Patent Publication Number: US-2023135562-A1

Title: Doppler-Based Vein-Artery Detection for Vascular Assessment

Description:
PRIORITY 
     This application claims the benefit of priority to U.S. Provisional Application No. 63/275,223, filed Nov. 3, 2021, which is incorporated by reference in its entirety into this application. 
    
    
     BACKGROUND 
     Ultrasound imaging is a widely accepted tool for guiding interventional instruments such as needles to targets such as blood vessels or organs in the human body. In order to successfully guide, for example, a needle to a blood vessel using ultrasound imaging, the needle is monitored in real-time both immediately before and after a percutaneous puncture in order to enable a clinician to determine the distance and the orientation of the needle to the blood vessel and ensure successful access thereto. However, through inadvertent movement of an ultrasound probe during the ultrasound imaging, the clinician can lose both the blood vessel and the needle, which can be difficult and time consuming to find again. In addition, it is often easier to monitor the distance and orientation of the needle immediately before the percutaneous puncture with a needle plane including the needle perpendicular to an image plane of the ultrasound probe. And it is often easier to monitor the distance and orientation of the needle immediately after the percutaneous puncture with the needle plane parallel to the image plane. As with inadvertently moving the ultrasound probe, the clinician can lose both the blood vessel and the needle when adjusting the image plane before and after the percutaneous puncture, which can be difficult and time consuming to find again. What is needed are ultrasound-imaging systems and methods thereof that can dynamically adjust the image plane to facilitate guiding interventional instruments to targets in at least the human body. 
     Doppler ultrasound is a noninvasive approach to estimating the blood flow through your blood vessels by bouncing high-frequency sound waves (ultrasound) off circulating red blood cells. A doppler ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). During a doppler ultrasound, a technician trained in ultrasound imaging (sonographer) positions an ultrasound probe against the skin over a predefined area. Doppler ultrasound may be performed as an alternative to more-invasive procedures, such as angiography, which involves injecting dye into the blood vessels so that they show up clearly on X-ray images. 
     A Doppler ultrasound may help diagnose many conditions, including blood clots, poorly functioning valves in your leg veins, which can cause blood or other fluids to pool in your legs (venous insufficiency), heart valve defects and congenital heart disease, a blocked artery (arterial occlusion), decreased blood circulation into your legs (peripheral artery disease), bulging arteries (aneurysms), and narrowing of an artery, such as in your neck (carotid artery stenosis) 
     Doppler ultrasound may also detect a direction of blood flow. For example, doppler ultrasound can differentiate an artery from a vein since the direction of blood flow within an artery is generally in the opposite direction from a blood flow within an adjacent vein. As doppler ultrasound applies to blood flow, ultrasound images that include doppler ultrasound commonly portray results in a manner that obstructs the visibility of the blood vessel thereby causing difficulty in visualizing an image of a medical device in relation to the blood vessel. 
     Disclosed herein are systems and methods providing visual notifications pertaining to doppler ultrasound that for identifying a blood vessel within an ultrasound image based on doppler ultrasound and providing visual notification pertaining to doppler ultrasound results that maintain visibility of the cross-sectional area of the blood vessel. 
     SUMMARY 
     Disclosed herein is an ultrasound-imaging system including, in some embodiments, an ultrasound probe, a console, and a display screen. The ultrasound probe includes an array of ultrasonic transducers, where activated ultrasonic transducers of the array of ultrasonic transducers are configured to emit generated ultrasound signals into a patient, receive reflected ultrasound signals from the patient, and convert the reflected ultrasound signals into corresponding electrical signals of the ultrasound signals for processing into ultrasound image data and doppler ultrasound data. The console is configured to communicate with the ultrasound probe, and the console includes one or more processors and a non-transitory computer-readable medium having stored thereon logic that, when executed by the one or more processors, causes system operations. 
     The operations include: (i) detecting a black hole within a predefined target area of the patient based on ultrasound image data, (ii) determining a blood flow condition within the black hole based at least partially on doppler ultrasound data, (iii) defining an ultrasound image of the predefined target area including an image of the black hole, and (iv) superimposing a notification atop the ultrasound image, where the notification indicates the direction of blood flow with respect to the image of the black hole, 
     In some embodiments, the operations further include determining a direction of blood flow within the black hole with respect to an image plane of the ultrasound image, and the notification indicates the direction of blood flow with respect to the image of the black hole 
     In some embodiments, the operations further include rendering the ultrasound image on a display coupled with the system. 
     In some embodiments, the notification does not obstruct the image of the black hole. In further embodiments, the operations further include defining a boundary surrounding the image of the black hole and superimposing the notification outside of the boundary. 
     The operations my further include identifying the blood vessel as a vein or alternatively as an artery, where identifying the blood vessel as a vein or an artery is based at least partially on the condition of the blood flow within the blood vessel. 
     The operations my further include identifying the blood vessel as a vein or alternatively as an artery, based at least partially on the direction of the blood flow with respect to the image plane. 
     In some embodiments, the doppler ultrasound data includes a measurement of a pulsatility of the blood flow, and identifying the blood vessel as a vein or an artery is based at least partially on the pulsatility measurement. 
     In some embodiments, the operations further include: (i) comparing the ultrasound image with one or more corresponding ultrasound images stored in memory, where the comparison including a comparison of spatial positioning of the black hole within the ultrasound image, and (ii) at least partially as a result of the comparison, identifying the blood vessel as a vein or an artery. The notification may indicate the identity of the blood vessel as a vein or an artery and the notification may further indicate a confidence for the identification of the blood vessel. 
     In some embodiments, the operations further include measuring a blood flow rate within the black hole, comparing the blood flow rate with a range of blood flow rates stored in memory and as a result of the comparison, determining that the blood flow rate within the blood vessel is compromised. The operations may further include, as a result of the comparison, determining that the blood vessel is partially and/or totally occluded. 
