Patent Application
20120253195
The present invention relates to an ultrasonic diagnostic apparatus, an elastic image storage/reproduction method, and an elastic image storage/reproduction program and in particular, to a technique for improving the usability for an examiner when an elastic image showing the hardness or softness of tissue of a sectional part of an object is stored in a memory and reproduced.
The ultrasonic diagnostic apparatus transmits an ultrasonic wave from an ultrasonic probe into the object, receives from the inside of the object a reflected echo signal of the ultrasonic wave corresponding to the structure of body tissue, forms a tomographic image, for example, a B-mode image, and displays the formed tomographic image for diagnosis.
In recent years, an elastic image showing the hardness or softness of body tissue has been generated by measuring an ultrasonic reception signal (RF signal) while pressing an object with an ultrasonic probe using a manual or mechanical method. That is, displacement of each part of the body occurring due to pressure is calculated on the basis of frame data of two ultrasonic reception signals (RF signal) measured at different times, elastic information such as distortion or an elastic modulus is calculated on the basis of the displacement frame data, and an elastic image is generated and displayed on the basis of the elastic frame data.
For example, as disclosed in PTL 1, an elastic image is displayed by giving color information including red and blue according to distortion or an elastic modulus of body tissue. By displaying mostly the hard part of body tissue, it is possible to easily diagnose the spread or size of a tumor.
On the other hand, for example, as disclosed in PTL 2 and PTL 3, evaluating the display value of an elastic image in terms of whether or not the pressure operation on the object is appropriate using various kinds of data, which are used in the process of measuring the elastic information, and not displaying an elastic image, which does not need to be displayed, are known.
However, it is thought that improving the usability for an examiner when an elastic image is stored in a Cine memory or an external recording medium (hereinafter, these are appropriately referred to collectively as a memory) and is reproduced is not considered.
That is, the ultrasonic diagnostic apparatus can store various images including an elastic image, for example, in a Cine memory provided in the ultrasonic diagnostic apparatus or in an external storage medium, such as a DVD (Digital Versatile Disk), and reproduce and display these images later. The examiner performs diagnosis while reproducing various images stored in the Cine memory in the ultrasonic diagnostic apparatus or while reproducing various images stored in the external storage medium using a PC (Personal Computer), for example.
In this respect, in the above-described Patent Literatures, an elastic image which does not need to be displayed is not displayed when elastic images are displayed in real time. For this reason, storing an elastic image in a memory and reproducing the elastic image are not taken into consideration. Accordingly, even an elastic image which is not effective for diagnosis because the pressure state is not appropriate is stored in a memory and is reproduced. As a result, the efficiency of diagnosis performed by an examiner while observing reproduced elastic images becomes worse or the examiner needs to select an elastic image effective for diagnosis by performing frame feeding or skipping manually when elastic images which are not effective for diagnosis continue. This is not preferable when the usability for the examiner is taken into consideration.
Therefore, it is an object of the present invention to improve the usability for an examiner when an elastic image is stored in a memory and is reproduced.
An ultrasonic diagnostic apparatus of the present invention which solves the above-described problems includes: an ultrasonic probe which transmits and receives an ultrasonic wave to and from an object; a phasing addition means that generates RF signal frame data of a sectional part of the object on the basis of a reflected echo signal measured by the ultrasonic probe; a displacement measurement means that generates displacement frame data by measuring displacement of tissue of the sectional part on the basis of a pair of RF signal frame data items acquired at different times; an elastic information calculation means that generates elastic frame data by calculating elastic information, which indicates hardness or softness of tissue of the sectional part, on the basis of the generated displacement frame data; an elastic image configuration means that generates an elastic image on the basis of the elastic frame data; an image display device which displays the elastic image; and a memory in which the elastic image is stored.
In particular, the ultrasonic diagnostic apparatus includes a pressure evaluating section which evaluates whether or not a pressure state of the object is appropriate on the basis of at least one of the displacement frame data of the tissue of the sectional part, the elastic frame data, and the pressure of the ultrasonic probe on an ultrasonic wave transmission/reception surface. The pressure evaluating section stores an elastic image in an appropriate pressure state in the memory selectively.
