Patent Publication Number: US-2023157669-A1

Title: Ultrasound imaging system and method for selecting an angular range for flow-mode images

Description:
FIELD OF THE INVENTION 
     This disclosure relates generally to an ultrasound imaging system and method for setting an angular range for use with flow-mode images. 
     BACKGROUND OF THE INVENTION 
     Using various conventional ultrasound modes, such as color flow and vector flow, it is possible to determine velocities for various flowing fluids, such as blood. For example, while in a color flow imaging mode, Doppler information is color-encoded and the colors are overlaid on a grey-scale (B-mode) image. While in a vector-flow imaging mode, the direction information of the fluid is represented using depictions of lines or vectors that are overlaid on a grey-scale (B-mode) image. 
     Using flow-mode imaging, such as color flow or vector flow imaging, provides the clinician with valuable information about the way the fluid is moving. However, since conventional flow-mode imaging typically represents velocity information of fluid moving in many different directions, it is oftentimes difficult for the clinician to use the flow-mode imaging to accurately assess a patient and/or diagnose a specific condition. For example, it may be difficult for the clinician to easily identify the relevant portions of the flow-mode images due to the presence of velocity information from many different directions when velocity information from only a subset of the directions is needed to make an assessment or diagnosis. 
     Therefore, for these and other reasons, an improved ultrasound imaging system and method of adjusting an angular range for use with the display of a flow-mode image is desired. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The above-mentioned shortcomings, disadvantages and problems are addressed herein which will be understood by reading and understanding the following specification. 
     In an embodiment, a method of ultrasound imaging includes displaying an initial ultrasound image, and receiving, through a user interface, a selection of a flow region, wherein the flow region includes a subset of the initial ultrasound image. The method includes receiving, through the user interface, a selection of an angular range, wherein the angular range is less than 360 degrees. The method includes displaying a flow-mode image on the display device after receiving both the selection of the flow region and the selection of the angular range, wherein the flow-mode image represents flow information that is both within the flow region and within the selected angular range, and wherein the flow-mode image does not represent flow information that is either outside the flow region or outside of the angular range. 
     In another embodiment, an ultrasound imaging system includes a user interface, an ultrasound probe, a display device, and a processor. The processor is configured to display an initial ultrasound image on the display device. The processor is configured to receive a selection of a flow region via the user interface, wherein the flow region includes a subset of the initial ultrasound image. The processor is configured to receive a selection of an angular range via the user interface, wherein the angular range is less than 360 degrees. The processor is configured to display a flow-mode image on the display device, wherein the flow-mode image represents flow information that is both within the flow region and within the selected angular range. Wherein the flow-mode image does not represent flow information that is either outside the flow region or outside the angular range. 
     Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the accompanying drawings and detailed description thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of an ultrasound imaging system in accordance with an embodiment; 
         FIG.  2    is an exploded representation of touchscreen in accordance with an embodiment; 
         FIG.  3    is a top view of a multi-function controller in accordance with an embodiment; 
         FIG.  4    is a side view of a multi-function controller in accordance with an embodiment; 
         FIG.  5    is a flow chart of a method in accordance with an embodiment; 
         FIG.  6    is a representation of an ultrasound image in accordance with an embodiment; 
         FIG.  7    is a schematic representation of an ultrasound image in accordance with an embodiment; 
         FIG.  8    is a representation of a flow-mode image in accordance with an embodiment; 
         FIG.  9    is a representation of a flow-mode image in accordance with an embodiment; 
         FIG.  10    is a representation of a flow-mode image in accordance with an embodiment; and 
         FIG.  11    is a representation of a flow-mode image in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized, and that logical, mechanical, electrical, and other changes may be made without departing from the scope of the embodiments. The following detailed description is, therefore, not to be taken as limiting the scope of the invention. 