     In some embodiments, the operations further include: (i) obtaining a first blood flow rate measurement for the blood vessel, (ii) obtaining a second blood flow rate measurement for the blood vessel, the second measurement subsequent to the first measurement, (iii) comparing the second measurement with the first measurement, and (iv) as a result of the flow rate measurement comparison, determining that the blood flow rate within the blood vessel is compromised. 
     In some embodiments, the operations further include detecting a plurality of black holes within the predefined target area of the patient based on ultrasound image data, determining a blood flow condition within each of the black holes based at least partially on doppler ultrasound data, and identifying each of the black holes as a blood vessel or alternatively as one or more nerves, where identifying the black hole as one or more nerves includes determining a non-flow condition of blood within the respective black hole. 
     The operations may further include defining a doppler ultrasound window extending at least partially across the ultrasound image and determining the blood flow condition within each of the one or more black holes encompassed by the doppler ultrasound window. In some embodiments, defining the doppler ultrasound window includes detecting the one or more black holes based on the ultrasound image data, and automatically defining the doppler ultrasound window to encompass the one or more black holes. 
     In some embodiments, defining the doppler ultrasound window includes receiving an input via an input device of the system, and defining the doppler ultrasound window based on the input, where the input includes a selected portion of the ultrasound image. 
     In some embodiments, the ultrasound probe further includes an array of magnetic sensors configured to convert magnetic signals from a magnetized medical device into corresponding electrical signals of the magnetic signals for processing by the processor into distance and orientation information with respect to the predefined target area for rendering of an iconographic representation of the medical device atop the ultrasound image. I n further embodiments, defining the doppler ultrasound window includes defining the doppler ultrasound window based on a position of the iconographic representation of the medical device atop the ultrasound image. 
     Disclosed herein also is method of an ultrasound-imaging system including a non-transitory computer-readable medium (“CRM”) having executable logic that cause the ultrasound-imaging system to perform a set of operations for ultrasound imaging when the logic is executed by a processor of a console of the ultrasound-imaging system, where the method includes performing the operations described above. 
     These and other features of the concepts provided herein will become more apparent to those of skill in the art in view of the accompanying drawings and following description, which describe particular embodiments of such concepts in greater detail. 
    
    
     
       DRAWINGS 
         FIG.  1    illustrates an ultrasound-imaging system and a patient in accordance with some embodiments. 
         FIG.  2    illustrates a block diagram of a console of the ultrasound-imaging system of  FIG.  1    in accordance with some embodiments. 
         FIG.  3 A  illustrates an ultrasound probe of the ultrasound-imaging system imaging a blood vessel in accordance with some embodiments. 
         FIG.  3 B  illustrates an ultrasound image of the blood vessel of  FIG.  3 A  on a display screen of the ultrasound-imaging system in accordance with some embodiments. 
         FIG.  4    illustrates the ultrasound probe of the ultrasound-imaging system configured as a 2-D ultrasound probe in accordance with some embodiments. 
         FIG.  5 A  illustrates an ultrasound image including black holes in accordance with some embodiments. 
         FIG.  5 B  illustrates an ultrasound image of  FIG.  5 A  further including a doppler ultrasound window in accordance with some embodiments. 
         FIG.  5 C  illustrates an ultrasound image of  FIG.  5 A  indicating blood flow through the black holes in accordance with some embodiments. 
         FIG.  5 D  illustrates an ultrasound image similar to the ultrasound image of  FIG.  5 C  where blood flow through the black holes is compromised in accordance with some embodiments. 
         FIG.  6    illustrates an exemplary screenshot of the ultrasound image of the  FIG.  5 A  including notifications superimposed atop the ultrasound in accordance with some embodiments. 
         FIG.  7    is a flow chart illustrating operations of a method performed by the system of  FIG.  1    in accordance with some embodiments. 
     
    
    
     DESCRIPTION 
     Before some particular embodiments are disclosed in greater detail, it should be understood that the particular embodiments disclosed herein do not limit the scope of the concepts provided herein. It should also be understood that a particular embodiment disclosed herein can have features that can be readily separated from the particular embodiment and optionally combined with or substituted for features of any of a number of other embodiments disclosed herein. 
     Regarding terms used herein, it should also be understood the terms are for the purpose of describing some particular embodiments, and the terms do not limit the scope of the concepts provided herein. Ordinal numbers (e.g., first, second, third, etc.) are generally used to distinguish or identify different features or steps in a group of features or steps, and do not supply a serial or numerical limitation. For example, “first,” “second,” and “third” features or steps need not necessarily appear in that order, and the particular embodiments including such features or steps need not necessarily be limited to the three features or steps. Labels such as “left,” “right,” “top,” “bottom,” “front,” “back,” and the like are used for convenience and are not intended to imply, for example, any particular fixed location, orientation, or direction. Instead, such labels are used to reflect, for example, relative location, orientation, or directions. Singular forms of “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. 
     With respect to “proximal,” a “proximal portion” or a “proximal-end portion” of, for example, a catheter disclosed herein includes a portion of the catheter intended to be near a clinician when the catheter is used on a patient. Likewise, a “proximal length” of, for example, the catheter includes a length of the catheter intended to be near the clinician when the catheter is used on the patient. A “proximal end” of, for example, the catheter includes an end of the catheter intended to be near the clinician when the catheter is used on the patient. The proximal portion, the proximal-end portion, or the proximal length of the catheter can include the proximal end of the catheter; however, the proximal portion, the proximal-end portion, or the proximal length of the catheter need not include the proximal end of the catheter. That is, unless context suggests otherwise, the proximal portion, the proximal-end portion, or the proximal length of the catheter is not a terminal portion or terminal length of the catheter. 
