Ultrasound imaging apparatus and method of generating ultrasound image

Provided are an ultrasound imaging apparatus and method of generating an ultrasound image. The ultrasound imaging apparatus includes: a memory configured to store instructions; and at least one processor configured to execute the stored instructions to: generate, based on echo signals reflected from an object, a first image showing a tissue of the object and a second image showing a contrast medium injected into the object; generate a third image by removing at least a portion of the tissue from the second image based on the first image; and display the generated third image.

BACKGROUND

The present disclosure relates to ultrasound imaging apparatuses and methods of generating an ultrasound image by using the same, and more particularly, to methods and apparatuses for generating an ultrasound image from which at least a portion of a tissue is removed.

2. Description of the Related Art

Ultrasound imaging apparatuses transmit ultrasound signals generated by transducers of a probe to an object and receive echo signals reflected from the object, thereby obtaining at least one image of an internal part of the object (e.g., soft tissues or blood flow). In particular, ultrasound imaging apparatuses are used for medical purposes including observing an inner area of an object, detecting foreign substances, and assessing injuries. Such ultrasound imaging apparatuses provide high stability, display images in real time, and are safe due to there being no radiation exposure, compared to X-ray apparatuses. Therefore, ultrasound imaging apparatuses are widely used together with other image imaging apparatuses including a computed tomography (CT) apparatus, a magnetic resonance imaging (MRI) apparatus, and the like.

Among imaging methods using an ultrasound system, contrast-enhanced ultrasound (CEUS) imaging involves the administration of a contrast medium to an object. Examination using a CEUS image allows a user to quantitatively determine whether an object such as a tumor is malignant or benign by observing a tendency of image signal values of the object over time after injection of the contrast medium into the object.

SUMMARY

Provided are ultrasound imaging apparatuses and methods of generating an ultrasound image by using the same so that a contrast-enhanced image from which at least a portion of a tissue is removed may be obtained.

Provided are ultrasound imaging apparatuses and methods of generating an ultrasound image so that a contrast-enhanced image with improved contrast between blood vessels and tissue may be obtained.

According to an aspect of an embodiment, an ultrasound imaging apparatus includes: a memory configured to store instructions; and at least one processor configured to execute the stored instructions to: generate, based on echo signals reflected from an object, a first image showing a tissue of the object and a second image showing a contrast medium injected into the object; generate a third image by removing at least a portion of the tissue from the second image based on the first image; and display the generated third image.

According to an aspect of another embodiment, a method of generating an ultrasound image includes: generating, based on echo signals reflected from an object, a first image showing a tissue of the object and a second image showing a contrast medium injected into the object; generating a third image by removing at least a portion of the tissue from the second image based on the first image; and displaying the generated third image.

According to an aspect of another embodiment, a computer-readable recording medium has recorded thereon a program for executing the method of generating an ultrasound image on a computer.

DETAILED DESCRIPTION

The terms used in this specification are those general terms currently widely used in the art in consideration of functions regarding the inventive concept, but the terms may vary according to the intention of those of ordinary skill in the art, precedents, or new technology in the art. Also, 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 herein have to be defined based on the meaning of the terms together with the description throughout the specification.

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. In addition, terms such as “ . . . unit”, “ . . . module”, or the like refer to units that perform at least one function or operation, and the units may be implemented as hardware or software or as a combination of hardware and software.

Throughout the specification, an “ultrasound image” refers to an image of an object, which is obtained using ultrasound waves. Furthermore, an “object” may be a human, an animal, or a part of a human or animal. For example, the object may be an organ (e.g., the liver, the heart, the womb, the brain, a breast, or the abdomen), a blood vessel, or a combination thereof. Also, the object may be a phantom. The phantom means 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.

Furthermore, in the present specification, the terms “first”, “second”, “1-1”, etc. are only used to distinguish one component, element, object, image, pixel, or patch from another component, element, object, image, pixel, or patch. Thus, these terms are not limited to representing the order or priority among elements or components. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

Embodiments will now be described more fully hereinafter with reference to the accompanying drawings.

FIG. 1is a block diagram of a configuration of an ultrasound imaging apparatus1000according to an embodiment

Referring toFIG. 1, the ultrasound imaging apparatus1000may include a probe20, an ultrasound transceiver1100, an image processor1200, a communication module1300, a display1400, a memory1500, an input device1600, and a controller1700, which may be connected to one another via buses1800.