       FIG.  1    is a schematic diagram of an ultrasound imaging system  100  in accordance with an embodiment. The ultrasound imaging system  100  includes a transmit beamformer  101  and a transmitter  102  that drive elements  104  within an ultrasound probe  106  to emit pulsed ultrasonic signals into a body (not shown) through one or more transmit events. The ultrasound probe  106  may be any type of ultrasound probe. For example, the ultrasound probe  106  may be a linear array probe, a curved-linear array probe, a convex array probe, a phased array probe, a  2 D matrix array probe capable of  3 D or  4 D scanning, a mechanical  3 D probe, etc. Still referring to  FIG.  1   , the pulsed ultrasonic signals are back-scattered from structures in the body to produce echoes that return to the elements  104 . The ultrasound probe  106  may be in electrical communication with one or more other components of the ultrasound imaging system  100  via wired and/or wireless techniques. The echoes are converted into electrical signals by the elements  104  and the electrical signals are received by a receiver  108 . The electrical signals representing the received echoes are passed through a receive beamformer  110  that outputs ultrasound data. According to some embodiments, the ultrasound probe  106  may contain electronic circuitry to do all or part of the transmit beamforming and/or the receive beamforming. For example, all or part of the transmit beamformer  101 , the transmitter  102 , the receiver  108  and the receive beamformer  110  may be situated within the ultrasound probe  106 . According to some embodiments, the ultrasound probe  106  may be configured to wirelessly communicate with a phone-sized or tablet-sized device and the ultrasound probe  106  and either the phone-sized device or the tablet-sized device may collectively perform all the functions associated with the elements identified on  FIG.  1   . The terms “scan” or “scanning” may also be used in this disclosure to refer to acquiring data through the process of transmitting and receiving ultrasonic signals. The terms “data” and “ultrasound data” may be used in this disclosure to refer to either one or more datasets acquired with an ultrasound imaging system  100 . A user interface  115  may be used to control operation of the ultrasound imaging system  100 . The user interface  115  may be used to control the input of patient data, or to select various modes, operations, parameters, and the like. The user interface  115  may include one or more user input devices such as a keyboard, hard keys, a touch pad, a track ball, rotary controls, sliders, soft keys, or any other user input devices. According to some embodiments, the user interface  115  may include a touch panel that is part of a touchscreen. An exemplary touchscreen will be described hereinafter with respect to  FIG.  2   . 
     The ultrasound imaging system  100  includes a display device  118 . The display device  118  may include any type of display screen or display that is configured to display images, text, graphical user interface elements, etc. The display device  118  may be, for example, a cathode ray tube (CRT) display, a light-emitting diode (LED) display, an organic light-emitting diode (OLED) display, a liquid crystal display (LCD), etc. According to some embodiments, the display device  118  may be a display screen that is a component of a touchscreen. 
     As discussed above, the display device  118  and the user interface  115  may be components in a touchscreen.  FIG.  2    is an exploded representation of a touchscreen  122  in accordance with an exemplary embodiment. The touchscreen  122  includes a touch panel  126  and a display screen  128  in accordance with an embodiment. The touch panel  126  may be located behind the display screen  128  or in front of the display screen  128  according to various non-limiting examples. For embodiments where the touch panel  126  is positioned in front of the display screen  128 , the touch panel  126  may be configured to be substantially transparent so that the user may see images displayed on the display screen  128 . The touch panel  126  may utilize any type of technology configured to detect a touch or gesture applied to the touch panel  126  of the touchscreen  122 . As discussed hereinabove, the display device  118  may include a display screen of a touchscreen such as the display screen  128 , and the user interface  115  may include a touch panel, such as the touch panel  126  of the touchscreen  122 . The touch panel  126  may be configured to detect single-point touch inputs and/or multi-point touch inputs according to various embodiments. The touch panel  126  may utilize any type of technology configured to detect a touch or gesture applied to the touch panel  126  of the touchscreen  122 . For instance, the touch panel  126  may include resistive sensors, capacitive sensors, infrared sensors, surface acoustic wave sensors, electromagnetic sensors, near-filed imaging sensor, or the like. Some embodiments may utilize the touch panel  126  of the touchscreen  122  to provide all of the user interface functionalities for the ultrasound imaging system  100 , while other embodiments may also utilize one or more other components as part of the user interface  115 . 
