System and method for pulsed-wave doppler ultrasound imaging

Abstract

A method and associated ultrasound imaging apparatus for Doppler ultrasound medical examinations. The method and apparatus automatically scroll a frozen 2D Color Doppler display frame to a previously obtained frame which is more optimal in terms of Color filling and / or being close to peak systole, as determined by one or more Color Doppler signal measures. The invention is enabled by a toggle between a 2D color Doppler live mode / Pulsed-Width (PW) Doppler standby mode to a PW-live mode / 2D color Doppler standby mode, providing a workflow improvement.

Description

2024PF00381SYSTEM AND METHOD FOR PULSED-WAVE DOPPLER ULTRASOUND IMAGINGBACKGROUND

[0001] This invention relates to medical diagnostic systems and in particular to diagnostic ultrasound systems for assessing blood flow through blood vessels or at other points in the cardiovascular system.

[0002] Procedures in many standard vascular ultrasound exams require the sonographer to obtain sufficient information to assess the health of a vein or artery. One such procedure is the assessment of a stenosis, or narrowing, of an artery. Another example is the determination venous vessel latency. Another example is the detections of hemodynamic narrowing. These assessments typically employ the use of a combination of both color Doppler imaging to find the stenosis and pulsed-wave (PW)-Doppler to measure the peak flow velocity, which is correlated with the degree of stenosis or narrowing. Although there is a well-established workflow for assessing a vascular condition, the workflow is subject to a number of limitations. First, the examination requires a large number of manual steps to be followed that require an experienced user in order to perform them successfully. Moreover, particular steps can also require a significant amount of time to perform. And because the user can only visualize the vessel flow by means of the color Doppler display in a single two dimensional (2D) image plane, the procedure requires quite extensive manual repositioning of the ultrasound probe to precisely obtain the location of peak velocity blood flow. It is difficult for the user to be sure that the ultrasound probe view and particular instant in time is actually aligned with the peak velocity flow. Experienced users may utilize the Doppler audio signal, commonly provided by current ultrasound systems, to blindly locate the highest stenotic site in the perpendicular plane of the image. This takes time and can also result in inaccurate peak velocity measurements when the alignment is not precise. Finally, it is difficult to obtain the proper angle correction, which attempts to set the optimal angle between the flow direction and the Doppler line (and is required to determine the actual flow velocity), which is correct when the vessel is only seen in one plane. Inaccurate angle correction can lead to the possibility of incorrect peak velocity measurements, and inconsistent results between repeat measurements, different users and different labs.2024PF00381

[0003] Vascular examination workflows have evolved to capture pertinent data in the difficult imaging environment described above. FIGURE 2 illustrates a display 200 which is commonly used in vascular practice which comprises capturing both of the aforementioned 2D color Doppler image 202 and the PW-Doppler waveform 214 at about the same anatomical location. The display 200 is used in subsequent analysis by a medical provider. Both of the 2D color Doppler image 202 and PW-Doppler waveform 214 are displayed on a display 200. 2D color Doppler image 202 may further be divided into a color box, also termed as a region of interest (ROI) 206, and an area 204 outside of the ROI 206. The ultrasound system may provide a graphic showing the color box 206 which may be moved into a desired location at the vessel by use of a trackball or the like. A point of desired measurement may further be delineated by a location icon 208 which preferably may be placed at a central location within the color box 206 or may otherwise be adjusted by the user interface. The display 200 may provide a color range scale 210 which assists the user in identifying the highest peak velocity flow within the frames. In practice, after the desired frame is selected by the user, both of the PW-Doppler waveform and the captured frame may be provided together on display 200 for subsequent analysis by a medical provider.

[0004] A significant number of steps are required to obtain the desired information described above. In addition, several subjective selections are needed, and so this method may easily become cumbersome, inconsistent, and inaccurate, and the result may inordinately depend on the skill of the sonographer. For example, when performing a spectral Doppler examination, also known as pulsed-wave (PW) Doppler examination, the user such as a sonographer generally first enters the ultrasound system’s two-dimensional (2D) color Doppler mode of operation in order to initially position the PW sample volume (SV). Then the user selects a PW live mode of operation, wherein the most recent 2D color Doppler image frame is shown in a frozen display above the PW live display. In some ultrasound systems, the user may be able to move the SV location on this frozen frame, whereupon the PW live display will update appropriately. In such systems, the 2D color Doppler image frame is the frame in view (current 2D color Doppler image frame) on the display when the user pushes the “Update” button. This frame may not be the most ideal for placing the PW SV, nor is the resulting display optimal for printing a “hardcopy” to document this part of the exam and provide to a physician for diagnosis.2024PF00381

[0005] In such vascular exams, the optimal 2D color Doppler image frame to use for positioning the PW SV, and for exam documentation purposes, is the image frame showing the peak systolic velocity, which may be indicated by a frame that offers the most, a maximum or an otherwise satisfactory Color filling inside the vessel of interest. Conversely, a clearly sub- optimal frame is one that may correspond to the diastolic part of the heart cycle and, thus, offers poor Color filling inside the vessel of interest. For the purposes of this description, the terms frame with the “peak systolic velocity” and “optimal / most Color fill” can be used interchangeably. Thus to have the peak-systolic color Doppler frame, e.g. the frame with optimal Color fill, shown on the frozen display, the user presses a key to switch the trackball arbitration to a Color cine mode showing a time-sequence of image frames, which allows the user to manually scroll back to the 2D color Doppler frame having the peak systolic velocity. Since typical vascular Doppler exams involve tens of vessel segments, the number of control manipulations required to select the peak-systolic color Doppler frames for all these vessel segments represents a major burden in terms of time and effort.

[0006] In addition to the substantial number of button pushes and trackball manipulations that must be performed tens of times during a single vascular Doppler exam, manual selection of the optimal 2D color Doppler image frame is prone to user error of selecting the wrong frame or not having time to effectively select one under pressure. Previous systems for conducting ultrasound Doppler examinations are suboptimal by requiring these numerous steps, and considerable skill, by the system user to obtain the optimal and most useful PW Doppler information that accompanies the color Doppler image. U.S. Patent Publication 202130284 Al for example simply freezes the color flow Doppler data and displays the corresponding PW information. U.S. Patent Publication No. 2021022716 for example merely shows an automatic switching from live PW Doppler mode to a live 2D Doppler mode. None of these systems are enabled to automatically obtain the best available color Doppler and PW Doppler information for display.