     With respect to “distal,” a “distal portion” or a “distal-end portion” of, for example, a catheter disclosed herein includes a portion of the catheter intended to be near or in a patient when the catheter is used on the patient. Likewise, a “distal length” of, for example, the catheter includes a length of the catheter intended to be near or in the patient when the catheter is used on the patient. A “distal end” of, for example, the catheter includes an end of the catheter intended to be near or in the patient when the catheter is used on the patient. The distal portion, the distal-end portion, or the distal length of the catheter can include the distal end of the catheter; however, the distal portion, the distal-end portion, or the distal length of the catheter need not include the distal end of the catheter. That is, unless context suggests otherwise, the distal portion, the distal-end portion, or the distal length of the catheter is not a terminal portion or terminal length of the catheter. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art. 
     Ultrasound-Imaging Systems 
       FIG.  1    illustrates an ultrasound-imaging system  100 , a needle  112 , and a patient P in accordance with some embodiments.  FIG.  2    illustrates a block diagram of the ultrasound-imaging system  100  in accordance with some embodiments.  FIG.  3 A  illustrates an ultrasound probe  106  of the ultrasound-imaging system  100  imaging a blood vessel of the patient P prior to accessing the blood vessel in accordance with some embodiments.  FIG.  3 B  illustrates an ultrasound image of the blood vessel of  FIG.  3 A  on a display screen  104  of the ultrasound-imaging system  100  with an iconographic representation of the needle  112  in accordance with some embodiments. 
     As shown, the ultrasound-imaging system  100  includes a console  102 , the display screen  104 , and the ultrasound probe  106 . The ultrasound-imaging system  100  is useful for imaging a target such as a blood vessel or an organ within a body of the patient P prior to a percutaneous puncture with the needle  112  for inserting the needle  112  or another medical device into the target and accessing the target. Indeed, the ultrasound-imaging system  100  is shown in  FIG.  1    in a general relationship to the patient P during an ultrasound-based medical procedure to place a catheter  108  into the vasculature of the patient P through a skin insertion site S created by a percutaneous puncture with the needle  112 . It should be appreciated that the ultrasound-imaging system  100  can be useful in a variety of ultrasound-based medical procedures other than catheterization. For example, the percutaneous puncture with the needle  112  can be performed to biopsy tissue of an organ of the patient P. 
     The console  102  houses a variety of components of the ultrasound-imaging system  100 , and it is appreciated the console  102  can take any of a variety of forms. A processor  116  and memory  118  such as random-access memory (“RAM”) or non-volatile memory (e.g., electrically erasable programmable read-only memory [“EEPROM”]) is included in the console  102  for controlling functions of the ultrasound-imaging system  100 , as well as executing various logic operations or algorithms during operation of the ultrasound-imaging system  100  in accordance with executable logic  120  therefor stored in the memory  118  for execution by the processor  116 . For example, the console  102  is configured to instantiate by way of the logic  120  one or more processes for dynamically adjusting a distance of activated ultrasonic transducers  149  from a predefined target area (e.g., an area including a blood vessel), an orientation of the activated ultrasonic transducers  149  to the predefined target area, or both the distance and the orientation of the activated ultrasonic transducers  149  with respect to the predefined target area, as well as process electrical signals from the ultrasound probe  106  into ultrasound images. Dynamically adjusting the activated ultrasonic transducers  149  uses ultrasound-imaging data, magnetic-field data, shape-sensing data, or a combination thereof received by the console  102  for activating certain ultrasonic transducers of a 2-D array of the ultrasonic transducers  148  or moving those already activated in a linear array of the ultrasonic transducers  148 . A digital controller/analog interface  122  is also included with the console  102  and is in communication with both the processor  116  and other system components to govern interfacing between the ultrasound probe  106  and other system components set forth herein. 
     The ultrasound-imaging system  100  further includes ports  124  for connection with additional components such as optional components  126  including a printer, storage media, keyboard, etc. The ports  124  can be universal serial bus (“USB”) ports, though other types of ports can be used for this connection or any other connections shown or described herein. A power connection  128  is included with the console  102  to enable operable connection to an external power supply  130 . An internal power supply  132  (e.g., a battery) can also be employed either with or exclusive of the external power supply  130 . Power management circuitry  134  is included with the digital controller/analog interface  122  of the console  102  to regulate power use and distribution. 
     Optionally, a stand-alone optical interrogator  154  can be communicatively coupled to the console  102  by way of one of the ports  124 . Alternatively, the console  102  can include an integrated optical interrogator integrated into the console  102 . Such an optical interrogator is configured to emit input optical signals into a companion optical-fiber stylet  156  for shape sensing with the ultrasound-imaging system  100 , which optical-fiber stylet  156 , in turn, is configured to be inserted into a lumen of a medical device such as the needle  112 , and convey the input optical signals from the optical interrogator  154  to a number of FBG sensors along a length of the optical-fiber stylet  156 . The optical interrogator  154  is also configured to receive reflected optical signals conveyed by the optical-fiber stylet  156  reflected from the number of FBG sensors, the reflected optical signals indicative of a shape of the optical-fiber stylet  156 . The optical interrogator  154  is also configured to convert the reflected optical signals into corresponding electrical signals for processing by the console  102  into distance and orientation information with respect to the target for dynamically adjusting a distance of the activated ultrasonic transducers  149 , an orientation of the activated ultrasonic transducers  149 , or both the distance and the orientation of the activated ultrasonic transducers  149  with respect to the target or the medical device when it is brought into proximity of the target. For example, the distance and orientation of the activated ultrasonic transducers  149  can be adjusted with respect to a blood vessel as the target. Indeed, an image plane can be established by the activated ultrasonic transducers  149  being perpendicular or parallel to the blood vessel in accordance with an orientation of the blood vessel. The distance and orientation information can also be used for displaying an iconographic representation of the medical device on the display. 