     Referring back to  FIG.  1   , the ultrasound imaging system  100  also includes a processor  116  to control the transmit beamformer  101 , the transmitter  102 , the receiver  108  and the receive beamformer  110 . The user interface  115  is in electronic communication with the processor  116 . The processor  116  may include one or more central processing units (CPUs), one or more microprocessors, one or more microcontrollers, one or more graphics processing units (GPUs), one or more digital signal processors (DSP), and the like. According to some embodiments, the processor  116  may include one or more GPUs, where some or all of the one or more GPUs include a tensor processing unit (TPU). According to embodiments, the processor  116  may include a field-programmable gate array (FPGA), or any other type of hardware capable of carrying out processing functions. The processor  116  may be an integrated component or it may be distributed across various locations. For example, according to an embodiment, processing functions associated with the processor  116  may be split between two or more processors based on the type of operation. For example, embodiments may include a first processor configured to perform a first set of operations and a second, separate processor to perform a second set of operations. According to embodiments, one of the first processor and the second processor may be configured to implement a neural network. The processor  116  may be configured to execute instructions accessed from a memory. According to an embodiment, the processor  116  may be in electronic communication with the ultrasound probe  106 , the receiver  108 , the receive beamformer  110 , the transmit beamformer  101 , and the transmitter  102 . For purposes of this disclosure, the term “electronic communication” may be defined to include both wired and wireless connections. The processor  116  may control the ultrasound probe  106  to acquire ultrasound data. The processor  116  controls which of the elements  104  are active and the shape of a beam emitted from the ultrasound probe  106 . The processor  116  is also in electronic communication with a display device  118 , and the processor  116  may process the ultrasound data into images for display on the display device  118 . According to embodiments, the processor  116  may also include a complex demodulator (not shown) that demodulates the RF data and generates raw data. In another embodiment the demodulation can be carried out earlier in the processing chain. The processor  116  may be adapted to perform one or more processing operations according to a plurality of selectable ultrasound modalities on the data. The data may be processed in real-time during a scanning session as the echo signals are received. The processor  116  may be configured to scan-convert the ultrasound data acquired with the ultrasound probe  106  so it may be displayed on the display device  118 . Displaying ultrasound data in real-time may involve displaying the ultrasound data without any intentional delay. For example, the processor  116  may display each updated image frame as soon as each updated image frame of ultrasound data has been acquired and processed for display during the display of a real-time image. Real-time frame rates may vary based on the size of the region or volume from which data is acquired and the specific parameters used during the acquisition. According to other embodiments, the data may be stored temporarily in a buffer (not shown) during a scanning session and processed in less than real-time. According to embodiments that include a software beamformer, the functions associated with the transmit beamformer  101  and/or the receive beamformer  110  may be performed by the processor  116 . 
     According to an embodiment, the ultrasound imaging system  100  may continuously acquire ultrasound data at a frame-rate of, for example, 10 Hz to 30 Hz. Images generated from the data may be refreshed at a similar frame-rate. Other embodiments may acquire and display data at different rates. For example, some embodiments may acquire ultrasound data at a frame rate of less than 10 Hz or greater than 30 Hz depending the size of each frame of data and the parameters associated with the specific application. For example, many applications involve acquiring ultrasound data at a frame rate of about 50 Hz. A memory  120  is included for storing processed frames of acquired data. In an exemplary embodiment, the memory  120  is of sufficient capacity to store frames of ultrasound data acquired over a period of time at least several seconds in length. The frames of data are stored in a manner to facilitate retrieval thereof according to its order or time of acquisition. The memory  120  may comprise any known data storage medium. 
     In various embodiments of the present invention, data may be processed by other or different mode-related modules by the processor  116  (e.g., B-mode, M-mode, color M-mode, spectral Doppler, Elastography, TVI, strain, strain rate, color flow, vector flow, and the like) to form  2 D or  3 D data. For example, one or more modules may generate B-mode, M-mode, color M-mode, spectral Doppler, Elastography, TVI, strain, strain rate, color flow, vector flow, and the like. The data may be processed to generate a flow-mode image. A flow-mode image is an ultrasound image that is used to present information about a moving or flowing fluid. The flow-mode image may, for instance present velocity information about a flowing fluid. Non-limiting examples of flow-mode images include color flow images and vector flow images. A color flow image may be generated while in a color flow imaging mode and a vector flow image may be generated while in a vector flow imaging mode. While color flow images and vector flow images were presented as two examples of flow-mode images, it should be appreciated by those skilled in the art that other types of flow-mode images may be used to show flow information according to various embodiments. The image beams and/or frames are stored, and timing information indicating a time at which the data was acquired in memory may be recorded. The modules may include, for example, a scan conversion module to perform scan conversion operations to convert the image frames from beam space coordinates to display space coordinates. A video processor module may be provided that reads the image frames from a memory, such as the memory  120 , and displays the image frames in real time while a procedure is being carried out on a patient. The video processor module may store the image frames in an image memory, from which the images are read and displayed. 