[0007] Accordingly it is desirable to provide an ultrasound workflow for a vascular procedure which overcomes these sources of error, inaccuracy, and procedural difficulty. A particularly desirable invention would be a method and system that automatically obtains a Doppler ultrasound image frame having the highest peak velocity flow along with a PW-Doppler2024PF00381 waveform obtained at about the same location and provides that information for subsequent purposes. What is needed therefore is a system and method that does so.SUMMARY

[0008] The present invention enables automation of the vascular ultrasound imaging procedure, and thus offers substantial workflow benefits. In accordance with the principles of the present invention, a diagnostic ultrasound system and workflow are described in which both a live PW waveform and an optimal 2D color Doppler image are obtained and displayed. The 2D color Doppler image need not be contemporaneous with the PW waveform, but instead is selected from a set of prior-obtained 2D color Doppler image frames based on a desired measure. The 2D color Doppler image selection is preferably conducted automatically when the user switches a mode of operation from a 2D color Doppler imaging mode to a live PW imaging mode, and thus begins obtaining the live PW waveform. The user consequently enjoys a more efficient workflow with fewer button presses, more consistency across exams and proficiencies of users, and greater accuracy of diagnostic information.

[0009] In a preferred embodiment, the invention automatically scrolls the frozen 2D Color Doppler display back to the frame in the last cardiac cycle with peak systolic velocity during the transition from 2D color Doppler-live / PW-standby mode to PW-live / 2D color Doppler- standby mode. The automation eliminates the prior need to manually scroll back through image frames to obtain the frame having the peak systolic velocity. The invention thus enables a major workflow improvement. A particular element of the invention is that, upon switching from 2D color Doppler live / PW Doppler standby mode to PW Doppler live / 2D color Doppler standby mode, the ultrasound system automatically scrolls back to the 2D color Doppler frame, within a specified time window, that corresponds to the peak systolic velocity or a similar measure.

[0010] One implementation of the invention always performs auto-scrolling back to the most recent peak-systolic color Doppler image frame. Alternatively, appropriate setup options may be provided so that users can select the presets in which auto-scrolling is available. In addition, a maximum “look back” time to limit the number of frames the algorithm searches could be set to a fixed value during optimization, or the system can provide a user interface (UI) control from2024PF00381 which users can select the optimal maximum “look back” time for a given exam (for example, a longer time may be needed when performing a vein augmentation procedure).

[0011] According to a representative embodiment, a system, computer program product and method provides a convenience to the user by automatically scrolling the 2D color Doppler frame to the frame with the peak systolic velocity when transitioning from 2D color Live / PW Doppler Standby to PW Doppler live / 2D color Doppler Standby. This eliminates the need to manually scroll back to the last peak-systolic color frame before printing an image for documentation purposes and as an added benefit, allowing the user to view and move the PW Doppler sample volume on the frame with the peak systolic velocity.

[0012] According to another representative embodiment of the invention, a method for ultrasound imaging of blood flow is described, comprising providing an ultrasound system configured to obtain a color Doppler image in a two dimensional (2D) color Doppler mode of operation and a Pulsed-Wave (PW) Doppler ultrasound signal in a PW Doppler mode of operation in a region of interest (ROI), operating the ultrasound system in the 2D color Doppler mode of operation, generating a time series of 2D color Doppler image frames, determining for each of the 2D color Doppler image frames a measure of Doppler signal, and switching, with a user control, from the 2D color Doppler mode of operation to the PW Doppler mode of operation. The method continues by automatically selecting, responsive to the switching, a prior 2D color Doppler image frame based on one or more of the determined measures, and obtaining a live PW waveform in the PW Doppler mode of operation responsive to the switching step. The method further displays the live PW waveform adjacent to the prior 2D color Doppler image frame.

[0013] According to another representative embodiment, an ultrasound imaging system is described, the system having a two dimensional (2D) color Doppler mode of operation and a Pulsed-Wave (PW) Doppler mode of operation. The ultrasound imaging system comprises a source of 2D color Doppler image data and Pulsed-Wave (PW) Doppler image data, a computer memory configured to store the 2D color Doppler image data, a user control mode switching input, and a processor. The processor is configured to generate a time series of 2D color Doppler image frames from the source, determine for each of the 2D color Doppler image frames a measure of Doppler signal, switch both of a display of the image frames at a current color2024PF00381Doppler image frame and from the 2D color Doppler mode of operation to the PW Doppler mode of operation in response to receiving the user control mode switching, automatically select, responsive to the user control mode switching input, a prior 2D color Doppler image frame based upon the determined measures, and obtain a live PW waveform responsive to the switching. A display under control of the processor is configured to display the live PW waveform adjacent to the prior 2D color Doppler image frame.

[0014] According to another representative embodiment, a computer program product implemented in a non-transitory computer readable medium is described, comprising instructions for controlling a processor to obtain a two dimensional (2D) color Doppler image and a Pulsed- Width (PW) Doppler ultrasound signal in a selected ultrasound image region of interest (ROI), generate a time series of 2D color Doppler image frames, determine for each of the 2D color Doppler image frames a measure of Doppler signal, and switch, in response to a sensed user control input, from a 2D color Doppler mode of operation to a PW Doppler mode of operation a display. The computer program product continues with instructions to automatically select, responsive to the switching, a prior 2D color Doppler image frame based on the determined measure, obtain a live PW waveform responsive to the switching, and display the live PW waveform adjacent to the prior 2D color Doppler image frame.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The example embodiments are best understood from the following detailed description when read with the accompanying drawing figures. It is emphasized that the various features are not necessarily drawn to scale. In fact, the dimensions may be arbitrarily increased or decreased for clarity of discussion. Wherever applicable and practical, like reference numerals refer to like elements.

[0016] FIGURE 1 illustrates in block diagram form an ultrasonic diagnostic imaging system constructed in accordance with the present invention.

[0017] FIGURE 2 shows a prior art example of a GUI and / or a display result for an ultrasound-based vascular assessment.