The ultrasound imaging apparatus1000may be a cart type apparatus or a portable type apparatus. Examples of portable ultrasound imaging 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 PC.

The probe20transmits ultrasound waves to an object10in response to a driving signal applied by the ultrasound transceiver1100and receives echo signals reflected by the object10. The probe20includes 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 probe20may be connected to the main body of the ultrasound imaging apparatus1000by wire or wirelessly, and according to embodiments, the ultrasound imaging apparatus1000may include a plurality of probes20.

A transmitter1110supplies a driving signal to the probe20. The transmitter110includes a pulse generator1112, a transmission delaying unit1114, and a pulser1116. The pulse generator1112generates pulses for forming transmission ultrasound waves based on a predetermined pulse repetition frequency (PRF), and the transmission delaying unit1114delays 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 probe20, respectively. The pulser1116applies a driving signal (or a driving pulse) to the probe20based on timing corresponding to each of the pulses which have been delayed.

A receiver1120generates ultrasound data by processing echo signals received from the probe20. The receiver120may include an amplifier1122, an analog-to-digital converter (ADC)1124, a reception delaying unit1126, and a summing unit1128. The amplifier1122amplifies echo signals in each channel, and the ADC1124performs analog-to-digital conversion with respect to the amplified echo signals. The reception delaying unit1126delays digital echo signals output by the ADC124by delay times necessary for determining reception directionality, and the summing unit1128generates ultrasound data by summing the echo signals processed by the reception delaying unit1166. In some embodiments, the receiver1120may not include the amplifier1122. In other words, if the sensitivity of the probe20or the capability of the ADC1124to process bits is enhanced, the amplifier1122may be omitted.

The image processor1200generates an ultrasound image by scan-converting ultrasound data generated by the ultrasound transceiver1100. The ultrasound image may be 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 showing a movement of an object via a Doppler effect. The Doppler image may be a blood flow Doppler image showing flow of blood (also referred to as a color Doppler image), a tissue Doppler image showing a movement of tissue, or a spectral Doppler image showing a moving speed of an object as a waveform. The image processor1200may include at least one selected from the group consisting of a processor, a central processing unit (CPU), a microprocessor, and a graphic processing unit (GPU), which process at least one function. The image processor1200may include a plurality of modules, and each of the plurality of modules may process at least one function. The at least one processor included in the image processor1200may be coupled to the memory1500to execute instructions stored in the memory1500. As illustrated inFIG. 1, the image processor1200and the controller1700may be embodied separately. In an exemplary embodiment, the image processor1200may be at least a part of the controller1700.

A B mode processor1212included in a data processor1210extracts B mode components from ultrasound data and processes the B mode components. An image generator1220may generate an ultrasound image indicating signal intensities as brightness based on the extracted B mode components1212.

Similarly, a Doppler processor1214included in the data processor1210may extract Doppler components from ultrasound data, and the image generator1220may generate a Doppler image indicating a movement of an object as colors or waveforms based on the extracted Doppler components.

According to an embodiment, the image generator1220may generate a three-dimensional (3D) ultrasound image via volume-rendering with respect to volume data and may also generate an elasticity image by imaging deformation of the object10due to pressure. Furthermore, the image generator1220may 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 memory1500.

A display1400displays the generated ultrasound image. The display1400may display not only an ultrasound image, but also various pieces of information processed by the ultrasound imaging apparatus1000on a screen image via a graphical user interface (GUI). In addition, the ultrasound imaging apparatus1000may include two or more displays1400according to embodiments.

The communication module1300is connected to a network30by wire or wirelessly to communicate with an external device or a server. The communication module1300may exchange data with a hospital server or another medical apparatus in a hospital, which is connected thereto via a PACS. Furthermore, the communication module1300may perform data communication according to the digital imaging and communications in medicine (DICOM) standard.