     According to some embodiments, the user interface  115  may include a multi-function controller. The multi-function controller is configured to accept inputs or commands by either tilting the multi-function controller like a joystick (i.e., “joystick inputs”) or by rotating some or all of the multi-function controller like a rotary or dial. The multi-function controller is therefore able to receive both rotational inputs and joystick inputs.  FIG.  3    is a top view of a multi-function controller  300  in accordance with an embodiment.  FIG.  4    is a side view of the multi-function controller  300  in accordance with an embodiment. The multi-function controller  300  is configured to receive commands through a variety of different physical inputs. For example, the multi-function controller  300  is configured to be tilted like a joystick. The multifunction controller  300  may, for instance, be tiled about a pivot point. The multi-function controller  300  is configured to be tilted in any direction as indicted by arrows  312 . The multifunction controller  300  is also configured to receive rotational inputs. The multi-function controller  300  may be configured to receive a command input selecting the angular range. For example, the multi-function controller  300  includes an outer bezel  304  that is configured to be rotated about an inner bezel  306 . The clinician may rotate the outer bezel  304  with respect to the inner bezel  306  as indicated by curved arrows  310 . According to other embodiments, the multi-function controller may not include a separate rotatable bezel. Instead, the multi-function controller may be configured as a joystick that is rotatable about a longitudinal axis. (not shown) The multi-function controller  300  shown in  FIG.  3    also includes a button  308 . Other embodiments may not include the button  308 , but may instead be configured to receive a press input by depressing the multi-function controller  300  in a direction parallel to a longitudinal axis. The clinician may input a button press command via the button  308 . The multi-function controller  300  is configured to receive physical commands through three different types of physical inputs: tilting, rotating, and pressing. According to other embodiments, the multi-function controller may not include the button  308 . 
       FIG.  5    illustrates a flowchart of an embodiment of a method  500 . The method  500  shown in  FIG.  5    may be performed with the ultrasound imaging system  100  shown in  FIG.  1    according to an exemplary embodiment. The technical effect of the method  300  is the display of a flow-mode image representing flow information of a selected flow region within a selected angular range. 
     At step  502 , the processor  116  accesses ultrasound data. The ultrasound data accessed by the processor  116  at step  502  may be accessed in real-time as the ultrasound data is acquired, or the ultrasound data accessed at step  512  may be retrieved from memory based an acquisition performed at an earlier time. According to an embodiment, the processor  116  may access the ultrasound data from a memory, such as the memory  120 . According to other embodiments, the processor  116  may access the ultrasound data from a remote memory or server. The ultrasound data may be accessed in real-time during a live ultrasound procedure or retrospectively after the ultrasound examination has been completed. For example, the processor  116  may access the ultrasound data from an ultrasound examination that was performed earlier on the same day as the method  500 . Or the processor  116  may access the ultrasound data from an ultrasound examination performed days before the implementation of the method  500 . According to various embodiments, the processor  116  may access the ultrasound data directly from other components, such as the receive beamformer  110 . 
     At step  504 , the processor  116  generates an initial ultrasound image. The initial ultrasound image may be generated while in any ultrasound image mode. For example, the initial image may be a B-mode image, a flow-mode image, such as a color flow image, a vector flow image, or any other type of ultrasound image. 
       FIG.  6    is an initial ultrasound image  600  in accordance with an embodiment. The initial ultrasound image  600  shown in  FIG.  6    is a color flow image, but, as discussed hereinabove, the initial ultrasound image in other embodiments may be any type of ultrasound image mode. For example, the initial ultrasound image may be a B-mode image according to various embodiments. 
     The initial ultrasound image  600  shown in  FIG.  6    is a color flow image. Color flow images typically use color to represent the direction of flow. In conventional color flow images, flow in a direction towards the transducer is represented in red and flow in a direction away from the transducer is represented in blue. In  FIG.  6   , red areas are represented with diagonal hatching and blue areas are represented with stippling. As discussed hereinabove, a color flow image is an example of a flow-mode image. As such, the initial ultrasound image  600  shown in  FIG.  6    is a flow-mode image. However, the initial ultrasound image may not be a flow-mode image according to other embodiments. For example, the initial ultrasound image  600  may be a B-mode image according to various embodiments. 
     At step  506 , the initial ultrasound image, such as the initial ultrasound image  600 , is displayed on the display device  118 . According to some embodiments, the initial ultrasound image may be based on the most recently acquired frame of ultrasound data during a live or real-time ultrasound acquisition. 
     At step  508 , the processor  116  receives a selection of a flow region via the user interface  115 . The flow region represents a subset of the initial ultrasound image. The selection of the flow region will be described in detail hereinafter. 
