Patent Publication Number: US-10327738-B2

Title: Ultrasound imaging apparatus and method of processing ultrasound image thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from Korean Patent Application No. 10-2015-0045331, filed on Mar. 31, 2015, and from Korean Patent Application No. 10-2015-0115415, filed on Aug. 17, 2015, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their respective entireties. 
     BACKGROUND 
     1. Field 
     Exemplary embodiments relate to ultrasound imaging apparatuses and methods for processing an ultrasound image thereof. 
     2. Description of the Related Art 
     An ultrasound imaging apparatus obtains at least one image that relates to an inner portion (for example, a soft tissue or blood flow) of an object by irradiating an ultrasound signal generated by a transducer of a probe toward the object, and receiving information of an echo signal reflected by the object. In particular, the ultrasound imaging apparatus is usable for a medical purpose, such as observation of the inside of the object, foreign substance detection, and injury measurement. Compared with a diagnosis apparatus that uses an X-ray, the ultrasound imaging apparatus has high stability, may display an image in real-time, and has an advantage of being relatively safe because there is no exposure to radiation. Therefore, an ultrasound imaging apparatus is widely used together with other imaging apparatuses including a computed tomography (CT) apparatus, a magnetic resonance imaging (MRI) apparatus, and other suitable apparatuses. 
     The ultrasound imaging apparatus may calculate an elasticity value, which is a value that represents the elasticity of an object, and provide the same to a user. The elasticity of an object is related to a pathological phenomenon of the object. When an ultrasound imaging apparatus provides an elasticity value to a user, the user needs to know whether the elasticity value provided to the user is an accurate value. U.S. Patent Publication No. 2013/02118011 A1 discloses a construction of providing the quality of a shear wave to a user by using a signal-to-noise ratio (SNR) and other relevant parameters of the shear wave. However, even when the quality (for example, an SNR) of the shear wave is good, a calculated elasticity value may not be a reliable value. In addition, it is difficult for a user to intuitively determine whether an elasticity value provided to the user is a reliable value based solely on the quality of a shear wave. 
     SUMMARY 
     Provided are methods and ultrasound imaging apparatuses for providing an elasticity value to a user. 
     Provided are ultrasound imaging apparatuses and methods for processing an ultrasound image thereof, that enable a user to more accurately and intuitively recognize whether an obtained elasticity value is a reliable value. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented exemplary embodiments. 
     According to an aspect of an exemplary embodiment, a method for processing an ultrasound image in which an ultrasound imaging apparatus provides an elasticity value is provided. The method includes: inducing a shear wave inside an object; obtaining an elasticity value that relates to the object based on the induced shear wave; determining a reliability value that relates to the obtained elasticity value based on a result of a comparison of the obtained elasticity value with a reference value that corresponds to the induced shear wave; and displaying a user interface screen that includes a respective representation of each of the obtained elasticity value and the determined reliability value. 
     The determining the reliability value may include: determining the reliability value based on a result of a comparison between a magnitude of the induced shear wave and the obtained elasticity value and the reference value. 
     The determining the reliability value may include: obtaining a residual value that corresponds to a difference between the obtained elasticity value and the reference value; and determining the reliability value based on a magnitude of the determined shear wave and the obtained residual value. 
     The determining the reliability value may include: when the shear wave is applied to a wave equation, obtaining a residual value that corresponds to an error of the shear wave with respect to the wave equation; and determining the reliability value based on a magnitude of the induced shear wave and the obtained residual value. 
     The obtaining the elasticity value may include: determining a magnitude of the induced shear wave and using the determined magnitude as the elasticity value, wherein the determining the reliability value may include: calculating a first numerical value based on the determined magnitude of the shear wave; calculating a second numerical value based on a result of the comparison; and determining the reliability value based on the calculated first numerical value and the calculated second numerical value. 
     The calculating the second numerical value may include: calculating the second numerical value based on a residual value that corresponds to a difference between the obtained elasticity value and the reference value. 
     The determined reliability value may be equal to or greater than zero and equal to or less than one. 
     The displaying may include: displaying the representation of the reliability value by using a numerical value. 
     The displaying may include: displaying a graph that indicates a magnitude of the determined reliability value. 
     The displaying may include: displaying the representation of the obtained elasticity value by using a color that corresponds to a magnitude of the determined reliability value. 
     The displaying may include: displaying at least one from among an image, a letter, an icon, and a symbol that corresponds to a magnitude of the determined reliability value. 
     The displaying may include: displaying a screen which includes an ultrasound image that includes a respective representation of each of the object, the obtained elasticity value, and the determined reliability value. 
     The displaying may include: displaying a screen which includes an elasticity image generated based on the induced shear wave, the obtained elasticity value, and the determined reliability value. 
     The method may further include: setting a region of interest (ROI) with respect to the object, wherein the obtaining the elasticity value may include: obtaining an elasticity value that relates to the object inside the region of interest based on an observation of the induced shear wave with respect to an inside of the ROI. 
     The method may further include: determining a quality of the induced shear wave, wherein the displaying may include: displaying a user interface screen which includes a respective representation of each of the obtained elasticity value, the determined reliability value, and the determined quality. 
     According to an aspect of another exemplary embodiment, a method for processing an ultrasound image in which an ultrasound imaging apparatus provides an elasticity value is provided. The method includes: obtaining an elasticity value for an object based on ultrasound data obtained by observing a shear wave that is induced with respect to the object; determining a reliability value that relates to the obtained elasticity value based on a result of a comparison of the obtained elasticity value with a reference value that corresponds to the induced shear wave; and displaying a user interface screen that includes a respective representation of each of the obtained elasticity value and the determined reliability value. 
     According to an aspect of another exemplary embodiment, an ultrasound imaging apparatus includes: a controller configured to obtain an elasticity value that relates to an object based on a shear wave induced inside the object, and to determine a reliability value that relates to the obtained elasticity value based on a result of a comparison of the obtained elasticity value with a reference value that corresponds to the induced shear wave; and a display configured to display a user interface screen that includes a respective representation of each of the obtained elasticity value and the determined reliability value. 
     The controller may be further configured to determine the reliability value based on a result of a comparison between a magnitude of the induced shear wave and the obtained elasticity value and the reference value. 
     The controller may be further configured to obtain a residual value that corresponds to a difference between the obtained elasticity value and the determined reference value, and to determine the reliability value based on a magnitude of the induced shear wave and the obtained residual value. 
     The controller may be further configured to obtain a residual value that corresponds to an error of the shear wave with respect to a wave equation when the shear wave is applied to the wave equation, and to determine the reliability value based on a magnitude of the induced shear wave and the obtained residual value. 
     The controller may be further configured to determine a magnitude of the induced shear wave and to use the determined magnitude as the elasticity value, to calculate a first numerical value based on the determined magnitude of the shear wave, to calculate a second numerical value based on a result of the comparison, and to determine the reliability value based on the calculated first numerical value and the calculated second numerical value. 
     The controller may be further configured to calculate the second numerical value based on a residual value that corresponds to a difference between the obtained elasticity value and the reference value. 
     The reliability value may be equal to or greater than zero and equal to or less than one. 
     The ultrasound imaging apparatus may further include: an ultrasound transceiver configured to induce the shear wave inside the object, and to observe the induced shear wave. 
     The ultrasound imaging apparatus may further include: a communication module configured to receive the induced shear wave from a wireless probe. 
     The display may be further configured to display the representation of the determined reliability value by using a numerical value. 
     The display may be further configured to display a graph which indicates a magnitude of the determined reliability value. 
     The display may be further configured to display the representation of the obtained elasticity value by using a color that corresponds to a magnitude of the determined reliability value. 
     The display may be further configured to display at least one from among an image, a letter, an icon, and a symbol that corresponds to a magnitude of the determined reliability value. 
     The controller may be further configured to determine a quality of the induced shear wave based on a displacement characteristic of the shear wave. 
     The display may be further configured to display a user interface screen which includes a respective representation of each of the obtained elasticity value, the determined reliability value, and the determined quality. 
     A non-transitory recording medium according to an exemplary embodiment may be a non-transitory computer-readable recoding medium having recorded thereon a program that is executable for performing the above-described method for processing an ultrasound image. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which reference numerals denote structural elements. 
         FIG. 1  is a block diagram illustrating a configuration of an ultrasound diagnosis apparatus, according to an exemplary embodiment; 
         FIG. 2  is a block diagram illustrating a configuration of a wireless probe, according to an exemplary embodiment; 
         FIG. 3A  is a block diagram illustrating a configuration of an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 3B  is a block diagram illustrating a configuration of an ultrasound imaging apparatus, according to another exemplary embodiment; 
