Patent Publication Number: US-2010125199-A1

Title: Ultrasound system and method providing acoustic radiation force impulse imaging with high frame rate

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2008-0114609, filed on Nov. 18, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field of the Invention 
     Embodiments of the present invention relate to an ultrasound system and method, and more particular, to an ultrasound system and method for providing an acoustic radiation force impulse image. 
     2. Description of the Related Art 
     An ultrasound system denotes a system that may emit ultrasound signals from the body surface of a subject to a selected interior portion of the body and provide images associated with blood flow or a section of soft tissue using information associated with reflected ultrasound signals. The ultrasound system is generally small and inexpensive, and also provides a display in real time. In addition, the ultrasound system has no absorbed dose such as with X rays and the like, and thus is highly stable. The ultrasound system is being widely used together with other image diagnostic apparatuses such as an X-ray diagnostic apparatus, a computerized tomography (CT) scanner, a magnetic resonance image (MRI) apparatus, a nuclear medicine diagnostic apparatus, and the like. In particular, the ultrasound system may display an interior body image in real time and thus is being variously used. 
     A human tissue has a characteristic of elasticity among various types of characteristics. The elasticity indicates a transformation level of the tissue with respect to a given unit force. As the elasticity increases, the transformation level may decrease. Conversely, as the elasticity decreases, the transformation level may increase. The elasticity may be a unique characteristic of the tissue. That the elasticity of the tissue has changed may mean that a physical property of the tissue has changed. For example, a cancer tissue generally has the elasticity by three times greater than a normal tissue. Such tissue generation may not be observed using a general ultrasound image. Accordingly, when the elasticity of the tissue is observed using ultrasound, it is possible to discern the cancer tissue from the normal tissue. 
     SUMMARY 
     According to an aspect of the present invention, there is provided an ultrasound method of providing an acoustic radiation force impulse image, the method including: transmitting, to a target tissue, a pushing ultrasound signal for generating of a displacement, using a probe; receiving a response signal from the target tissue in correspondence to a tracking ultrasound signal transmitted via the probe; detecting displacement information associated with the target tissue using the response signal; and generating the acoustic radiation force impulse image based on the displacement information. 
     Here, the transmitting of the pushing ultrasound signal may include simultaneously transmitting the pushing ultrasound signal along a plurality of scan lines that are spaced apart from each other by a predetermined distance. 
     Also, the transmitting of the pushing ultrasound signal may include sequentially transmitting the pushing ultrasound signal with respect to a plurality of focal points along a scan line. Also, a frequency of the pushing ultrasound signal may be variable according to each of the focal points. 
     Also, the pushing ultrasound signal may be transmitted with respect to different focal points for each of the scan lines. Also, a frequency of the pushing ultrasound signal may be variable according to each of the different focal points. 
     Also, the probe may include two-dimensionally arranged transducers and the transducers may be classified into a plurality of sections. While the pushing ultrasound signal is being transmitted using a transducer included in a first section among the plurality of sections, the tracking ultrasound signal may be transmitted using a transducer included in a second section among the plurality of sections. 
     Also, the method may further include transmitting a control command to a cooling device associated with the target tissue in correspondence to transmitting of the pushing ultrasound signal. 
     According to another aspect of the present invention, there is provided an ultrasound system for providing an acoustic radiation force impulse image, the system including: a transceiving unit to transmit, to a target tissue, a pushing ultrasound signal for generating of a displacement, using a probe, and to receive a response signal from the target tissue in correspondence to a tracking ultrasound signal transmitted via the probe; a detection unit to detect displacement information associated with the target tissue using the response signal; and a generation unit to generate the acoustic radiation force impulse image based on the displacement information. 
     According to embodiments of the present invention, there may be provided an ultrasound system and method for providing an acoustic radiation force impulse image that may apply a pushing ultrasound signal along a plurality of scan lines and thereby improve a frame rate. 
     Also, according to embodiments of the present invention, there may be provided an ultrasound system and method for providing an acoustic radiation force impulse image that may apply a pushing ultrasound signal with respect to a plurality of focal points for each single scan line and thereby prevent overheating of a target tissue and may also improve a frame rate. 
     Also, according to embodiments of the present invention, there may be provided an ultrasound system and method for providing an acoustic radiation force impulse image that may simultaneously apply a pushing ultrasound signal and a tracking ultrasound signal using different transducers and thereby more effectively obtain an acoustic radiation force impulse image. 