According to this, since elastic images generated in a state where the object is appropriately pressed are selectively stored in a memory, an elastic image suitable for diagnosis is selectively reproduced when an examiner performs diagnosis by reproducing the elastic image stored in the memory. Therefore, since time is not taken for frame feeding or skipping when elastic images which are not suitable for diagnosis continue, good usability for the examiner is realized and it is possible to shorten the diagnostic time by improving the diagnostic efficiency.
In addition, the pressure evaluating section may read and reproduce an elastic image in the appropriate pressure state selectively when reproducing elastic images stored in the memory. That is, even if all the elastic images are first stored in a memory and an elastic image in the appropriate pressure state is selectively read and reproduced when elastic images are reproduced instead of selectively storing an elastic image in the appropriate pressure state in the memory, good usability for the examiner is similarly realized. In addition, since the diagnostic efficiency is improved, it is possible to shorten the diagnostic time.
Here, whether or not the pressure state is appropriate is evaluated on the basis of points of view, such as whether or not the amount of pressure on the object or the pressure speed is appropriate, whether pressure is not performed in a state where the ultrasonic probe is inclined in a beam line direction with respect to the body surface of the object (in a biased pressure state), or whether the pressure operation itself is performed.
According to the present invention, it is possible to improve the usability for an examiner when an elastic image is stored in a memory and is reproduced.
Hereinafter, embodiments of an ultrasonic diagnostic apparatus, an elastic image storage/reproduction method, and an elastic image storage/reproduction program to which the present invention is applied will be described. In addition, in the following explanation, the same reference numerals are given to the same functional components, and repeated explanation thereof will be omitted.
In addition, the ultrasonic diagnostic apparatus 100 includes: an RF signal frame data selecting section 28 which selects a pair of RF signal frame data items, which are measured at different times, from the RF signal frame data output from the phasing addition section 18; a displacement measuring section 30 which measures displacement caused in body tissue of the object 10 on the basis of the pair of RF signal frame data items and generates displacement frame data; an elastic information calculating section 32 which generates elastic frame data by calculating elastic information (distortion or an elastic modulus), which indicates the hardness or softness of body tissue of the object in a continuous pressure process, on the basis of the displacement frame data measured by the displacement measuring section 30; an elastic image configuration section 34 which generates an elastic image from the distortion or the elastic modulus calculated by the elastic information calculating section 32; and a color scan converter 36 which converts an output signal of the elastic image configuration section 34 so as to fit the display of the image display device 26.
In addition, the ultrasonic diagnostic apparatus 100 includes: a pressure measuring section 46, such as a pressure sensor, which measures the pressure of the ultrasonic probe 12 on the ultrasonic wave transmission/reception surface; a Cine memory 48 in which the elastic image generated by the elastic image configuration section 34 is stored and which is provided in the ultrasonic diagnostic apparatus; a recording medium 50, such as a DVD, in which the elastic image generated by the elastic image configuration section 34 is stored; and a pressure evaluating section 52 which evaluates whether or not the pressure state of the object 10 is appropriate on the basis of at least one of the displacement frame data generated by the displacement measuring section 30, the elastic frame data generated by the elastic information calculating section 32, and the pressure measured by the pressure measuring section 46 and which is a characteristic configuration of the present embodiment. Details of the pressure evaluating section 52 will be described later. In addition, in this specification, the Cine memory 48 and the recording medium 50, such as a VCR or a DVD, are collectively called a memory. Accordingly, memory simply referred to in this specification includes at least one the Cine memory 48 and the recording medium 50, such as a VCR or a DVD.
In addition, the ultrasonic diagnostic apparatus 100 includes a controller 54 which controls each of the constituent components described above, for example, a CPU (Central Processing Unit) and an interface section 56, such as a mouse, a keyboard, a touch panel, or a track ball, which gives an instruction to control a tint or an ROI (Region Of Interest) of an elastic image, a frame rate, and the like.