[0018] FIGURE 3 is an illustrative process flow diagram used by an ultrasound imaging system to provide one embodiment of the present invention.

[0019] FIGURE 4 is a block diagram illustrating an example processor and memory in2024PF00381 accordance with examples of the present disclosure.

[0020] FIGURE 5 is a flow chart illustrating a method for providing a vascular imaging examination, according to a representative embodiment.

[0021] FIGURE 6 illustrates an embodiment of a user interface for a vascular imaging examination, according to a representative embodiment.

[0022] FIGURE 7a, FIGURE 7b, and FIGURE 7c illustrate outputs of exemplary embodiments of algorithms for use in the vascular imaging apparatuses, methods, and computer program products.

[0023] FIGURE 8 illustrates the output of another embodiments of algorithms for use in the vascular imaging apparatuses, methods, and computer program products.DETAILED DESCRIPTION

[0024] In the following detailed description, for purposes of explanation and not limitation, representative embodiments disclosing specific details are set forth in order to provide a thorough understanding of an embodiment according to the present teachings. Descriptions of known systems, devices, materials, methods of operation and methods of manufacture may be omitted so as to avoid obscuring the description of the representative embodiments. Nonetheless, systems, devices, materials and methods that are within the purview of one of ordinary skill in the art are within the scope of the present teachings and may be used in accordance with the representative embodiments. It is to be understood that the terminology used herein is for purposes of describing particular embodiments only, and is not intended to be limiting. The defined terms are in addition to the technical and scientific meanings of the defined terms as commonly understood and accepted in the technical field of the present teachings.

[0025] It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Thus, a first element or component discussed below could be termed a second element or component without departing from the teachings of the inventive concept.

[0026] The terminology used herein is for purposes of describing particular embodiments2024PF00381 only, and is not intended to be limiting. As used in the specification and appended claims, the singular forms of terms “a,” “an” and “the” are intended to include both singular and plural forms, unless the context clearly dictates otherwise. Additionally, the terms “comprises,” and / or “comprising,” and / or similar terms when used in this specification, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0027] Unless otherwise noted, when an element or component is said to be “connected to,” “coupled to,” or “adjacent to” another element or component, it will be understood that the element or component can be directly connected or coupled to the other element or component, or intervening elements or components may be present. That is, these and similar terms encompass cases where one or more intermediate elements or components may be employed to connect two elements or components. However, when an element or component is said to be “directly connected” to another element or component, this encompasses only cases where the two elements or components are connected to each other without any intermediate or intervening elements or components.

[0028] As used in the specification and appended claims, and in addition to their ordinary meanings, the term “about” and “approximately” mean to with acceptable limits or degree. For example, “approximately 2 MHz” means one of ordinary skill in the art would consider the signal to be 2 MHz within reasonable measure. Also, as used in the specification and appended claims, in addition to its ordinary meaning, the term “substantially” means within acceptable limits or degree. For example, the term “substantially simultaneously” means one of ordinary skill in the art would consider occurrence at the same time.

[0029] In view of the foregoing, the present disclosure, through one or more of its various aspects, embodiments and / or specific features or sub-components, is thus intended to bring out one or more of the advantages as specifically noted below. For purposes of explanation and not limitation, example embodiments disclosing specific details are set forth in order to provide a thorough understanding of an embodiment according to the present teachings. However, other embodiments consistent with the present disclosure that depart from specific details disclosed herein remain within the scope of the appended claims. Moreover, descriptions of well-known2024PF00381 apparatuses and methods may be omitted so as to not obscure the description of the example embodiments. Such methods and apparatuses are within the scope of the present disclosure.

[0030] Now turning to FIGURE 1, an ultrasound system 100 constructed in accordance with the principles of the present invention is shown in block diagram form. An ultrasound probe 10 contains a transducer array 12 of transducer elements which transmit ultrasound waves into the body and receive returning echo signals. Ultrasound probe 10 may thus be a source 10 of data for the invention, and in particular for two dimensional (2D) color Doppler and Pulsed-Wave (PW) Doppler image data.

[0031] The transmitted waves are directed in beams or scanlines to interrogate a region of interest in the body. A one-dimensional array can be used to transmit beams over a single plane for two dimensional imaging. For a vascular assessment exam in accordance with the present invention, the probe 10 may be a matrix array probe having a two-dimensional array of transducer elements 700 coupled to a probe microbeamformer 702. Such array and microbeamformer are optional and may not be required to practice the following inventions. For example, the source 10 of data may alternatively be from pre-obtained ultrasound examinations which has been stored for later use.

[0032] A matrix array probe may be used to transmit beams over a volumetric region of the body for three dimensional imaging. The beams can be steered and focused in different directions by the probe to interrogate tissue in specific locations or blood flow in specific directions as explained more fully below. Control and processing of beams on transmit and receive is provided by beamformer controller 16, which controls the microbeamformer 702 and a system beamformer 14 to transmit properly formed beams and beamform the received signals through delay and summation into coherent echo signals. In a two-stage beamforming system as shown in FIGURE 1 , partial beamforming of received signals is performed by the microbeamformer 702 and completion of the beamforming process is performed by the system beamformer 14. The beamformers can control the transducer array to scan beams over a desired image plane, for example, and to repetitively scan beams over an area of the image plane in which blood flow is to be assessed at a pulse repetition frequency (PRF) appropriate for the velocities of blood flow present in that region of the body.

[0033] A quadrature bandpass filter 18 processes the echo signals into quadrature I and Q2024PF00381 components. The separate components are used by a Doppler angle estimator 20 to estimate the phase or frequency shift of a Doppler signal at points where Doppler interrogation is to be performed. A B mode detector 22 uses the I and Q components to perform B mode detection for tissues images by taking the square root of the sum of the squares of the I and Q components. The detected echo intensities are processed by a B mode image processor 24 on a spatial basis to form a two or three dimensional image of the tissue in the body, which is processed for display by display processor 36 and displayed on display screen 52 under processor 36 control.