     The display screen  104  is integrated into the console  102  to provide a GUI and display information for a clinician during such as one-or-more ultrasound images of the target area of the patient P attained by the ultrasound probe  106 . In addition, the ultrasound-imaging system  100  enables the distance and orientation of a magnetized medical device such as the needle  112  to be superimposed in real-time atop an ultrasound image of the target, thus enabling a clinician to accurately guide the magnetized medical device to an intended target. Notwithstanding the foregoing, the display screen  104  can alternatively be separate from the console  102  and communicatively coupled thereto. A console button interface  136  and control buttons  110  (see  FIG.  1   ) included on the ultrasound probe  106  can be used to immediately call up a desired mode to the display screen  104  by the clinician for assistance in an ultrasound-based medical procedure. In some embodiments, the display screen  104  is an LCD device. 
     The ultrasound probe  106  is employed in connection with ultrasound-based visualization of a target such as a blood vessel (see  FIG.  3 A ) in preparation for inserting the needle  112  or another medical device into the target. Such visualization gives real-time ultrasound guidance and assists in reducing complications typically associated with such insertion, including inadvertent arterial puncture, hematoma, pneumothorax, etc. As described in more detail below, the ultrasound probe  106  is configured to provide to the console  102  electrical signals corresponding to both the ultrasound-imaging data, the magnetic-field data, the shape-sensing data, or a combination thereof for the real-time ultrasound guidance. 
       FIG.  4    illustrates the ultrasound probe  106  of the ultrasound-imaging system  100  configured as a 2-D ultrasound probe  106  in accordance with some embodiments. The ultrasound probe  106  includes a probe head  114  that houses a mounted and moveable (e.g., translatable or rotatable along a central axis) linear array of the ultrasonic transducers  148  or a 2-D array of the ultrasonic transducers  148 , wherein the ultrasonic transducers  148  are piezoelectric transducers or capacitive micromachined ultrasonic transducers (“CMUTs”). When the ultrasound probe  106  is configured with the 2-D array of the ultrasonic transducers  148 , a subset of the ultrasonic transducers  148  is linearly activated as needed for ultrasound imaging in accordance with ultrasound-imaging data, magnetic-field data, shape-sensing data, or a combination thereof to maintain the target in an image plane or switch to a different image plane (e.g., from perpendicular to a medical-device plane to parallel to the medical-device plane) including the target. 
     The probe head  114  is configured for placement against skin of the patient P proximate a prospective needle-insertion site where the activated ultrasonic transducers  149  in the probe head  114  can generate and emit the generated ultrasound signals into the patient P in a number of pulses, receive reflected ultrasound signals or ultrasound echoes from the patient P by way of reflection of the generated ultrasonic pulses by the body of the patient P, and convert the reflected ultrasound signals into corresponding electrical signals for processing into ultrasound images by the console  102  to which the ultrasound probe  106  is communicatively coupled. In this way, a clinician can employ the ultrasound-imaging system  100  to determine a suitable insertion site and establish vascular access with the needle  112  or another medical device. 
     The ultrasound probe  106  further includes the control buttons  110  for controlling certain aspects of the ultrasound-imaging system  100  during an ultrasound-based medical procedure, thus eliminating the need for the clinician to reach out of a sterile field around the patient P to control the ultrasound-imaging system  100 . For example, a control button of the control buttons  110  can be configured to select or lock onto the target (e.g., a blood vessel, an organ, etc.) when pressed for visualization of the target in preparation for inserting the needle  112  or another medical device into the target. Such a control button can also be configured to deselect the target, which is useful whether the target was selected by the control button or another means such as by holding the ultrasound probe  106  stationary over the target to select the target, issuing a voice command to select the target, or the like. 
       FIG.  2    shows that the ultrasound probe  106  further includes a button and memory controller  138  for governing button and ultrasound probe  106  operation. The button and memory controller  138  can include non-volatile memory (e.g., EEPROM). The button and memory controller  138  is in operable communication with a probe interface  140  of the console  102 , which includes an input/output (“I/O”) component  142  for interfacing with the ultrasonic transducers  148  and a button and memory I/O component  144  for interfacing with the button and memory controller  138 . 
     Also as seen in  FIGS.  2  and  3 A , the ultrasound probe  106  can include a magnetic-sensor array  146  for detecting a magnetized medical device such as the needle  112  during ultrasound-based medical procedures. The magnetic-sensor array  146  includes a number of magnetic sensors  150  embedded within or included on a housing of the ultrasound probe  106 . The magnetic sensors  150  are configured to detect a magnetic field or a disturbance in a magnetic field as magnetic signals associated with the magnetized medical device when it is in proximity to the magnetic-sensor array  146 . The magnetic sensors  150  are also configured to convert the magnetic signals from the magnetized medical device (e.g., the needle  112 ) into electrical signals for the console  102  to process into distance and orientation information for the magnetized medical device with respect to the predefined target, as well as for display of an iconographic representation of the magnetized medical device on the display screen  104 . (See the magnetic field B of the needle  112  in  FIG.  3 A .) Thus, the magnetic-sensor array  146  enables the ultrasound-imaging system  100  to track the needle  112  or the like. 
     Though configured here as magnetic sensors, it is appreciated that the magnetic sensors  150  can be sensors of other types and configurations. Also, though they are described herein as included with the ultrasound probe  106 , the magnetic sensors  150  of the magnetic-sensor array  146  can be included in a component separate from the ultrasound probe  106  such as a sleeve into which the ultrasound probe  106  is inserted or even a separate handheld device. The magnetic sensors  150  can be disposed in an annular configuration about the probe head  114  of the ultrasound probe  106 , though it is appreciated that the magnetic sensors  150  can be arranged in other configurations, such as in an arched, planar, or semi-circular arrangement. 
