1. Field of the Invention
The present invention relates to an ultrasound diagnostic apparatus and a medical image-processing apparatus. The ultrasound diagnostic apparatus is an apparatus that transmits ultrasound to the inside of a subject using an ultrasonic probe, and obtains medical images of the subject based on waves reflected therefrom. The medical image-processing apparatus is an apparatus for processing medical images obtained by the ultrasound diagnostic apparatus. In particular, the present invention relates to the art used for comparative evaluation of motor functions of the same biological tissue obtained at different timing.
2. Description of the Related Art
The ultrasound diagnostic apparatus has a merit whereby it is possible to observe an image instantly by a simple operation such as the operation of simply placing the ultrasonic probe in contact with a body surface. Thus, the ultrasound diagnostic apparatus has been widely used to diagnose the shape and function of biological tissue. In recent years, more attention is being paid to an evaluation of a motor function of biological tissue, such as heart wall motion, and especially an evaluation of a three-dimensional motor function.
Additionally, the ultrasound diagnostic apparatus is used for obtaining images of biological tissue at a plurality of times at different timing (time and days), comparing such images, and thereby observing the time elapsed changes in condition of the biological tissue. A typical example of such a use includes stress echocardiography. Other than that, the ultrasound diagnostic apparatus is used in observation of a clinical course, preoperative/postoperative observation, and so on.
Stress echocardiography is an examination for evaluating the motor function of a heart by comparing an image obtained at a time when a patient is not subjected to stress such as motion or medication, with an image obtained at a time in which the patient is subjected to stress. There is also an examination for evaluating heart function by applying stress in stages and comparing images of the respective phases (e.g., refer to Japanese Unexamined Patent Application Publication No. 2005-304757).
In stress echocardiography using two-dimensional images, images are obtained from multiple views (tomographic planes) for each phase of the stress. Examples of such images include views such as an apical four-chamber view, an apical two-chamber view, a long-axis view of the left ventricle, and a short-axis view of the left ventricle.
Additionally, in recent years, stress echocardiography using three-dimensional images has been proposed. This method is to generate, at each phase of the stress, volume data by three-dimensionally scanning ultrasound, and obtain a desired cross-sectional image by subjecting this volume data to MPR (Multi-Planar Reconstruction).
However, regarding a conventional ultrasound diagnostic apparatus the following problems are pointed out. Firstly, there has been a problem in which stress echocardiography using two-dimensional images needs to variously change the way in which the ultrasonic probe is placed on the subject in order to obtain multiple images as described above, resulting in a complicated and long-time examination.
Secondly, although an image of the short-axis viewal view of the left ventricle is suitable for the observation of heart wall motion, it is possible in stress echocardiography using two-dimensional images, to obtain only short-axis tomographic images at the papillary muscle level, so that there has been a problem in which the condition of the left ventricle cannot be observed comprehensively.
Meanwhile, stress echocardiography using three-dimensional images is to obtain volume data at each phase to generate an MPR image and thus designate a cross-section that makes it possible to adequately observe the condition of the cardiac muscle. However, there has been a problem in which this operation is highly complicated and time consuming.
Additionally, because there has been no means for comparative observation by displaying both a past MPR image and a new MPR image, it has been particularly troublesome and time consuming to match a cross-sectional position of a past MPR image with a cross-sectional position of a new MPR image.
Furthermore, in the comparative observation, it is preferable to observe tomographic images at the same cross-section for each phase, but it has been difficult to set the same cross-section for each phase in a conventional configuration.
Moreover, even in the case of three-dimensionally scanning ultrasound, it is still necessary to place the ultrasonic probe properly on the subject in order to observe the condition of biological tissue. However, it is not possible to verify the manner of placement of the ultrasonic probe until an image is displayed for viewing.
Therefore, it has been particularly troublesome and time consuming to determine the manner of placement of an ultrasonic probe.
In addition, even in the case of observation of the clinical course, preoperative/postoperative observation, and the like, it has been difficult to designate the same cross-section for each timing when tomographic images based on volume data obtained at different timings are comparatively observed.
The present invention was made in order to solve the aforementioned problems, and an object of the present invention is to provide an ultrasound diagnostic apparatus and a medical image-processing apparatus that are capable of easily obtaining tomographic images of the same cross section of biological tissue in an examination for observing time-elapsed changes of the biological tissue.
Further, another object of the present invention is to provide an ultrasound diagnostic apparatus and a medical image-processing apparatus that are capable of making an examination for observing time-elapsed changes of biological tissue simple and short-time.
In a first aspect of the present invention, an ultrasound diagnostic apparatus comprises: an ultrasonic probe configured to transmit ultrasound while three-dimensionally scanning, and receive ultrasound reflected by a biological tissue; an image data generator configured to generate image data of a tomographic image of the biological tissue based on reception results of ultrasound; a memory configured to store cross-sectional-position information showing a cross-section a position of the tomographic image; a display part; and a controller configured to: control the image data generator so as to, based on a cross-sectional position shown in cross-sectional-position information obtained when image data of a tomographic image of the biological tissue has been generated previously, and reception results of new ultrasound, generate image data of a new tomographic image in the relevant cross-sectional position; and cause the display part to display the new tomographic image.
According to the first aspect, it is possible to, based on a cross-sectional position shown in past cross-sectional-position information and reception results of new ultrasound, generate and display a new tomographic image in a past cross-sectional position. Consequently, it is possible to easily obtain a tomographic image of the same cross section of a biological tissue, in an examination of observing time change of the biological tissue.
In a second aspect of the present invention, an ultrasound diagnostic apparatus comprises: an ultrasonic probe configured to transmit ultrasound while scanning, and receive ultrasound reflected by a biological tissue; an image data generator configured to generate image data of a tomographic image of the biological tissue, based on reception results of ultrasound; a memory configured to store scanning position in formation showing a scanning position of ultrasound by the ultrasonic probe; a display part; and a controller configured to: control the ultrasonic probe at the time of generation of image data of a new tomographic image of the biological tissue so as to transmit ultrasound to a scanning position shown in scanning position information obtained at the time of past generation of image data of a tomographic image; control the image data generator so as to generate image data of a new tomographic image based on reception results of the ultrasound; and cause the display part to display the new tomographic image.
According to the second aspect, it is possible to transmit ultrasound to a scanning position shown in past scanning position information, and generate and display a new tomographic image based on reception results of this ultrasound. Consequently, it is possible to easily obtain a tomographic image of the same cross section of a biological tissue, in an examination of observing time change of the biological tissue. Moreover, it is possible to simplify and shorten time for an examination of observing time change of a biological tissue.
In a third aspect of the present invention, a medical image-processing apparatus comprising: an image data generator configured to generate image data of an MPR image, based on volume data of a biological tissue generated by an ultrasound diagnostic apparatus; a memory configured to store cross-sectional-position information showing a cross-sectional position of the MPR image; a display part; and a controller configured to: control the image data generator so as to, based on cross-sectional-position information of an MPR image from volume data generated on a first date, and volume data generated on a second date, generate image data of an MPR image of the second date in a cross-sectional position shown in cross-sectional information of the first date; and cause the display part to display an MPR image of the second date.
According to the third aspect, it is possible to, based on a cross-sectional position shown in cross-sectional-position information of a first date, and volume data of a second date, generate and display an MPR image of the second time in the cross-sectional position of the first date. Consequently, it is possible to easily obtain a tomographic image of the same cross section of a biological tissue, in an examination of observing time change of the biological tissue. Moreover, it is possible to simplify and shorten time for an examination of observing time change of a biological tissue.
In a fifth aspect of the present invention, a medical image-processing apparatus that processes volume data generated by an ultrasound diagnostic apparatus for each of a plurality of phases in a stress echocardiography examination of a biological tissue, comprising: an image data generator configured to generate image data of an MPR image, based on the volume data; a memory configured to store cross-sectional-position information showing a cross-sectional position of the MPR image; a display part; and a controller configured to: in a case where a second phase examination is performed after a first phase examination, control the image data generator so as to, based on cross-sectional-position information obtained at the time of generation of image data of an MPR image of the first phase, and volume data of each of the first phase and the second phase, generate image data of an MPR image of each of the first phase and the second phase in a cross-sectional position shown in cross-sectional-position information of the first phase; and cause the display part to display an MPR image of the first phase and an MPR image of the second phase side by side.
According to the fifth aspect, it is possible to, based on cross-section-position in formation of a first phase, and volume data of each of the first phase and a second phase, generate an MPR image of each of the first phase and the second phase in a cross-sectional position of the first phase, and display these MPR images side by side. Consequently, it is possible to easily obtain a tomographic image of the same cross section of a biological tissue, in a stress echocardiography examination of the biological tissue. Moreover, it is possible to simplify and shorten time for a stress echocardiography examination.
