Patent Publication Number: US-2023138970-A1

Title: Optimized Functionality Through Interoperation of Doppler and Image Based Vessel Differentiation

Description:
PRIORITY 
     This application claims the benefit of priority to U.S. Provisional Application No. 63/275,242, 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. Although, it may be difficult to identify the blood vessel as a vein or artery as portrayed in an ultrasound image. 
     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). 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. 
     Disclosed herein are systems and methods for enhancing the identification of blood vessels within ultrasound images via doppler ultrasound. 
     SUMMARY 
     Disclosed herein is an ultrasound-imaging system including, in some embodiments, an ultrasound probe coupled with a console. 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 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 operations including: (i) obtaining an ultrasound image of a predefined target area of the patient, (ii) detecting one or more blood vessels within the ultrasound image, (iii) obtaining doppler ultrasound data pertaining to blood flow within the one or more blood vessels, (iv) determining a condition of the blood flow based at least partially on doppler ultrasound data, and (v) identifying the one or more blood vessels as a vein or alternatively as an artery based at least partially on the condition of the blood flow within the one or more blood vessels. 
     In some embodiments, the operations further include determining a direction of the blood flow within the one or more blood vessels based on doppler ultrasound data, where the direction is determined with respect to an image plane of the ultrasound image, and the operations further include identifying the one or more blood vessels as a vein or an artery based at least partially on the direction of the blood flow. 
     In some embodiments, the operations further include determining a magnitude of the blood flow within the one or more blood vessels based on doppler ultrasound data and further identifying the one or more blood vessels as a vein or an artery based at least partially on the magnitude of the blood flow. 
     In some embodiments, the operations further include determining a pulsatility of the blood flow within the one or more blood vessels based on doppler ultrasound data, comparing the pulsatility with a pulsatility limit stored in memory, and as a result of the comparison, further at least partially identifying the one or more blood vessels (i) as an artery when the pulsatility exceeds the pulsatility limit or (ii) as a vein when the pulsatility is less than the pulsatility limit. 
     In some embodiments, the system is configured to obtain an ECG signal, and the operations further include determining the pulsatility of the blood flow in coordination with the ECG signal. 
     In some embodiments, determining the condition includes determining a pulse timing difference between a blood flow pulse within a first blood vessel and a corresponding blood flow pulse within an second blood vessel based on doppler ultrasound data and the operations further include identifying at least one of the first blood vessel or the second blood vessel as a vein or as an artery based at least partially on the pulse timing difference. 
     In some embodiments, the operations further include determining a cross-sectional shape of the one or more blood vessels and further identifying the one or more blood vessels as a vein or an artery based at least partially on the cross-sectional shape. In further embodiments, identifying the one or more blood vessels based on the cross-sectional shape includes comparing the shape of the one or more blood vessels with an elliptical shape limit stored in memory and further as a result of the comparison, identifying the one or more blood vessels (i) as an artery when the cross-sectional shape is less than the elliptical shape limit or (ii) as a vein when the cross-sectional shape exceeds the elliptical shape limit. 
     In some embodiments, the operations further include determining a confidence for the identity of the one or more blood vessels based on one or more of the direction of the blood flow, the magnitude of the blood flow, the pulsatility of the blood flow, the pulse timing difference of the blood flow, or the cross-sectional shape. 
     In some embodiments, the operations further include defining a doppler ultrasound window extending at least partially across the ultrasound image, where the doppler ultrasound window defines a portion of the ultrasound image for obtaining doppler ultrasound data and the doppler ultrasound window encompasses the one or more blood vessels. Defining the doppler ultrasound window may include automatically defining the doppler ultrasound window upon detecting the one or more blood vessels. Defining the doppler ultrasound window may also include 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. The input device may include a graphical user interface of the display and/or control buttons of the ultrasound probe. 
     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 position and/or orientation information of the magnetized medical device with respect to the predefined target area. In further embodiments, the operations further include superimposing an iconographic representation of the medical device atop the ultrasound image and the operations may further include defining the doppler ultrasound window based on the position and/or orientation of the iconographic representation of the medical device atop the ultrasound image. In some embodiments, the operations further include selecting a blood vessel of interest from the one or more blood vessels based on the position and/or orientation of the iconographic representation of the medical device atop the ultrasound image. 
     In some embodiments, the ultrasound probe further includes an accelerometer, a gyroscope, a magnetometer, or a combination thereof configured to provide tracking data to the console, where the tracking data pertains to the position and/or orientation of the ultrasound probe with respect to a trajectory of the one or more blood vessels. In such embodiments, the operations may further include processing the tracking data in combination with obtaining the doppler ultrasound data to enhance an accuracy of the determining of the direction and/or magnitude of blood flow within the one or more blood vessels. 
     In some embodiments, the operations further include portraying the ultrasound image on a display of the system and superimposing a notification atop the ultrasound image, where the notification includes the identity of the blood vessel. In some embodiments, the notification further includes the confidence for the identity of the blood vessel. 