[0034] The Doppler frequencies at locations in the image plane which are produced by the Doppler angle estimator 20 can be mapped directly to velocity values of flow at those locations. This Doppler data is coupled to a colorflow processor 30 which spatially processes the data into a two or three dimensional image format, in which the velocity values are color-coded. This 2D Doppler color image map is overlaid over the spatially corresponding B mode image by the display processor 36 to illustrate the locations in the anatomy where flow is taking place and the velocity and direction of that flow by the color coding. Doppler data from a particular point in the image, selected by placement of a sample volume SV over that location in the image, may be coupled to a spectral Doppler processor 32 which produces a spectral display of the variation and distribution of flow velocities at that point with time. The spectral, Pulsed-Wave (PW), Doppler display is forwarded to the display processor 36 for processing and display of the spectral Doppler (PW Doppler) display on the display screen 52.

[0035] Fig. 2 illustrates a prior art display 200, e.g. as might be displayed on display 52. Display 200 is an example of an ultrasound-derived 2D color Doppler image 202 in a region of interest (ROI) 206, along with a display of a PW Doppler waveform 214. The ROI 206 is represented here as a parallelogram, but may be represented in other shapes. Inside ROI 206, 2D Doppler data is displayed with velocity indicated by color. A corresponding color range scale 210 shows colors by velocity. In this example, colors near the top are a light red and correspond to relatively high velocity in one direction, whereas colors near the bottom of the scale 210 are a light blue which correspond to relatively high velocity in the opposite direction. A black Doppler color indication in the center of the scale indicates low or no velocity. A location icon 208 corresponds to the location of interest (LOI) preferably placed at a location within the ROI that is of particular diagnostic value in the vascular exam. The LOI may be placed in the ROI by use of2024PF00381 a trackball or mouse or the like on the user control panel 50. The location icon 208 in this example is a cross-hair on a line placed parallel with a side of the ROI.

[0036] The area 204 of the 2D color Doppler image that is outside the ROI is typically shown as a B mode image without Doppler data, for purposes of improving frame rate and processing efficiency.

[0037] In this prior art display, PW Doppler waveform 214 is located below the 2D Doppler color display, and generally corresponds to a time-varying velocity display along the horizontal axis, with velocity values on the vertical axis. A corresponding audio presentation of the flow commonly accompanies the displayed PW waveform.

[0038] The aforementioned problem identified by the inventors is shown by reference to the Fig. 2 display. The optimal display includes a 2D color Doppler image frame having a relatively high peak velocity such as a peak systolic velocity, displayed in conjunction with a live PW waveform from substantially the same location. But the optimal 2D color Doppler image frame may not be, and often is not, coexistent in time with the live PW waveform. In order to obtain both desired objects for display, substantial efforts and adjustments by the user are needed. The invention described here solves these problems.

[0039] For a vascular exam workflow of the present invention, colorflow data from the colorflow processor 30 and, preferably, spatially corresponding B mode data from the B mode processor 24, is coupled to a color box position and steering angle processor 40. The color box position and steering angle processor controls the automation of settings and features of the colorflow image, including properly positioning the color box, setting the Doppler angle of the Doppler beams, locating the sample volume (SV) in the image, and proper positioning of the flow angle cursor for Doppler angle correction. For control of the Doppler angle the color box position and steering angle processor is coupled to the beamformer controller 16 to control the Doppler beam directions. Setup and control of the color box position and steering angle processor is provided by the setting of controls on a user control panel 50. Graphical display of functions controlled by the color box position and steering angle processor, such as the outline of the color box, the sample volume graphic, and the flow angle cursor, is provided through a graphics processor 34 which is coupled to the display processor 36 to overlay the graphics over the ultrasound images. The operation of the color box position and steering angle processor 40 is2024PF00381 more fully described in US patent number 10,342,515, entitled ULTRASOUND SYSTEM WITH AUTOMATED DOPPLER FLOW SETTINGS, filed September 30, 2011, and which is here fully incorporated by reference. In some embodiments, the colorbox may correspond in display to a displayed Region of Interest (ROI).

[0040] Various controls on the user control panel 50 may be provided to steer and adjust the locations of the colorbox and the cursor. A trackball may provide input of the placement of the color box on the B-Mode image and / or may provide input of the cursor location which may be a central location around which a measure of a Doppler signal is determined. One or more buttons may provide a user control mode switching input 50, 301 and / or a freeze input 302, see Fig. 3, which freezes a display of the color Doppler image frame at the current frame, and then triggers additional automated actions. Exemplary automated actions may include a toggling of operating modes between a live 2D color Doppler mode / standby PW Doppler mode and a standby 2D color Doppler mode / live PW Doppler mode, selection of a prior 2D color Doppler image frame for display and an initiation of a live PW waveform display, and the like.

[0041] Display screen 52 may further comprise a touchscreen display that may alternatively perform the trackball and selector button functions, including as the user control switching and freezing input.

[0042] Fig. 1 also illustrates a computer memory 42 for storing and subsequently providing 2D color Doppler data and PW Doppler data generated within the ultrasound system. Memory 42 may be configured to store not only 2D color Doppler image frame information, but also may be configured to store measures or numerical scores of the frame’s Doppler information. Memory 42 may further be configured to be allocated by a processor for storing a pre-determined number of the image frames in a buffer, wherein the buffer represents the number of frames that matches a desired look-back time. Details of this feature will be described with reference to Fig. 6 below.

[0043] The computer memory also interacts with the one or more processors 30, 34, 36, 40 to fulfill the display features enabled by the present invention. For clarity, processor 44 encompasses the one or more processors 34, 36, 40 for indications that the processor functions might be included within a single hardware component such as an ASIC.

[0044] In accordance with the invention and enabled to function as described in more detail below, the ultrasound system 100 comprises the source 10 of 2D color Doppler and PW Doppler2024PF00381 image data, the computer memory 42, the user control mode switching input 50, and a display 52 configured to display a live PW waveform adjacent to a prior 2D color Doppler image frame that is automatically selected from memory 42 by a processor. The processor may be one or a combination of processors in the system, such as processors 30, 34, 36, 40, and / or 44.

[0045] The ultrasound system 100 processor is configured to operate as follows, and as described in more detail below. The processor or processors generate a time series of 2D color Doppler image frames from the source. The frames may be displayed as shown in FIG. 3. For each of the 2D color Doppler image frames, processor 30 determines a measure of the Doppler signal. For example, the measure of Doppler signal may be indicative of a peak systolic velocity, such as by a sum of absolute velocity pixels within the ROI, a power measure of the flow within the colorbox or ROI, or the number of pixels with non-zero Doppler signal values within the ROI. The measure may be one, a combination of, or a weighted combination of the measure approaches. The measure of each frame may be stored with the image in memory 42.