     The clinician may interact with the user interface  115  to select the flow region that is received by the processor  116  at step  508 . The clinician may interface with the user interface  115  in any number of ways to select the flow region. A non-limiting list of ways that the clinician may interact with the user interface  115  to select the flow region includes: designating a boundary around the flow region, highlighting the flow region, positioning a ROI (region of interest) around the flow region, or positioning an origin on the initial image  600  to define the flow region. 
     According to an embodiment, the clinician may select the flow region by designating a boundary around the flow region. The clinician may, for example, drawn or trace an outline or boundary around the flow region on the initial ultrasound image using inputs to a mouse, a trackball, a touchpad, or a touch panel of touchscreen to designate the boundary. According to embodiments where the clinician designates the boundary on a touchscreen, the clinician may simply input a gesture or gestures tracing the boundary of the desired flow region on the initial ultrasound image. According to embodiments where the clinician designates the flow region using a mouse, trackball, or touchpad, the clinician may move a cursor or pointer on the initial ultrasound image to designate the flow region. 
     At step  510 , the processor  116  receives a selection of an angular range from the user interface  115 . The angular range determines the directional range of flow information displayed in the flow region. For example, according to an embodiment, the processor  116  will only display flow information that is flowing in a direction within the selected angular range. 
     For instance, the clinician may provide one or more user inputs through the user interface  115 . For example, the clinician may select the angular range using one or more of numbers on a keyboard or keypad, one or more gestures entered through a touchscreen or touchpad; or using a touchscreen, touchpad, mouse, or trackball to interface with a graphical user interface displayed on the display  118 . The clinician may provide the selection of the angular range via a multi-function controller, such as the multi-function controller  300 . 
     According to an exemplary embodiment, the clinician may input a selection of the angular range using the multi-function controller  300 . The clinician may rotate the multi-function controller  300  to designate the angular range. For example, the clinician may rotate the outer bezel  304  of the multi-function controller  300  to a first rotational position and press a button (i.e., a first button press input), such as the button  308 . The press of the button  308  may establish a first limit of the angular range. The user may then rotate the outer bezel  304  to a second rotational position and press the button  308  (i.e., a second button press input) to establish a second limit of the angular range. The angular range may be defined as the range of angles between the first limit of the angular range and the second limit of the angular range. According to various embodiments the button pressed to designate the first limit of the angular range and the second limit of the angular range may be located on a part of the user interface  115  other than the multi-function controller  300 . 
     After the processor  116  has received the selection of the flow region at step  508  and the selection of the angular range at step  510 , the method  500  advances to step  512  where the processor  116  accesses ultrasound data. The ultrasound data may be accessed in real-time during a live ultrasound procedure or the ultrasound data may be accessed retrospectively after the ultrasound examination has been completed. The ultrasound data accessed at step  512  may be either the same ultrasound data that was accessed at step  502 , or the ultrasound data accessed at step  512  may be different than the ultrasound data that was accessed at step  502 . The processor  116  may access the ultrasound data at step  512  from a memory such as the memory  120 . According to other embodiments, the processor  116  may access the ultrasound data from a remote memory or server. According to various embodiments, the processor  116  may access the ultrasound data directly from other components, such as the receive beamformer  110 . The ultrasound data accessed by the processor  116  at step  512  may be accessed in real-time as the ultrasound data is acquired, or the ultrasound data accessed at step  512  may be retrieved from memory based an acquisition performed at an earlier time. 
     As ultrasound is oftentimes used as a real-time imaging modality, it is anticipated that in many embodiments the method  500  will be implemented in real-time while ultrasound data is being acquired during an ultrasound examination. During embodiments where the data is acquired in real-time, it is anticipated that the ultrasound data accessed at step  512  will have been acquired more recently than the ultrasound data accessed at step  502 . For example, the ultrasound data accessed at step  502  may have been acquired at an earlier point in time during the ultrasound examination than the ultrasound data accessed at step  512 . 
     At step  514 , the processor  116  generates a flow-mode image based on the ultrasound data accessed at step  512 . The flow-mode image represents flow information that is both within the flow region (selected during step  508 ) and within the angular range (selected during step  510 ), and wherein the flow-mode image does not represent flow information that is either outside the flow region or outside of the angular range. 