FIG. 1 is a schematic block diagram illustrating an example of the entire configuration for an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 2A and FIG. 2B are schematic explanatory diagrams for explaining an example of an ultrasonic scanning mode in an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 3 is a schematic explanatory diagram for explaining an example of an ultrasonic scanning mode in an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 4 is a flow chart illustrating an example of an operation mode in an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 5 is a schematic diagram illustrating an example of a display screen that is displayed by an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 6 is a schematic diagram illustrating an example of a display screen that is displayed by an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 7 is a schematic diagram illustrating an example of a display screen that is displayed by an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 8 is a schematic diagram illustrating an example of a display screen that is displayed by an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 9 is a schematic block diagram illustrating an example of the entire configuration in a modification example for an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 10 is a schematic explanatory diagram for explaining an image-displaying mode in a modification example for an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 11A and FIG. 11B are schematic explanatory diagrams for explaining a setup process of a cross-sectional position in a modification example for an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 12 is a schematic block diagram illustrating an example of the entire configuration for an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 13 is a flowchart illustrating an example of an operation mode in an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIGS. 14A and 14B are schematic explanatory diagrams for explaining a scanning mode for a multi-plane scan of the ultrasound in an embodiment of an ultrasound diagnostic apparatus according to the present invention.
FIG. 15 is a schematic block diagram illustrating an example of the entire configuration for an embodiment of a medical image-processing apparatus according to the present invention.
FIG. 16 is a schematic explanatory diagram for explaining a modification example for an embodiment of an ultrasound diagnostic apparatus and a medical image-processing apparatus according to the present invention.
An embodiment of an ultrasound diagnostic apparatus and a medical image-processing apparatus according to the present invention will be described in detail with reference to drawings.
FIG. 1 illustrates an example of the entire configuration for the first embodiment of an ultrasound diagnostic apparatus according to the present invention. An ultrasound diagnostic apparatus 1 is an apparatus that is used, for example, for obtaining an image showing the shape of biological tissue such as a heart and an image showing a blood flow condition.
The ultrasound diagnostic apparatus 1 comprises a two-dimensional ultrasonic probe 2 , a transceiver 3 , a signal processor 4 , an image processor 5 , an information memory 6 , an image data memory 7 , a user interface 8 , and a controller 9 . Specific examples for each part composing the ultrasound diagnostic apparatus 1 will be described below.
First, the user interface 8 and the controller 9 will be described hereunder. A display part 81 and an operation part 82 are provided in the user interface 8 .
The display part 81 corresponds to an example of a “display part” in the present invention. The display part 81 is composed of any display device such as an LCD (Liquid Crystal Display) and a CRT (Cathode Ray Tube).
The display part 81 displays various images such as an ultrasonic image obtained by the ultrasound diagnostic apparatus 1 . Additionally, the display part 81 displays various kinds of information such as DICOM (Digital Imaging and Communications in Medicine) supplemental information about the image.
The operation part 82 is composed of any operational device or input device, such as a mouse, a trackball, a joystick, a control panel and a keyboard. The operation part 82 is used as an example of an “operation part” in the present invention.
The controller 9 comprises a microprocessor such as a CPU, and a storage unit such as a memory and a hard disk drive. The storage unit stores a control program 91 beforehand. The microprocessor operates based on the control program 91 , and thus causes the ultrasound diagnostic apparatus 1 to execute operations that are characteristic of the present invention.
Thus, the controller 9 causes the display part 81 to display an image and a screen. Additionally, the controller 9 causes the ultrasound diagnostic apparatus 1 to execute an operation in response to a control signal transmitted from the operation part The controller 9 functions as an example of a “controller” for the present invention.
The two-dimensional ultrasonic probe 2 (may simply be referred to as an ultrasonic probe 2 ) is provided with a plurality of ultrasonic transducers. The plurality of ultrasonic transducers are arranged two-dimensionally (e.g., in a matrix state (lattice-like state)) (an illustration thereof is omitted). The plurality of ultrasonic transducers are individually driven by the transceiver 3 to transmit the ultrasound. Additionally, the plurality of ultrasonic transducers receive the ultrasound reflected by the biological tissue.
FIGS. 2A, 2 B and FIG. 3 illustrate an ultrasonic scanning mode performed by the two-dimensional ultrasonic probe 2 . As shown in FIG. 2A, the ultrasonic probe 2 scans an ultrasonic beam transmitted from the arrangement surface of the ultrasonic transducers in the main scanning direction X. Thus, a two-dimensional scan plane P is formed in a radial pattern (in a fan shape). Additionally, the ultrasonic probe 2 scans the ultrasound in the sub scanning direction Y that is orthogonal to the main scanning direction X, and thereby sequentially forms a plurality of fan-shaped two-dimensional scan planes P 1 , P 2 , . . . and Pn, which are arranged in the sub scanning direction Y as shown in FIG. 2B. As described above, the ultrasonic probe 2 transmits while three-dimensionally scanning the ultrasound to form a three-dimensional scanning range R shown in FIG. 3.
A cross-sectional position for a tomographic image (B-mode image) obtained by the ultrasound diagnostic apparatus is generally determined by the relative position of the ultrasonic probe or the scanning origin with respect to the biological tissue. In other words, if the position of the ultrasonic probe or scanning origin changes, the tomographic image of the cross-sectional position corresponding thereto will be obtained.
The transceiver 3 comprises a transmission part for supplying an electrical signal to the ultrasonic probe 2 and transmitting ultrasound. Additionally, the transceiver 3 comprises a receiving part for receiving echo signals (reception signals), which are outputted from the ultrasonic probe 2 that has received a reflected wave of this ultrasound (both illustrations are omitted).
The transmission part of the transceiver 3 comprises a clock-signal-generating circuit, a transmission delay circuit, a pulse circuit, etc., which are not shown in the figure. The clock-signal-generating circuit generates a clock signal that determines the transmission timing and transmission frequency of the ultrasound. The transmission delay circuit performs transmission focus by imposing a delay when transmitting the ultrasound. The pulse circuit incorporates pulse generators, the number of which is equivalent to the number of individual channels corresponding to each ultrasonic transducer.
That will cause the pulse circuit to generate a drive pulse at a transmission timing at which the delay is imposed and then supply it to each ultrasonic transducer of the ultrasonic probe 2 .
Furthermore, the receiving part of the transceiver 3 comprises a pre-amplifier circuit, an A/D conversion circuit, and a reception delay/addition circuit, which are not shown in the figure. The pre-amplifier circuit amplifies, for every reception channel, echo signals outputted from each transducer of the ultrasonic probe 2 . The A/D conversion circuit converts the amplified echo signals from A (analog) to D (digital). The reception delay/addition circuit applies the delay time necessary for determination of the reception tendency to the A/D-converted echo signals, and performs addition. This addition process will emphasize a reflection component from the direction according to the reception tendency. In some cases, a signal after the addition process may be referred to as “RF data (raw data).” The transceiver 3 inputs the RF data that has been obtained in this way into the signal processor 4 .
The signal processor 4 visualizes the amplitude information of the echo signal, based on the RF data having been in putted from the transceiver 3 . The data generated by the signal processor 4 is transmitted to the controller 9 to be displayed on the display part 81 of the user interface 8 , or inputted into the image processor 5 . The signal processor 4 mainly comprises a B-mode process or 41 , a Doppler processor 42 , and a CFM processor 43 .
The B (Brightness) Mode Processor 41 Generates B-mode ultrasound raster data, based on the RF data. In concrete, the B-mode processor 41 performs a band-pass filter process on the RF data, detects an envelope of the output signal thereof, and compresses this detected data by a logarithmic transformation. Thus, with respect to the respective two-dimensional scan planes P 1 to Pn, image data of the tomographic image in which the signal strength is expressed by brightness is generated.
The Doppler processor 42 generates blood flow information by a pulse Doppler method (PW Doppler method), a continuous wave Doppler method (CW Doppler method) or the like. These methods are selectively applied, for example, by operating the operation part 82 of the user interface 8 .
In the pulse Doppler method, a shift of frequency of the ultrasound (Doppler shift frequency component) arising from the Doppler effect caused by blood flow at a certain depth (distance from the ultrasonic probe 2 ) is detected using a pulse wave. Thus, the pulse Doppler method has a good distance resolution, and therefore is preferably used for depth measurement of tissue and blood flow for a specified site.
In a case where the pulse Doppler method is applied, the Doppler processor 42 extracts, with respect to the RF data inputted from the transceiver 3 , the Doppler shift frequency component by performing a phase detection of the signals at a specified size of blood-flow observation range. Additionally, the Doppler processor 42 performs FFT (Fast Fourier Transformation) and then generates data showing the Doppler frequency distribution that represents the blood velocity in the blood-flow observation range.
Meanwhile, in the case of the continuous wave Doppler method, signals superposed with the Doppler shift frequency components for all sites in the transmission/reception direction of the ultrasound (radial direction in the two-dimensional scan plane P) are obtained using a continuous wave. These signals are signals that reflect all blood flow conditions in the path of the ultrasound. The continuous wave Doppler method has the merit that the speed of the measurement is excellent.
In a case where the continuous Doppler method is applied, the Doppler processor 42 extracts, with respect to the RF data that is inputted from the transceiver 3 , the Doppler shift frequency component by performing phase detection on the signals received in a sample line of blood-flow observation. Additionally, the Doppler processor 42 performs FFT (Fast Fourier Transformation) and then generates data showing a Doppler frequency distribution that represents the blood velocity in the sample line.