[0046] During operation of system 100 in the 2D color Doppler mode of operation, the current color Doppler image frame is displayed on display 52. Also during this time, the PW Doppler mode of operation may be in standby. Either during operation or prior to these modes of operation, system 100 enables the user to manipulate the location of the ROI with an e.g. trackball to locate a central position around which the measure of Doppler is made, and otherwise to place the ROI at the desired location over a vessel of interest.

[0047] With reference to the left side of Figure 3, one embodiment of system 100 operation during the Live 2D color Doppler mode / Standby PW mode of operation 310 is illustrated. Display 200 provides a user display of a current 2D color Doppler image frame 314 overlaid of a B-mode image of a vessel. ROI 316 is a colorbox within which the Doppler data is obtained by the system. In this display, the PW waveform 312 may be provided as shown, and may be accompanied by an audible signal indicating flow velocity near that location icon 318. A location icon 318, position able by the user via the trackball 304 on control panel 300, indicates a position around which the measure of Doppler signal is determined and optionally as the location of the PW waveform data. System 100 includes a switch mode button 301 which serves as a user control mode switching input. System 100 also includes a freeze button 302 which serves to capture the final desired display of 2D color Doppler and PW live waveform into memory for2024PF00381 later use by medical reviewers. Although shown separately, switch mode button 301 and freeze button 302 may be combined as one button performing both actions depending on the context and state of the examination.

[0048] System and display settings for the system may also be entered via touchscreen display 306. The invention envisions that switch mode and freeze buttons 301 and 302, and trackball functions, may optionally (and / or additionally) be provided on touchscreen display 306.

[0049] Switching between modes of operation in the invention is indicated by the toggle of Live 2D color Doppler / Standby PW Doppler mode 310 to Live PW Doppler / Standby 2D color Doppler mode of operation 320 at toggling 303. Although shown at 303 as one-way between switching from the 2D color Doppler mode of operation to the PW Doppler mode of operation, it is understood that the mode switching can be toggled back to the previous mode. Toggling is accomplished by the processor responsive to receiving an input from the user control mode switching input 50, 301 / 302, whereupon the processor switches from 2D color Doppler mode of operation to the PW Doppler mode of operation. The toggling also initiates the change from displaying the current 2D color Doppler image frame to a different display.

[0050] Responsive to the user control mode switching input at toggle operation 303, system 100 processor automatically selects and displays one of the prior 2D color Doppler image frames 324 stored in memory 42. The processor automatically selects the prior image frame 324 based on the best measure of Doppler signal determined previously for each frame, for example based on the frame in the memory 42 buffer which has the calculated highest peak systolic velocity score. It can be seen by the arrows extending from the ROI to the color bar that the measure of Doppler signal at the prior image frame at 320 is much higher as indicated by the red color at top of the color bar than is the Doppler signal at the image frame at 310 just prior to the switching / toggling. At the toggling, system 100 processor also begins a live PW Doppler mode of operation, and begins to display the PW Doppler waveform 322 with data obtained from the point of location icon 318 in ROI 326.

[0051] System 100 may further be enabled to allow the user to adjust, via trackball 304 or the like, the location icon 326 within ROI 326 of the prior 2D color Doppler image frame 324. Adjustment of the location icon 326 enables the processor to calculate and display the PW Doppler waveform 322 from Doppler data obtained at that new location.2024PF00381

[0052] The display under control of the processor then displays the selected prior 2D color Doppler image frame 324 adjacent to the Live PW Doppler waveform 322. A time bar 328 may optionally be provided in order to indicate the relative time location 330 of the displayed prior 2D color Doppler image frame 326 to the time of toggling from the current 2D color Doppler image 314. The length of time bar 328 corresponds to a predetermined look-back time. The look- back time further corresponds to the number of prior 2D color Doppler image frames allocated to memory 42. As will be described in more detail with respect to FIG. 6, the look-back time may be predetermined using controls on the control panel 300 and / or touch screen display 306. For example, the predetermined look-back time may be selected by the user based on a desired number of cardiac cycles to be monitored during an ultrasound examination or may be based on a type of examination such as a vein augmentation examination. The range of look-back times is from about 1 second to greater than about 5 seconds.

[0053] FIG. 4 is a block diagram illustrating an example processor 400 in accordance with examples of the present disclosure. Processor 400 may be used to implement one or more processors described herein, for example, processor 44 as shown in FIG. 1. Processor 400 may be any suitable processor type including, but not limited to, a microprocessor, a microcontroller, a digital signal processor (DSP), a field programmable array (FPGA) where the FPGA has been programmed to form a processor, a graphical processing unit (GPU), an application specific circuit (ASIC) where the ASIC has been designed to form a processor, or a combination thereof.

[0054] The processor 400 may include one or more cores 402. The core 402 may include one or more arithmetic logic units (ALU) 404. In some examples, the core 402 may include a floating point logic unit (FPLU) 406 and / or a digital signal processing unit (DSPU) 408 in addition to or instead of the ALU 404.

[0055] The processor 400 may include one or more registers 412 communicatively coupled to the core 402. The registers 412 may be implemented using dedicated logic gate circuits (e.g., flipflops) and / or any memory technology. In some examples the registers 412 may be implemented using static memory. The register may provide data, instructions and addresses to the core 402.

[0056] In some examples, processor 400 may include one or more levels of cache memory 410 communicatively coupled to the core 402. The cache memory 410 may provide computer-readable instructions to the core 402 for execution. The cache memory 410 may provide data for processing2024PF00381 by the core 402. In some examples, the computer-readable instructions may have been provided to the cache memory 410 by a local memory, for example, local memory attached to the external bus 416. The cache memory 410 may be implemented with any suitable cache memory type, for example, metal-oxide semiconductor (MOS) memory such as static random access memory (SRAM), dynamic random access memory (DRAM), and / or any other suitable memory technology.