The ultrasonic probe 12 is formed by arraying plural transducers, and has a function of performing beam scanning electronically to transmit and receive an ultrasonic wave to and from the object 10 through the transducers. The signal transmitting section 14 has a function of generating a transmission wave pulse for generating an ultrasonic wave by driving the ultrasonic probe 12 and setting the convergent point of transmitted ultrasonic waves at a certain depth. In addition, the signal receiving section 16 generates an RF signal, that is, a reception wave signal by amplifying the reflected echo signal received by the ultrasonic probe 12 with a predetermined gain. The phasing addition section 18 controls the phase of the input RF signal amplified by the signal receiving section 16, and generates RF signal frame data by forming ultrasonic beams converged at plural convergent points.
The tomographic image configuration section 20 generates a gray-scale tomographic image of the object, for example, a monochrome tomographic image of the object on the basis of the RF signal frame data from the phasing addition section 18. The monochrome scan converter 22 acquires the tomographic frame data in the object 10, which is stored in a frame memory, as one image and reads the acquired tomographic frame data in synchronization with a television.
The monochrome scan converter 22 acquires RE signal frame data within the object 10 including moving tissue at periods of ultrasonic waves and converts the frame data into an image and displays it.
The switching addition section 24 is configured to include a frame memory, an image processing section, and an image selecting section. Here, the frame memory stores a tomographic image from the monochrome scan converter 22 and an elastic image from the color scan converter 36. In addition, the image processing section combines the tomographic image and the elastic image, which are secured in the frame memory, at the set ratio according to the command of the controller 54. The brightness information and the color information regarding each pixel of the composite image are acquired by adding the information on the monochrome tomographic image and the information on the color elastic image at the set ratio. In addition, the image selecting section selects an image, which is to be displayed on the image display device 26, from the tomographic image and the elastic image in the frame memory and the composite image of the image processing section according to the command of the controller 54. In addition, the tomographic image and the elastic image may be separately displayed without being combined.
The RF signal frame data selecting section 28 is configured to include a frame memory and a selection section. The RF signal frame data selecting section 28 stores plural RF signal frame data items from the phasing addition section 18 in a frame memory and selects a pair of RF signal frame data items, that is, two items of the RF signal frame data from the stored RF signal frame data group. For example, the RF signal frame data selecting section 28 secures RF signal data generated in time series from the phasing addition section 18, that is, generated on the basis of a frame rate of an image in a frame memory sequentially and selects the currently secured RF signal frame data (N) as first data according to the command from the controller 54 using the selection section and also selects one RF signal frame data item (X) from the RF signal frame data group (N-1, N-2, N-3, N-M) stored in the past. In addition, N, M, and X herein are index numbers given to the RF signal frame data, and are assumed to be natural numbers.
The displacement measuring section 30 calculates the displacement of body tissue and the like from the pair of RF signal frame data items. For example, the displacement measuring section 30 performs one-dimensional or two-dimensional correlation processing on the pair of data items selected by the RF signal frame data selecting section 28, that is, the RF signal frame data (N) and the RF signal frame data (X) to calculate a displacement or movement vector in body tissue corresponding to each point of the tomographic image, that is, one-dimensional or two-dimensional displacement distribution regarding the displacement direction and size. Here, in order to detect the movement vector, a block matching method is used. The block matching method is to perform processing in which an image is divided into blocks with, for example, “N×N” pixels, a block in a region of interest is observed, the most similar block to the observed block is searched for from previous frames, and a sample value is determined by predictive coding, that is, by the difference referring to this.