         FIG. 4  is a flowchart illustrating a process for providing an elasticity value, according to an exemplary embodiment; 
         FIG. 5  is a flowchart illustrating a process for providing a reliability value, according to an exemplary embodiment; 
         FIG. 6  is a diagram for explaining a shear wave; 
         FIG. 7  is a diagram for explaining a shear wave generated inside an object; 
         FIG. 8  is a diagram illustrating a screen displayed by an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 9  is a flowchart illustrating a process of displaying a reliability value in an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 10  is a diagram illustrating another screen displayed by an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 11  is a diagram for explaining a graph displayed by an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 12  is a flowchart illustrating a process for displaying a reliability value in an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 13  is a flowchart illustrating a process for displaying a reliability value in an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 14  is a diagram for explaining a method for displaying a reliability value in an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 15  is a diagram for explaining a method for displaying a reliability value and quality in an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 16  is a diagram illustrating another screen displayed by an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 17  is a diagram illustrating another screen displayed by an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 18  is a diagram illustrating another screen displayed by an ultrasound imaging apparatus, according to an exemplary embodiment; 
         FIG. 19  is a diagram illustrating another screen displayed by an ultrasound imaging apparatus, according to an exemplary embodiment; and 
         FIG. 20  is a diagram illustrating another screen displayed by an ultrasound imaging apparatus, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments are described in detail with reference to the accompanying drawings so as to enable a person of ordinary skill in the art to easily implement the present inventive concept. In this regard, the present exemplary embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Further, for clarity, portions irrelevant to the description are omitted from the drawings, and like reference numerals are used for like components throughout the specification. 
     The terms used in this specification are those general terms currently widely used in the art in consideration of functions that relate to the exemplary embodiments, but the terms may vary according to the intention of those of ordinary skill in the art, precedents, or new technology in the art. Further, some terms may be arbitrarily selected by the applicant, and in this case, the meaning of the selected terms will be described in detail in the detailed description of the present specification. Thus, the terms used in the specification should be understood not as simple names but based on the meaning of the terms and the overall description of the exemplary embodiments. 
     It will be understood that when a certain portion is referred to as being “connected” to another portion, it may be “directly connected” to the other portion or may be “electrically connected” to the other portion with other device interposed therebetween. When a part “includes” or “comprises” an element, unless there is a particular description contrary thereto, the part can further include other elements, not excluding the other elements. 
     Throughout the specification, an “ultrasound image” refers to an image of an object, which is obtained by using ultrasound waves. Furthermore, an “object” may be any of a human, an animal, or a part of a human or animal. For example, the object may be an organ (e.g., the liver, heart, womb, brain, breast, or abdomen), a blood vessel, or a combination thereof. Further, the object may be a phantom. The phantom refers to a material having a density, an effective atomic number, and a volume that are approximately the same as those of an organism. For example, the phantom may be a spherical phantom having properties similar to a human body. 
     Throughout the specification, a “user” may be, but is not limited to, a medical expert, for example, a medical doctor, a nurse, a medical laboratory technologist, or a medical imaging expert, or a technician who repairs medical apparatuses. 
     Throughout the specification, an “elasticity value” denotes a value representing a degree of elasticity held by a tissue of an object. Further, a “reliability value” that relates to the elasticity value denotes a value representing a degree to which the elasticity value calculated by an ultrasound imaging apparatus is reliable. The “reliability value” may be referred to as a reliable measurement index or a measure reliability index. In addition, a residual value may denote a difference between a value obtained from an observed value or a measurement value for an elasticity value, and a calculated value or a theoretical value. Exemplary embodiments are described below with reference to the accompanying drawings. 
       FIG. 1  is a block diagram showing a configuration of an ultrasound diagnosis apparatus  1000 , according to an exemplary embodiment. Referring to  FIG. 1 , the ultrasound diagnosis apparatus  1000  may include a probe  20 , an ultrasound transceiver  1100 , an image processor  1200 , a communication module  1300 , a display  1400 , a memory  1500 , an input device  1600 , and a controller  1700 , all of which may be connected to one another via buses  1800 . 
     The ultrasound diagnosis apparatus  1000  may be a cart type apparatus or a portable type apparatus. Examples of portable ultrasound diagnosis apparatuses may include, but are not limited to, a picture archiving and communication system (PACS) viewer, a smartphone, a laptop computer, a personal digital assistant (PDA), and a tablet personal computer (PC). 
     The probe  20  transmits ultrasound waves to an object  10  in response to a driving signal applied by the ultrasound transceiver  1100  and receives echo signals reflected by the object  10 . The probe  20  includes a plurality of transducers, and the plurality of transducers oscillate in response to electric signals and generate acoustic energy, that is, ultrasound waves. Furthermore, the probe  20  may be connected to the main body of the ultrasound diagnosis apparatus  1000  by wire or wirelessly, and according to exemplary embodiments, the ultrasound diagnosis apparatus  1000  may include a plurality of probes  20 . 
     A transmitter  1110  supplies a driving signal to the probe  20 . The transmitter  110  includes a pulse generator  1112 , a transmission delaying unit (also referred to herein as a “transmission delayer”)  1114 , and a pulser  1116 . The pulse generator  1112  generates pulses for forming transmission ultrasound waves based on a predetermined pulse repetition frequency (PRF), and the transmission delaying unit  1114  delays the pulses by delay times necessary for determining transmission directionality. The pulses which have been delayed correspond to a plurality of piezoelectric vibrators included in the probe  20 , respectively. The pulser  1116  applies a driving signal (or a driving pulse) to the probe  20  based on timing that corresponds to each of the pulses which have been delayed. 
     A receiver  1120  generates ultrasound data by processing echo signals received from the probe  20 . The receiver  1120  may include an amplifier  1122 , an analog-to-digital converter (ADC)  1124 , a reception delaying unit (also referred to herein as a “reception delayer”)  1126 , and a summing unit (also referred to herein as a “summer” or an “adder”)  1128 . The amplifier  1122  amplifies echo signals in each channel, and the ADC  1124  performs analog-to-digital conversion with respect to the amplified echo signals. The reception delaying unit  1126  delays digital echo signals output by the ADC  124  by delay times necessary for determining reception directionality, and the summing unit  1128  generates ultrasound data by summing the echo signals processed by the reception delaying unit  1166 . In some exemplary embodiments, the receiver  1120  may not include the amplifier  1122 . In this aspect, if the sensitivity of the probe  20  or the capability of the ADC  1124  to process bits is enhanced, the amplifier  1122  may be omitted. 
     The image processor  1200  generates an ultrasound image by scan-converting ultrasound data generated by the ultrasound transceiver  1100 . The ultrasound image may include not only a grayscale ultrasound image obtained by scanning an object in an amplitude (A) mode, a brightness (B) mode, and a motion (M) mode, but also a Doppler image which illustrates a movement of an object via a Doppler effect. The Doppler image may be any of a blood flow Doppler image that shows flow of blood (also referred to as a color Doppler image), a tissue Doppler image that shows a movement of tissue, or a spectral Doppler image that shows a moving speed of an object as a waveform. 
     A B mode processor  1212  included in a data processor  1210  extracts a B mode component from ultrasound data and processes the extracted B mode component. An image generator  1220  may generate an ultrasound image which indicates signal intensities as brightnesses based on the extracted B mode components  1212 . 
     Likewise, a Doppler processor  1214  included in the data processor  1210  may extract a Doppler component from ultrasound data, and the image generator  1220  may generate a Doppler image which expresses a movement of an object in a color or a waveform based on the extracted Doppler component. 
     According to an exemplary embodiment, the image generator  1220  may generate a three-dimensional (3D) ultrasound image via volume-rendering with respect to volume data and may also generate an elasticity image by imaging a deformation of the object  10  due to pressure. Furthermore, the image generator  1220  may display various pieces of additional information in an ultrasound image by using text and graphics. In addition, the generated ultrasound image may be stored in the memory  1500 . 
     A display  1400  displays the generated ultrasound image. The display  1400  may display not only an ultrasound image, but also various pieces of information processed by the ultrasound diagnosis apparatus  1000  on a screen image via a graphical user interface (GUI). In addition, the ultrasound diagnosis apparatus  1000  may include two or more displays  1400  according to exemplary embodiments. 
     The communication module  1300  is connected to a network  30  by wire or wirelessly in order to communicate with an external device or a server. The communication module  1300  may exchange data with a hospital server or another medical apparatus in a hospital, which is connected thereto via a PACS. Furthermore, the communication module  1300  may perform data communication according to the digital imaging and communications in medicine (DICOM) standard. 
     The communication module  1300  may transmit or receive data which relates to a diagnosis of an object, e.g., an ultrasound image, ultrasound data, and Doppler data of the object, via the network  30  and may also transmit or receive medical images captured by another medical apparatus, e.g., a computed tomography (CT) apparatus, a magnetic resonance imaging (MRI) apparatus, or an X-ray apparatus. Furthermore, the communication module  1300  may receive information which relates to a diagnosis history or medical treatment schedule of a patient from a server and may utilize the received information to diagnose the patient. Furthermore, the communication module  1300  may perform data communication not only with a server or a medical apparatus in a hospital, but also with a portable terminal of a medical doctor or patient. 