     Also, according to embodiments of the present invention, there may be provided an ultrasound system and method for providing an acoustic radiation force impulse image that may prevent overheating of a target tissue via a cooling device and thereby prevent a degeneration and a necrosis of the target tissue. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects, features, and advantages of the invention will become apparent and more readily appreciated from the following description of exemplary embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a block diagram illustrating an ultrasound system for providing an acoustic radiation force impulse image according to an embodiment of the present invention; 
         FIG. 2  is a flowchart illustrating an ultrasound method of providing an acoustic radiation force impulse image according to an embodiment of the present invention; 
         FIG. 3  illustrates an example of transmitting a pushing ultrasound signal along a plurality of scan lines according to an embodiment of the present invention; 
         FIG. 4  illustrates an example of transmitting a pushing ultrasound signal with respect to a plurality of focal points according to an embodiment of the present invention; and 
         FIG. 5  illustrates an example of transmitting a different ultrasound signal for each transducer section according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Exemplary embodiments are described below to explain the present invention by referring to the figures. 
       FIG. 1  is a block diagram illustrating an ultrasound system  110  for providing an acoustic radiation force impulse image according to an embodiment of the present invention. 
     As shown in  FIG. 1 , the ultrasound system  110  may receive a response signal in correspondence to a tracking ultrasound signal that is transmitted to a subject  120  via a probe  114 . The response signal denotes a signal that is transmitted or reflected from the subject  120  by the tracking ultrasound signal. Also, the ultrasound system  110  may generate ultrasound image data using the response signal, generate an ultrasound image from the ultrasound image data, and display the ultrasound image via an internal or external display device  115 . Here, the ultrasound image may be displayed in either a two-dimensional (2D) form or a three-dimensional (3D) form. Also, the subject  120  may be a human body. The probe  114  may include transducers that transmit and receive the tracking ultrasound signal. 
     The ultrasound system  110  may transmit a pushing ultrasound signal to the subject  120  via the probe  120 . In this case, the pushing ultrasound signal may cause a displacement  122  in a target tissue  121  of the subject  120 . The pushing ultrasound signal may be transmitted to the subject  120  prior to transmitting of the tracking ultrasound signal and reception of the response signal. 
     The ultrasound system  110  may detect displacement information associated with the target tissue  121  using the response signal and generate the acoustic radiation force impulse image based on the displacement information. The displacement information may include a displacement level of the target tissue  121  that is caused by the pushing ultrasound signal. 
     The acoustic radiation force impulse image may indicate an elasticity level of the target tissue  121 . A user may determine a state of the target tissue  121  based on the elasticity level of the target tissue  121 . For example, the user may detect a tissue such as a wen having an elasticity less than a general tissue and may also detect a tissue degeneration such as a cancer having an elasticity greater than the general tissue, using the acoustic radiation force impulse image. 
     As described above, the ultrasound system  110  may provide the acoustic radiation force impulse image of the target tissue  121  together with the general ultrasound image. 
     The ultrasound system  110  may include a transceiving unit  111 , a detection unit  112 , and a generation unit  113 . Here, the transceiving unit  111  may transmit, to the target tissue  121 , a pushing ultrasound signal for generating of a displacement using the. probe  114  and may receive a response signal from the target tissue  11  in correspondence to a tracking ultrasound signal transmitted via the probe  114 . The detection unit  112  may detect displacement information associated with the target tissue  121  using the response signal. The generation unit  113  may generate the acoustic radiation force impulse image based on the displacement information. Also, although not shown in  FIG. 1 , the ultrasound system  110  may further include a cooling device to decrease a temperature of the target tissue  121 . The transceiving unit  111  may transmit a control command to the cooling device in correspondence to transmitting of the pushing ultrasound signal. 
     Hereinafter, an operating method of the ultrasound system  110  constructed as above will be further described in detail with reference to  FIGS. 2 through 5 . 
       FIG. 2  is a flowchart illustrating an ultrasound method of providing an acoustic radiation force impulse image according to an embodiment of the present invention. 
     As shown in  FIG. 2 , the ultrasound method of providing the acoustic radiation force impulse image may be performed via operations S 201  through S 204 . Here, operations S 201  and S 202  may be performed by the transceiving unit  111 . Operation S 203  may be performed by the detection unit  112 . Operation S 204  may be performed by the generation unit  113 . 
     In operation S 201 , the transceiving unit  111  may transmit, to a target tissue, a pushing ultrasound signal for generating of a displacement using a probe. Here, the pushing ultrasound signal may induce a displacement of the target tissue. Specifically, the target tissue may be moved by the pushing ultrasound signal. This movement may induce the displacement. The displacement of the target tissue may be in inverse proportion to an elasticity of the target tissue. A recovering speed of a tissue may be in proportion to a viscoelasticity of the target tissue. 