     Each magnetic sensor of the magnetic sensors  150  includes three orthogonal sensor coils for enabling detection of a magnetic field in three spatial dimensions. Such 3-dimensional (“3-D”) magnetic sensors can be purchased, for example, from Honeywell Sensing and Control of Morristown, N.J. Further, the magnetic sensors  150  are configured as Hall-effect sensors, though other types of magnetic sensors could be employed. Further, instead of 3-D sensors, a plurality of 1-dimensional (“1-D”) magnetic sensors can be included and arranged as desired to achieve 1-, 2-, or 3-D detection capability. 
     Five magnetic sensors  150  are included in the magnetic-sensor array  146  so as to enable detection of a magnetized medical device such as the needle  112  in three spatial dimensions (e.g., X, Y, Z coordinate space), as well as the pitch and yaw orientation of the magnetized medical device itself. Detection of the magnetized medical device in accordance with the foregoing when the magnetized medical device is brought into proximity of the ultrasound probe  106  allows for dynamically adjusting a distance of the activated ultrasonic transducers  149 , an orientation of the activated ultrasonic transducers  149 , or both the distance and the orientation of the activated ultrasonic transducers  149  with respect to the target or the magnetized medical device. For example, the distance and orientation of the activated ultrasonic transducers  149  can be adjusted with respect to a blood vessel as the target. Indeed, an image plane can be established by the activated ultrasonic transducers  149  being perpendicular or parallel to the blood vessel in accordance with an orientation of the blood vessel. Note that in some embodiments, orthogonal sensing components of two or more of the magnetic sensors  150  enable the pitch and yaw attitude of the magnetized medical device to be determined, which enables tracking with relatively high accuracy. In other embodiments, fewer than five or more than five magnetic sensors of the magnetic sensors  150  can be employed in the magnetic-sensor array  146 . More generally, it is appreciated that the number, size, type, and placement of the magnetic sensors  150  of the magnetic-sensor array  146  can vary from what is explicitly shown here. 
     As shown in  FIG.  2   , the ultrasound probe  106  can further include an inertial measurement unit (“IMU”)  158  or any one or more components thereof for inertial measurement selected from an accelerometer  160 , a gyroscope  162 , and a magnetometer  164  configured to provide positional-tracking data of the ultrasound probe  106  to the console  102  for stabilization of an image plane. The processor  116  is further configured to execute the logic  120  for processing the positional-tracking data for adjusting the distance of the activated ultrasonic transducers  149  from the target, the orientation of the activated ultrasonic transducers  149  to the target, or both the distance and the orientation of the activated ultrasonic transducers  149  with respect to the target to maintain the distance and the orientation of the activated ultrasonic transducers  149  with respect to the target when the ultrasound probe  106  is inadvertently moved with respect to the target. 
     It is appreciated that a medical device of a magnetizable material enables the medical device (e.g., the needle  112 ) to be magnetized by a magnetizer, if not already magnetized, and tracked by the ultrasound-imaging system  100  when the magnetized medical device is brought into proximity of the magnetic sensors  150  of the magnetic-sensor array  146  or inserted into the body of the patient P during an ultrasound-based medical procedure. Such magnetic-based tracking of the magnetized medical device assists the clinician in placing a distal tip thereof in a desired location, such as in a lumen of a blood vessel, by superimposing a simulated needle image representing the real-time distance and orientation of the needle  112  over an ultrasound image of the body of the patient P being accessed by the magnetized medical device. Such a medical device can be stainless steel such as SS 304 stainless steel; however, other suitable needle materials that are capable of being magnetized can be employed. So configured, the needle  112  or the like can produce a magnetic field or create a magnetic disturbance in a magnetic field detectable as magnetic signals by the magnetic-sensor array  146  of the ultrasound probe  106  so as to enable the distance and orientation of the magnetized medical device to be tracked by the ultrasound-imaging system  100  for dynamically adjusting the distance of the activated ultrasonic transducers  149 , an orientation of the activated ultrasonic transducers  149 , or both the distance and the orientation of the activated ultrasonic transducers  149  with respect to the magnetized medical device. 
     During operation of the ultrasound-imaging system  100 , the probe head  114  of the ultrasound probe  106  is placed against skin of the patient P. An ultrasound beam  352  is produced so as to ultrasonically image a portion of a target area that may include a blood vessel beneath a surface of the skin of the patient P such as the blood vessel  351  of  FIG.  3 A . (See  FIG.  3 A .). The ultrasound beam defines an image plane  353  having a front side  353 A consistent with a front side of the ultrasound probe  106  and an opposite facing back side  353 B. The ultrasonic image of the blood vessel  351  can be depicted and stabilized on the display screen  104  of the ultrasound-imaging system  100  as shown in  FIG.  3 B . 
       FIGS.  5 A- 5 C  illustrate an exemplary ultrasound image as may be obtained via the ultrasound probe  106  and as may be rendered the display  104 . The ultrasound image  501  includes a predetermined target area  502  of the patient such as a subcutaneous portion of the patient&#39;s arm including blood vessels as further described below. 
       FIG.  5 A  illustrates the darker areas of the ultrasound image  501  having shapes that indicate specific anatomical structures of the subcutaneous tissue. Herein some darker areas are referred to as black holes, such as the black holes  506 ,  507 , and  508 . In some instances, the black holes may indicate blood vessels within the subcutaneous tissue or more specifically, the blood flow area of the blood vessels. In the illustrated embodiment, the logic  120  is configured to identify black holes within the ultrasound image that may be consistent with blood vessels and/or in some embodiments, nerves or nerve bundles. In the illustrated exemplary image  501 , the logic  120  has identified the black holes  506 ,  507 , and  508  as blood vessels and as such, the black holes  506 ,  507 , and  508  may be referred to the blood vessels  506 ,  507 , and  508  herein below. 
     In some embodiments, the logic  120  may identify one of the blood vessels  506 ,  507 , and  508  as a target blood vessel in accordance with a predefined medical procedure. For example, the blood vessel  507  may be identified as a target blood vessel for receiving the needle  112  (see  FIGS.  1 ,  3 A ). In some embodiments, identifying a black hole as a blood vessel may include comparing the ultrasound image with one or more corresponding ultrasound images stored in memory  118  (see  FIG.  1   ) as further described below. 