     The communication module  1300  is connected to the network  30  by wire or wirelessly in order to exchange data with a server  32 , a medical apparatus  34 , or a portable terminal  36 . The communication module  1300  may include one or more components which are configured for facilitating communication with external devices. For example, the communication module  1300  may include a local area communication module  1310 , a wired communication module  1320 , and a mobile communication module  1330 . 
     The local area communication module  1310  refers to a module configured for performing local area communication within a predetermined distance. Examples of local area communication technology according to an exemplary embodiment include, but are not limited to, a wireless local area network (LAN), Wi-Fi, Bluetooth, ZigBee, Wi-Fi direct (WFD), ultra wideband (UWB), infrared data association (IrDA), Bluetooth low energy (BLE), and near field communication (NFC). 
     The wired communication module  1320  refers to a module configured for performing communication by using electric signals or optical signals. Examples of wired communication techniques according to an exemplary embodiment may include communication via a twisted pair cable, a coaxial cable, an optical fiber cable, and an Ethernet cable. 
     The mobile communication module  1330  transmits or receives wireless signals to or from at least one selected from a base station, an external terminal, and a server on a mobile communication network. The wireless signals may include voice call signals, video call signals, and/or various types of data for transmission and reception of text/multimedia messages. 
     The memory  1500  stores various data processed by the ultrasound diagnosis apparatus  1000 . For example, the memory  1500  may store medical data that relates to a diagnosis of an object, such as ultrasound data and an ultrasound image that are input or output, and may also store algorithms or programs which are to be executed in the ultrasound diagnosis apparatus  1000 . 
     The memory  1500  may include any of various storage media, e.g., a flash memory, a hard disk drive, EEPROM, and/or any other suitable type of storage medium. Furthermore, the ultrasound diagnosis apparatus  1000  may utilize web storage or a cloud server that performs the storage function of the memory  1500  online. 
     The input device  1600  refers to a means via which a user inputs data for controlling the ultrasound diagnosis apparatus  1000 . The input device  1600  may include hardware components, such as any of a keypad, a mouse, a touch pad, a touch screen, and a jog switch. However, exemplary embodiments are not limited thereto, and the input device  1600  may further include any of various other input units such as, for example, an electrocardiogram (ECG) measuring module, a respiration measuring module, a voice recognition sensor, a gesture recognition sensor, a fingerprint recognition sensor, an iris recognition sensor, a depth sensor, a distance sensor, and/or any other suitable type of input device. 
     The controller  1700  may control all operations of the ultrasound diagnosis apparatus  1000 . In particular, the controller  1700  may control operations among the probe  20 , the ultrasound transceiver  1100 , the image processor  1200 , the communication module  1300 , the display  1400 , the memory  1500 , and the input device  1600  shown in  FIG. 1 . 
     All or some of the probe  20 , the ultrasound transceiver  1100 , the image processor  1200 , the communication module  1300 , the display  1400 , the memory  1500 , the input device  1600 , and the controller  1700  may be implemented as software modules. Furthermore, at least one selected from the ultrasound transceiver  1100 , the image processor  1200 , and the communication module  1300  may be included in the controller  1600 . However, exemplary embodiments are not limited thereto. 
       FIG. 2  is a block diagram showing a configuration of a wireless probe  2000 , according to an exemplary embodiment. As described above with reference to  FIG. 1 , the wireless probe  2000  may include a plurality of transducers, and, according to exemplary embodiments, may include some or all of the components of the ultrasound transceiver  100  shown in  FIG. 1 . 
     The wireless probe  2000  according to the exemplary embodiment shown in  FIG. 2  includes a transmitter  2100 , a transducer  2200 , and a receiver  2300 . Since descriptions thereof are provided above with reference to  FIG. 1 , detailed descriptions thereof will be omitted here. In addition, according to exemplary embodiments, the wireless probe  2000  may selectively include a reception delaying unit (also referred to herein as a “reception delayer”)  2330  and a summing unit (also referred to herein as a “summer” and/or as an “adder”)  2340 . 
     The wireless probe  2000  may transmit ultrasound signals to the object  10 , receive echo signals from the object  10 , generate ultrasound data, and wirelessly transmit the ultrasound data to the ultrasound diagnosis apparatus  1000  shown in  FIG. 1 . 
     An ultrasound imaging apparatus that enables a user to intuitively recognize whether an obtained elasticity value is a reliable value according to an exemplary embodiment is described below with reference to  FIGS. 3A to 20 . 
     The ultrasound imaging apparatus according to an exemplary embodiment may include any medical imaging apparatus that is configured to obtain ultrasound data, and to obtain and process an elasticity value based on the obtained ultrasound data. In particular, the ultrasound imaging apparatus according to an exemplary embodiment may correspond to the ultrasound imaging apparatus  1000  illustrated in  FIG. 1 . Further, the ultrasound imaging apparatus according to an exemplary embodiment may include a medical imaging apparatus that transmits/receives data to/from a wireless probe illustrated in  FIG. 2  via a wireless network. In particular, the ultrasound imaging apparatus according to an exemplary embodiment may include any medical imaging apparatus that is configured to obtain and process an elasticity value by using ultrasound data received from the wireless probe illustrated in  FIG. 2 . 
       FIG. 3A  is a block diagram illustrating a configuration of an ultrasound imaging apparatus  300 , according to an exemplary embodiment. 
     The ultrasound imaging apparatus  300  according to an exemplary embodiment may include a controller  310  and a display  320 . The controller  310  and the display  320  of  FIG. 3A  may correspond to the controller  1700  and the display  1400  of  FIG. 1 , respectively. In particular, the ultrasound imaging apparatus  300  may be included in or equivalently correspond to the ultrasound imaging apparatus  1000  illustrated in  FIG. 1 . 
     The controller  310  according to an exemplary embodiment may control each component of the ultrasound imaging apparatus  300 . The controller  310  may obtain an elasticity value of an object by controlling each component of the ultrasound imaging apparatus  300 . A method for obtaining an elasticity value may be implemented in any of various ways based on an exemplary embodiment. 
     According to an exemplary embodiment, an elasticity value may denote a modulus of elasticity. For example, an elasticity value is a value that represents a degree of transformation of an object to which a shear wave has been induced, and may be expressed as a shear modulus of elasticity, a Young&#39;s modulus, a shear velocity value, an/or any other suitable type of value. 
     In the case in which the ultrasound imaging apparatus  300  equivalently corresponds to the ultrasound imaging apparatus  1000  illustrated in  FIG. 1 , the ultrasound imaging apparatus  300  may further include some or all of internal components of the ultrasound imaging apparatus  1000 , in addition to the inclusions of the controller  310  and the display  320 . For example, the ultrasound imaging apparatus  300  may further include the transceiver  1100  and the probe  20  of  FIG. 1 . 
     The controller  310  may be configured to obtain ultrasound data by tracking and/or observing a shear wave induced to an object  10 , and to obtain an elasticity value of the object  10  based on the obtained ultrasound data. In particular, the obtained ultrasound data is ultrasound data which is obtainable by tracking and/or observing a shear wave induced to the object  10 , and which may be self-obtained by using a probe provided inside the ultrasound imaging apparatus  300  and/or which may be received from outside. 
     According to an exemplary embodiment, the controller  310  may induce a shear wave to the object  10  by using the ultrasound transceiver  1100  and the probe  20  of  FIG. 1 . Further, the controller  310  may observe the induced shear wave and obtain an elasticity value of the object  10  based on the observation of the shear wave. 
     According to an exemplary embodiment, the controller  310  may obtain an elasticity value of the object  10  based on a velocity of a shear wave included in elasticity data which is obtained by tracking the induced shear wave by using the ultrasound transceiver  1100  and the probe  20 . In this aspect, the elasticity value may be an elasticity value of an object inside a region of interest set for an ultrasound image. For another example, the controller  310  may obtain an elasticity value stored in the memory  1500  of  FIG. 1 . For another example, the controller  310  may receive information which includes an elasticity value from other devices by using the communication module  1300 . However, the exemplary embodiment is not limited thereto. 
     In addition, the controller  310  may be configured to determine a reliability value that relates to an obtained elasticity value. According to an exemplary embodiment, the controller  310  may calculate a reliability value based on information related to an elasticity value. According to an exemplary embodiment, the controller  310  may determine a reliability value for an obtained elasticity value based on a result of a comparison between the obtained elasticity value and a reference value that corresponds to an induced shear wave. 
     As described above, the “reliability value” for the elasticity value denotes a value which represents a degree to which the elasticity value calculated by the ultrasound imaging apparatus is reliable. 
     For example, when a shear wave is applied to a wave equation, the “reliability value” may be a value which represents a degree to which the shear wave matches the wave equation. An elasticity value may be calculated by inducing a shear wave to an object and using the induced shear wave. A reliability value may be a statistical value of theoretical differences between an elasticity value calculated by using an induced shear wave and an induced shear wave. In particular, the “theoretical difference” may denote a residual value which remains after an elasticity value and an observed shear wave are input into a wave equation. Further, the “statistical value of the theoretical differences” may denote a value calculated by using a sum of the theoretical differences. 
     For example, the controller  310  may calculate a reliability value based on a magnitude of a shear wave and a residual value obtained during a process of calculating an elasticity value. In this aspect, the controller  310  may determine a relatively high reliability value when a magnitude of a shear wave is large, and determine a relatively high reliability value when a residual value is small. 
     A residual value may be a value obtained based on a result of a comparison between an obtained elasticity value and a reference value that corresponds to an induced shear wave. 
     A residual value may be defined by using any of various methods based on an exemplary embodiment. For example, a residual value may be defined by Equation 1 below based on a wave equation. 
     