[0057] The processor 400 may include a controller 414, which may control input to the processor 400 from other processors and / or components included in a system (e.g., control panel 300, trackball 304, touchscreen display 306, mode switching input button 301 or freeze button 302 shown in FIG. 3) and / or outputs from the processor 400 to other processors and / or components included in the system (e.g., display 200 shown in FIG. 3). Controller 414 may control the data paths in the ALU 404, FPLU 406 and / or DSPU 408. Controller 414 may be implemented as one or more state machines, data paths and / or dedicated control logic. The gates of controller 414 may be implemented as standalone gates, FPGA, ASIC or any other suitable technology.

[0058] The registers 412 and the cache memory 410 may communicate with controller 414 and core 402 via internal connections 420A, 420B, 420C and 420D. Internal connections may implemented as a bus, multiplexor, crossbar switch, and / or any other suitable connection technology.

[0059] Inputs and outputs for the processor 400 may be provided via a bus 416, which may include one or more conductive lines. The bus 416 may be communicatively coupled to one or more components of processor 400, for example the controller 414, cache memory 410, and / or register 412. The bus 416 may be coupled to one or more components of the system, such as display 52 and control panel 50 mentioned previously.

[0060] The bus 416 may be coupled to one or more external memories. The external memories may include Read Only Memory (ROM) 432. ROM 432 may be a masked ROM, Electronically Programmable Read Only Memory (EPROM) or any other suitable technology. The external memory may include Random Access Memory (RAM) 433. RAM 433 may be a static RAM, battery backed up static RAM, Dynamic RAM (DRAM) or any other suitable technology. The external memory may include Electrically Erasable Programmable Read Only Memory (EEPROM) 435. The external memory may include Flash memory 434. The external2024PF00381 memory may include a magnetic storage device such as disc 436. In some examples, the external memories may be included in a system, such as ultrasound imaging system 100 shown in FIG. 1, for example memory 42.

[0061] A computer program product implemented in a non-transitory computer readable medium such as in one or more of memories 432-436 may comprise instructions for controlling the described processor 400 to enable the features of the inventive system and methods described herein. The instructions control the processor to obtain obtain a two dimensional (2D) color Doppler image and a Pulsed-Width (PW) Doppler ultrasound signal in a selected ultrasound image region of interest (ROI), generate a time series of 2D color Doppler image frames, and determine for each of the 2D color Doppler image frames a measure of Doppler signal. The instructions further control the processor to switch, in response to a sensed user control input, from a 2D color Doppler mode of operation to a PW Doppler mode of operation a display. The instructions further control the processor to automatically select, responsive to the switching, a prior 2D color Doppler image frame based on the determined measure, obtain a live PW waveform responsive to the switching, and to display the live PW waveform adjacent to the prior 2D color Doppler image frame.

[0062] The instructions for determining the measure of Doppler signal may be devised from one or more algorithms. Measures may be a measured peak systolic velocity from the ROI in each frame, a sum of absolute (or relative) velocity pixels in each frame, a measure of the Doppler Power values (such as the average of median Doppler power value), and / or the area of non-zero Doppler signals in each frame or ROI. Other measures known or modified from the art may be used for this measurement.

[0063] Exemplary criteria for selecting the peak-systolic and / or maximum-color-fill frame are based on the various measures of the Doppler signal per frame are provided following. The algorithms include but are not limited to the following examples.

[0064] The sum or number of valid Color Doppler pixels per frame may be obtained by Equation 1;

[0065] NumberOfValidColorPixelsPerFrm^f) = Sr=i Sc=i ^e^(r< c, / ) * {| Vel(r, c, f) > 0|]

[0066] where R and C denote the number of Color Doppler rows and columns, f denotes the2024PF00381Color Doppler frame, Vel(r,c,f) denotes the Color Doppler velocity at pixel {r,c} and frame f. The operator |x | denotes the absolute value of x. Valid Color Doppler pixels are those with nonzero absolute Color Doppler velocities.

[0067] FIGURE 7a illustrates the output of the Valid Color Doppler pixels per frame algorithm, as derived from a Common Carotid Artery Color Doppler loop of 54 frames.

[0068] The average absolute Doppler Velocity per frame may be obtained by Equation 2:

[0069] AvgAbsDopplerVelPerFrm(f) = Sr=i Sc=i |VeZ(r, c, / ) |

[0070] where R and C denote the number of Color Doppler rows and columns, f denotes the Color Doppler frame, and Vel(r,c,f) denotes the Color Doppler velocity at pixel {r,c} and frame f. The operator |x | denotes the absolute value of x.

[0071] FIGURE 7b illustrates the output of the average absolute Doppler Velocity per frame algorithm, as derived from the Common Carotid Artery Color Doppler loop of 54 frames.

[0072] The average Doppler Power per frame may be obtained by Equation 3:

[0073] AvgDopplerPwrPerFrm(f') = Sr=i Sc=i Pwr(r, c, f)

[0074] where R and C denote the number of Color Doppler rows and columns, f denotes the Color Doppler frame, and Pwr(r,c,f) denotes the Color Doppler power at pixel {r,c} and frame f.

[0075] FIGURE 7c illustrates the output of the average Doppler Power per frame algorithm, as derived from the Common Carotid Artery Color Doppler loop of 54 frames.

[0076] Possible criteria for automatically selecting a frame based upon the above-described measures for identifying the peak-systolic and / or maximum-color-fill frame may be

[0077] 1). the frame corresponding to the maximum value of a given measure, shown as point 706 in FIGs. 7a-7c, or

[0078] 2). the frame corresponding to the maximum 1st derivative of a given measure, shown by example as point 704 in FIGs.7a-7c.

[0079] The peak-systolic and / or maximum-color-fill could alternatively be determined by obtaining different frame estimates from a plurality of the above-described measures, followed by applying an aggregate operator such as the median of the different frame estimates.

[0080] The measures of the Doppler signal may alternatively be more elaborate than the simple temporal waveforms as defined above and shown in FIGs. 7a - 7c. FIGURE 8 illustrates an alternative approach for selecting the peak-systolic and / or maximum-color-fill frame, by a2024PF00381 method of

[0081] i. Calculating the “virtual spectrogram” of the Color Doppler velocities which provides a PW-Doppler-like spectrogram of the Color Doppler velocity histogram per Color Doppler frame,

[0082] ii. Finding the peak positive and negative velocities present in the virtual spectrogram, and

[0083] iii. automatically selecting the frame corresponding to the highest value of the peak positive and negative velocities.