       FIG.  5 B  further illustrates the ultrasound image  501 . The ultrasound probe  106  is configured to detect motion of elements included in the ultrasound image  501  via doppler ultrasound. For example, the ultrasound probe  106  is configured to detect motion consistent with blood flow within the black holes (blood vessels)  506 ,  507 , and  508 . As such, the logic  120  may, based at least partially on doppler ultrasound, determine a blood flow within one or more of the black holes  506 ,  507 , and  508  including a direction of the blood flow and, in some embodiments, a blood flow rate. 
     The logic  120  may further identify the black hole as a vein or alternatively as artery based on the determined direction of the blood flow within the black hole in relation to the image plane  353  of the ultrasound probe  106 . For example, in further reference to  FIG.  3 A , the clinician in some instances may orient the ultrasound probe  106  consistent with a medical procedure, i.e., such that the front side of the ultrasound probe  106  and the corresponding front side  353 A of the image plane  353  face upstream in relation to the venous flow. In such an instance, the logic  120  may identify a black hole having blood flow directed into the front side  353 A of the image plane  353  as a vein. Conversely, in accordance with the same orientation of the ultrasound probe  106 , the logic  120  may identify a black hole having blood flow directed out of the front side  353 A of the image plane  353  as an artery. 
     In some embodiments, alternatively or in addition to direction of the blood flow, the logic  120  may identify a blood vessel as a vein or an artery based on a pulsatility of the blood flow. Typically, arterial blood flow is more pulsatile that venous blood flow. As such, the logic  120  may compare the pulsatility of the blood flow within a given blood vessel/black hole as measured via doppler ultrasound with a pulsatility limit stored in memory  118 . In a first instance, where the measured pulsatility exceeds the pulsatility limit, the logic  120  may identify the blood vessel/black hole as an artery. Conversely, in a second instance, where the measured pulsatility is below the pulsatility limit, the logic  120  may identify the blood vessel/black hole as a vein. 
     In further embodiments, the logic  120  may identify a blood vessel as a vein or an artery based on the pulsatile motion of a blood vessel wall defining a cyclical change in black hole shape or size. In other words, pressure pules within a blood vessel due to pulsatile blood flow therethrough may cause the cross-sectional area (i.e., black hole area) of the blood vessel to expand and contract. As the arterial blood flow is more pulsatile that venous blood flow, the logic  120  may compare a magnitude of cyclical expansion and contraction of the blood vessel wall for a given blood vessel/black hole as measured via doppler ultrasound with an expansion and contraction magnitude limit stored in memory  118 . In a first instance, where the measured magnitude of cyclical expansion and contraction exceeds the expansion and contraction magnitude limit, the logic  120  may identify the blood vessel/black hole as an artery. In a second instance, where the measured magnitude of cyclical expansion and contraction is below the expansion and contraction magnitude limit, the logic  120  may identify the blood vessel/black hole as a vein. 
     Generally, the ultrasound probe  106  may be configured to detect motion (e.g., blood flow) within a doppler ultrasound window  510 . The doppler ultrasound window  510  may extend across all or a portion of the ultrasound image  501 . In some embodiments, the logic  120  may automatically define the doppler ultrasound window  510  based on identified black holes within the ultrasound image  501 . For example, the logic  120  may automatically define the doppler ultrasound window  510  to encompass one or more of the black holes  506 ,  507 , and  508  within the ultrasound image  501 . 
     In some embodiments, the logic  120  may automatically define the doppler ultrasound window  510  based partially on the comparison of the ultrasound image  501  with the corresponding ultrasound images stored in memory  118 . For example, the corresponding ultrasound images may include a predefined doppler ultrasound window to be applied to the ultrasound image  501  and the logic  120  may define the doppler ultrasound window  510  according to the predefined doppler ultrasound window. 
     In some embodiments, the clinician may define the doppler ultrasound window  510  via input to the system  100  via an input device such as a computer mouse or other pointing device. In some embodiments, the input maybe facilitated via a GUI interface of the display  104 . In other embodiments, the input may be facilitated via the control buttons  110  (see  FIG.  1   ) on the ultrasound probe  106 . 
       FIG.  5 C  further illustrates the ultrasound image  501 . As stated above, the logic  120  may determine motion within the ultrasound window including blood flow with the black holes  506 ,  507 , and  508 . The doppler ultrasound process may operate in the background of the ultrasound imaging process. As shown in  FIG.  5 C , results of the doppler ultrasound process may include a direction of blood flow as illustrated by the direction indications  506 A,  507 A, and  508 A which are shown in  FIG.  5 C  for illustration purposes only, i.e., the direction indications  506 A,  507 A, and  508 A may not be rendered on the display  104  along with the ultrasound image  501  because they obstruct the images of the black holes  506 ,  507 , and  508 . The direction indications  506 A,  507 A, and  508 A may be based on the orientation of the image plane  353  (see  FIG.  3 A ). In the illustrated embodiment, the direction indications  506 A,  508 A indicate a direction of the blood flow into the page (e.g., into the front side  353 A of the image plane  353  of  FIG.  3 A ). Conversely, the direction indication  507 A indicates a direction of the blood flow out of the page (e.g., out of the front side  353 A of the image plane  353  of  FIG.  3 A ). 