The communication module1300may transmit or receive data related to diagnosis of an object, e.g., an ultrasound image, ultrasound data, and Doppler data of the object, via the network30and 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 module1300may receive information about a diagnosis history or medical treatment schedule of a patient from a server and utilizes the received information to diagnose the patient. Furthermore, the communication module1300may 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 module1300is connected to the network30by wire or wirelessly to exchange data with a server32, a medical apparatus34, or a portable terminal36. The communication module1300may include one or more components for communication with external devices. For example, the communication module1300may include a local area communication module1310, a wired communication module1320, and a mobile communication module1330.

The local area communication module1310refers to a module for local area communication within a predetermined distance. Examples of local area communication techniques according to an embodiment may include, but are not limited to, wireless 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 module1320refers to a module for communication using electric signals or optical signals. Examples of wired communication techniques according to an embodiment may include communication via a twisted pair cable, a coaxial cable, an optical fiber cable, and an Ethernet cable.

The mobile communication module1330transmits 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 be voice call signals, video call signals, or various types of data for transmission and reception of text/multimedia messages.

The memory1500stores various data processed by the ultrasound imaging apparatus1000. For example, the memory1500may store medical data related to 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 imaging apparatus1000. For example, the memory1500may store one or more instructions executable by at least one processor.

The memory1500may be any of various storage media, e.g., a flash memory, a hard disk drive, EEPROM, etc. Furthermore, the ultrasound imaging apparatus1000may utilize web storage or a cloud server that performs the storage function of the memory1500online.

The input device1600refers to a means via which a user inputs data for controlling the ultrasound imaging apparatus1000. The input device1600may include hardware components, such as a keypad, a mouse, a touch pad, a touch screen, and a jog switch. However, embodiments are not limited thereto, and the input device1600may further include any of various other input units including 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, etc.

The controller1700may control all operations of the ultrasound imaging apparatus1000. In other words, the controller1700may control operations among the probe20, the ultrasound transceiver1100, the image processor1200, the communication module1300, the display1400, the memory1500, and the input device1600shown inFIG. 1. The controller1700may include at least one selected from the group consisting of a processor, a CPU, a microprocessor, and a GPU, which process at least one function. The controller1700may include a plurality of modules, and each of the plurality of modules may process at least one function. The at least one processor included in the controller1700may be coupled to the memory1500to execute instructions stored in the memory1500. As illustrated inFIG. 1, the controller1700and the image processor1200may be embodied separately. In an exemplary embodiment, the controller1700may be at least a part of the image processor1200.

All or some of the probe20, the ultrasound transceiver1100, the image processor1200, the communication module1300, the display1400, the memory1500, the input device1600, and the controller1700may be implemented as software modules. Furthermore, at least one selected from the ultrasound transceiver1100, the image processor1200, and the communication module1300may be included in the controller1700. However, embodiments of the present invention are not limited thereto.

FIG. 2is a block diagram of a configuration of a wireless probe2000according to an embodiment.

As described above with reference toFIG. 1, the wireless probe2000may include a plurality of transducers, and, according to embodiments, may include some or all of the components of the ultrasound transceiver100shown inFIG. 1.

The wireless probe2000according to the embodiment shown inFIG. 2includes a transmitter2100, a transducer2200, and a receiver2300. Since descriptions thereof are given above with reference toFIG. 1, detailed descriptions thereof will be omitted here. In addition, according to embodiments, the wireless probe2000may selectively include a reception delaying unit2330and a summing unit2340.

The wireless probe2000may transmit ultrasound signals to the object10, receive echo signals from the object10, generate ultrasound data, and wirelessly transmit the ultrasound data to the ultrasound imaging apparatus1000shown inFIG. 1.

FIG. 3is a block diagram of a configuration of an ultrasound imaging apparatus1000according to an embodiment.

Referring toFIG. 3, the ultrasound imaging apparatus1000may include an image processor1200and a display1400. However, all of the components shown inFIG. 3are not essential components. The ultrasound imaging apparatus1000may include more or fewer components than those shown inFIG. 3.

The image processor1200may process ultrasound image data according to an image display mode. The image processor1200may acquire brightness (B) mode data by performing processing such as amplification, logarithmic compression, and envelope detection on echo signals reflected from an object or obtain contrast enhanced mode data by intravenously injecting ultrasound contrast medium containing microbubbles into the object.