       
         
           
             
               
                 
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     In Equation 1, the right side is an expression that represents a wave equation, and a value of the right side becomes equal to zero when a waveform completely matches a wave equation. However, an error included in a transverse wave may appear due to an environment that relates to observing a shear wave, an environment that relates to inducing a shear wave, and/or based on other factors, so that a value of the left side may not be equal to zero. 
     In Equation 1, the left side (res) represents a residual value, and the residual value may be a value that corresponds to an error of a transverse wave which appears in an application of the above-described wave equation. In particular, Equation 1 may be a value that represents a difference between an obtained elasticity value and a reference value that corresponds to an induced shear wave. 
     Alternatively, a residual value may be also defined by Equation 2 below based on a Voigt model. 
     
       
         
           
             
               
                 
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     In Equation 2, 
     
       
         
           
             
               
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               ⁢ 
               u 
             
             = 
             
               
                 
                   
                     ∂ 
                     2 
                   
                   ⁢ 
                   u 
                 
                 
                   ∂ 
                   
                     x 
                     2 
                   
                 
               
               + 
               
                 
                   
                     ∂ 
                     2 
                   
                   ⁢ 
                   u 
                 
                 
                   ∂ 
                   
                     y 
                     2 
                   
                 
               
               + 
               
                 
                   
                     ∂ 
                     2 
                   
                   ⁢ 
                   u 
                 
                 
                   ∂ 
                   
                     z 
                     2 
                   
                 
               
             
           
         
       
       
         
           
             
               
                 ∇ 
                 2 
               
               ⁢ 
               u 
             
             = 
             
               
                 
                   1 
                   r 
                 
                 ⁢ 
                 
                   
                     ∂ 
                     
                         
                     
                   
                   
                     ∂ 
                     r 
                   
                 
                 ⁢ 
                 
                   ( 
                   
                     r 
                     ⁢ 
                     
                       
                         ∂ 
                         u 
                       
                       
                         ∂ 
                         r 
                       
                     
                   
                   ) 
                 
               
               + 
               
                 
                   1 
                   
                     r 
                     2 
                   
                 
                 ⁢ 
                 
                   
                     
                       ∂ 
                       2 
                     
                     ⁢ 
                     u 
                   
                   
                     ∂ 
                     
                       θ 
                       2 
                     
                   
                 
               
             
           
         
       
       
         
           
             
               
                 ∇ 
                 2 
               
               ⁢ 
               u 
             
             = 
             
               
                 
                   1 
                   r 
                 
                 ⁢ 
                 
                   
                     ∂ 
                     
                         
                     
                   
                   
                     ∂ 
                     r 
                   
                 
                 ⁢ 
                 
                   ( 
                   
                     r 
                     ⁢ 
                     
                       
                         ∂ 
                         u 
                       
                       
                         ∂ 
                         r 
                       
                     
                   
                   ) 
                 
               
               + 
               
                 
                   1 
                   
                     r 
                     2 
                   
                 
                 ⁢ 
                 
                   
                     
                       ∂ 
                       2 
                     
                     ⁢ 
                     u 
                   
                   
                     ∂ 
                     
                       φ 
                       2 
                     
                   
                 
               
               + 
               
                 
                   
                     ∂ 
                     2 
                   
                   ⁢ 
                   u 
                 
                 
                   ∂ 
                   
                     z 
                     2 
                   
                 
               
             
           
         
       
     
     In this aspect, since the above equation is based on a three-dimensional (3D) image, some terms may not be calculable based on a two-dimensional (2D) ultrasound image. According to an exemplary embodiment, a value that may not be calculable based on a 2D ultrasound image may be processed as being equal to zero. 
     Further, according to an exemplary embodiment, a residual value may denote a normalized value as expressed in Equation 3. 
     
       
         
           
             
               
                 
                   
                     
                       res 
                       n 
                     
                     = 
                     
                       res 
                       
                         ∑ 
                         
                           
                              
                             
                               
                                 ∇ 
                                 2 
                               
                               ⁢ 
                               u 
                             
                              
                           
                           2 
                         
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   or 
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       res 
                       n 
                     
                     = 
                     
                       res 
                       
                         ∑ 
                         
                           
                              
                             
                               
                                 
                                   ∂ 
                                   2 
                                 
                                 ⁢ 
                                 u 
                               
                               
                                 ∂ 
                                 
                                   t 
                                   2 
                                 
                               
                             
                              
                           
                           2 
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   3 
                 
               
             
           
         
       
     
     In Equations 1, 2, and 3, “u” denotes a particle displacement of an observed shear wave or a particle velocity, “c” denotes a transfer velocity of a shear wave, “η” denotes the viscosity of an object, and “ρ” denotes the density of an object. 
     For another example, a residual value may be also defined by Equation 4 based on a time-to-peak method. 
     