[0084] FIGURE 8 illustrates the output of this example of the virtual spectrogram obtained from the set of 54 Common Carotid Artery Color Doppler frames used to derive the measures plotted in FIGURES 7a, 7b, and 7c plus the peak positive and negative velocities per frame (magenta 801 and green 802 traces, respectively). The virtual spectrogram illustrated in FIGURE 8 was in this example generated using a maximum baseline shift, so positive velocities can be measured from top to bottom AND negative velocities can be measured from bottom to top of the graph with a Doppler frequency shift range from {0 to +PRF] and {-PRF to 0], respectively.

[0085] The magenta and green dots in FIGURE 8 represent the peak positive frequency vs time and peak negative frequency vs time. In this example, the green dots correspond to a flat trace at the bottom of the virtual spectrogram because there are no negative velocities and therefore the peak negative frequency is always zero.

[0086] The instructions optionally control the processor to locate, responsive to a user input such as a trackball, a position on one of the 2D color Doppler image frames of a Region of Interest (ROI) within which the measure of the Doppler signal is determined. Also, the instructions optionally control the processor for enabling the setting of a time series predetermined look-back time from which the prior 2D color Doppler image frame is selected.

[0087] Now turning to FIGURE 5, a method 500 for ultrasound imaging of blood flow are described. These methods may be implemented in ultrasound systems and in computer programs as described above. The method begins at step 502 with the providing of an ultrasound system, such as system 100, configured to obtain a color Doppler image in a two dimensional (2D) color Doppler mode of operation and a Pulsed-Wave (PW) Doppler ultrasound signal in a PW Doppler mode of operation in a region of interest (ROI). Providing step 502 may further include an2024PF00381 ultrasound system that is configured to obtain and store in computer memory 2D color Doppler image data for each of a plurality of time-sequential 2D color Doppler image frames. The method may optionally allow for setup of parameters to capture the desired blood flow information, such as by the steps 503 of pre-selecting an ROI and / or a location of interest (LOI) for examination. Also, the method may optionally include a setup step for configuring a desired look-back time at 502, further described with reference to Fig. 6. The look-back time step 502 may be selected as a function of a desired number of cardiac cycles for a subject Doppler ultrasound examination, or as a function of a vein augmentation examination workflow.

[0088] The method continues at operating step 503 with the ultrasound system operating in the 2D color Doppler mode of operation. Optionally, the system also operates in a PW Doppler standby mode which may provide displayed and / or audible indications of the Doppler waveform at the ROI LOI. The method continues by generating a time series of 2D color Doppler image frames, which are preferably stored in memory 42. Each image frame is preferably displayed as it is generated to show a current 2D color Doppler image frame.

[0089] The method continues with a determining step 508 which calculates and determines a measure of Doppler signal for each 2D color Doppler image frame. The determining is preferably conducted as each image frame is generated. The measure is preferably stored in memory indexed to the image frame. Alternatively, the determining step may be conducted later in the method after some or all of the image frames are generated. As previously indicated, the invention scope includes known methods for determining measures of Doppler signal, including for example a sum of absolute velocity values, a measure of the Doppler Power values (such as the average of median Doppler power value), and / or the number of non-zero Color Doppler pixels in each Color Doppler frame. The measures are preferably applied to the ROI, and may be also weighted toward an LOI within the ROI.

[0090] The generating and measuring steps 506, 508 continue until the method senses a user control operation that switches at switching step 510 from the 2D color Doppler mode of operation to the PW Doppler mode of operation. The user control may be a dedicated switch mode button, a freeze button, a touch screen display button, or the like. The user control may also be configured to allow toggling back and forth between modes.

[0091] Upon execution of switching step 510, the method enters a live PW mode of2024PF00381 operation and enters a 2D color Doppler standby mode of operation at step 511. The method automatically selects 512 from the set of stored 2D color Doppler image frames a prior image frame that is optimal based upon one or more of the determined measures. For example, method step 512 may select the stored image frame that has the highest peak systolic velocity. This selected frame is then sent to the display at step 514 such as seen at image 320 in Fig. 3.

[0092] The LOI for PW Doppler data may optionally be adjusted, by use of trackball or the like, on the displayed 2D color Doppler image frame at step 515. The method then obtains the live PW Doppler waveform at step 516 for display using information from that LOI, if adjusted. The live PW Doppler waveform is displayed adjacent to the prior 2D color Doppler display at display step 518. A time bar 328 may additionally be displayed to indicate which of the prior image frames is displayed relative to the time of the switching step 510.

[0093] Once the desired display screen of optimal 2D color Doppler image frame and PW Doppler waveform is obtained, the user may save the examination result at freeze step 520. This may be done by pressing the freeze button 302 or similar selection. Upon sensing the freeze button selection, the method accepts and preferably stores the displayed information in memory at store step 522 for subsequent medical review.

[0094] FIGURE 6 illustrates the system and method for pre-determining and configuring the look-back time feature. A look-back time configuration screen 600 may be provided to the user on the display 200 or touch screen display 306. The configuration screen is preferably arranged for easy and logical pre-setting. Look-back time indicator and control button 602 may be provided on screen 600 to simultaneously show the current setting for the look-back time, here as an example 2 seconds, and provide a user input to change the look-back time. If the user selects control button 602, a sub-screen look-back time selector 604 is displayed. There, the user may select the desired look-back time. In these embodiments, the range of look-back times is from 0 to 4 seconds, but may be 5 or 10 seconds, or alternatively may be an integer number of sensed cardiac cycles. Of course, different adjustment screens may be provided within the scope of the invention.

[0095] Although the present specification describes components and functions that may be implemented in particular embodiments with reference to particular standards and protocols, the disclosure is not limited to such standards and protocols. Such standards are periodically2024PF00381 superseded by more efficient equivalents having essentially the same functions. Accordingly, replacement standards and protocols having the same or similar functions are considered equivalents thereof.

[0096] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of the disclosure described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.

[0097] One or more embodiments of the disclosure may be referred to herein, individually and / or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.

[0098] The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all of the features of any of the disclosed embodiments. Thus, the following claims are incorporated into the2024PF00381Detailed Description, with each claim standing on its own as defining separately claimed subject matter.