     Based on the selection of the flow region (received at step  508 ) and the selection of the angular range (received at step  510 ), the processor  116  is able to generate and display a flow-mode image that shows only the flow information that is desired to be seen by the clinician. For example, the clinician may select the flow region to include only a subset of the anatomical regions displayed in the initial ultrasound image. This allows the clinician to view only the organs or structures that are specifically of interest for the current ultrasound examination. Additionally, the method  500  only presents flow information within the angular range selected at step  510 . The clinician is therefore able to use the angular range like a filter to limit the total amount of flow information displayed in the flow-mode image at step  516 . For example, the clinician may select the first limit of the angular range and the second limit of the angular range so that the angular range only includes the flow directions that are specifically of interest for a particular ultrasound examination or study. By displaying only the flow information from within the angular range, the method  500  presents a flow-mode image that includes only the flow information that the clinician requested. 
     If it is desired to access additional ultrasound data at step  518 , the method  500  returns to step  508 . Steps  508 ,  510 ,  512 ,  514 ,  516 , and  518  may be iteratively repeated multiple times as long as it is desired to access additional ultrasound data at step  518 . If it is not desired to access additional ultrasound data at step  518 , the method  500  advances to step  520 , wherein the method  500  ends. 
     According to an embodiment, the method  500  may iteratively repeat steps  508 ,  510 ,  512 ,  514 ,  516 , and  518  during a real-time or live ultrasound acquisition. For example, the processor  116  may generate and display an updated flow-mode image during each iteration of steps  508 ,  510 ,  512 ,  514 ,  516 , and  518 . If the clinician does not enter an updated selection of the flow region at step  508 , the processor  116  may use the selection of the flow region from the previous iteration of steps  508 ,  510 ,  512 ,  514 ,  516 , and  518 . Likewise, if the clinician does not enter an updated selection of the angular range at step  510 , the processor  116  may use the selection of the flow region from the previous iteration of steps  508 ,  510 ,  512 ,  514 ,  516 , and  518 . However, if the clinician enters an updated selection of the flow region and/or an updated selection of the angular range at steps  508  and  510  respectively, the processor  116  will use the updated flow region  508  and/or the updated angular range when generating and displaying the flow mode image during that iteration of steps  514  and  516 . 
     The method  500  provides an easy way for the clinician to select the flow region and the angular range for a flow-mode image. As discussed hereinabove, the selection of the flow region and/or the selection of the angular range may be used as filters to allow the clinician to only see specific flow information in the flow-mode image. The method  500  allows the clinician to adjust the selection of flow region and/or the angular range while multiple iterations of steps  508 ,  510 ,  512 ,  514 ,  516 , and  518  are being performed. This allows the clinician greater flexibility and enhances the ease with which the clinician is able to make a diagnosis or assessment based on the flow-mode image. 
     For example, the clinician may fine-tune the size and position of the flow region in order to result in a flow-mode image that only shows the desired anatomy. Additionally, the clinician may adjust the angular range of the flow information displayed in the flow-mode image. As described previously, the clinician may adjust the angular range while in the process of a real-time ultrasound acquisition. The clinician may make a change in one or both of the selection of the flow region and/or the selection of the angular range and quickly see the result of the change in the flow-mode image generated and displayed after the change. The clinician may, for instance, quickly and easily view flow information in the flow-mode image from different angular ranges until the clinician identifies the angular range that would be the most helpful for the current diagnosis or evaluation. Since it is possible to be acquiring additional frames of ultrasound data in real-time while the method  500  is being performed, it is possible to display flow-mode images reflecting the changes in the selection of the flow region and/or the selection of the angular range in real-time or in near real-time. 
       FIG.  7    is a schematic representation of the flow information that is represented by the initial ultrasound image  600  ( FIG.  6   ), which is a color flow image in accordance with an embodiment.  FIG.  7    represents the same anatomy that is shown in the initial ultrasound image  600 .  FIG.  7    includes 5 separate regions that are depicted in the initial ultrasound image  600 .  FIG.  7    includes a first region  650 , a second region  652 , a third region  654 , a fourth region  656 , and a fifth region  658 . Within each of the regions, the direction of flow is generally the same.  FIG.  7    includes an arrow in each of the regions. The arrow represents the direction of flow in the respective region. For example, the first region  650  includes a first arrow  700 ; the second region  652  includes a second arrow  702 ; the third region  654  includes a third arrow  704 ; the fourth region  656  includes a fourth arrow  706 ; and the fifth region  658  includes a fifth arrow  708 . The first arrow  700  and the second arrow  702  are both pointed at 145 degrees. This means that the direction of flow in the first region  658  is the same as the direction of flow in the second region  652 . The fourth arrow  656  and the fifth arrow  658  are both pointed at 330 degrees. This means that the direction of flow in the fourth region  656  is the same as the direction in the fifth region  658 . The third arrow  704  is pointed at 170 degrees.  FIG.  7    will be used to help explain  FIGS.  8 ,  9 ,  10 , and  11   . 