The CFM (Color Flow Mapping) processor 43 operates when a color flow mapping method is performed. The color flow mapping method is a method for displaying at real-time in a color format by superposing the blood flow information of the biological tissue on a B-mode image having a binary format. Examples of the blood flow information include the velocity, distribution, and strength of blood flow. The blood flow information is obtained as binary format information. It should be noted that “real-time” allows for a time lag to the extent that the ultrasonic image based on the ultrasonic scan can be obtained while the ultrasonic probe 2 is placed on the subject.
The CFM processor 43 comprises a phase detection circuit, a MTI (Moving Target Indication) filter, an autocorrelator, and a flow speed/variance operator. The CFM processor 43 separates a shape signal reflecting the shape of the biological tissue and a blood flow signal reflecting the blood flow, by means of a high-pass filter process (MTI filter process). Additionally, the CFM processor 43 calculates information such as the velocity, distribution and strength of blood flow for a plurality of positions by performing an autocorrelation process. In some cases, the CFM processor 43 may perform a non-linear process to reduce the shape signal.
The image processor 5 performs various kinds of image processing based on data generated by the signal processor 4 . For example, the image processor 5 has a DSC (Digital Scan Converter). The DSC converts the data synchronized with the ultrasonic scan having been generated by the signal processor 4 , into data used for display (TV scan mode data). This process is called a scan conversion process.
Additionally, the image processor 5 is provided with a volume data generator 51 and an MPR processor 52 , which will be described below.
The volume data generator 51 generates volume data (voxel data) by interpolating the image data of two-dimensional scan planes P 1 to Pn generated by the B-mode processor 41 . The volume data generator 51 comprises, for example, a DSC and a microprocessor.
In the case of display of a quasi three-dimensional image based on the volume data, the image processor 5 generates image data for display by performing image-processing such as a volume rendering process and an MIP (Maximum Intensity Projection) process. The controller 9 causes the display part 81 to display the quasi three-dimensional image based on the image data for display.
The MPR (Multi-Planar Reconstruction) processor 52 generates image data for a tomographic image (an MPR image) in an arbitrary cross-sectional position of the biological tissue by converting a cross-section of the volume data generated by the volume data generator 51 . The MPR processor 52 comprises, for example, a DSC and a microprocessor.
As described above, the signal processor 4 (the B-mode processor 41 thereof) and the image processor 5 generate image data for the tomographic image (MPR image based on the volume data) of the biological tissue, based on the results (data outputted from the transceiver 3 ) of the ultrasound received by the ultrasonic probe 2 . The signal processor 4 and the image processor 5 correspond to an example of an “image data generator” in the present invention.
The information memory 6 stores cross-sectional-position information D showing the cross-sectional position of the MPR image. The information memory 6 corresponds to an example of a “storage part” in the present invention. The cross-sectional position indicated in the cross-sectional-position information D is expressed, for example, by using a three-dimensional coordinate system defined in the volume data.
The cross-sectional-position information D is stored so as to be associated with patient identification information such as a patient ID. The controller 9 is capable of searching the intended cross-sectional-position information D by using the patient identification information as a search key. Additionally, the cross-sectional-position information D is also associated with examination date in formation showing the date (and time) of generation of the image data of the MPR image. The examination date information is used as a search key when the cross-sectional-position information D is searched based on the examination date.
The information memory 6 comprises a storage unit such as a memory and a hard disk drive. The microprocessor or the like (controller 9 ) performs a process of writing/reading data in/out of the information memory 6 .
The image data memory 7 stores various kinds of image data such as volume data V generated by the volume data generator 51 and the image data for the MPR image. Additionally, various data such as the DICOM supplemental information for the image data is also stored in the image data memory 7 .
The image data memory 7 comprises a comparatively high-capacity storage unit, examples of which are memory such as a DRAM (Dynamic Random Access Memory) and a hard disk drive. The microprocessor or the like (controller 9 ) performs a process of writing/reading data in/out of the information memory 7 .
An example of a usage of an ultrasound diagnostic apparatus 1 will be described with reference to FIG. 4 to FIG. 7.
The usage for a case of stress echocardiography of a heart will be described hereunder. Stress echo cardiography is an examination for observing how the motion (function) of a cardiac muscle has changed by stress applied to the subject. Accordingly, as described above, with respect to phases before and after stress is applied (or each phase of the stress), it is important to comparatively observe the same section of the cardiac muscle by obtaining images of the same cross-sectional position of the heart.
The usage for obtaining (almost) the same cross-sectional position of the heart in the case of examination in the resting phase and examination in a stress phase will be described hereunder. The resting phase means a condition in which the subject is not subjected to stress such as motion or medication. The stress phase means a condition in which the subject is subjected to stress.
First, examination in the resting phase is performed. For that, a coupling medium such as an ultrasound jelly is applied to the body surface of the subject and the ultrasound-outputting surface of the ultrasonic probe 2 . Then, an ultrasonic three-dimensional scan is performed with the ultrasonic probe 2 placed on the body surface located adjacent to an apex of the heart (S 1 ). Such a manner of placement of the ultrasonic probe 2 is called an apical approach.
The results received by the ultrasonic probe 2 are transmitted to the B-mode processor 41 through the transceiver 3 . The B-mode processor 41 generates image data for the tomographic image, based on data having been inputted from the transceiver 3 . Thus, the image data for the tomographic image in each of the two-dimensional scan planes P 1 , P 2 , . . . and Pn shown in FIG. 2B can be obtained.
The volume data generator 51 generates the volume data based on the image data (S 2 ). The volume data is stored, for example, in the image data memory 7 .
Here, Steps S 1 and S 2 are repeated at specified time intervals. That enables the volume data to be obtained at specified time intervals (frame rate). The volume data stored in the image data memory 7 includes a plurality of sets of volume data obtained at the frame rate.
The MPR processor 52 generates image data for the MPR image based on the volume data (S 3 ). The controller 9 causes the display part 81 to display this MPR image (S 4 ). In some cases, the image data of the MPR image can be directly generated from data obtained by a three-dimensional scan shown in Step S 1 .
In Step S 3 , the MPR images at a plurality of different cross-sectional positions of the heart can be displayed. Additionally, because an apical approach using the three-dimensional ultrasound scan (volume scan) is performed in this usage, it is possible (in principle) to obtain and display the MPR image for an optional cross-sectional position of the heart. This makes it possible to display, for example, the MPR image for a short-axis view of the left ventricle that is optimum for evaluation of heart wall motion at any level (an arbitrary position (depth) in the direction of connecting the apex and base).
In Steps S 3 and S 4 , the MPR processor 52 sequentially generates image data for the MPR image in the specified cross-sectional position, based on the volume data obtained at the specified frame rate, and further, the controller 9 causes the display part 81 to display, at the specified frame rate, the sequentially generated MPR images.
Here, a user specifies a desired cross-sectional position by operating the operation part 82 when needed. The MPR processor 52 generates image data for the MPR image in the cross-sectional position specified by the user, based on the volume data obtained at the specified frame rate. The controller 9 causes the display part 81 to display the sequentially generated MPR images. This makes it possible to display, on the display part 81 , a moving image (specified frame rate) of the MPR image for the heart in the cross-sectional position specified by the user.
FIG. 5 illustrates an example of a display mode of the MPR image in Step S 4 . A plurality of MPR images are displayed on a tomographic image display screen 1000 . Five display ranges 1001 to 1005 are provided in this tomographic image display screen 1000 . An MPR image is displayed on each of the display ranges 1001 to 1005 .
The display ranges 1001 , 1002 and 1003 , which are arranged in the vertical direction of the screen, respectively display moving images G 1 , G 2 and G 3 of the MPR image for a short-axis view of the left ventricle at an apex level, a papillary muscle level and a base level.
Here, the cross-sectional position and the number of the MPR image displayed on the tomographic image display screen 1000 are preferably set so that sites (segments) recommended by ASE (American Society of Echocardiography) are all included. Alternatively, in order to observe the heart in more detail than that, the MPR images in more cross-sectional positions can also be displayed by setting, for example, sixteen cross-sectional positions of the heart.
Additionally, on the tomographic image display screen 1000 , in addition to the above MPR images G 1 to G 3 , moving images G 4 and G 5 of the MPR images of an apical four-chamber view and an apical two-chamber view are respectively displayed in the display ranges 1004 and 1005 .
The user can change each of the cross-sectional positions of the MPR images displayed in each of the display ranges 1001 to 1005 by moving the cross-sectional positions shown in an operation part 1006 of changing the cross-sectional position, which is displayed under the display ranges 1004 and 1005 by means of the operation part 82 . The operation is performed, for example, by dragging a plane in the figure showing the cross-sectional positions to a desired cross-sectional position.
Additionally, the user causes the moving images of the cross-sectional position (in particular, moving images G 1 , G 2 and G 3 of a short-axis view of the left ventricle) in which the heart wall motion can be adequately observed to be displayed by adjusting the manner of placement of the ultrasonic probe 2 on the subject while observing the MPR images displayed on the tomographic image display screen 1000 (S 5 ).