The elastic information calculating section 32 generates elastic frame data by calculating elastic information (distortion or an elastic modulus), which indicates the hardness or softness of body tissue of the object in a continuous pressure process, on the basis of the displacement frame data measured by the displacement measuring section 30. In this case, distortion data is calculated by spatial differentiation of the amount of movement of body tissue, for example, by spatial differentiation of the displacement. In addition, data of the elastic modulus is calculated by dividing the pressure change by the change in the amount of movement. For example, assuming that the displacement measured by the displacement measuring section 30 is ΔL and the pressure measured by the pressure measuring section 46 is ΔP, distortion (S) can be calculated by spatial differentiation of ΔL. Accordingly, the distortion (S) can be calculated using Expression S=ΔL/ΔX. In addition, Young's modulus m of elastic modulus data is calculated by Expression of m=(ΔP)/(ΔL/L). Since the elastic modulus of body tissue corresponding to each point of a tomographic image is calculated from this Young's modulus m, it is possible to acquire the two-dimensional elastic image data continuously. In addition, Young's modulus is a ratio of simple tensile stress applied to the body to the tensile strain occurring in parallel to the tensile stress.
The elastic image configuration section 34 is configured to include a frame memory and an image processing section. The elastic image configuration section 34 secures elastic frame data, which is output in time series from the elastic information calculating section 32, in a frame memory and performs image processing on the secured elastic frame data using the image processing section.
The color scan converter 36 converts the frame data into color information on the basis of the elastic image data from the elastic image configuration section 34. That is, the color scan converter 36 converts the frame data into three primary colors of light, that is, red (R), green (G), and blue (B) on the basis of the elastic image data. For example, the color scan converter 36 converts the data of an elastic image with large distortion into a red code and also converts the data of an elastic image with small distortion into a blue code. In addition, the gradation of red (R), green (G), and blue (B) is 256 levels, and 255 means displaying with a maximum brightness and 0 means being not displayed on the contrary.
The operation of the ultrasonic diagnostic apparatus 100 configured in this way will be described. In the ultrasonic diagnostic apparatus 100, the signal transmitting section 14 transmits an ultrasonic wave repeatedly to the object 10 at intervals through the ultrasonic probe 12 being in contact with the object 10, the signal receiving section 16 receives time-series reflected echo signals generated from the object 10, and phasing addition is performed on the reflected echo signals to generate RF signal frame data. On the basis of the RF signal frame data, a gray-scale tomographic image, for example, a monochrome B-mode image is acquired by the tomographic image configuration section 20. In this case, when the ultrasonic probe 12 is scanned in a fixed direction, one tomographic image is acquired. On the other hand, an elastic image is acquired by the elastic image configuration section 34 on the basis of the RF signal frame data after performing phasing addition by the phasing addition section 18. Then, a composite image is generated by adding the acquired monochrome tomographic image and the acquired color elastic image by the switching addition section 24.
Meanwhile, in the ultrasonic diagnostic apparatus 100 capable of generating such an elastic image, it is possible to store a tomographic image and an elastic image automatically in the Cine memory 48 in time series or to store a tomographic image and an elastic image in the recording medium 50, such as a DVD, in time series. In addition, it is possible to perform diagnosis while reproducing the tomographic image and the elastic image, which are stored in the Cine memory 48, in the ultrasonic diagnostic apparatus or while reproducing the tomographic image and the elastic image, which are stored in the recording medium 50, using a PC, for example.
Here,
That is, in order to acquire an elastic image which is effective for diagnosis, it is necessary to cause tissue of a sectional part to be properly displaced by pressing the object appropriately on the ultrasonic wave transmission/reception surface of the ultrasonic probe 12, for example. However, an elastic image which is not effective for diagnosis may be generated because pressure is performed in a state where the ultrasonic probe 12 is inclined in a beam line direction with respect to the body surface of the object 10 (in a biased pressure state), in which the amount of the pressure onto the object 10 and the pressure speed are not appropriate, or because the pressure operation itself is not performed, for example. In a conventional ultrasonic diagnostic apparatus, since all generated elastic images are stored in a memory as shown in
As a result, when the efficiency of diagnosis performed by an examiner while observing reproduced elastic images becomes worse or when elastic images which are not effective for diagnosis continue, the examiner needs to select an elastic image effective for diagnosis by performing frame feeding or skipping manually. This is not preferable when the usability for the examiner is taken into consideration.
Therefore, the pressure evaluating section 52 is provided in the ultrasonic diagnostic apparatus of the present embodiment.