The image processor1200may use strong nonlinear effects of an ultrasound contrast medium in a contrast enhanced ultrasound (CEUS) mode. Due to the nonlinear effects of ultrasound contrast medium, waves reflected from microbubbles are greatly distorted compared to incident waves, which causes generation of harmonic components. Based on the above characteristics, the image processor1200may use a contrast harmonic imaging technique to suppress fundamental waves by imaging a harmonic wave having a frequency twice the frequency of fundamental waves while the ultrasound contrast medium is further enhanced. By using the contrast harmonic imaging technique, it is possible to obtain an image in which waves reflected from a contrast medium are enhanced since waves reflected from microbubbles contain more second harmonic wave components than waves reflected from a biological tissue.

The image processor1200may generate a first image showing tissue of the object based on echo signals reflected from the object. In an exemplary embodiment, the first image may be a B mode ultrasound image.

The image processor1200may generate, based on echo signals reflected by the object, a second image showing contrast medium injected into the object. In an exemplary embodiment, the second image may be a contrast enhanced ultrasound image. The second image may be generated based on echo signals reflected from the contrast medium injected into the object.

During generation of the second image, a signal reflected due to a movement of the tissue of the object may interfere with a signal reflected by the ultrasound contrast medium, which may degrade the contrast of blood vessels in the second image. To mitigate this effect of the signal reflected due to the movement of the tissue of the object, an intensity of the signal may be supressed during signal processing. However, according to this method, the intensity of the signal may be suppressed insufficiently.

To solve these problems, the image processor1200may generate a third image by removing at least a portion of a tissue from the second image based on the first image. Like the second image, the third image may be a contrast-enhanced ultrasound image. A method of removing at least a portion of a tissue from the second image based on the first image will be described in more detail below with reference toFIGS. 4A and 4B.

The third image from which at least a portion of the tissue is removed may exhibit improved contrast of blood vessels in comparison to the second image.

The display1400may display 2D and/or 3D ultrasound images. Furthermore, the display1400may display the first image together with the second or third image. For example, the display1400may display a B mode ultrasound image together with a contrast-enhanced ultrasound image or an improved contrast-enhanced ultrasound image.

FIG. 4Ais an exemplary diagram of first through third images410,420, and430aaccording to an embodiment.

Referring toFIG. 4A, the first and second images410and420may respectively show tissues411and421. In the first and second images410and420, the tissues411and412may appear brighter than other regions. The first and second images410and420may be a B mode ultrasound image and a contrast-enhanced ultrasound image, respectively.

The image processor1200may generate the third image430aby removing at least a portion of a tissue from the second image420based on the first image410. Similar to the second image420, the third image430amay be a contrast-enhanced ultrasound image.

According to an embodiment, the image processor1200may generate the third image430aby removing from the second image420a portion of a tissue which the first and second images410and420have in common. For example, as shown inFIG. 4A, the image processor1200may generate the third image430aby removing tissue421from the second image420.

As shown inFIG. 4A, a portion431ain the generated third image430acorresponding to the tissue421in the second image420may be significantly suppressed.

According to an embodiment, to remove a portion which the first and second images410and420have in common from the second image420, the image processor1200may perform image subtraction by subtracting the first image410from the second image420. The third image430amay be generated as a result of performing the image subtraction. The generated third image430amay be less affected by the tissue411in the first image410than the second image420. Since a portion which the first and second images410and420have in common is removed and is not shown in the third image430a, the third image430amay exhibit improved contrast of blood vessels in comparison to the second image420.

According to an embodiment, a portion shown in the second image420but not in the first image410may be emphasized in the third image430a. For example, blood vessels depicted by a contrast medium may be emphasized in the third image430a.

FIG. 4Bis an exemplary diagram of third and fourth images430aand430baccording to an embodiment.

Referring toFIGS. 4A and 4B, the image processor1200may generate the fourth image430bby removing at least a portion of a tissue from the second image420based on the first image410. Portions removed from the second image420in order to generate the third and fourth images430aand430bmay have different sizes. For example, as shown in431aand431bofFIG. 4B, a portion removed in order to generate the fourth image430bmay be larger than a portion removed in order to generate the third image430a. Like the second image420, the third and fourth images430aand430bmay both be contrast-enhanced ultrasound images.