Upon displaying the moving images of the appropriate cross-sectional position, the user performs a predetermined operation for storing the image data with the operation part 82 (S 6 ). Examples of this operation include double-click of a mouse. Once this operation is performed, the controller 9 stores, in the image data memory 7 , the volume data for the specified frame rate that is the basis of the moving images as volume data V 1 for the resting phase (S 7 ).
Instead of storing the volume data V 1 , it is possible to configure so as to store the image data for the moving images G 1 to G 5 of the MPR images, which are respectively displayed in the display ranges 1001 to 1005 . Additionally, it is also possible to configure so as to store both the volume data V 1 and the image data for the moving images G 1 to G 5 .
Furthermore, the controller 9 stores, in the information memory 6 , the cross-sectional-position information D 1 showing the appropriate cross-sectional position in the resting phase (S 8 ). The cross-sectional-position information D 1 includes, for example, the cross-sectional positions of the moving images G 1 to G 5 of the MPR images, which are displayed in the respective display ranges 1001 to 1005 . Each cross-sectional position is shown, for example, in the three-dimensional coordinate system defined in the volume data V 1 . This is the end of the examination in the resting phase.
Subsequently, examination in the stress phase will be performed. For that, the user firstly causes the display part 81 to display a screen that displays the MPR image of the stress phase, such as a tomographic-image-comparing screen 2000 shown in FIG. 6 (S 9 ).
The display ranges 2001 to 2004 are provided in the tomographic-image-comparing screen 2000 . The display ranges 2001 to 2004 display images of two different phases side by side. In FIG. 6, the MPR images of the resting phase are respectively displayed in the display ranges 2001 and 2002 , and the MPR images of the stress phase are respectively displayed in the display ranges 2003 and 2004 .
The controller 9 reads out the volume data V 1 for the resting phase stored in Step S 7 from the image data memory 7 and transmits to the MPR processor 52 . Additionally, the controller 9 transmits, to the MPR processor 52 , the cross-sectional-position information D 1 stored in Step S 8 .
The MPR processor 52 generates image data of the MPR images of the resting phase, based on the volume data V 1 and the cross-sectional-position information D 1 . The controller 9 causes the tomographic-image-comparing screen 2000 to display the MPR images of the resting phase, based on the generated image data (S 10 ).
In the display ranges 2001 and 2002 shown in FIG. 6, the moving images G 4 and G 5 of the MPR image of an apical four-chamber view and an apical two-chamber view are respectively displayed as an example of a display mode. The displayed images are not necessarily moving images but may be still images at a certain phase of a heartbeat.
Additionally, the MPR image based on the volume data V 1 is displayed in the above Step S 10 , but it is not limited to this. For example, in the case of storing the image data for the MPR image in Step S 7 and displaying this MPR image in Step S 10 , it is possible to display, for example, the MPR image at the cross-sectional position specified by the user selectively in the display ranges 2001 and 2002 .
The user applies an ultrasound jelly or the like when needed in order to obtain the images of the heart to which the stress is applied, and places the ultrasonic probe 2 on the body surface located near an apex of the heart for performing the ultrasonic three-dimensional scan (S 11 ).
The results received by the ultrasonic probe 2 are transmitted to the B-mode processor 41 through the transceiver 3 , whereby image data for the tomographic image is generated. Furthermore, the volume data generator 51 generates volume data based on these sets of image data for the tomographic images (S 12 ). Steps S 11 and S 12 are repeated at specified time intervals in the same way as Steps S 1 and S 2 . That enables the volume data to be obtained at specified frame rate.
The MPR processor 52 generates image data for the MPR images (in this case, an apical four-chamber view and an apical two-chamber view) in the cross-sectional positions shown in the cross-section information D 1 , based on the volume data and the cross-sectional-position information D 1 (S 13 ). The controller 9 causes the tomographic-image-comparing screen 2000 to display the MPR images of the apical four-chamber view and the apical two-chamber view (S 14 ).
Consequently, as illustrated in FIG. 6, in the display ranges 2003 and 2004 of the tomographic-image-comparing screen 2000 , moving images G 4 ′ and G 5 ′ for the MPR images of the apical four-chamber view and the apical two-chamber view in the stress phase are displayed at real time at the specified frame rate. The MPR images G 4 ′ and G 5 ′ respectively have cross-sectional positions matched with the cross-sectional positions of the MPR images G 4 and G 5 for the resting phase.
In FIG. 6, the display range 2001 and the display range 2003 are placed side by side, and the display range 2002 and the display range 2004 are placed side by side.
The display range 2001 displays the MPR image (moving image) G 4 of the apical four-chamber view in the resting phase, and the display range 2003 displays the MPR image (moving image) G 4 ′ of the apical four-chamber view in the stress phase. That enables the user to easily perform a comparative observation of the MPR images G 4 and G 4 ′ of the apical four-chamber view, which are obtained in different phases.
Further, the display range 2002 displays the MPR image (moving image) G 5 of the apical two-chamber view in the resting phase, and the display range 2004 displays the MPR image (moving image) G 5 ′ of the apical two-chamber view in the stress phase. That enables the user to easily perform a comparative observation of the MPR images G 5 and G 5 ′ of the apical two-chamber view, which are obtained in different phases.
Here, the user adjusts the manner of placement of the ultrasonic probe 2 on the subject as needed so that the cross-sectional position of the MPR image G 4 ′ of the apical four-chamber view coincides with the cross-sectional position of the MPR image G 4 of the apical four-chamber view (or so that the cross-sectional position of the MPR image G 5 ′ of the apical two-chamber view coincides with the cross-sectional position of the MPR image G 5 of the apical two-chamber view). In other words, the user adjusts the manner of placement of the ultrasonic probe 2 so that the MPR images having (almost) the same cross-sectional position can be displayed in the display range 2001 and 2003 , while comparative observation the images displayed in the display ranges 2001 and 2003 (S 15 ).
As described above, once one cross-sectional position is matched, other cross-sectional positions (an apical two-chamber view, and a short-axis view of the left ventricle at an apex level, at a papillary muscle level, and at a base level) are also matched. It is necessary at this moment to keep the positional relation between two cross sections not to change.
Once the cross-sectional position of the MPR image G 4 ′ in the stress phase, which is real-time displayed, matches the cross-sectional position of the MPR image G 4 in the resting phase, the user performs an operation of requesting storage of the image data (S 16 ). Once this operation is performed, the controller 9 stores, in the image data memory 7 , volume data V 2 in the stress phase that is real-time generated at the specified frame rate (S 17 ).
Here, instead of storing the volume data V 2 , it is possible to configure so as to display the image data of the moving images G 4 ′ and G 5 ′ of the MPR images, which are respectively displayed in the display ranges 2003 and 2004 . Additionally, it is also possible to configure so as to store both the volume data V 2 and the image data of the moving images G 4 ′ and G 5 ′.
Additionally, the controller 9 stores, in the information memory 6 , cross-sectional-position information D 2 showing the cross-sectional position of the MPR image in the stress phase (S 18 ). The cross-sectional-position information D 2 includes, for example, the cross-sectional positions of the moving images G 4 ′ and G 5 ′ of the MPR images, which are displayed in the display ranges 2003 and 2004 . This cross-sectional position is shown, for example, in the three-dimensional coordinate system defined in the volume data V 2 .
If there is a next phase (e.g., higher-stress phase) (S 19 ; Y), the above steps S 11 to S 18 will be repeated. In this next phase, the MPR image for a phase (e.g., the previous phase) other than the resting phase can be displayed with the MPR image for the next stress phase. After observation for all phases are completed (S 19 ; N), the examination in the stress phase ends.
The number of examinations in the stress phase is accordingly determined depending on the stress amount and the clinical condition of the biological tissue intended for observation, etc. Additionally, the number of examinations in the stress phase can also be determined beforehand, or accordingly determined depending on the intermediate examination results and the like.
In the stress phase examination as described above, the cross-sectional positions for the MPR images of the apical four-chamber view or the apical two-chamber view are matched in the different phases by referring to the tomographic-image-comparing screen 2000 . However, other MPR images, such as the MPR image of a short-axis view of the left ventricle can also be used for matching the cross-sectional positions.
FIG. 7 is an example of a tomographic-image-comparing screen 3000 for comparative observation of the MPR images of a short-axis view of the left ventricle. The tomographic-image-comparing screen 3000 includes display ranges 3001 to 3006 , which display the MPR images.
The display ranges 3001 and 3004 , which are placed side by side, respectively display the MPR images G 1 and G 1 ′ of the short-axis view of the left ventricle at an apex level in the resting phase and in the stress phase. That enables the user to easily perform a comparative observation of the MPR images G 1 and G 1 ′ of the short-axis view of the left ventricle at an apex level in the resting phase and in the stress phase. The MPR image G 1 ′ in the stress phase is generated from the volume data V 2 based on the cross-sectional-position information D 1 . That results in that the MPR image G 1 ′ is an image for the cross-sectional position that matches the one of the MPR image G 1 in the resting phase (the following are the same as above).