       
         
           
             
               
                 
                   res 
                   = 
                   
                     
                       ∑ 
                       i 
                     
                     ⁢ 
                     
                       
                          
                         
                           
                             c 
                             · 
                             
                               x 
                               i 
                             
                           
                           - 
                           
                             t 
                             i 
                           
                         
                          
                       
                       2 
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                 
               
             
           
         
       
     
     In Equation 4, t i  denotes an arrival time of an i-th peak, and x i  denotes a lateral distance of an i-th peak. 
     As described in Equations 1, 2, 3, and 4, a residual value may be a value which represents a difference between an obtained elasticity value and a reference value that corresponds to an induced shear wave. In particular, the “reference value that corresponds to the induced shear wave” may be an ideal elasticity value of a shear wave as applied to a wave equation. 
     The display  320  may display a user interface screen that includes a respective representation of each of an obtained elasticity value and a reliability value. In particular, a method for displaying an elasticity value and a reliability value may vary based on an exemplary embodiment. According to an exemplary embodiment, the display  320  may display each of an elasticity value and a reliability value as a respective numerical value. In this aspect, the reliability value may be equal to or greater than zero (0) and equal to or less than one (1). According to an exemplary embodiment, the display  320  may display a graph that represents a magnitude of a reliability value. Further, according to an exemplary embodiment, the display  320  may display an elasticity value by using a color that corresponds to a magnitude of a reliability value. As described above, when a reliability value is equal to or greater than about 0.7, the display  320  may display an elasticity value as a green letter, and when a reliability value is less than about 0.7, the display  320  may display an elasticity value as a red letter. Alternatively, the display  320  may display at least one from among an image, a letter, an icon, and a symbol that corresponds to a magnitude of a reliability value. Alternatively, the display  320  may display an elasticity value and a reliability value by using a combination of the above exemplary embodiments. 
       FIG. 3B  is a block diagram illustrating a configuration of an ultrasound imaging apparatus  350 , according to another exemplary embodiment. The same components of the ultrasound imaging apparatus  350  as those of the ultrasound imaging apparatus  300  illustrated in  FIG. 3A  are denoted by using the same reference numerals. 
     Compared with the ultrasound imaging apparatus  300 , the ultrasound imaging apparatus  350  may further include at least one of a communication module  360 , an image processor  370 , and a user interface  380 . 
     The communication module  360  may transmit/receive data to/from at least one of an external server, a medical apparatus, and a portable terminal via a wired/wireless communication network. According to an exemplary embodiment, the communication module  360  may equivalently correspond to the communication module  1300  of  FIG. 1 . 
     The ultrasound imaging apparatus  350  may be configured to receive ultrasound data for obtaining an elasticity value of an object from an external medical apparatus, such as, for example, a wireless probe (not shown), and to obtain an elasticity value based on the received ultrasound data. In this case, the communication module  360  may receive ultrasound data from the wireless probe (not shown) via a wireless network. 
     According to an exemplary embodiment, the controller  310  may control to facilitate an inducement of a shear wave to the object  10  via the externally connected wireless probe (not shown). Further, when the wireless probe (not shown) observes the induced shear wave, obtains corresponding ultrasound data, and transmits the obtained ultrasound data to the ultrasound imaging apparatus  350 , the controller  310  may obtain an elasticity value of the object based on the ultrasound data that represents the observation of the induced shear wave. 
     In addition, the controller  310  may determine a reliability value for an obtained elasticity value. According to an exemplary embodiment, the controller  310  may calculate a reliability value based on information that relates to an elasticity value. 
     The display  320  may display a user interface screen that includes a respective representation of each of an obtained elasticity value and a reliability value. 
     The image processor  370  may generate an ultrasound image based on ultrasound data that corresponds to an ultrasound echo signal received from the wireless probe  2000  (see  FIG. 2 ) or the probe  10  (see  FIG. 1 ). The image processor  370  may equivalently correspond to the image processor  1200  of  FIG. 1 . According to an exemplary embodiment, an ultrasound image generated by the image processor  370  may include not only an image of a gray scale obtained by scanning an object under an A mode, a B mode, and an M mode, but also a Doppler image that illustrates a moving object by using a Doppler effect. Further, an ultrasound image generated by the image processor  370  may include an elasticity image that is generated based on ultrasound data. 
     The display  320  may display an ultrasound image generated by the image processor  370 . According to an exemplary embodiment, the display  320  may display a user interface screen that includes each of an ultrasound image, an elasticity value obtained by the controller  310 , and a reliability value that relates to the obtained elasticity value. For example, the display  320  may display a user interface screen that includes each of an ultrasound image in which an elasticity image overlaps on a portion, for example, an ROI of a B mode ultrasound image, an elasticity value obtained by the controller  310 , and a reliability value for the obtained elasticity value. 
     The user interface  380  is configured for receiving a predetermined instruction and/or data from a user. The user interface  380  may correspond to the input device  1600  of  FIG. 1 . 
     According to an exemplary embodiment, the user interface  380  may generate and output a user interface screen for receiving a predetermined instruction and/or data from a user. Further, the user interface  380  may receive a predetermined instruction and/or data from a user via the user interface screen. A user may recognize predetermined information by viewing the user interface screen displayed via the display  320 , and input a predetermined instruction or data via the user interface  380 . 
     According to an exemplary embodiment, the user interface  380  may receive a user input for setting a region of interest (ROI), and set a predetermined region of an ultrasound image as an ROI according to the received user input. 
     An operation of an ultrasound imaging apparatus according to an exemplary embodiment is described below with reference to the ultrasound imaging apparatus illustrated in  FIG. 3B . 
       FIG. 4  is a flowchart illustrating a process for providing an elasticity value, according to an exemplary embodiment. 
     In operation S 4100 , the ultrasound imaging apparatus  350  may obtain an elasticity value of an object. A method for obtaining an elasticity value may be implemented in any of various ways based on an exemplary embodiment. For example, the ultrasound imaging apparatus  350  may induce a shear wave to the object  10  by using the ultrasound transceiver  1100  and the probe  20  of  FIG. 1 . Further, the ultrasound imaging apparatus  350  may obtain an elasticity value of the object  10  based on a velocity of a shear wave included in elasticity data obtained by tracking the shear wave induced by using the ultrasound transceiver  1100  and the probe  20 . For another example, the ultrasound imaging apparatus  350  may receive information which includes an elasticity value from other devices by using the communication module  360 , but is not limited thereto. 
     Then, in operation S 4200 , the ultrasound imaging apparatus  350  may determine a reliability value that relates to the obtained elasticity value. According to an exemplary embodiment, the ultrasound imaging apparatus  350  may calculate a reliability value based on information that relates to an elasticity value. For example, the ultrasound imaging apparatus  350  may calculate a reliability value based on a magnitude of a shear wave and a residual value obtained during a process of calculating an elasticity value. In particular, the ultrasound imaging apparatus  350  may determine a relatively high reliability value when a magnitude of a shear wave is large, and determine a relatively high reliability value when a residual value is small. 
     Then, in operation S 4300 , the ultrasound imaging apparatus  350  may display a respective representation of each of an elasticity value and a reliability value via the display  320 . In this aspect, a method for displaying the elasticity value and the reliability value may vary based on an exemplary embodiment. According to an exemplary embodiment, the display  320  may display each of an elasticity value and a reliability value as a respective numerical value. In particular, the reliability value may be equal to or greater than 0 and equal to or less than 1. According to an exemplary embodiment, the display  320  may display a graph that represents a magnitude of a reliability value. Further, according to an exemplary embodiment, the display  320  may display a representation of an elasticity value by using a color that corresponds to a magnitude of a reliability value. For example, when a reliability value is equal to or greater than about 0.7, the display  320  may display an elasticity value as a green letter, and when a reliability value is less than about 0.7, the display  320  may display an elasticity value as a red letter. Alternatively, the display  320  may display at least one from among an image, a letter, an icon, and a symbol that corresponds to a magnitude of a reliability value. Alternatively, the display  320  may display an elasticity value and a reliability value by using a combination of the above exemplary embodiments. 
       FIG. 5  is a flowchart illustrating a process for obtaining a reliability value, according to an exemplary embodiment. 
     In operation S 5100 , the ultrasound imaging apparatus  350  may induce a shear wave inside an object. The ultrasound imaging apparatus  350  may facilitate the generation of a shear wave inside the object by transmitting an ultrasound wave that pushes a tissue inside the object. Then, in operation S 5200 , the ultrasound imaging apparatus  350  may track the induced shear wave. The ultrasound imaging apparatus  350  may calculate a velocity of the tracked shear wave. 
     In operation S 5300 , the ultrasound imaging apparatus  350  may calculate a magnitude (i.e., an amplitude) of the induced shear wave and an elasticity value based on observations obtained in operation S 5200 . Generally, the velocity of a shear wave is proportional to elasticity. In this aspect, the ultrasound imaging apparatus  350  may calculate an elasticity value based on the velocity of a shear wave. Further, the ultrasound imaging apparatus  350  may obtain a residual value that relates to the obtained elasticity value in operation S 5350 . A residual value may be obtained by using any of various methods based on an exemplary embodiment. 
     Then, in operation S 5400 , the ultrasound imaging apparatus  350  may convert the determined magnitude of the shear wave into a first numerical value. In particular, the first numerical value denotes a value which represents the reliability of an elasticity value as determined based on a magnitude of a shear wave. Generally, since the reliability of an elasticity value is relatively high when a magnitude of a shear wave is large, the ultrasound imaging apparatus  350  may determine the first numerical value based on a magnitude of a shear wave. The first numerical value may be defined by Equation 5 below. 
     