First, the pressure evaluating section 52 evaluates whether or not the pressure state of the object 10 is appropriate on the basis of at least one of the displacement frame data and the elastic frame data of the tissue of the sectional part of the object 10 and the pressure measured by the pressure measuring section 46. A specific evaluation method will be described in detail later. Then, as shown in
According to this, since elastic images generated in a state where the object 10 is appropriately pressed are selectively stored in a memory, an elastic image suitable for diagnosis is selectively reproduced when an examiner performs diagnosis by reproducing the elastic image stored in the memory. Therefore, since it does not take time for frame feeding or skipping when elastic images which are not suitable for diagnosis continue, good usability for the examiner is realized and it is possible to shorten the diagnostic time by improving the diagnostic efficiency.
Hereinafter, a specific evaluation method of the pressure evaluating section 52 will be described through each example. In addition, in the following examples, a case where an elastic image in an appropriate pressure state is selectively stored in a memory will be described. However, when reproducing elastic images stored in a memory, an elastic image in an appropriate pressure state may also be selectively read and reproduced. Similarly, in this case, good usability for the examiner is realized and it is possible to shorten the diagnostic time by improving the diagnostic efficiency.
In addition, when the pressure evaluating section 52 stores an elastic image in an appropriate pressure state in a memory selectively or reads and reproduces the elastic image in the appropriate pressure state from the memory selectively, a tomographic image of a frame corresponding to the elastic image in the appropriate pressure state may be similarly stored in the memory or may be similarly read and reproduced from the memory for the tomographic image. In this specification, the “pressure evaluating section 52 stores an elastic image in an appropriate pressure state in a memory selectively or reads and reproduces the elastic image in the appropriate pressure state from the memory selectively” is assumed to include storing not only the elastic image in the appropriate pressure state but also a tomographic image of a frame, which corresponds to the elastic image in the appropriate pressure state, in the memory or reading and reproducing not only the elastic image in the appropriate pressure state but also the tomographic image of the frame from the memory. In the following explanation, a case where a tomographic image and an elastic image in an appropriate pressure state are selectively stored in a memory will be described as an example.
In a first example, it is evaluated that the pressure state is appropriate when at least one of the variance or deviation of displacement of plural measurement points of displacement frame data and the variance or deviation of elastic information of plural measurement points of elastic frame data is smaller than the threshold value set in advance. That is, a fine pressure operation is required in order to acquire an elastic image which is generally effective for diagnosis, and an elastic image which is not suitable for diagnosis is generated if excessive pressure is performed. In this example, therefore, in order to estimate an inappropriate elastic image from a variation in displacement, it is determined whether or not the pressure state is appropriate using statistical features, such as displacement in each frame, distortion, or an elastic modulus, and a tomographic image and an elastic image in the appropriate pressure state are selectively stored and reproduced.
For example, the amount of displacement in a pixel (i, j) (0≦i≦M, 0≦j≦N) of certain displacement frame data output by the displacement measuring section 30 is assumed to be l(i, j). Then, the variance uk of displacement of displacement frame data is expressed as the following Expression 1.
l(i, j)ave is an average of l(i, j) over the entire frame region. When fine pressure is repeated, a displacement change becomes small, and the variance is decreased accordingly. On the contrary, when excessive pressure is performed, the displacement change becomes large, and the variance is increased accordingly. Then, assuming that the threshold value set in advance is uth, the pressure evaluating section 52 stores a tomographic image and an elastic image in the Cine memory 48 or the recording medium 50, such as a DVD, only when uk<uth. The examiner can set an optimal value of Uth through the interface section 56 according to a diagnostic part, for example.
Although the variance is calculated over the entire frame in the above, it is also possible to calculate the variance of displacement of eight points adjacent to the pixel (i, j) as uk(i, j) and to store an elastic image only when ukave, which is an average of uk(i, j) over the entire frame region, becomes smaller than uth, for example. In addition, a tomographic image and an elastic image may also be stored only when the number of pixels satisfying uk(i, j)<uth becomes equal to or larger than a certain rate.