       FIG.  8    is a representative of a flow-mode image  800  in accordance with an embodiment. The flow-mode image  800  is generated using the same underlying flow information as that shown in  FIGS.  6  and  7    in accordance with an embodiment. However,  FIG.  8    is generated after the selection of a flow region and the selection of an angular range. In  FIG.  6   , flow information for the entire image is represented from an angular range of 0 degrees to 360 degrees. As a result, only a subset of the flow information is represented in  FIG.  8    compared to that shown in  FIG.  7   .  FIG.  8    includes an origin  802 .  FIG.  8    also includes an x-axis  804  and a y-axis  806  that define a flow region  850  in accordance with an embodiment. The origin  802  represents the location where the x-axis  804  and the y-axis  806  meet. The origin  802  is represented by a triangular icon in  FIG.  8   , but the origin may be represented differently according to various embodiments. For example the origin may be represented by other shapes, such as a dot, a crosshair, an “X”, a circle, a square, a star, etc. Additionally, some embodiments may not display the x-axis  804  and/or the y-axis  806 . In the embodiment shown in  FIG.  8   , the flow region  850  is defined by the origin  802  and is the region below the x-axis  804  and to the right of the y-axis  806 . It should be appreciated that the flow region  850  may be defined in a different location with respect to the origin  802  in other embodiments. For example, the flow region may be defined to be the region below the x-axis  804  and to the left of the y-axis  806 ; the flow region may be defined to be the region above the x-axis  804  and to the right of the y-axis  806 ; or the flow region may be defined to be the region above the x-axis and to the left of the y-axis  806  according to various embodiments. According to an exemplary embodiment, the clinician may be able to select the position of the flow region with respect to the origin  802 . For example, the clinician may be able to toggle through the four options described with respect to the origin and/or select one of the four options described hereinabove with respect to the origin based on inputs made through the user interface  115 .  FIG.  8    represents an exemplary embodiment where the selected angular range is 270 degrees to 30 degrees. 
     In  FIG.  8   , flow information from all of the fourth region  656  is represented in the flow-mode image  800 . All of the fourth region  656  is within the flow region  850  and the flow information in the fourth region  656  is moving in a direction within the selected angular range (i.e., the flow information in the fourth region  656  is moving in a direction of 330 degrees, which is within the selected angular range of 270 degrees to 90 degrees). Additionally, flow information from a portion of the fifth region  658  within the flow region  850  is represented in the flow-mode image  800  since the flow information within the fifth region  658  is also moving in a direction within the selected angular range. Flow information from the portion of the fifth region  658  that is outside the flow region  850  is not represented on the flow-mode image  800  since it is outside of the selected flow region  850 . The flow information from the third region  654  is not represented in the flow-mode image  800  since the flow information in the third region  654  is outside of the selected angular range (i.e., the flow information direction of the third region  654  is 170 degrees, which is not within the selected angular range of 270 degrees to 30 degrees). 
     According to an embodiment, the clinician may use a multi-function controller, such as the multi-function controller  300 , to position an origin to designate a flow region. For example, the clinician may control the position of the origin  802  by tilting the multi-function controller  300  like a joystick. That is, the clinician may use the joystick functionality of the multi-function controller  300  to position the origin  802  with respect to the initial ultrasound image  600  or the image that is currently displayed on the display device  118 . In order to obtain the exemplary flow-mode image shown in  FIG.  8   , the user may have used the multi-function controller  300  to position the origin  802  at the location shown in  FIG.  8    during step  508  of the method  500 . It should be appreciated that the origin may be positioned at any arbitrary position with respect to the currently displayed ultrasound image, depending upon the anatomy that the clinician would like to evaluate. 