       FIG.  5 D  further illustrates a second exemplary ultrasound image of a target area  512 . In some instances, the target area  512  may be positioned adjacent the target area  502  of  FIGS.  5 A- 5 C , such as downstream of the target area  502 , for example. In other instances, the target area  512  may be the same as the target area  502  with the ultrasound image  511  having been acquired at a different time than the ultrasound image  501 , such as a subsequent time, for example. In the second exemplary image  511 , the blood flow through the blood vessels is compromised (i.e., reduced). As shown, the size of the blood vessels  507  and  508  are reduced in relation to the areas of the blood vessels  507  and  508  of  FIGS.  501 A- 501 C . According to one example, the size of the black hole  506  of  FIGS.  5 A- 5 C  is sufficiently reduced so that the logic  120  does not detect the black hole  506  in  FIG.  5 D . Similar to the  FIG.  5 C , direction indications  507 B and  508 B indicate the direction of the blood flow through blood vessels  507  and  508  consistent with the direction indications  507 A and  508 A of  FIG.  5 C . 
     In some embodiments, the logic  120  may compare the image  511  with corresponding images stored in memory  118  and as a result of the comparison determine the that the blood flows through the blood vessels  507  and  508  are reduced according to a size of the black holes. Alternatively, and/or in addition to the comparison of the image  511  with corresponding images stored in memory  118 , the logic  120  may determine the reduction in blood flow via doppler ultrasound. 
       FIG.  6    illustrates an exemplary screenshot as may be rendered on the display  104 . In the illustrated embodiment, the screenshot  601  includes the ultrasound image  501  and one or more notifications pertaining to the ultrasound image  501 . The notifications may include one or more indicia relating to a target blood vessel, such as the blood vessel  507 , for example. The notifications may include a condition of the blood flow within the blood vessel. The notifications may more specifically include a target indicium  606  indicating the identified black hole  507  as the target blood vessel pertaining to a defined medical procedure. The target indicium  606  is disposed outside the area of the black hole  507  so as to not obstruct the image of the black hole  507 . In some embodiments, the target indicium  606  may include a border extending around the image of the black hole  507 . 
     The notifications include a flow direction indicium  605  indicating the direction of the blood flow in relation to the black hole  507  as depicted in the ultrasound image  501 . For example, in an instance where the direction of blood flow is out of the image plane (i.e., out of the screen of the display  104 ), the flow direction indicium  605  may include an arrow, pointer, or other shape pointing away from the black hole  507  indicating the direction of the blood flow out of the blood vessel  507  as shown in  FIG.  6   . Alternatively, in an instance where the direction of the blood flow is in the opposite direction, the flow direction indicium  605  may point toward the blood vessel  507 . As may be appreciated by one of ordinary skill, the flow direction indicium  605  may include any shape, symbol, word, etc., suitable for indicating the direction of blood flow. In some embodiments, the target indicum  606  and the flow direction indicium  605  may be combined in a single indicum. 
     The notification may include a black hole identity indicator  609  for indicating the black hole as a vein or an artery. In some embodiments, the notifications may also include a confidence indicator  607  regarding the identification of the black hole  507  as an artery or alternatively as a vein. The confidence indicator  607  may be a number such as a percent probability or any other indicator suitable for communicating a confidence level of the identification. 
     In some embodiments, the screenshot  601  of the ultrasound image  501  may include an iconographic representation  612  of the needle  112  superimposed atop the ultrasound image  501  in accordance with some embodiments. 
     Methods 
     Methods of the foregoing ultrasound-imaging systems include methods implemented in the ultrasound-imaging systems. For example, a method of the ultrasound-imaging system  100  includes a non-transitory CRM (e.g., EEPROM) having the logic  120  stored thereon that causes the ultrasound-imaging system  100  to perform a set of operations for ultrasound imaging when the logic  120  is executed by the processor  116  of the console  102 . Such a method may, for description purposes, be referred to herein as activating operations, processing operations, and displaying operations. Any methods disclosed herein comprise one or more steps, actions or operations for performing the described method. The method includes operations (e.g., steps or actions) that may be interchanged with one another. In other words, unless a specific order of the operations is required for proper operation of the embodiment, the order and/or use of specific operations may be modified. 
       FIG.  7    is a flow chart illustrating an exemplary method of the system  100 . The method  700  includes operations in accordance with a reference numbers  710 - 750 . The method  700  generally includes defining an ultrasound image including a black hole (block  710 ). 
     Defining the ultrasound image may include activating include activating the ultrasonic transducers of the array of the ultrasonic transducers  148  of the ultrasound probe  106  communicatively coupled to the console  102 . With the activating operation, the ultrasonic transducers  148  emit generated ultrasound signals into the patient P, receive reflected ultrasound signals from the patient P, and convert the reflected ultrasound signals into corresponding electrical signals for processing into ultrasound images. The activating operations can include activating an approximately linear subset of the ultrasonic transducers  148  of a 2-D array of the ultrasonic transducers  148 . Alternatively, the activating operations can include activating a subset of the ultrasonic transducers  148  up to all the ultrasonic transducers  148  in the movable linear array of the ultrasonic transducers  148 . 
     Defining the ultrasound image may further include analyzing ultrasound data to detect black holes within the ultrasound image. In doing so, the logic  120  may analyze ultrasound image data to search for and detect black holes within the predefined target area. 
     Upon detecting a black hole, the logic  120  may determine an identity of the black hole (block  720 ). The logic  120  may determine a blood flow condition within the black hole by obtaining doppler ultrasound data. The blood flow condition may include a presence or absence of blood flow. The processing operations may include determining the black hole to be blood vessel. The logic  120  may detect, via doppler ultrasound, a blood flow within the black hole and thereby determine the black hole to be a blood vessel. The logic  120  may further determine a direction of the blood flow with respect to the image plane or more specifically with respect to an orientation of the image plane and thereby, determine the blood vessel to be vein or alternatively an artery. The logic  120  may also detect a non-flow condition of the black hole (i.e., absence of blood flow), and thereby, determine the black hole to be anatomical element other than a blood vessel such as a nerve or a bundle of nerves. 