FIG. 5is an exemplary diagram of a user interface (UI) for displaying a plurality of contrast-enhanced ultrasound images, according to an embodiment

As shown inFIG. 5, the display1400may alternately display a plurality of contrast-enhanced ultrasound images530based on a user input. In this case, sizes of the portions removed based on a B mode ultrasound image510may vary across the plurality of contrast-enhanced ultrasound images530. For example, the plurality of contrast-enhanced ultrasound images530may be displayed alternately on the display1400in an order from a contrast-enhanced ultrasound image530afrom which a portion overlapping with the B mode ultrasound image510is not removed, to a contrast-enhanced ultrasound image530dfrom which a portion overlapping with the B mode ultrasound image510is removed, the portion being larger than other portions of contrast-enhanced ultrasound images530a,530b, and530c. In this case, a lowest weight may be assigned to the contrast-enhanced ultrasound image530a, and a highest weight may be assigned to the contrast-enhanced ultrasound image530d.

In this case, the user input may be received by the ultrasound imaging apparatus100via the input device1600. For example, if a user input for increasing “FlowMAX index” is received by the ultrasound imaging apparatus1000via the input device1600, the display1400may display a contrast-enhanced ultrasound image with the portion overlapping with the B mode ultrasound image510removed to a greater extent. If a user input for decreasing “FlowMax Index” is received by the ultrasound imaging apparatus1000, the display1400may display a contrast-enhanced ultrasound image with the portion overlapping with the B mode ultrasound image510removed to a lesser extent or to no extent.

AlthoughFIG. 5shows that the input device1600is a touch screen, the input device1600may be implemented as a jog switch.

FIG. 6is a diagram for explaining a method of generating a third image according to an embodiment.

Referring toFIG. 6, the image processor1200may extract a region of interest (ROI) from a first image610. The ROI may be extracted based on a predetermined criterion. For example, a region having a brightness that is greater than or equal to a predetermined threshold value in the first image610may be extracted as the ROI.

A white mask612may be detected by extracting regions having a brightness that is greater than or equal to the predetermined threshold value from the first image610.

According to an embodiment, at least one of the first and second images610and620may be corrected so that regions corresponding to the white mask612in the first and second images610and620have the same average brightness. For example, the first image610may be normalized so that regions corresponding to the white mask612in the normalized first image614and the second image620have the same average brightness. Since at least one of the first and second images610and620is normalized so that regions corresponding to the white mask612in the first and second images610and620have an equal average brightness, image subtraction may be performed by subtracting the normalized first image614from the second image620. After preforming the image subtraction, a third image630may be generated by removing the region corresponding to the white mask612in the second image620.

According to an embodiment, by removing the region corresponding to the white mask612in the second image620, tissues other than blood vessels may be removed from the second image620. Thus, the third image630may exhibit improved contrast of blood vessels compared to other contrast-enhanced ultrasound images as well as the second image620.

In an embodiment, a decrease in an intensity of a B mode signal due to injection of a contrast medium may offset saturation of a contrast-enhanced signal by adjusting image parameters of the third image630. For example, a brightness of the third image630may be adjusted. In this case, the brightness of the third image630may be adjusted based on a threshold value, a minimum value, a maximum value, etc.

For example, the third image630may be corrected so that a brightness of the third image630is approximately equal to that of the second image620. As shown inFIG. 6, since a brightness of a corrected third image632approximates that of the second image, the corrected third image632may appear darker than the third image630.

By adjusting the brightness of the third image630, speckles in the third image630and flickering caused by regions removed from the second image620may be eliminated. For example, if the plurality of contrast-enhanced ultrasound images530displayed as shown inFIG. 5have different brightnesses, speckles may occur and flickering may be caused by a change of removed regions. According to an embodiment, by adjusting brightness of the plurality of contrast-enhanced ultrasound images530, speckles and flickering may be suppressed in the plurality of contrast-enhanced ultrasound images530.

FIG. 7illustrates second and third images of different body parts according to an embodiment.

Referring toFIG. 7, according to an embodiment, second and third images720aand730ashowing an aorta, second and third images720band730bshowing a kidney720band730b, second and third images720cand730cshowing a gallbladder, and second and third images720dand730dshowing a liver may be generated.