     Generally, a short and strong sound wave may cause a greater displacement in comparison to a long and weak sound wave. Accordingly, examples of the pushing ultrasound signal may include an ultrasound signal that has a single pulse and a great amplitude. Since a maximum output of the ultrasound signal of the ultrasound system  110  is pre-determined, the transceiving unit  111  may generate the pushing ultrasound signal by extending the ultrasound signal of the maximum output as long as possible. Also, according to an embodiment of the present invention, the transceiving unit  111  may generate the pushing ultrasound signal using a sufficiently long color Doppler pulse signal with a great amplitude. 
     In operation S 202 , the transceiving unit  111  may receive a response signal from the target tissue in correspondence to a tracking ultrasound signal transmitted via the probe. Here, the tracking ultrasound signal may be used to measure a level of the displacement of the target tissue. The response signal may include information associated with the level of the displacement. For example, the tracking ultrasound signal may include a B mode ultrasound signal. The tracking ultrasound signal may be transmitted to a region of interest (ROI) including the target tissue. The response signal may be reflected from the ROI and thereby be received. 
     According to an embodiment of the present invention, the transceiving unit  111  may simultaneously transmit the pushing ultrasound signal along a plurality of scan lines that are spaced apart from each other by a predetermined distance. 
       FIG. 3  illustrates an example of transmitting a pushing ultrasound signal along a plurality of scan lines according to an embodiment of the present invention. 
     As shown in a block  301 , the transceiving unit  111  may transmit the pushing ultrasound signal to a target tissue via a single scan line. Also, as shown in a block  302 , the transceiving unit  111  may simultaneously transmit the pushing ultrasound signal along the plurality of scan lines that are spaced apart from each other by a predetermined distance. As described above, the transceiving unit  111  may measure a displacement of the target tissue at the plurality of scan lines at one time by simultaneously transmitting the pushing ultrasound signals via the plurality of scan lines. Also, since the transceiving unit  111  may transmit the pushing ultrasound signal via the plurality of scan lines that are spaced apart from each other by the predetermined distance, it is possible to distribute a temperature rise of the target tissue and thereby prevent overheating or damage of the target tissue. 
     Also, the transceiving unit  111  may transmit the tracking ultrasound signal to the target tissue along the plurality of scan lines and receive a response signal that is reflected from the target tissue in correspondence to transmitting of the tracking ultrasound signal. 
     According to an embodiment of the present invention, the transceiving unit  111  may sequentially transmit the pushing ultrasound signal to a plurality of focal points along a scan line. 
       FIG. 4  illustrates an example of transmitting a pushing ultrasound signal with respect to a plurality of focal points according to an embodiment of the present invention. 
     As shown in a block  401 , the transceiving unit  111  may sequentially transmit the pushing ultrasound signal with respect to the plurality of focal points along a scan line. For example, the transceiving unit  111  may sequentially transmit the pushing ultrasound signal with respect to the focal points from A to I along a single scan line. Here, a frequency of the pushing ultrasound signal may be variable according to each of the focal points. For example, the transceiving unit  111  may transmit a relatively low frequency of pushing ultrasound signal with respect to a focal point with a relatively deep depth and thereby make the pushing ultrasound signal reaching a deep target tissue be less attenuated. Generally, the attenuation may incur more frequently as the frequency of the pushing ultrasound signal is higher and the depth of the focal point is deeper. Also, the transceiving unit  111  may transmit the tracking ultrasound signal with respect to the plurality of focal points along the scan line and receive a response signal reflected from the target tissue in correspondence to transmitting of the tracking ultrasound signal. 
     According to an embodiment of the present invention, when transmitting the pushing ultrasound signal to the target tissue via a plurality of scan lines, the transceiving unit  111  may simultaneously transmit the pushing ultrasound signal with respect to different focal points for each of the scan lines. 
     For example, as shown in a block  402 , the transceiving unit  111  may apply the pushing ultrasound signal in a focal point order of A, B, and C via a first scan line, apply the pushing ultrasound signal in a focal point order of B, C, and A via a second scan line, and apply the pushing ultrasound signal in a focal point order of C, A, and B via a third scan line at the same time. Also, a frequency of the pushing ultrasound signal may be variable according to each of the different focal points. Displacement information associated with each of the different focal points may be simultaneously detected. Also, the transceiving unit  111  may simultaneously transmit the tracking ultrasound signal with respect to the different focal points and receive a response signal reflected from the target tissue in correspondence to transmitting of the tracking ultrasound signal. 