       
         
           
             
               
                 
                   
                     
                       score 
                       u 
                     
                     = 
                     
                       
                         
                           ( 
                           
                             a 
                             
                               
                                 u 
                                 max 
                               
                               - 
                               
                                 u 
                                 min 
                               
                             
                           
                           ) 
                         
                         ⁢ 
                         u 
                       
                       - 
                       
                         ( 
                         
                           
                             a 
                             · 
                             
                               u 
                               min 
                             
                           
                           
                             
                               u 
                               max 
                             
                             · 
                             
                               u 
                               min 
                             
                           
                         
                         ) 
                       
                     
                   
                   , 
                   
                     
 
                   
                   ⁢ 
                   
                     ( 
                     
                       0 
                       ≤ 
                       a 
                       ≤ 
                       1 
                     
                     ) 
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   5 
                 
               
             
           
         
       
     
     In Equation 5, score u  is a first numerical value, “u” is a size (i.e., magnitude or amplitude) of a transverse wave, and u max  and u min  denote values set in advance for obtaining the first numerical value. Further, “a” may represent a maximum value according to a weight for the first numerical value from among reliability values. For example, the first numerical value may be equal to or greater than 0 and equal to or less than “a”. 
     In addition, the ultrasound imaging apparatus  350  may convert a residual value into a second numerical value in operation S 5450 . In particular, the second numerical value denotes the reliability of an elasticity value as determined based on a residual value. Generally, since the reliability of an elasticity value is relatively high when a residual value is small, the ultrasound imaging apparatus  350  may determine the second numerical value based on a residual value. The second numerical value may be defined by Equation 6 below. 
     
       
         
           
             
               
                 
                   
                     
                       score 
                       res 
                     
                     = 
                     
                       
                         
                           - 
                           
                             ( 
                             
                               b 
                               
                                 
                                   res 
                                   n 
                                 
                                 - 
                                 
                                   res 
                                   n 
                                 
                               
                             
                             ) 
                           
                         
                         ⁢ 
                         res 
                       
                       - 
                       
                         ( 
                         
                           
                             b 
                             · 
                             
                               res 
                               min 
                             
                           
                           
                             
                               res 
                               max 
                             
                             - 
                             
                               res 
                               min 
                             
                           
                         
                         ) 
                       
                     
                   
                   , 
                   
                     
 
                   
                   ⁢ 
                   
                     ( 
                     
                       0 
                       ≤ 
                       b 
                       ≤ 
                       1 
                     
                     ) 
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   6 
                 
               
             
           
         
       
     