The third image730aof the aorta shows improved distinguishability between blood vessels and tissue compared to the second image720a. In detail, by darkening tissue that appears bright in the second image720ain the third image730a, distinguishability between blood vessels and tissue is improved in the third image730a. Furthermore, as shown in a white-rimmed oval shape within the third image730a, the aorta that is difficult to distinguish in the second image720ais clearly depicted in the third image730a.

The third image730bof the kidney shows improved distinguishability between blood vessels and tissue compared to the second image720b. In detail, as shown in a white-rimmed oval shape within the third image730b, the shape of the kidney is clearly defined so that the kidney is easily distinguishable from other body parts. Furthermore, blood vessels in the kidney are more clearly depicted in the third image730bthan in the second image720b.

The third image730cof the gallbladder shows improved distinguishability between blood vessels and tissue compared to the second image720c. In detail, as shown in a white-rimmed oval shape within the third image730c, polyps may appear in the third image730cand a boundary of the gallbladder in the third image730cis more clearly defined than in the second image720c.

The third image730dof the liver shows improved distinguishability between blood vessels and tissue compared to the second image720d. In detail, as shown in a white-rimmed oval shape within the third image730d, polyps may appear, and a boundary of metastatic cancer is more clearly defined than in the second image720d.

FIG. 8illustrates first through fourth images obtained in the case of a healthy individual, according to an embodiment, andFIG. 9illustrate first through fourth images obtained in the case of an individual with mild renal artery stenosis, according to an embodiment.

As shown inFIGS. 8 and 9, first images810and910, second images820and920, third images830aand930a, and fourth images830band930bmay be generated by an ultrasound imaging apparatus according to an embodiment. Renal arteries and cross-sections of aorta are more clearly depicted in the fourth images830band930bwith improved contrast of blood vessels than in the other contrast-enhanced ultrasound images820,920,830a, and930a.

FIG. 10is a flowchart of a method of generating a third image according to an embodiment.

An image processor of an ultrasound imaging apparatus generates first and second images based on echo signals reflected from an object (S1000).

The first image mainly shows tissue of the object, and the second image mainly shows a contrast medium injected into the object. In this case, the first and second images may be a B mode ultrasound image and a contrast-enhanced ultrasound image, respectively.

The image processor generates a third image by removing at least a portion of a tissue from the second image based on the first image (S1010).

According to an embodiment, the image processor may generate the third image by removing a portion which the first and second images have in common from the second image.

According to an embodiment, in order to remove the portion which the first and second images have in common from the second image, the image processor may perform image subtraction by subtracting the first image from the second image.

According to an embodiment, a portion shown in the second image but not in the first image may be emphasized in the third image. For example, blood vessels depicted by a contrast medium may be emphasized in the third image.

According to an embodiment, the image processor may extract an ROI from the first image. The ROI may be extracted based on a predetermined criterion. For example, a region having a brightness that is greater than or equal to a predetermined threshold value in the first image may be extracted as the ROI.

A white mask may be detected by extracting regions having a brightness that is greater than or equal to a predetermined threshold value from the first image.

According to an embodiment, the image processor may correct at least one of the first and second images so that regions corresponding to the white mask in the first and second images have the same average brightness.

In an embodiment, a decrease in intensity of a B mode signal due to injection of a contrast medium may offset saturation of a contrast-enhanced signal by adjusting image parameters of the third image. For example, a brightness of the third image may be adjusted based on a threshold value, a minimum value, a maximum value, etc.

A display of the ultrasound imaging apparatus displays the third image generated in operation S1010(S1020).

The third image may be displayed parallel to the first image. Furthermore, as described above with reference toFIG. 5, the third image as a contrast-enhanced ultrasound image may be displayed alternately with other contrast-enhanced ultrasound images.

Embodiments may be implemented through non-transitory computer-readable recording media having recorded thereon computer-executable instructions such as program modules that are executed by a computer. The non-transitory computer-readable recording media may be any available media that can be accessed by a computer and include both volatile and nonvolatile media and both detachable and non-detachable media. Furthermore, the non-transitory computer-readable recording media may include computer storage media and communication media. The computer storage media include both volatile and nonvolatile and both detachable and non-detachable media implemented by any method or technique for storing information such as computer-readable instructions, data structures, program modules, or other data. The communication media typically embody computer-readable instructions, data structures, program modules, other data of a modulated data signal, or other transmission mechanism, and may include any information transmission media