In the modification shown in FIG. 10, the probe rest period is determined in S25, and n is determined based on the probe rest period. n is an integer greater than or equal to 2 and less than or equal to N. In S26, volume rendering is performed based on n pieces of volume data (latest volume data set) including the latest volume data, thereby forming a fine 3D image.

In S26, the latest volume data is set as reference volume data, and past volume data are sequentially selected in reverse order on the time axis. A correlation value is calculated between the reference volume data and past volume data. A period that can be considered as a stationary state is determined from a change in the correlation value. For example, the period from the timing when the reference volume data is acquired until the correlation value exceeds the threshold value is determined as the probe stationary period.

According to the above modification, since n pieces of volume data over a probe stationary period can be subjected to volume rendering, spatial distortion and temporal distortion included in a fine 3D image can be extremely reduced. If priority is given to spatial uniformity of beam density or resolution, N may be given to n. By adopting a configuration that automatically determines n and N, the burden on the user can be reduced.

According to the above embodiment, when a freeze operation is performed in 4D mode, a 3D image of high quality that could not be obtained in the past can be displayed. At that time, there is no need to change the mode, that is, change the transmission/reception sequence, so no time lag occurs. Note that in the 4D mode, a 4D image and a fine 3D image based on Doppler information may be formed and displayed.

10 3D probe, 12 three-dimensional space (three-dimensional data acquisition area), 14 transmission beam, 16 reception beam group, 24 cine memory, 28 tomographic image formation section, 30 4D image formation section, 32 synthesis section, 34 fine 3D image formation Section, 36 Display processing section.

Claims (8)

a transmitting/receiving means for acquiring a volume data sequence by cyclically forming N (where N is an integer of 2 or more) 2D receiving beam arrays having a spatially shifted relationship in a 4D mode;
In the 4D mode, a 4D image is formed based on the volume data string, and when a freeze operation is performed in the 4D mode, a temporally continuous n selected from the volume data string (however, n is 2 or more N An image forming means for forming a fine 3D image based on the following (integer) volume data;
including, and further,
determination means for determining a probe rest period before a freeze operation based on a data string acquired before starting execution of the 4D mode;
Setting means for setting a numerical value to be given to the N based on the probe stationary period;
An ultrasonic diagnostic device comprising : The ultrasonic diagnostic apparatus according to claim 1,
The n is the N,
The image forming means forms the fine 3D image based on N pieces of volume data including the latest volume data when transitioning to the frozen state.
An ultrasonic diagnostic device characterized by: The ultrasonic diagnostic apparatus according to claim 2,
The image forming means includes:
4D image forming means for forming a 3D image sequence as the 4D image by individual rendering based on a plurality of volume data forming the volume data sequence;
Fine 3D image forming means for forming the fine 3D image by rendering based on a volume data set made up of the N volume data selected from the volume data string;
An ultrasonic diagnostic device comprising: The ultrasonic diagnostic apparatus according to claim 1,
including an input means for specifying a numerical value to be given to the N;
An ultrasonic diagnostic device characterized by: The ultrasonic diagnostic apparatus according to claim 1,
The data string is a data string acquired during B-mode execution before starting execution of the 4D mode.
An ultrasonic diagnostic device comprising: The ultrasonic diagnostic apparatus according to claim 1,
The N 2D receive beam arrays include:
a first 2D receive beam array;
a second 2D receive beam array offset in a first scanning direction with respect to the first 2D receive beam array;
a third 2D receive beam array that is offset from the first 2D receive beam array in a second scanning direction intersecting the first scanning direction; and
a fourth 2D receive beam array that is offset in the first scan direction and the second scan direction with respect to the first 2D receive beam array;
An ultrasonic diagnostic device characterized by comprising: The ultrasonic diagnostic apparatus according to claim 1,
comprising display processing means for displaying the numerical value given to the n when displaying the fine 3D image;
An ultrasonic diagnostic device characterized by: A method of processing a volume data sequence obtained by cyclically forming N (N is an integer of 2 or more) 2D receiving beam arrays spatially shifted in a 4D mode, the method comprising:
forming a 4D image consisting of a plurality of 3D images arranged in chronological order based on the volume data sequence in the 4D mode;
When a freeze operation is performed in the 4D mode, each of the 3D images is processed based on n (where n is an integer between 2 and N) consecutive volume data selected from the volume data string. a step of forming a highly detailed 3D image;
including;
determining a probe quiescent period before a freeze operation based on a data sequence acquired before starting execution of the 4D mode;
setting a numerical value to be given to the N based on the probe rest period;
A three-dimensional image forming method comprising :