     In Equation 6, score res  is a second numerical value, res n  is a normalized residual value, and res max  and res min  denote values set in advance for obtaining the second numerical value. Further, “b” may represent a maximum value according to a weight for the second numerical value from among reliability values. For example, the second numerical value may be equal to or greater than 0 and equal to or less than two (2). In particular, in the case in which the reliability value is represented by a numerical value equal to or greater than 0 and equal to or less than 1, sum of “a” and “b” may be 1. For example, “a” may be equal to 0.2, and “b” may be equal to 0.8. 
     Then, in operation S 5500 , the ultrasound imaging apparatus  350  may sum the first numerical value and the second numerical value. In operation S 5600 , the ultrasound imaging apparatus  350  may determine a result of summing the first numerical value and the second numerical value in operation S 5500  as a reliability value. 
       FIG. 6  is a diagram for explaining a shear wave. 
     Referring to  FIG. 6 , in the case in which a force of a point impulse is exerted in a z-axis direction, a “p” wave, which is a longitudinal wave, an “s” wave, which is a transverse wave, and a “ps” wave, in which the two waves are coupled, are generated. In particular, the shear wave is an “s” wave that vibrates in a wave progression direction and progresses in a y-axis direction from a vibration source by which the force is exerted. 
       FIG. 7  is a diagram for explaining a shear wave generated inside an object. 
     As illustrated in  FIG. 7 , the ultrasound imaging apparatus  350  may transmit, to an object  10 , an ultrasound signal  710  (referred to as a “push ultrasound signal”, for convenience of description) for pushing a portion of the object  10 . For example, the ultrasound imaging apparatus  350  may transmit the push ultrasound signal  710 , which has a relatively long wavelength, to the object  10  by using some of channels of the probe  20 . According to an exemplary embodiment, the ultrasound imaging apparatus  350  may transmit the focused push ultrasound signal  710  to a portion of the object  10 . 
     In this case, a shear wave  720  may be generated by the push ultrasound signal  710  inside the object  10 . For example, the shear wave  720  may be generated with a relatively close proximity to a region pushed by the push ultrasound signal  710 . The shear wave  720  may propagate at a velocity of between about 1 m/s and about 10 m/s. Since the velocity of the shear wave  720  is very slow compared with an average velocity (e.g., about 1540 m/s) of an ultrasound signal inside the object  10 , the ultrasound imaging apparatus  350  may use an ultrasound signal (hereinafter referred to as a “tracking ultrasound signal”) in order to track the shear wave  720 . For example, the ultrasound imaging apparatus  350  may track the velocity of the shear wave  720  by transmitting a tracking ultrasound signal in a progression direction of the shear wave  720 . In this case, the wavelength of a tracking ultrasound signal may be shorter than the wavelength of the push ultrasound signal  710 . 
       FIG. 8  is a diagram illustrating a screen displayed by an ultrasound imaging apparatus  350 , according to an exemplary embodiment. 
     The ultrasound imaging apparatus  350  according to an exemplary embodiment may display an ultrasound image  8000 . In particular, when a region of interest (ROI)  8100  is set inside the ultrasound image  8000  based on a user input, the ultrasound imaging apparatus  350  may calculate an elasticity value for the set region of interest, and may determine a reliability value that relates to the elasticity value. The ultrasound imaging apparatus  350  may display a reliability value as a numerical value. The ultrasound imaging apparatus  350  may display the calculated elasticity value and reliability value  8200  as illustrated in  FIG. 8 .  FIG. 8  is a diagram illustrating the case in which an elasticity value is about 3.5 kPa and a reliability value is about 0.9. 
       FIG. 9  is a flowchart illustrating a process of displaying a reliability value in an ultrasound imaging apparatus according to an exemplary embodiment,  FIG. 10  is a diagram illustrating a screen displayed by an ultrasound imaging apparatus according to an exemplary embodiment, and  FIG. 11  is a diagram for explaining a graph displayed by an ultrasound imaging apparatus according to an exemplary embodiment. 
     According to an exemplary embodiment, in operation S 9100 , the ultrasound imaging apparatus  350  may generate a graph that indicates a reliability value which is determined based on an obtained elasticity value. Then, in operation S 9200 , the ultrasound imaging apparatus  350  may display the obtained elasticity value and the generated graph. 
     Referring to  FIG. 10 , when a region  10100  of interest is set with respect to an ultrasound image  10300 , the ultrasound imaging apparatus may display a block  10200  which includes characters that respectively represent an elasticity value and a reliability value. Though  FIG. 10  displays a reliability value as letters, the reliability value may be represented by any of various shapes based on an exemplary embodiment. In particular, the ultrasound imaging apparatus  350  may generate a graph that includes at least one from among a dot, a straight line, a curve, a bar, a circle, and a figure, and that represents a reliability value. Referring to  FIG. 11 , in the case  11010  where an elasticity value is approximately equal to 3.5 kPa and a reliability value is approximately equal to 0.2, the ultrasound imaging apparatus  350  may display an elasticity value and a reliability value  11012  by using a bar  11012 - 1  having a length which corresponds to about 0.2, or may display an elasticity value and a reliability value  11014  by using a portion  11014 - 1  of a circle having an area that corresponds to about 0.2. Further, in the case  11020  in which an elasticity value is approximately equal to 3.5 kPa and a reliability value is approximately equal to 0.9, the ultrasound imaging apparatus  350  may display an elasticity value and a reliability value  11022  by using a bar  11022 - 1  having a length that corresponds to about 0.9, or may display an elasticity value and a reliability value  11024  by using a portion  11024 - 1  of a circle having an area that corresponds to about 0.9. 
       FIG. 12  is a flowchart illustrating a process for displaying a reliability value in an ultrasound imaging apparatus  350 , according to an exemplary embodiment. 
     According to an exemplary embodiment, in operation S 12010 , the ultrasound imaging apparatus  350  may determine a color that corresponds to a reliability value based on a magnitude of the determined reliability value. For example, the ultrasound imaging apparatus  350  may determine that a red color is a color that corresponds to a reliability value when a magnitude of the reliability value is less than 0.3, determine that a yellow color is a color that corresponds to a reliability value when a magnitude of the reliability value is equal to or greater than 0.3 and less than 0.6, and determine that a green color is a color that corresponds to a reliability value when a magnitude of the reliability value is equal to or greater than 0.6. 
     Then, in operation S 12020 , the ultrasound imaging apparatus  350  may display an elasticity value based on the color determined in operation S 12010 . For example, in the case in which an elasticity value is displayed in the red color, a user may recognize that the reliability of the elasticity value is relatively low. 
       FIG. 13  is a flowchart illustrating a process for displaying a reliability value in an ultrasound imaging apparatus  350  according to an exemplary embodiment, and  FIG. 14  is a diagram for explaining a method for displaying a reliability value in an ultrasound imaging apparatus  350  according to an exemplary embodiment. 
     According to an exemplary embodiment, in operation S 13010 , the ultrasound imaging apparatus  350  may select at least one from among an image, one or more letters or words, a symbol, and an icon that corresponds to a reliability value. In this aspect, the image, the letter, the symbol, and the icon are only exemplary, and may be replaced by an arbitrary object that may be visually displayed. 
     Then, in operation S 13020 , the ultrasound imaging apparatus  350  may display the selected at least one from among an elasticity value, the selected image, letter(s) or word(s), symbol, and icon. 
     Referring to  FIG. 14 , when an elasticity value is 3.5 kPa and a reliability value is 0.2 ( 14010 ), the ultrasound imaging apparatus  350  may display the elasticity value and the reliability value  14012  by using a word “poor” ( 14012 - 1 ), which represents that the reliability of an elasticity value is relatively bad. Alternatively, the ultrasound imaging apparatus  350  may display the elasticity value and the reliability value  14014  by using a symbol  14014 - 1  that represents that the reliability of an elasticity value is relatively low. Further, when an elasticity value is 3.5 kPa and a reliability value is 0.9 ( 14020 ), the ultrasound imaging apparatus  350  may display the elasticity value and the reliability value  14022  by using the words “very good” ( 14022 - 1 ), which represents that the reliability of an elasticity value is relatively good. Alternatively, the ultrasound imaging apparatus  350  may display the elasticity value and the reliability value  14024  by using a symbol  14024 - 1  that represents that the reliability of an elasticity value is relatively high. 
     Further, the ultrasound imaging apparatuses  300  and  350  according to an exemplary embodiment may determine the quality of a shear wave observed in response to the induced shear wave. For example, the controller  310  may determine the quality of the shear wave. 
     In this aspect, the quality of the shear wave denotes the quality of the shear wave itself induced to the object  10 . The quality of the shear wave may be determined based on a degree of a noise component that exists in the observed shear wave. In particular, when a noise component is relatively small with respect to a shear wave, the controller  310  may determine that the quality of the shear wave is relatively high, and when a noise component is relatively large with respect to a shear wave, the controller  310  may determine that the quality of the shear wave is relatively high. 
     More particularly, the quality of the shear wave may be calculated based on a signal-to-noise ratio (SNR) of the observed shear wave. 
     Referring to  FIG. 7 , one point  731  inside the object  10  is moved by a shear wave  720  induced to the object  10 . In particular, a maximum distance up to a point  732  to which the one point  731  inside the object  10  is moved is referred to as displacement. The quality of the shear wave may be calculated based on a measured displacement. 
     For example, the quality of the shear wave may be determined based on a calculated displacement profile. According to an exemplary embodiment, a signal-to-noise ratio (SNR) of displacement which varies as a function of time may be determined as the quality of the shear wave. According to an exemplary embodiment, when a displacement occurring while a predetermined point inside the object  10  moves is expressed as an amplitude after the shear wave is induced inside the object  10 , an amplitude graph with respect to time may be referred to as a displacement profile. The quality of the shear wave may extract a high frequency component as a noise component in a displacement profile. Further, an SNR of a displacement may be determined by calculating a root mean square (RMS) value of the extracted noise component as a signal value of a noise component, and calculating the remaining components that exclude the high frequency component as a signal component in a displacement profile. 
     Further, the quality of a shear wave may be calculated by using any of various methods that may quantify a noise component inside the shear wave. 
     In addition, the quality of a shear wave may be determined on a point or region basis, such as a quality determination with respect to at least one point inside an object or a predetermined region of the object, for example, a region of interest (ROI), and/or any other suitable portion of the object. 
     The following description is based on the case of obtaining the quality of a shear wave in a region of interest (ROI) as an example. 
     The display  320  may display a user interface screen which includes a representation of the quality of a shear wave. According to an exemplary embodiment, the display  320  may display a user interface screen which includes a respective representation of each of an obtained elasticity value, a reliability value that relates to the obtained elasticity value, and the determined quality of a shear wave under control of the controller  310 . In particular, the user interface screen may include information which represents each of an ultrasound image, an obtained elasticity value, a reliability value of the obtained elasticity value, and the quality of a shear wave on one screen. 
     Examples of a user interface screen output based on an exemplary embodiment are described below with reference to  FIGS. 15 to 20 . 
       FIG. 15  is a diagram for explaining a method for displaying a reliability value and quality in an ultrasound imaging apparatus  350 , according to an exemplary embodiment. 