Similarly, the display ranges 3002 and 3005 respectively display the MPR images G 2 and G 2 ′ for the short-axis view of the left ventricle at a papillary muscle level in the resting phase and in the stress phase. Additionally, the display ranges 3003 and 3006 respectively display the MPR images G 3 and G 3 ′ for the short-axis view of the left ventricle at a base level in the resting phase and in the stress phase. That enables the user to easily perform a comparative observation of the MPR images G 1 and G 1 ′ respectively for the short-axis view of the left ventricle at a papillary muscle level and at a base level in the resting phase and in the stress phase.
As in Step S 15 , the user can ad just the manner of placement of the ultrasonic probe 2 on the subject as needed so that the cross-sectional position of the MPR image G 1 ′ at an apex level is the same as the MPR image G 1 (or so that the cross-sectional position of the MPR image G 2 ′ or G 3 ′ at a papillary muscle level or at a base level is the same as the MPR image G 2 or G 3 ).
Additionally, phase switching operation parts 3010 and 3020 are provided in the tomographic-image-comparing screen 3000 . The phase switching operation parts 3010 and 3020 are operated for displaying the MPR images obtained in different phases. Examples of the stress phase include no stress (resting phase; the condition in which stress such as a drug is not applied), low stress (low dose; the condition in which stress such as a drug is low), and high stress (high dose; the condition in which stress such as a drug is high).
In the display condition shown in FIG. 7, once the user operates the phase switching operation part 3010 (clicks one of right and left direction arrows by mouse), the images displayed in the display ranges 3001 , 3002 and 3003 are respectively switched from the MPR images G 1 , G 2 and G 3 in the resting phase into, for example, the MPR images G 1 ′, G 2 ′ and G 3 ′ for the low stress condition. This switching process of the display image is performed by the controller 9 having received a signal from the user interface 8 (the following are the same as above).
Additionally, in the display condition shown in FIG. 7, once the user operates the phase switching operation part 3020 (clicks one of right and left direction arrows with mouse), the images displayed in the display ranges 3004 , 3005 and 3006 are respectively switched from the MPR images G 1 ′, G 2 ′ and G 3 ′ in the low stress condition into, for example, the MPR images G 1 ″, G 2 ″ and G 3 ″ (not shown) in the high stress condition.
In a case where the images of the same phase are displayed when the phase switching operation part 3010 or 3020 is operated and the displayed images are switched, images of different phases may be displayed by automatically switching the images displayed in the other side of the display range.
Actions and advantageous effects of the ultrasound diagnostic apparatus 1 are described. When obtaining the image data for the tomographic image (MPR image) of biological tissue such as a heart, the ultrasound diagnostic apparatus 1 stores, in the information memory 6 , the cross-sectional-position information D (D 1 ) showing the cross-sectional position of that tomographic image. Additionally, when obtaining the image data for a new tomographic image of the biological tissue, the ultrasound diagnostic apparatus 1 obtains the image data for new tomographic image corresponding to the cross-sectional position shown in the cross-section location information D of the image data for the tomographic image having been obtained in the past and then displays this new tomographic image and the past tomographic image side by side.
In particular, in a case in which a stress echocardiography is performed by obtaining volume data from the three-dimensional ultrasonic scan, the ultrasound diagnostic apparatus 1 operates, based on the cross-sectional-position information D for the MPR image stored by the examination in the past phase, to display at real time the MPR image for the cross-section corresponding to the MPR image for this past phase.
According to the ultrasound diagnostic apparatus 1 , in the examination for observing the time-elapsed changes in biological tissue, it is possible to automatically obtain the tomographic image for the cross-sectional position corresponding to the tomographic image observed in the past examination, and therefore easily obtain the tomographic images in the same cross-sectional position of the biological tissue. Examples of such examination include a stress echocardiography, an observation of the clinical course, a pre-treatment/post-treatment observation (periodical medical examination such as a prognostic follow-up), and a preoperative/postoperative observation.
Additionally, according to the ultrasound diagnostic apparatus 1 , the tomographic image obtained in the past examination can be placed side by side with the tomographic image obtained in new examination in a condition in which the mutual cross-sectional positions are matched, which makes it possible to comparatively observe these images easily.
Additionally, the user can match the cross-sectional position of the new tomographic image with the cross-sectional position of the past tomographic image by simply adjusting the manner of placement of the ultrasonic probe 2 as needed. This makes it possible to easily perform an examination such as a stress echocardiography examination for observing the time-elapsed changes in biological tissue. It is also possible to shorten the examination time.
Furthermore, according to the ultrasound diagnostic apparatus 1 , a plurality of pairs of the past tomographic image and the new tomographic image, which are matched with the cross-sectional position, can be simultaneously displayed as shown in FIG. 6 and FIG. 7. That enables the user to perform a comprehensive diagnosis, while comparative observation of the images of various cross-sectional positions of the biological tissues.
It is possible to modify the ultrasound diagnostic apparatus 1 as described below.
In the above embodiment, the usage for the case of obtaining a new image at real time has been described, but it is not limited to this. For example, the present invention can also be applied to a case of comparative observation (review) of the images obtained at a plurality of different dates in the past (timing that is different in date or time).
In the case of comparison of the images obtained at two different dates, the image obtained at the earlier date may be referred to as a “past” image, where as the image obtained at the later date may be referred to as a “new” image.
Now, a review of the examination for observing the time-elapsed changes in biological tissue, such as stress echocardiography, is performed using, for example, a tomographic-image-comparing screen 4000 shown in FIG. 8. The tomographic-image-comparing screen 4000 includes display ranges 4001 to 4006 as in the case of the tomographic-image-comparing screen 3000 of FIG. 7. Additionally, the tomographic-image-comparing screen 4000 includes phase switching operation parts 4010 and 4020 , which are similar to those in FIG. 7.
The display ranges 4001 and 4004 respectively display the MPR images G 1 and G 1 ′ of a short-axis view of the left ventricle at an apex level in the resting phase and in the stress phase. The MPR images G 1 and G 1 ′ are mutually matched in cross-sectional position, for example, in the same way as shown in Step S 15 of FIG. 4.
Additionally, the display ranges 4002 and 4005 respectively display the MPR images G 2 and G 2 ′ for a short-axis view of the left ventricle at a papillary muscle level in the resting phase and in the stress phase. The MPR images G 2 and G 2 ′ are also mutually matched in the cross-sectional position.
The display ranges 4003 and 4006 respectively display the MPR images G 3 and G 3 ′ for a short-axis view of the left ventricle at a base level in the resting phase and the stress phase. The MPR images G 3 and G 3 ′ are also mutually matched in cross-sectional position.
In a case in which the volume data for each MPR image is stored, the user can adjust the cross-sectional position for the MPR image as needed. This adjustment operation is performed, for example, by specifying the MPR image intended for changing the cross-section through a click using a mouse, and further by dragging an operation part 4030 for changing cross-sectional position.
Additionally, in a case where the volume data for each MPR image is stored, once a pair of MPR images (e.g., MPR images G 1 and G 1 ′) intended for a comparative observation are specified, and the operation part 4030 for changing cross-sectional position is operated, it is possible to change the cross-sectional positions of this pair of MPR images at one time.
This case will be described more specifically. For example, when the MPR images G 1 and G 1 ′ are specified, and a new cross-sectional position is set by the cross-sectional-position change operation part 4030 , the controller 9 transmits the content of the setting of the new cross-sectional position to the MPR processor 52 . This content of the setting is information shown in a three-dimensional coordinate system defined in the volume data V 1 and V 2 . Additionally, the controller 9 reads out the volume data V 1 and V 2 from the memory 7 , and transmits them to the MPR processor 52 . The MPR processor 52 generates image data for the MPR image of the new cross-sectional position, based on the volume data V 1 . Additionally, the MPR processor 52 generates image data for the MPR image of the new cross-sectional position, based on the volume data V 2 . The controller 9 causes the display range 4001 to display the MPR image for the new cross-sectional position in the resting phase, as well as causes the display range 4002 to display the MPR image for the new cross-sectional position in the stress phase, based on the image data generated from the MPR processor 52 .
In this modification example, the MPR images in two different phases are displayed side by side, but it is also possible to display side by side the MPR images in three or more phases. In this case, it is possible to configure so that such one-time change for the cross-sectional position is performed at one time for the MPR images in all phases (a group of three or more MPR images intended for the comparison).
By enabling this one-time change of the cross-sectional position, the need for individually setting the desired cross-sectional position for each phase is eliminated, and therefore, it becomes possible to efficiently perform the reviewing operation in a shorter time.
Additionally, a polar map (may be referred to as a bull's eye) 4040 is displayed on the tomographic-image-comparing screen 4000 . The polar map 4040 , in which a three-dimensional heart is projected on a two-dimensional image, quantifies the motion state of a partial region of the heart, and represents the result of the quantification using a color distribution or numerical value. To quantify the motion state, it is possible to employ speckle tracking using MPR two-dimensional images or three-dimensional images.