[0099] The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to practice the concepts described in the present disclosure. As such, the above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.2024PF003812024PF003812024PF00381

Claims

2024PF00381CLAIMS:

1. A method for ultrasound imaging of blood flow (500), comprising: providing (501) an ultrasound system configured to obtain a color Doppler image in a two dimensional (2D) color Doppler mode of operation and a Pulsed-Wave (PW) Doppler ultrasound signal in a PW Doppler mode of operation in a region of interest (ROI); operating (504) the ultrasound system in the 2D color Doppler mode of operation; generating (506) a time series of two dimensional (2D) color Doppler image frames; determining (508) for each of the 2D color Doppler image frames one or more measures of Doppler signal; switching (510), with a user control, from the 2D color Doppler mode of operation to the PW Doppler mode of operation; automatically selecting (512), responsive to the switching, a prior 2D color Doppler image frame based on one or more of the determined measures; obtaining (516) a live PW waveform in the PW Doppler mode of operation responsive to the switching step; and displaying (518) the live PW waveform adjacent to the prior 2D color Doppler image frame.

2. The method of Claim 1, wherein the measure of the Doppler signal is indicative of a peak systolic velocity, and is a function of one or more of a sum of absolute velocity values, a power measure of the Doppler Power values (such as the average of median Doppler power value) , and / or number of of non-zero Color Doppler pixels in each 2D color Doppler image frame.2024PF003813. The method of Claim 1, wherein the user control is an ultrasound system button configured to toggle between the 2D color mode of operation and the PW Doppler mode of operation.

4. The method of Claim 1, further comprising: selecting a location at which the PW Doppler waveform is obtained (515) within the ROI of the displayed prior 2D color Doppler image frame.

5. The method of Claim 1, wherein the providing also provides an ultrasound system configured to pre-select a look-back time for the time series, and further comprising pre-selecting a look- back time.

6. The method of Claim 5, wherein the look-back time is a function of a desired number of cardiac cycles for a subject Doppler ultrasound examination.

7. The method of Claim 1 wherein the providing further provides an ultrasound system configured to obtain and store in a memory 2D color Doppler image data for each of the 2D color Doppler image frames.

8. The method of Claim 1 wherein the displaying step further comprises displaying on a time series time bar a time location of the prior 2D color Doppler image frame relative to a time of the switching step.2024PF003819. An ultrasound imaging system (100) having a two dimensional (2D) color Doppler mode of operation and a Pulsed-Wave (PW) Doppler mode of operation, comprising: a source (10) of 2D color Doppler image data and Pulsed-Wave (PW) Doppler image data; a computer memory (42) configured to store the 2D color Doppler image data; a user control mode switching input (50, 301, 302); a processor (30, 34, 36, 40, 44) configured to generate a time series of 2D color Doppler image frames from the source, determine for each of the 2D color Doppler image frames a measure of Doppler signal, switch both of a display of the image frames at a current color Doppler image frame and from the 2D color Doppler mode of operation to the PW Doppler mode of operation in response to receiving the user control mode switching, automatically select, responsive to the user control mode switching input, a prior 2D color Doppler image frame based upon the determined measures, and obtain a live PW waveform responsive to the switching; and a display (52) under control of the processor and configured to display the live PW waveform adjacent to the prior 2D color Doppler image frame.

10. The ultrasound imaging system of Claim 9, wherein the processor and display are further configured to toggle the displaying from a current 2D color Doppler image frame to the live PW waveform adjacent to the prior 2D color Doppler image in response to receiving the user control mode switching input.2024PF0038111. The ultrasound imaging system of Claim 10, wherein the display further comprises a touchscreen display, and wherein the touchscreen display comprises the user control mode switching input.

12. The ultrasound imaging system of Claim 9, further comprising a user control panel comprising a trackball and a button, wherein the trackball provides an input of a region of interest (ROI) within which the measure of the Doppler signal is determined and wherein the button comprises the user control mode switching input.

13. The ultrasound imaging system of Claim 9, wherein the measure of the Doppler signal is indicative of a peak systolic velocity, and is one or more of a sum of absolute velocity values, a power measure of the Doppler Power values (such as the average of median Doppler power value), and / or a number of of non-zero Color Doppler pixels in each Color Doppler frame.

14. The ultrasound imaging system of Claim 9, further comprising a user control look-back input for setting a predetermined look-back time, wherein the processor further allocates computer memory for storing a number of the 2D color Doppler image frames based on the predetermined look-back time.

15. The ultrasound imaging system of Claim 14, wherein the predetermined look-back time is based on a desired number of cardiac cycles in an ultrasound examination.2024PF0038116. The ultrasound imaging system of Claim 9, wherein the display is further configured to display a time bar indicating a relative time location of the selected prior 2D color Doppler image relative to the current 2D color Doppler image.

17. A computer program product implemented in a non-transitory computer readable medium, comprising instructions for controlling a processor (400) to: obtain a two dimensional (2D) color Doppler image and a Pulsed-Width (PW) Doppler ultrasound signal in a selected (504) ultrasound image region of interest (ROI); generate (506) a time series of 2D color Doppler image frames; determine (508) for each of the 2D color Doppler image frames a measure of Doppler signal; switch (510), in response to a sensed user control input, from a 2D color Doppler mode of operation to a PW Doppler mode of operation a display; automatically select (512), responsive to the switching, a prior 2D color Doppler image frame based on the determined measure; obtain (516) a live PW waveform responsive to the switching; and display (518) the live PW waveform adjacent to the prior 2D color Doppler image frame.

18. The computer program product of Claim 17, further comprising instructions to determine the measure of the Doppler signal by one or more of a sum of absolute velocity values, a power measure of the Doppler Power values (such as the average of median Doppler power value), and / or a number of non-zero Color Doppler pixels in each Color Doppler frame2024PF0038119. The computer program product of Claim 18, further comprising instructions to locate responsive to a second user input a position on one of the 2D color Doppler image frames of a Region of Interest (ROI) within which the measure of the Doppler signal is determined.

20. The computer program product of Claim 17, further comprising instructions for setting a time series predetermined look-back time from which the prior 2D color Doppler image frame is selected.

Images