In addition, although the displacement is used as a reference parameter of pressure evaluation in the above, distortion or an elastic modulus of elastic frame data output from the elastic information calculating section 32 maybe used as a reference parameter, and a combination thereof may be used. This is because the distortion or the elastic modulus is calculated using displacement and the elastic frame data reflects a local discreteness of displacement frame data. In addition, it is possible to use not only the variance but also an average value, a deviation, or the like as statistical features.
Next, a second example will be described. A pressure evaluating section in this example evaluates that the pressure state is appropriate when an absolute value of at least one of the average value of displacement of plural measurement points of displacement frame data and the average value of elastic information of plural measurement points of elastic frame data is larger than the threshold value set in advance.
That is,
Therefore, in this example, the pressure state is evaluated using a method described in
In addition, whether to store in the Cine memory 48 an image at tmin or tmax may be arbitrarily selected by external control of an examiner using an input interface, such as a keyboard. Thus, a tomographic image and an elastic image when the amount of pressure becomes a maximum value or a minimum value during the periodic temporal change in the amount of pressure can be selectively stored in the Cine memory 48 or the recording medium 50, such as a DVD. Alternatively, a tomographic image and an elastic image when the absolute value of the amount of pressure is larger than the threshold value set in advance can also be recorded selectively instead of selectively recording a tomographic image and an elastic image at tmax and tmin.
In addition, although the evaluation is performed on the basis of the amount of pressure in the above explanation, a temporal change in pressure data acquired by the pressure measuring section 46 may also be used. That is, it is possible to evaluate that the pressure state is appropriate when the absolute value of the rate of change of the pressure acquired by the pressure measuring section 46 is larger than the threshold value set in advance.
Next, a third example of the present invention will be described. In this example, it is evaluated that the pressure state is appropriate when the variance or deviation of the pressure at plural places including at least both ends of the ultrasonic wave transmission/reception surface of the ultrasonic probe 12 in the beam line direction is smaller than the threshold value set in advance.
That is, in order to acquire an elastic image as described above, it is necessary to press the object 10 with the ultrasonic probe 12. However, a useful elastic image is not acquired if uniform pressure is not performed.
On the other hand,
More specifically, pressure measured by several pressure sensors provided on the surface of the ultrasonic probe 12 in contact with an object can be calculated by the pressure measuring section 46. Pressure acquired in each place is set as p(x, y) (0≦x≦X, 0≦y≦Y). x and y indicate the coordinates of the contact surface between the ultrasonic probe 12 and the object 10. Then, the average value pm and the variance pv (pressure variance) of pressure on the contact surface are acquired by the following Expressions 2 and 3, respectively.
In addition, the standard deviation pa is acquired by the following Expression 4.
pσ=√{square root over (pv)} [Expression 4]
It is thought that the size of pressure changes with a place when the variance and the deviation are large. On the other hand, it is thought that a variation in the size of pressure according to a place is small when the variance and the deviation are small. Accordingly, assuming that the variance as a threshold value set in advance is vth and the standard deviation is ath, the pressure evaluating section 52 stores a tomographic image and an elastic image at the time of pv<vth or pσ<σth selectively in the Cine memory 48 or the recording medium 50, such as a DVD. In addition, it is also possible to use values other than the variance and the deviation as long as they are statistic values through which the pressure distribution of the ultrasonic probe contact surface can be quantitatively evaluated.
In addition, in the above explanation, a pressure variation is detected by the pressure acquired from the pressure measuring section 46. However, it is also possible to use elements other than the pressure as long as they are elements through which being pressed in a state where the ultrasonic probe 12 is inclined can be detected. For example, when the object 10 is pressed in a state where the ultrasonic probe 12 is inclined, displacement on the object 10 becomes non-uniform as shown in
Next, a fourth example will be described. In this example, a correlation between at least one of a graph showing a temporal change in the pressure of the ultrasonic probe 12 on the ultrasonic wave transmission/reception surface, a graph showing a temporal change in the displacement of tissue of a sectional part, and a graph showing a temporal change in the elastic information of tissue of a sectional part and a corresponding one of an optimal pressure graph, an optimal displacement graph, and an optimal elastic information graph, which are set in advance for the graphs, is calculated, and it is evaluated that the pressure state is appropriate when the correlation is larger than the threshold value set in advance.