Examples of the motion state of biological tissue (heart) represented by the polar map 4040 include displacement of the heart wall and displacement velocity, torsional motion and torsional motion velocity, shortening and shortening velocity, and strain of motion of the heart wall and strain rate, and relative rotation gradient.
The polar map 4040 represents, for example, the difference in numerical values showing the motion state for each partial region with respect to the MPR images of the two phases (in which the cross-sectional positions are matched) displayed on the tomographic-image-comparing screen 4000 .
A polar map 4040 displayed based on the MPR image G 1 and G 1 ′ will be described hereunder. The controller 9 quantifies the motion state for each partial region of each of the MPR images G 1 and G 1 ′ by using the same method as the conventional one. Here, each partial region is shown in a three-dimensional coordinate system defined in the volume data V 1 and V 2 . Additionally, the controller 9 , for example, subtracts the numerical value of MPR image G 1 from the numerical value of MPR image G 1 ′ with respect to each partial region. Then, the controller 9 displays the polar map 4040 in which this difference is represented by a color or a numerical value.
By using this polar map 4040 , it is possible to quantitatively evaluate the changes in motion state of the cross-sectional position in different phases. This makes it possible to improve the reliability and effectiveness of diagnosis.
It may also be possible to quantitatively evaluate changes in motion state of the biological tissue by applying other methods. Examples of these methods include TDI (Tissue Doppler Imaging). TDI measures and two-dimensionally displays, in a color format, the velocity of motion exercised by a comparatively faster-moving biological tissue such as a heart wall.
According to the modification example described above, it is possible to automatically display side by side, the tomographic images in the same cross-sectional position, which have been obtained at different dates. This makes it possible to easily perform a comparative observation of the images in a review of the examination for observing the time-elapsed changes in biological tissue.
Because stress echocardiography examination for the heart is to observe how the motion of the cardiac muscle has changed according to the presence and amount of stress, the time-elapsed comparisons (comparison between phases) for the same cross-section of the heart is critical.
In the above embodiment, the case of real-time observation during three-dimensional scanning of the biological tissue with ultrasound has been described, but the present invention can also be applied to observation of biological tissue (heart) via an ECG-gated scan.
FIG. 9 illustrates a configuration example of an ultrasound diagnostic apparatus used for observation of biological tissue by ECG-gated scan. An ultrasound diagnostic apparatus 10 has a configuration in which an electrocardiograph 11 is added to the abovementioned ultrasound diagnostic apparatus 1 .
The electrocardiograph 11 is a device for generating an electrocardiogram (ECG) that records the time-elapsed changes in electrical activities of the heart. The electrocardiogram provides information showing the time-elapsed changes in electrical activities of the heart. The electrocardiograph 11 has a plurality of electrodes attached to the body surface of the subject in the same manner as conventionally conducted. Further, the electrocardiograph 11 has a circuit for generating the electrocardiogram based on the time-elapsed changes in potential difference detected by the plurality of electrodes. The electrocardiogram generated by the electrocardiograph 11 is displayed on the display part 81 by the controller 9 . The electrocardiograph 11 functions as one example of an “electrocardiogram generator” in the present invention.
Additionally, the controller 9 obtains a period T of the electrocardiogram inputted from the electrocardiograph 11 . The period T is obtained by detecting the interval between an R wave and an adjacent R wave (R-R interval), for example. Furthermore, the controller 9 transmits, to the transceiver 3 , a control signal according to the period T of the electrocardiogram.
The transceiver 3 drives the ultrasonic probe 2 based on this control signal to transmit the ultrasound. The ultrasonic probe 2 transmits the ultrasound while scanning in a circulative manner a plurality of partial regions of the heart at every period T of the electrocardiogram.
For example, in a case where the heart is divided into a number k of the partial regions Q 1 to Qk (i=1 to k representing the order of scanning), the ultrasonic probe 2 operates so as to scan the partial region Q 1 during the first one period T, scan the partial region Q 2 during the next one period T . . . and, in this way, scan the last partial region Qk, and further, scan the first partial region Q 1 during the next one period T.
The result of reception of the reflected ultrasonic waves sequentially received by the ultrasonic probe 2 is transmitted to the B-mode processor 41 through the transceiver 3 . The B-mode processor 41 generates image data for the tomographic images based on the sequentially inputted reception results, and inputs them in the volume data generator 51 .
The volume data generator 51 sequentially generates the volume data Wi for each partial region Qi, based on the image d at a for the sequentially input tomographic images. Each volume data Wi is stored in the image data memory 7 by the controller 9 (refer to FIG. 9).
Furthermore, the MPR processor 52 sequentially generates image data for the MPR images of the partial regions Qi, based on the plurality of sets of volume data Wi. The cross-sectional position for this MPR image is set by, for example, a user. The cross-sectional position may be automatically set based on cross-sectional-position information E (described later).
The controller 9 causes the display part 81 to sequentially display the MPR images corresponding to the partial regions Q 1 to Qk, based on the image data sequentially generated by the MPR processor 52 . At this moment, the controller 9 causes the MPR images corresponding to the partial regions Q 1 to Qk to be sequentially displayed in synchronization with, for example, the period T of the electrocardiogram.
An example of the display mode of the MPR image in a case where the heart is divided into four partial regions Q 1 to Q 4 will be described with reference to FIG. 10. The display range Q of the ultrasonic image (MPR image in a specified cross-sectional position) is divided into the display ranges Q 1 ′ to Q 4 ′, which correspond to the four partial regions Q 1 to Q 4 .
The controller 9 causes the display range Q 1 ′ to display the MPR image based on the volume data W 1 corresponding to the partial region Q 1 . When the next one period T is passed and the image data of the MPR image based on the volume data W 2 corresponding to the partial region Q 2 is generated, the controller 9 causes the display range Q 2 ′ to display this MPR image. When the next one period T is passed and the image data of the MPR image based on the volume data W 3 corresponding to the partial region Q 3 is generated, the controller 9 causes the display range Q 3 ′ to display this MPR image. When the next one period T is passed and the image data of the MPR image based on the volume data W 4 corresponding to the partial region Q 4 is generated, the controller 9 causes the display range Q 4 ′ to display this MPR image.
When the period T is passed once again and the image data of the MPR image based on the volume data W 1 corresponding to the partial region Q 1 is generated, the controller 9 causes the display range Q 1 ′ to display a new MPR image of the partial region Q 1 .
Thus, the controller 9 updates, in the circulative manner, the MPR images of the partial regions Q 1 to Q 4 , which are displayed in the display ranges Q 1 ′ to Q 4 ′, at every one period T.
Another display mode will be described hereunder. In this display mode, displayed MPR images are updated every time interval (k×period T) according to the number k of the partial regions Qi. It will be described in detail with reference to the FIG. 10. The controller 9 updates, every four periods (=4T), all of the MPR images of the partial regions Q 1 to Q 4 , which are generated every one period T.
This display mode will be described in more detail. As described above, four new MPR images corresponding to the partial regions Q 1 to Q 4 are generated at every four periods. For the four new images, the controller 9 causes the MPR images of the partial region Q 1 , the partial region Q 2 , the partial region Q 3 and the partial region Q 4 to be displayed at one time in the display range Q 1 ′, the display range Q 2 ′, the display range Q 3 ′ and the display range Q 4 ′, respectively. That enables four display images to be updated at every four periods.
In the case of imaging with ECG-gated scan, it is possible to employ a display mode other than described above.
Based on the above preparations, a process according to the present invention will be described As illustrated in FIG. 9, the ultrasound diagnostic apparatus 10 stores the cross-sectional-position information E showing the cross-sectional position of the MPR image obtained in the past. Additionally, the ultrasound diagnostic apparatus 10 stores the volume data W having been the basis of this MPR image. The volume data W includes the number k of volume data corresponding to the partial regions Q 1 to Qk of the heart.
As in the above embodiment, it is possible to store the image data of the MPR image based on the volume data W instead of storing the volume data W, or it is possible to store the image data of the MPR image based on the volume data W together with the volume data W.
In a case where a new ultrasonic image of the relevant heart is obtained using the ECG-gated scan method, the controller 9 sets a partial region of the heart intended for this-time examination, based on division information showing a division mode of the heart. The division information is stored, for example, in the information memory 6 .
The division information may include, for example, information on the number k of partial regions, or information on the range for each partial region (e.g., a range for the ultrasonic scan, and a range for display of an image). The controller 9 sets the partial region for the heart, based on the division information. Additionally, the controller 9 sets a process of generating the image data by the volume data generator 51 and the MPR processor 52 , based on the division information. Additionally, the controller 9 sets the number of the display ranges for displaying the MPR images, based on the division information. A description will be made below assuming the number k of the partial regions is 4.
The controller 9 transmits the cross-sectional-position information E stored in the information memory 6 to the MPR processor 52 . Then, the MPR processor 52 generates image data for the MPR image in the cross-sectional position shown in the cross-sectional-position information E.