     Referring to  FIG. 15 , the ultrasound imaging apparatus  350  may generate and display information that represents the quality of a shear wave in addition to an operation of the ultrasound imaging apparatus  350  illustrated in  FIG. 11 . According to an exemplary embodiment, the ultrasound imaging apparatus  350  may generate and display information that represents the quality of a shear wave in addition to the generating and displaying of the reliability value as illustrated in  FIG. 11 . In  FIG. 15 , like reference numerals are used for the like components of  FIG. 11 . 
     In  FIG. 15 , a quality value  15010  of a shear wave obtained by the ultrasound imaging apparatus  350  is represented by “Q”, and a reliability value is represented by “R”. Further, the case in which a quality value  15010  of a shear wave is converted and displayed so that the quality value  15010  of the shear wave may have a value between 0 and 1 is exemplarily illustrated. 
     Referring to  FIG. 15 , the ultrasound imaging apparatus  350  may generate a graph which includes at least one from among a dot, a straight line, a curve, a bar, a circle, and a figure, and which represents each of a reliability value and a quality value. Referring to  FIG. 15 , the case in which an elasticity value is about 3.5 kPa, a reliability value is about 0.2 ( 11010 ), and a quality value  15010  is about 0.2 is exemplarily illustrated. 
     Referring to a block  15021 , the ultrasound imaging apparatus  350  may display a reliability value R by using a bar  15022  having a length that corresponds to about 0.2, and display a quality value Q by using a bar  15023  having a length that corresponds to about 0.2. 
     Further, referring to a block  15031 , the ultrasound imaging apparatus  350  may display a reliability value R by using a portion  15032  of a circle having an area that corresponds to about 0.2, and display a quality value Q by using a portion  15033  of a circle having an area that corresponds to about 0.2. 
     In addition, the ultrasound imaging apparatus  350  may display a reliability value and a quality value by using a symbol or one or more letters or words which represent that the reliability of an elasticity value is good or bad, and a symbol or one or more letters or words which represent that a quality value of a shear wave is good or bad. 
     According to an exemplary embodiment, referring to a block  15041 , when an elasticity value is about 3.5 kPa, a reliability value is about 0.2, and a quality value is about 0.2, the ultrasound imaging apparatus  350  may display a reliability value R by using a word “poor”  15042  which represents that the reliability of an elasticity value is relatively bad, and display a quality value Q by using a word “poor”  15043  which represents that the quality of a shear wave is relatively bad. 
     Further, referring to a block  15051 , when an elasticity value is about 3.5 kPa, a reliability value is about 0.2, and a quality value is about 0.2, the ultrasound imaging apparatus  350  may display a reliability value R by using a symbol V  15052  which represents that the reliability of an elasticity value is relatively bad, and display a quality value Q by using a symbol V  15053  which represents that the quality of a shear wave is relatively bad. 
     In addition, referring to  FIG. 15 , the case in which an elasticity value is about 3.5 kPa, a reliability value is about 0.9 ( 11020 ), and a quality value ( 15020 ) is about 0.8 is exemplarily illustrated. 
     Referring to a block  15025 , the ultrasound imaging apparatus  350  may display a reliability value R by using a bar  15026  having a length that corresponds to about 0.9, and display a quality value Q by using a bar  15027  having a length that corresponds to about 0.8. 
     Further, referring to a block  15035 , the ultrasound imaging apparatus  350  may display a reliability value R by using a portion  15036  of a circle having an area that corresponds to about 0.9, and display a quality value Q by using a portion  15037  of a circle having an area that corresponds to about 0.8. 
     Still further, the ultrasound imaging apparatus  350  may display a reliability value and a quality value by using a symbol or one or more letters or words which represent that the reliability of an elasticity value is good or bad, and a symbol or one or more letters or words which represent that a quality value of a shear wave is good or bad. 
     According to an exemplary embodiment, referring to a block  15045 , when an elasticity value is about 3.5 kPa, a reliability value is about 0.9, and a quality value is about 0.8, the ultrasound imaging apparatus  350  may display a reliability value R by using the words “very good”  15046 , which represent that the reliability of an elasticity value is relatively high, and display a quality value Q by using the words “very good”  15047 , which represent that the quality of a shear wave is relatively good. 
     Further, referring to a block  15055 , when an elasticity value is about 3.5 kPa, a reliability value is about 0.9, and a quality value is about 0.8, the ultrasound imaging apparatus  350  may display a reliability value R by using a symbol Δ  15056  which represents that the reliability of an elasticity value is relatively high, and display a quality value Q by using a symbol Δ  15057  which represents that the quality of a shear wave is relatively good. 
     Still further, the ultrasound imaging apparatus  350  may display each of a reliability value and an elasticity value by combining at least one of the above-described graph, numerical value, letter, and symbol. 
     In addition, the ultrasound imaging apparatus  350  may display a reliability value and an elasticity value on one screen together with an ultrasound image. An ultrasound image included in the screen may be the above-described A mode image, B mode image, M mode image, elasticity image, Doppler image, etc. Further, an ultrasound image included in the screen may be an image that combines the B mode image, the elasticity image, or the Doppler image with the elasticity image. For example, an ultrasound image displayed on the screen of the ultrasound imaging apparatus  350  may be an image in which the elasticity image overlaps an ROI of the B mode image. 
     Exemplary embodiments of a screen displayed by the ultrasound imaging apparatus  350  are described below with reference to  FIGS. 16 to 20 .  FIGS. 16 to 20  exemplarily illustrate the case where an elasticity value is about 3.5 kPa, a reliability value R is about 0.9, and a quality value Q is about 0.9. 
       FIG. 16  is a diagram illustrating another screen  16000  displayed by an ultrasound imaging apparatus  350 , according to an exemplary embodiment. 
     Referring to  FIG. 16 , the screen  16000  displayed by the ultrasound imaging apparatus  350  includes an ultrasound image  16020 , and a box  16010  that displays an elasticity value, a reliability value, and a quality value. In particular, the elasticity value, the reliability value, and the quality value displayed in the box  16010  may be displayed numerically. Further, the elasticity value, the reliability value, and the quality value displayed in the box  16010  may be values that correspond to a region  16030  of interest inside the ultrasound image  16020 . In addition, the elasticity value, the reliability value, and the quality value displayed in the box  16010  may be an elasticity value, a reliability value, and a quality value that correspond to one specific point inside the ultrasound image  16020 , respectively. 
       FIG. 17  is a diagram illustrating another screen  17000  displayed by an ultrasound imaging apparatus  350 , according to an exemplary embodiment. 
     Referring to  FIG. 17 , the screen  17000  displayed by the ultrasound imaging apparatus  350  includes an ultrasound image  17020 , and a box  17010  that displays an elasticity value, a reliability value, and a quality value. In particular, the elasticity value may be displayed numerically, and the reliability value and the quality value displayed in the box  17010  may be displayed in the form of a graph. According to an exemplary embodiment, as described in  FIG. 15 , the reliability value and the quality value may be displayed by using a graph which includes at least one from among a dot, a straight line, a curve, a bar, a circle, and a figure. Further, the elasticity value, the reliability value, and the quality value displayed in the box  17010  may be values that correspond to a region  17030  of interest inside the ultrasound image  17020 . 
       FIG. 18  is a diagram illustrating another screen  18000  displayed by an ultrasound imaging apparatus  350 , according to an exemplary embodiment. 
     Referring to  FIG. 18 , the screen  18000  displayed by the ultrasound imaging apparatus  350  includes an ultrasound image  18020 , and a box  18010  that displays an elasticity value, a reliability value, and a quality value. In particular, the elasticity value may be displayed numerically, and the reliability value and the quality value displayed in the box  18010  may be displayed in the form that combines a graph with words. 
     For example, referring to the box  18010 , a reliability value and a quality value may be displayed by combining the bar graph illustrated in the block  15025  of  FIG. 15  with the words illustrated in the block  15045  of  FIG. 15 . Further, the elasticity value, the reliability value, and the quality value displayed in the box  18010  may be values that correspond to a region  18030  of interest inside the ultrasound image  18020 . 
       FIG. 19  is a diagram illustrating another screen  19000  displayed by an ultrasound imaging apparatus  350 , according to an exemplary embodiment. 
     Referring to  FIG. 19 , the screen  19000  displayed by the ultrasound imaging apparatus  350  includes an ultrasound image  19020 , and a box  19010  that displays an elasticity value, a reliability value, and a quality value. In particular, the reliability value and the quality value displayed in the region  19010  may be displayed by using a symbol which represents that the reliability value and the quality value are either good or bad. 
     For example, referring to the box  19010 , the reliability value and the quality value may be displayed by using the symbol illustrated in the block  15055  of  FIG. 15 . Further, the elasticity value, the reliability value, and the quality value displayed in the box  19010  may be values that correspond to a region  19030  of interest inside the ultrasound image  19020 . 
       FIG. 20  is a diagram illustrating another screen  20000  displayed by an ultrasound imaging apparatus  350 , according to an exemplary embodiment. 
     Referring to  FIG. 20 , the screen  20000  displayed by the ultrasound imaging apparatus  350  includes an ultrasound image  20020 , and a box  20010  that displays an elasticity value and a reliability value. Further, a quality value may be displayed on a region  20030  of interest in a color level or a gray level  20031  that corresponds to the quality value. According to an exemplary embodiment, the screen  20000  may display a color scale or a gray scale  20040  which represents a quality value. For example,  FIG. 20  illustrates the case where the color scale  20040  which represents a quality value expressed in a value between 0 and 1 is displayed, and a quality value is displayed on the region  20030  of interest by using a color  20041  that corresponds to a value of 0.9 on the color scale  20040 . 
     As described above, the ultrasound imaging apparatus according to an exemplary embodiment may calculate a reliability of an obtained elasticity value more accurately by determining the reliability of the elasticity value by using a residual value. 
     Further, the ultrasound imaging apparatus according to an exemplary embodiment may output a user interface screen that enables a user to recognize a reliability value, or a reliability value and a quality value more intuitively. 
     Exemplary embodiments may be implemented in the form of a recording medium which includes a command that is executable by a computer, such as a program module executed by a computer. A non-transitory computer-readable medium may be an arbitrary available medium that may be accessed by a computer, and include all of a volatile medium, a non-volatile medium, a separation type medium, and a non-separation type medium. Further, a non-transitory computer-readable medium may include both a computer storage medium and a communication medium. The computer storage medium includes all of a volatile medium, a non-volatile medium, a separation type medium, and a non-separation type medium implemented by using an arbitrary method or technology for storing information, such as a computer-readable command, a data structure, a program module, or other data. The communication medium may include a computer-readable command, a data structure, a program module, or other data of a modulated data signal, or other transmission mechanisms, and include an arbitrary information transfer medium. 
     The above explanation is provided for exemplary purposes, and a person of ordinary skill in the art will understand that other specific changes may be easily made without changing the technical spirit or the essential characteristic of the present inventive concept. Therefore, the above described exemplary embodiments should be understood as being exemplary in all aspects, not being limited. For example, each component described as a single form may be distributed and implemented, and likewise, components described as being distributed may be implemented in the form of a combination. 
     The scope of the present inventive concept is defined by the following claims rather than the above detailed descriptions, and it should be construed that all modifications or changed forms derived from the meaning and scope of the claims and the equivalent concept thereof are included in the scope of the present inventive concept.