That is, since it is necessary to perform optimal pressure repeatedly in order to acquire a useful elastic image, the pressure graph 60 in
More specifically, p(tn)×p(tn−1)≦0 is satisfied at a point of the pressure graph crossing p=0 as shown in
Assuming that a correlation between P(t) and P0(t) is Co, Co can be calculated by the following Expression 5.
In addition, Pave and POave are averages of P (t) and P0(t) in a section from L to N, respectively. Only when Co is higher than a reference value Cstd set in advance, the pressure evaluating section 52 stores a tomographic image and an elastic image in the Cine memory 48 or the recording medium 50, such as a DVD. In addition, it is also possible to calculate a correlation between the pressure graph 62 showing a temporal change in pressure of the ultrasonic probe 12 on the ultrasonic wave transmission/reception surface and the optimal pressure graph set in advance and to store a tomographic image and an elastic image in the Cine memory 48 or the recording medium 50, such as a DVD, only when the correlation is larger than the threshold value set in advance.
Next, a fifth example of the present invention will be described. In this example, a correlation between a pair of frames, which are adjacent to each other in time series, of either displacement frame data or elastic frame data is calculated and it is evaluated that the pressure state is appropriate when the correlation is larger than the threshold value set in advance. That is, a correlation between elements of a pair of elastic frame data items adjacent to each other in time series is calculated and a pair of a tomographic image and an elastic image, which are highly correlated, are stored in the Cine memory 48 or the recording medium 50, such as a DVD, as shown in
More specifically, elastic frame data output at time tk, among the elastic frame data output from the elastic information calculating section 32, is set as Frk and each element of the elastic frame data is set as Ek(i, j) (0≦i≦N, 0≦j≦M), as shown in
In addition, Ekave is an average of the element data Ek (i, j) in all items of the elastic frame data Frk. Only when Ck is higher than the reference value Cstd set in advance, Frk and Frk−1 are stored in the Cine memory 48 or the like. In addition, it is also possible to calculate a correlation between a pair of frames, which are adjacent to each other in time series, of the displacement frame data and to store a tomographic image and an elastic image in the Cine memory 48 or the recording medium 50, such as a DVD, only when the correlation is larger than the threshold value set in advance.
In addition, although a correlation between a pair of elastic frame data items adjacent to each other is calculated in the above, an examiner may select a frame, which is considered to be optimal, from the elastic frame data stored in advance in the Cine memory 48 or the recording medium 50, such as a DVD, and a correlation between the selected elastic frame data and elastic frame data acquired in real time may be calculated to evaluate the value of the image.
Alternatively, for example, as shown in
Next, a sixth example will be described. In this example, average displacement frame data or average elastic frame data is calculated by averaging at least either displacement of plural corresponding measurement points of plural displacement frame data items belonging to a predetermined time section or elastic information of plural corresponding measurement points of plural elastic frame data items belonging to a predetermined time section, a correlation between the average displacement frame data or the average elastic frame data and the plural displacement frame data items or the plural elastic frame data items belonging to the predetermined time section is calculated, and it is evaluated that the pressure state is appropriate when the correlation is larger than the threshold value set in advance.
That is, elements of elastic frame data belonging to a certain designated time section are equalized and average elastic frame data 66 having these as elements is generated as shown in
More specifically, as shown in
Then, a correlation CI between Em(i, j) and El(i, j) is calculated by the following Expression 8.
In addition, Elave is an average of the element data El (i, j) in all items of the elastic frame data Frl. Similarly, Emave is an average of the element data Em(i, j) in all items of the elastic frame data Frave. Only when the correlation is higher than the predetermined reference value Cstd, a tomographic image and an elastic image are stored in the Cine memory 48 or the recording medium 50, such as a DVD. In addition, the predetermined reference value Cstd correlated with a certain time section may be arbitrarily selected by external control of an examiner using a keyboard.