The display part 81 displays a cross-sectional image-comparing screen that is the same as in FIG. 7, for example. This cross-sectional-image-comparing screen is provided with display ranges Q′ and R′ (not shown), which are the same as in FIG. 10. The display range Q′ displays the past MPR image. The display mode thereof is, for example, the abovementioned one-time update performed at every four period. Meanwhile, the display range R′ displays the MPR image obtained by this-time examination in the same display mode (describe later).
Here, the past examination is assumed to be an examination in the resting phase for stress echocardiography, and this-time examination is assumed to be an examination in the stress phase. Accordingly, it is general that the period T′ of the electrocardiogram for this-time examination is shorter than the period T for the examination in the resting phase or less stress phase (T′<T).
The controller 9 detects the period T′ based on the electrocardiogram inputted from the electrocardiograph 11 . The ultrasound diagnostic apparatus 10 performs processes of generating the volume data and generating the image data for the MPR image, in synchronization with the period T′. At this time, a new MPR image is generated so as to match with the cross-sectional position shown in the cross-sectional-position information E for the past examination.
The controller 9 updates, at one time, the MPR images to be displayed in the display range R′ at every four periods (=4T′). At this time, the controller 9 also updates, at one time, the past MPR images in synchronization with the four periods (=4T′) (in other words, one-time updates at every four periods (=4T′)). Thus, both the past MPR images and the new MPR images are displayed in synchronization with the period T′ (period: display update interval=1:4).
It should be noted that the di splay mode for the past MPR images and the new MPR images is not limited to the above. As an example thereof, in consideration with T′<T, display of the image range according to the ratio between the period T and the period T′, can be omitted out of all the past MPR images. For example, in the case of T′: T=1:2, the images corresponding to scan performed during the first half period T/2 are displayed in a circulative manner, in synchronization with the period T′. At this time, the range for the scan performed during each period of T and T′ is the same, but the number of obtained volume data is different.
According to this modification example, it is possible to automatically obtain the tomographic image for the cross-sectional position so as to match with the tomographic image observed in the past examination, in the examination conducted for observing the time-elapsed changes in biological tissue by the ECG-gated scan method. Therefore, it is possible to easily obtain the tomographic image for the same cross-sectional position of this biological tissue.
Additionally, since the tomographic image obtained in the past examination and the tomographic image obtained in the new examination, can be displayed side-by-side, these images can be easily compared. In particular, both the tomographic images are displayed in synchronization with the period of the electrocardiograph, whereby it is possible to easily understand the condition of the heart in a desired phase of the heartbeat.
Additionally, the user can match the cross-sectional position of the new tomographic image with the cross-sectional position of the past tomographic image by simply adjusting the manner of placement of the ultrasonic probe 2 as needed. This makes it possible to easily perform an examination for observing the time-elapsed changes in biological tissue. It is also possible to shorten the examination time.
Furthermore, according to this modification example, it is possible to simultaneously display a plurality of pairs of the past tomographic image and the new tomographic image, whose cross-sectional positions are matched with each other. That enables the user to perform a comprehensive diagnosis, while comparative observation of the images of various cross-sectional positions of the biological tissues.
The ultrasound diagnostic apparatus according to this modification example functions so as to, when a imaging mode is changed, obtain the cross-section image for the cross-sectional position in accordance with the new imaging mode.
Here, an imaging mode means a type of imaging that is set beforehand according to the difference in the biological tissues intended for observation and the difference in the imaging methods. Examples of the imaging mode include a “stress echo mode” for performing a stress echocardiography examination of the heart, an “abdomen mode” for observing the inside condition of the abdomen, and a “fetus mode” for observing the condition of the fetus. The imaging mode may be called “protocol,” since each mode is provided with a program (protocol) to be used.
By setting the imaging mode, the ultrasound diagnostic apparatus scans the ultrasound in the mode that is suitable for the object intended for observation and the imaging method (a program used for scanning control). Additionally, the ultrasound diagnostic apparatus performs a process of generating the image data in the mode that is suitable for the object intended for observation and so on.
In order to set the imaging mode, the user interface 8 is used. For that, the controller 9 , for example, causes the display part 81 to display the screen for setting the imaging mode. The user refers to this screen and specifies a desired imaging mode using the operation part 82 . The controller 9 sets each part in the apparatus to the condition according to the specified imaging mode.
An example of a process according to this embodiment will be described hereunder. In this example, the case of performing an examination in the resting phase for stress echocardiography, subsequently performing an examination for an abdomen and then back to performing an examination in the stress phase for stress echo cardiography will be described hereunder.
In stress echocardiography using, for example, the drug stress, such examination flow is employed for the case of performing another examination (in this case, the examination for an abdomen) during the period until the drug starts working.
First, the cross-sectional-position information D showing the cross-sectional position of the MPR image obtained by the examination in the resting phase is stored in the information memory 6 . Additionally, volume data V 1 obtained in this examination (and/or the image data for the MPR image) is stored in the image data memory 7 (refer to FIG. 1).
Once the examination for the resting phase is completed, the user changes the imaging mode into the abdomen mode by using the user interface 8 . Then, the user applies the ultrasound jelly to the abdomen of the subject and placing the ultrasonic probe 2 on the abdomen, thereby performing the examination.
Once the examination for the abdomen is completed, the user puts the imaging mode back to the stress echo mode by using the user interface 8 , and starts the examination for the stress phase. The controller 9 causes the display part 81 (display ranges 3001 to 3003 of the tomographic-image-comparing screen 3000 ) to display the MPR images obtained in the stress phase.
The controller 9 transmits the cross-sectional-position information D in the examination for the resting phase to the MPR processor 52 . Thus, the MPR images of the stress phase having the cross-sectional position matched with those of the MPR images of the resting phases are generated based on the reception results obtained in the 3-dimensional ultrasonic scan by the ultrasonic probe 2 , and are displayed respectively in the display ranges 3004 to 3006 of the tomographic-image-comparing screen 3000 .
The user matches the cross-sectional position of the MPR image for the stress phase, which is displayed in real-time, with the cross-sectional position of the MPR image for the resting phase, by adjusting the manner of placement of the ultrasonic probe 2 as needed. Once the cross-sectional positions are matched, the user performs the specified operation, and stores volume data V 2 (and/or the image data for the MPR image) for the stress phase.
According to this modification example, when the imaging mode is changed, the cross-sectional position is automatically set in accordance with the new imaging mode, so that it is possible to easily match the cross-section in an examination after the change. In particular, in the case of performing another examination during an interval period between examinations for observing the time-elapsed changes in biological tissue, it is possible to automatically obtain the tomographic image for the cross-sectional position matched with that of the tomographic image observed before another examination, and therefore, it is possible to easily obtain the tomographic images at the same cross-sectional position.
Additionally, since the tomographic image obtained before the other examination and the tomographic image obtained after the other examination are displayed side-by-side, these images can be easily comparatively observed.
Additionally, the user can match the cross-sectional position of the tomographic image after the other examination with the cross-sectional position of the tomographic image before the other examination by simply adjusting the manner of placement of the ultrasonic probe 2 as needed. This makes it possible to easily perform an examination for observing the time-elapsed changes in biological tissue. It is also possible to shorten the examination time.
This modification example is to perform a process based on Modification Example 3 applying the cross-sectional position according to the change of the imaging mode. In particular, a sub-mode is provided for each phase in the stress echo mode.
Once the drug stress is applied, the size of the heart may become smaller than in the resting phase. In order to deal with such phenomenon, for example, the following configuration can be made. First, it is configured so that a screen for selection of a phase is displayed on the display part 81 and a phase can be specified with the operation part 82 . In particular, it is configured so that the stress phase mode can be specified at the time of shift to the stress phase. In the case of performing the examination for the stress phase in stages (e.g., low stress phase and high stress phase, etc.), it is preferable that each stress phase can be individually specified.
FIGS. 11A and 11B illustrate a change in size of a heart H between the resting phase and the stress phase. Here, the length from an apex to a base is considered as a size of the heart H. The length of the heart H for the resting phase is denoted by L. Additionally, the length of the heart H when the drug stress is applied is denoted by α×L (α<1). The contraction rate α for the heart H is a parameter that is dependent on a phase type and a drug type.
The contraction rate α can be clinically obtained like an average value of the multiple clinical data. The contraction rate α is also obtained from the results of the examination conducted to the relevant subject in the past. The contraction rate a can be obtained by calculating L′/L (=α) in addition to measuring the length L based on the volume data V 1 obtained in the resting phase, and measuring the length L′ based on the volume data V 2 real-time obtained in the resting phase. It is desirable to calculate the contraction rate for each stress phase, in the case of performing the examination for the stress phase in stages.
It is assumed that in the resting phase, a cross-sectional position h 1 for a short-axis view of the left ventricle at an apex level, a cross-sectional position h 2 for a short-axis view of the left ventricle at a papillary muscle level, and a cross-sectional position h 3 for a short-axis view of the left ventricle at a base level are individually set as shown in FIG. 11A. The respective cross-sectional positions h 1 , h 2 and h 3 are represented, for example, in a three-dimensional coordinate system defined in the volume data V 1 . These cross-sectional positions h 1 , h 2 and h 3 are stored as the cross-sectional-position information D 1 in the information memory 6 .