       FIG.  9    is representative of a flow-mode image  900  in accordance with an embodiment. The flow-mode image  900  is generated using the same underlying flow information as that shown in  FIGS.  6 ,  7 , and  8    in accordance with an embodiment. The flow region  850  in flow-mode image  900  is different than the flow region  850  in flow-mode image  800  as indicated by the different locations of the origin  802  in  FIGS.  800  and  900   . According to an exemplary embodiment, the user may have used the user interface  115 , such as, for example, the multi-function controller  300 , to move the origin  802  from the position depicted in  FIG.  8    to the position depicted in  FIG.  9   . As discussed hereinabove, the position of the origin  802  may be selected using user interface controls other than the multi-function controller  300 . For example, the clinician may use one or more input devices such as a keyboard, hard keys, a touch pad, a touch panel of a touchscreen, a track ball, rotary controls, sliders, soft keys, or any other user input devices to control the position of the flow region  850 . 
     As discussed previously, the flow information displayed in flow region  850  is only the flow information within the angular range selected at step  510 . According to the exemplary embodiment shown in  FIG.  8   , the angular range is from 270 degrees to 30 degrees. This means that all the flow information that is moving in a direction between 270 degree and 30 degrees is represented on the flow-mode image. As discussed previously, the flow information in the fourth region  656  and the fifth region  658  is 330 degrees. As such, the flow information in the fourth region  656  and the fifth region  658  is within the angular range that was selected for  FIG.  9   . Flow information that is outside of this range—i.e., the flow information that is moving in a direction that is greater than 30 degrees but less than 270 degrees—is not represented in the flow-mode image. The flow information in the third region  654  is 170 degrees. As such, the flow information in the third region  654  is outside of the selected angular range of 270 degrees to 30 degrees. Therefore, in  FIG.  9   , flow information from the portion of the fourth region  656  within the flow region  850  and the portion of the fifth region  658  within the flow region  850  are represented on the flow-mode image  900 . However, the portion of the third region  654  within the flow region  850  is not represented on the flow-mode image  800  since the flow information in the third region  656  is outside of the selected angular range. It should be appreciated by those skilled in that art that the angular range of 270 degrees to 30 degrees is an exemplary angular range and that other angular ranges may be used. Additionally, as was described hereinabove, the user may adjust the selected angular range as multiple iterations of steps  508 ,  510 ,  512 ,  514 ,  516 , and  518  are being performed. As such, the clinician can fine-tune the angular range to show exactly the desired angular range in the flow-mode image or vary the angular range to see how much flow is within the flow region within different specified angular ranges. 
       FIG.  10    is a representation of a flow-mode image  1000  in accordance with an embodiment. The flow-mode image  1000  is generated using the same underlying flow information as that shown in  FIGS.  6 ,  7 ,  8 , and  9    in accordance with an embodiment. However,  FIG.  10    is generated after the selection of a flow region  850  and the selection of an angular range. In  FIG.  10   , the flow region  850  is of an arbitrary shape. The clinician may have used the user interface  115  to designate a boundary  852  of the flow region  850 . The angular range for the flow-mode image  1000  is between 270 degrees and 30 degrees, which is the same as the flow region used in  FIGS.  8  and  9   . However, the size and shape of the flow region  850  in the flow-mode image  1000 , the flow information represented in the flow-mode image  1000  is different than that represented in the flow-mode image  800  or the flow-mode image  900 . 
       FIG.  11    is a flow-mode image  1100  in accordance with an embodiment. The flow-mode image  1100  includes the flow region  850 . The flow-mode image  1100  is generated using the same underlying flow information as that shown in  FIGS.  6 ,  7 ,  8 ,  9 ,  10 , and  11   . The flow region  850  is the same size and shape as the flow region  850  in flow-mode image  1000 . However, in the flow-mode image  1100 , the angular range is from 90 degrees to 270 degrees. As such, the flow information represented in the flow-mode image  1100  is different than the flow information represented in the flow-mode image  1000  even though the flow region  850  is the same in both flow-mode image  1000  and flow-mode image  1100 . 
       FIGS.  8 ,  9 ,  10 , and  11    show some exemplary ways that the flow region  850  could be graphically indicated. For example, in  FIGS.  8  and  9   , the origin  802 , the x-axis  804  and the y-axis  806  define the flow region  850 . According to another embodiment,  FIGS.  10  and  11    each include a boundary  852  graphically indicating the flow region  850 . The boundary  852  is a dashed line, but in other embodiments, the boundary may be represented by a solid line, a dotted line, a dot-dash line, or any other type of line. It should be appreciated that the flow region could be graphically indicated in other ways according to various embodiments. Additionally,  FIGS.  8 ,  9 ,  10 , and  11    include examples of flow mode images that may be displayed at step  516  during the method  500  according to various embodiments. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.