Next, a seventh example will be described. In this example, it is evaluated that the pressure state is not appropriate when a state where the pressure of the ultrasonic probe 12 on the ultrasonic wave transmission/reception surface is smaller than the threshold value set in advance continues for a predetermined time or more. In addition, it is evaluated that the pressure state is not appropriate when a state where at least one of the average value of displacement of plural measurement points of displacement frame data and the average value of elastic information of plural measurement points of elastic frame data is smaller than the threshold value set in advance continues for a predetermined time or more.
That is, in the examination process of actual ultrasonic diagnosis, the examiner does other work while continuing ultrasonic imaging even after the diagnosis ends and accordingly, a diagnostic image and an image useless for diagnosis may be stored in the Cine memory 48 or the like. Therefore, in this example, as shown in
More specifically, when diagnosis is not performed, the ultrasonic probe 12 is usually fixed to the holder without being in contact with the object 10. For this reason, the probe surface pressure is equal to 0 and there is no variation either. Accordingly, as an example of a method of detecting a time for which diagnosis is not performed, when the pressure acquired from the pressure measuring section 46 is equal to 0 and there is no change for a predetermined period, the pressure evaluating section 52 sets a pressure determination flag to 0 so that a tomographic image and an elastic image in the predetermined period are not stored in the Cine memory 48 or the recording medium 50, such as a DVD.
Alternatively, as a method of detecting a time for which diagnosis is not performed, it is also possible to use “elastic modulus is 0 for all elements in a frame”, “distortion is 0 for all elements in a frame”, and “displacement is 0 for all elements in a frame”.
Next, an eighth example will be described. In this example, it is evaluated whether or not the pressure state is appropriate using each method described above. Also, only when the ratio of elastic images in the appropriate pressure state to elastic images belonging to a predetermined time section is larger than the threshold value set in advance, the elastic images in the appropriate pressure state are stored in a memory. Alternatively, when reproducing elastic images stored in the memory, the elastic images in the appropriate pressure state are selectively read and reproduced.
That is, when it is determined whether or not the pressure state is appropriate using the method described until now and corresponding images are stored in the Cine memory 48 or the like, continuity between elastic images 68 and 70 stored in the Cine memory 48 or the like may disappear if a frame, in which the pressure state is not appropriate, continues as shown in
In addition, although the ultrasonic diagnostic apparatus and the elastic image storage/reproduction method have been mainly described in the above examples, the present invention is not limited to these. For example, the present invention may also be applied as an elastic image storage/reproduction program which can be installed in an ultrasonic diagnostic apparatus or a computer, such as a PC, and be executed. The elastic image storage/reproduction program is configured to include: evaluating whether or not a pressure state of an object is appropriate on the basis of at least one of displacement frame data of tissue of a sectional part generated on the basis of a pair of RF signal frame data items which are based on reflected echo signals measured in advance by an ultrasonic probe and whose acquisition times are different, elastic frame data indicating the hardness or softness of the tissue of the sectional part generated on the basis of the displacement frame data, and pressure of the ultrasonic probe on the ultrasonic wave transmission/reception surface; and storing an elastic image in the appropriate pressure state in a memory selectively or reading and reproducing an elastic image in the appropriate pressure state selectively when reproducing elastic images stored in the memory.
According to this, since elastic images generated in a state where the object 10 is appropriately pressed are selectively stored in a memory, an elastic image suitable for diagnosis is selectively reproduced when an examiner performs diagnosis by reproducing the elastic image stored in the memory. Alternatively, when reproducing elastic images stored in the memory, an elastic image in the appropriate pressure state is read and reproduced selectively. Therefore, since it does not take time for frame feeding or skipping when elastic images which are not suitable for diagnosis continue, good usability for the examiner is realized and it is possible to shorten the diagnostic time by improving the diagnostic efficiency.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-172747 | Jul 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/062135 | 7/20/2010 | WO | 00 | 1/20/2012 |