Once the user specifies the stress phase, the controller 9 individually calculates the cross-sectional position h 1 ′ for a short-axis view of the left ventricle at the apex level, the cross-sectional position h 2 ′ for a short-axis view of the left ventricle at the papillary muscle level, and the cross-sectional position h 3 ′ for the short-axis view of the left ventricle at a base level, which are obtained in the stress phase, based on the contraction rate α and the cross-sectional-position information D 1 .
An example of the calculating process for obtaining the cross-sectional positions h 1 ′, h 2 ′ and h 3 ′ will be described hereunder. First, the controller 9 obtains the coordinates (x 0 , y 0 , z 0 ) for the apex for the heart H and the coordinates (x 4 , y 4 , z 4 ) for the base, based on the volume data V 1 for the resting phase. Additionally, a new coordinate axis (heart length coordinate axis) ζ is set in the direction from the apex to the base, based on this xyz coordinate system. Here, the coordinate value of the apex is to be ζ=ζ 0 , and the coordinate value of the base is to be ζ=ζ 4 .
Additionally, it is assumed that coordinate values of intersection points between the cross-sectional positions h 1 , h 2 and h 3 for the MPR images in the resting phase and the heart length coordinate axis ζ are respectively (x 1 , y 1 , z 1 ) (=ζ 1 ), (x 2 , y 2 , z 2 ) (=ζ 2 ), and (x 3 , y 3 , z 3 ) (=ζ 3 ). These piece of coordinate value information are stored as the cross-sectional-position information D 1 for the resting phase. Additionally, the coordinates of the apex for the heart H (x 0 , y 0 , z 0 ) (=ζ 0 ), and the coordinates of the base (x 4 , y 4 , z 4 ) (=ζ 4 ), for the resting phase are also stored as the cross-sectional-position information D 1 .
At the time of shift to the stress phase, the user specifies the stress phase mode using the user interface 8 . Once the volume data V 2 is generated in the stress phase, the controller 9 obtains the coordinates (x 0 ′, y 0 ′, z 0 ′) for the apex of the heart H and the coordinates (x 4 ′, y 4 ′, z 4 ′) for the base, based on the volume data V 2 . Additionally, the controller 9 obtains the coordinate value for these coordinates based on the heart length coordinate axis ζ. At this time, the position of the apex is to be ζ=ζ 0 ′, while the position of the base is to be ζ=ζ 4 ′.
Additionally, the controller 9 obtains the coordinate values for the intersection points (x 1 ′, y 1 ′, z 1 ′) (=ζ 1 ′), (x 2 ′, y 2 ′, z 2 ′) (=ζ 2 ′), and (x 3 ′, y 3 ′, z 3 ′) (=ζ 3 ′), between each of the cross-sectional positions h 1 ′, h 2 ′ and h 3 ′ for the stress phase and the heart length coordinate axis ζ, based on the contraction rate α for the heart H and the coordinate values for the above intersection points in the resting phase (x 1 , y 1 , z 1 ) (=ζ 1 ), (x 2 , y 2 , z 2 ) (=ζ 2 ), and (x 3 , y 3 , z 3 ) (=ζ 3 ). For the contraction rate α, the predetermined value can be used as described above, or it can be obtained at every examination based on the length L and L′ of the heart H for each phase.
An example of a process of obtaining the intersection points will be described hereunder. First, distances Δζ 1 , Δζ 2 and Δζ 3 between the apex position ζ=ζ 0 in the resting phase and each of the intersection points ζ=ζ 1 , ζ 2 and ζ 3 are calculated. Next, the contraction rate α is multiplied to each of the distances Δζ 1 , Δζ 2 and Δζ 3 : Δζ 1 ′=α×Δζ 1 , Δζ 2 ′=α×Δζ 2 , and Δζ 3 ′=α×Δζ 3 .
Subsequently, the coordinates, which are positioned the distance Δζ 1 ′, Δζ 2 ′ and Δζ 3 ′ away from the apex position ζ=ζ 0 ′ are individually calculated for the volume data obtained in the stress phase: ζ 1 ′=ζ 0 +Δζ 1 ′, ζ 2 ′=ζ 0 +Δζ 2 ′, and ζ 3 ′=ζ 0 +Δζ 3 ′ (a direction from the apex to the base is to defined as a + direction for the heart length coordinate axis ζ).
Each of the positions ζ 1 ′, ζ 2 ′ and ζ 3 ′ is converted into a coordinate value shown in the three-dimensional coordinate system defined in the volume data. Thus, the coordinate values (x 1 ′, y 1 ′, z 1 ′), (x 2 ′, y 2 ′, z 2 ′) and (x 3 ′, y 3 ′, z 3 ′) for the intersection points between the cross-sectional positions h 1 ′, h 2 ′ and h 3 ′ for the stress phase, and the heart length coordinate axis ζ, can be obtained.
Each of the cross-sectional positions h 1 ′, h 2 ′ and h 3 ′ is set as a plane of a specified direction, such as a plane orthogonal to the heart length coordinate axis ζ. In other words, a direction of the normal line of the plane that forms the respective cross-section a positions h 1 ′, h 2 ′ and h 3 ′ is predetermined. For example, the normal direction is set to be equal to the direction of the heart length coordinate axis ζ. The controller 9 obtains a plane having the normal line and passing through the coordinate value (x 1 ′, y 1 ′, z 1 ′), and then sets the plane to the cross-sectional position h 1 ′. The same setting can be performed with the cross-sectional positions h 2 ′ and h 3 ′.
The MPR processor 52 generates image data for the MPR image obtained in the cross-sectional positions h 1 ′, h 2 ′ and h 3 ′, based on the volume data obtained in the stress phase. The controller 9 causes the MPR images of the stress phase and the MPR images of the resting phase, to be displayed side-by-side.
According to this modification example, it is possible to efficiently perform an examination in the stress phase for stress echocardiography.
An example of a case of performing further examination after performing two or more examinations in the past will be described hereunder. The information memory 6 stores the cross-sectional-position information obtained in the respective past examinations. The image data memory 7 stores the volume data (and/or the image data for the MPR image) obtained in the respective past examinations. Here, each of the cross-sectional-position information and the volume data are individually associated with the examination date information showing the examination date.
In the case of performing a third-time examination and more, the controller 9 searches the cross-sectional-position information for the previous examination (latest examination performed in the past) based on the examination date information and, based on the cross-sectional-position information, sets the cross-sectional position for this-time examination. The MPR processor 52 generates image data for the MPR image in the relevant cross-sectional position, based on the volume data obtained in the previous examination.
In many cases, in the examination for observing the time-elapsed changes in biological tissue, this-time examination result and the previous examination result are comparatively observed. Therefore, according to this modification example, it is possible to increase the efficiency of such an examination.
Additionally, like the case in which there are two or more stress phases in the above embodiment, if images are obtained at three or more different dates and times, in the case of comparative observation of the images of arbitrary two dates and times, the image obtained at the earlier date, out of these two dates and times is equivalent to a “past” image, while the image obtained at the later date is equivalent to a “new” image.
Additionally, it is also possible to comparatively observe images of three or more dates and times. In that case, the image obtained at the latest date, out of these three or more dates and times is equivalent to a “new” image, while the image obtained at each date before that is equivalent to a “past” image.
It should be noted that simultaneous display of the images obtained at three or more dates and times can be applied to the case of real-time observation of images of the biological tissue, and can also be applied to the case of reviewing the images previously obtained at three or more dates and times.
A second embodiment of an ultrasound diagnostic apparatus according to the present invention will be described hereunder. In the first embodiment described above, the cross-sectional position for the MPR image generated from the volume data is pre-stored, and the relevant cross-sectional position is reproduced in a later examination. Meanwhile, in the second embodiment, a scanning position of ultrasound by an ultrasonic probe is pre-stored, and the ultrasonic scan is controlled so that the relevant scanning position is reproduced in a later examination.
FIG. 12 illustrates an example of an ultrasound diagnostic apparatus according to the second embodiment. An ultrasound diagnostic apparatus 100 has the similar configuration as the ultrasound diagnostic apparatus 1 according to the first embodiment. Below, the similar components as in the first embodiment will be denoted by the same reference numerals.
The information memory 6 stores scanning position information F that shows an ultrasonic scanning position by the ultrasonic probe 2 . Additionally, the image data memory 7 stores image data M such as image data for a tomographic image and volume data.
The ultrasound diagnostic apparatus 100 is configured to perform operations that are characteristic of this embodiment, based on a control program 92 .
The usage of the ultrasound diagnostic apparatus 100 will be described hereunder. A flow chart shown in FIG. 13 illustrates an example of a usage in the case in which the ultrasound diagnostic apparatus 100 is applied to a stress echocardiography examination.
First, an examination in the resting phase is performed. At the start, the ultrasonic scan is performed on the heart using the ultrasonic probe 2 (S 21 ).
Here, a multi-plane scan of scanning each of a plurality of cross-sectional positions is performed. For example, a bi-plane scan of scanning each of two cross-sectional positions, a tri-plane scan of