     In some embodiments, the processing operations may further determine the blood vessel to be a vein or an artery based on a pulsatility of the blood flow. The logic  120  measure, via doppler ultrasound, a pulsatility of the blood flow within the black hole. As the arterial blood flow is generally more pulsatile than venous blood flow, the logic  120  may compare a measured pulsatility with a predefined pulsatility limit stored in memory. The logic  120  may thereby determine the blood vessel to be (1) an artery if the measured pulsatility exceeds the pulsatility limit or (2) a vein if the measured pulsatility is less than the pulsatility limit. 
     In some embodiments, the processing operations may further determine the blood vessel to be a vein or an artery based on a spatial positioning of the black hole within the ultrasound image. The logic  120  may compare the ultrasound image with one or more corresponding ultrasound images stored in memory. The logic  120  may more specifically compare the spatial positioning of the black hole within the ultrasound image with the spatial positioning of the corresponding black hole in the one or more corresponding ultrasound images, where the spatial positioning includes a subcutaneous depth of the black hole. As a result of the comparison, the logic  120  may identify the blood vessel as a vein or an artery. 
     In some embodiments, the processing operations may further include determining a confidence (e.g., a percent probability) for the determined identity of the black hole. The logic  120  may determine the confidence from the determined direction of blood flow, the measured pulsatility of the blood flow, the spatial positioning assessment of the black hole, or any combination thereof. The notification may include a number (e.g., a percent probability) or other confidence indication such as a low, medium, or high level indication of confidence. 
     The processing operations may further include establishing a doppler ultrasound window (block  730 ) within the ultrasound image, where the doppler ultrasound window defines a portion of the ultrasound window for assessing blood flow. In some embodiments, the logic  120  automatically may define the doppler ultrasound window to encompass one or more black holes detected within the ultrasound image. According to further embodiments, the logic  120  may receiving an input via an input device as may be entered by a clinician and the logic  120  may define the doppler ultrasound window based on the input. In other words, the clinician may select a portion of the ultrasound image as the doppler ultrasound window and the logic  120  may define the doppler ultrasound window in accordance with the selection. 
     The displaying operations further include rendering the ultrasound image on the display coupled with the console (block  740 ). The displaying operations may further include superimposing a visual notification atop the ultrasound image. The notification may indicate the direction of blood flow with respect to the image of the black hole. The logic  120  may cause the notification to be superimposed so as to not obstruct the black hole so that an image of a medical device may superimposed on the ultrasound image over the black hole. The logic  120  may specifically define a boundary or border surrounding the black hole in the ultrasound image. Having defined the boundary, the logic  120  may cause the notification to be superimposed the outside of the boundary. Having identified the black hole to be a vein or an artery, the logic  120  may include the identity of the black hole as a vein or an artery in the notification. 
     The processing operations may further include assessing the blood flow rate of the blood vessel (block  750 ). The logic  120  may determine a blood flow rate based on doppler ultrasound data. In some embodiments, the logic  120  may measure a velocity of blood flow across an area of the blood vessel and thereby determine a blood flow rate. 
     In some embodiments, the logic  120  may compare the measured blood flow rate with a range of blood flow rates for corresponding blood vessels stored in memory. As a result of the comparison, the logic  120  may determine that the blood flow within the blood vessel is compromised, e.g., low with respect to the range of blood flow rates. As a result of the comparison, the logic  120  may determine that the blood vessel is partially and/or totally occluded. 
     In some embodiments, the logic  120  may obtain a first blood flow rate measurement for the blood vessel and subsequently obtain a second blood flow rate measurement. The logic  120  may then comparing the second measurement with the first measurement and determine from the comparison that the blood flow rate is compromised when blood flow rate of the second measurement is less than the blood flow rate of the first measurement. In some instances, the second measurement may be obtained at a second location along the blood vessel different from a first location of the first measurement. 
     Other methods may include magnetic signal-related operations. The magnetic signal-related operations can include a converting operation. The converting operation includes converting magnetic signals from a magnetized medical device (e.g., the needle  112 ) with the magnetic-sensor array  146  of the ultrasound probe  106  into corresponding electrical signals. The processing operations further include processing the corresponding electrical signals of the magnetic signals with the processor  116  into distance and orientation information with respect to the predefined target area. The displaying operations further include displaying an iconographic representation of the medical device on the display screen  104 . In some embodiments, the logic  120  may define the doppler ultrasound window based on the location of the iconographic representation of the medical device in relation to the ultrasound image. 
     Other methods may further include a number of optical signal-related operations in combination with further processing and displaying operations. The optical signal-related operations include emitting input optical signals, receiving reflected optical signals, and converting the reflected optical signals into corresponding electrical signals of the optical signals by the optical interrogator  154 . The optical signal-related operations also include conveying the input optical signals from the optical interrogator  154  to the number of FBG sensors along the length of the optical-fiber stylet  156 , as well as conveying the reflected optical signals from the number of FBG sensors back to the optical interrogator  154  with the optical-fiber stylet  156  disposed in a lumen of the medical device. The processing operation further include processing the corresponding electrical signals of the optical signals with the processor  116  into distance and orientation information with respect to the predefined target area. The displaying operations further include displaying an iconographic representation of a medical device on the display screen  104 . 
     Other method operations can include a data-providing operation in combination with further processing operations. The data-providing operation includes providing positional-tracking data to the console  102  from the accelerometer  160 , the gyroscope  162 , the magnetometer  164 , or a combination thereof of the ultrasound probe  106 . The processing operations further include processing the positional-tracking data with the processor  116 . 
     While some particular embodiments have been disclosed herein, and while the particular embodiments have been disclosed in some detail, it is not the intention for the particular embodiments to limit the scope of the concepts provided herein. Additional adaptations and/or modifications can appear to those of ordinary skill in the art, and, in broader aspects, these adaptations and/or modifications are encompassed as well. Accordingly, departures may be made from the particular embodiments disclosed herein without departing from the scope of the concepts provided herein.