     According to an embodiment of the present invention, when transmitting, to a target tissue, a pushing ultrasound signal for generating of a displacement and receiving a response signal from the target tissue in correspondence to transmitting of the tracking ultrasound signal, the transceiving unit  111  may use a probe including two-dimensionally arranged transducers. Here, the transducers may be classified into a plurality of sections. While transmitting the pushing ultrasound signal using a transducer included in a first section among the plurality of sections, the transceiving unit  111  may transmit the tracking ultrasound signal using a transducer included in a second section among the plurality of sections. 
       FIG. 5  illustrates an example of transmitting a different ultrasound signal for each transducer section according to an embodiment of the present invention. 
     Referring to  FIG. 5 , the transceiving unit  111  may transmit a pushing ultrasound signal using a transducer  511  included in a first section among a plurality of two-dimensionally arranged transducers  510  and simultaneously transmit a tracking ultrasound signal using a transducer  510  included in a second section. Also, while transmitting the pushing ultrasound signal using the transducer  511  of the first section, the transceiving unit  111  may receive a response signal using the transducer  512  of the second section. Also, while transmitting the pushing ultrasound signal to a first target tissue, a first ROI, or a first focal point using the transducer  511  of the first section, the transceiving unit  511  may transmit the pushing ultrasound signal to a second target tissue, a second ROI, or a second focal point using the transducer  512  of the second section. 
     According to an embodiment of the present invention, the transceiving unit  111  may use transducers, included in a particular section among the two-dimensionally arranged transducers  510  in order to generate a constant B mode ultrasound image. For example, the transceiving unit  111  may use an array corresponding to a bottom line among the arranged transducers  510  in order to generate the constant B mode ultrasound image. Specifically, the transceiving unit  111  may use transducers, included in a particular section, to transmit a constant tracking ultrasound signal and receive a response signal in correspondence thereto. 
     As described above, the transceiving unit  111  may allocate a different role to the transducers  510  for each section and thereby making it possible to more effectively obtain an acoustic radiation force impulse image. 
     Referring again to  FIG. 2 , in operation S 203 , the detection unit  112  may detect displacement information associated with the target tissue using the response signal. Here, the response signal may include displacement information associated with the target tissue. 
     Specifically, the detection unit  112  may perform an envelope detection process that detects the magnitude of the response signal based on the response signal to thereby form ultrasound image data. Specifically, the detection unit  112  may form the ultrasound image data based on location information associated with a plurality of points existing in each scan line and data that is obtained from each of the points to thereby form ultrasound image data. Here, the ultrasound image data may include coordinates on an XY coordinate system at each point, angle information associated with each scan line with respect to a vertical scan line, data obtained at each point, and the like. Also, the detection unit  112  may compare ultrasound image data before and after a displacement of the target tissue occurs due to the applied pushing ultrasound signal and thereby may detect the displacement information. 
     In operation S 204 , the generation unit  113  may generate an acoustic radiation force impulse image based on the displacement information. 
     For example, the generation unit  113  may generate ultrasound image data associated with the target tissue or the ROI based on the response signal and generate a B mode ultrasound image using the ultrasound image data. Also, the generation unit  113  may generate the acoustic radiation force impulse image by overlapping the displacement information associated with the target tissue and the B mode ultrasound image. 
     Although not shown in  FIG. 2 , the ultrasound system  110  may further perform transmitting a control command to a cooling device associated with the target tissue in correspondence to transmitting of the pushing ultrasound signal. Through this, the ultrasound system  110  may control a temperature rise of the target tissue caused by the pushing ultrasound signal. In particular, the ultrasound system  110  may operate the cooling device positioned on the epidermis of the target tissue, while transmitting the pushing ultrasound signal to the transducers of the probe. 
     The ultrasound method for providing the acoustic radiation force impulse image according to the above-described exemplary embodiments of the present invention may be recorded in computer-readable media including program instructions to implement various operations embodied by a computer. The media may also include, alone or in combination with the program instructions, data files, data structures, and the like. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD ROM disks and DVDs; magneto-optical media such as floptical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like. Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. The described hardware devices may be configured to act as one or more software modules in order to perform the operations of the above-described exemplary embodiments of the present invention, or vice versa. 
     Although a few exemplary embodiments of the present invention have been shown and described, the present invention is not limited to the described exemplary embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.