     Also disclosed herein is a method of an ultrasound-imaging system including a non-transitory computer-readable medium (“CRM”) having executable logic that causes 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. The method includes activating ultrasonic transducers of an array of ultrasonic transducers of an ultrasound probe communicatively coupled to the console, where the ultrasonic transducers 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 method further includes (i) obtaining an ultrasound image of a predefined target area of the patient, (ii) detecting one or more blood vessels within the ultrasound image, (iii) obtaining doppler ultrasound data pertaining to blood flow within the one or more blood vessels, (iv) determining a condition of the blood flow based at least partially on doppler ultrasound data, and (v) identifying the one or more blood vessels as a vein or alternatively as an artery based at least partially on the condition of the blood flow within the one or more blood vessels. 
     In some embodiments, the method further includes determining a direction of the blood flow within the one or more blood vessels based on doppler ultrasound data, where the direction is determined with respect to an image plane of the ultrasound image, and the method further includes identifying the one or more blood vessels as a vein or an artery based at least partially on the direction of the blood flow. 
     In some embodiments, the method further includes determining a magnitude of the blood flow within the one or more blood vessels based on doppler ultrasound data and further identifying the one or more blood vessels as a vein or an artery based at least partially on the magnitude of the blood flow. 
     In some embodiments, the method further includes determining a pulsatility of the blood flow within the one or more blood vessels based on doppler ultrasound data, comparing the pulsatility with a pulsatility limit stored in memory, and as a result of the comparison, further at least partially identifying the one or more blood vessels (i) as an artery when the pulsatility exceeds the pulsatility limit or (ii) as a vein when the pulsatility is less than the pulsatility limit. In some embodiments of the method, the system is configured to obtain an ECG signal, and the method further includes determining the pulsatility of the blood flow in coordination with the ECG signal. 
     In some embodiments, determining the condition includes determining a pulse timing difference between a blood flow pulse within a first blood vessel and a corresponding blood flow pulse within an second blood vessel based on doppler ultrasound data and the method further includes identifying at least one of the first blood vessel or the second blood vessel as a vein or as an artery based at least partially on the pulse timing difference. 
     In some embodiments, the method further includes determining a cross-sectional shape of the one or more blood vessels and further identifying the one or more blood vessels as a vein or an artery based at least partially on the cross-sectional shape. 
     In some embodiments, the method further includes determining a confidence for the identity of the one or more blood vessels based on one or more of the direction of the blood flow, the magnitude of the blood flow, the pulsatility of the blood flow, the pulse timing difference of the blood flow, or the cross-sectional shape. 
     In some embodiments, the method further includes defining a doppler ultrasound window extending at least partially across the ultrasound image, where the doppler ultrasound window defines a portion of the ultrasound image for obtaining doppler ultrasound data and the doppler ultrasound window encompasses the one or more blood vessels. 
     In some embodiments of the method, defining the doppler ultrasound window includes automatically defining the doppler ultrasound window upon detecting the one or more blood vessels. In some embodiments of the method 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 and where the input device includes one or more of a graphical user interface of the display or control buttons of the ultrasound probe. 
     In some embodiments, the method further includes portraying the ultrasound image on a display of the system and superimposing a notification atop the ultrasound image, where the notification includes the identity of the blood vessel and/or the confidence for the identity of the blood vessel. 
     In some embodiments of the method, 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 position and/or orientation information of the magnetized medical device with respect to the predefined target area. In such embodiments, the method further includes superimposing an iconographic representation of the medical device atop the ultrasound image and defining the doppler ultrasound window based on the position and/or orientation of the iconographic representation of the medical device atop the ultrasound image. 
     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  illustrate an exemplary subcutaneous target area of a patient including a blood vessel for ultrasound imaging in accordance with some embodiments. 
         FIG.  5 B  illustrate the exemplary subcutaneous target area of  FIG.  5 A  further illustrating the application of doppler ultrasound in accordance with some embodiments. 
         FIG.  6 A  illustrate another exemplary subcutaneous target area of a patient for ultrasound imaging including a blood vessel and an additional anatomical element in accordance with some embodiments. 
         FIG.  6 B  illustrate the subcutaneous target area of  FIG.  6 A  further illustrating the application of doppler ultrasound in accordance with some embodiments. 
         FIG.  7    illustrates a display of the system of  FIG.  1    portraying an ultrasound image of a blood vessel in accordance with some embodiments. 
         FIG.  8    illustrates a method of system operations that may executed according to system logic 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 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. 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 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 system  100  may optionally include an ECG monitor  170  communicatively coupled with the console  102  by way of one of the ports  124 . Alternatively, the console  102  can include an ECG monitor integrated into the console  102 . The ECG monitor  170  includes one or more electrodes (not shown) coupleable with the patient P for obtaining ECG signals. The ECG monitor  170  is configured to receive the ECG signals from the electrodes coupled with the patient P and convert the ECG signals into electrical signals for processing by the console  102 . 
     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 micro-machined 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 tracking the position and/or orientation of the image plane. 
     The processor  116  is further configured to execute the logic  120  for processing the positional-tracking data for assessing a distance of the activated ultrasonic transducers  149  from the blood vessel, the orientation of the activated ultrasonic transducers  149  with respect to the blood vessel, or both the distance and the orientation of the activated ultrasonic transducers  149  with respect to the blood vessel to define an orientation of the image plane with respect the blood vessel. 
     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 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 B  illustrate a subcutaneous target area of a patient for ultrasound imaging (i.e., for display in an ultrasound image) in accordance with some embodiments. Referring to  FIG.  5 A , the predefined target area  502  for defining the ultrasound image includes a blood vessel  506  shown in conjunction with an image plane  353  (see  FIG.  3 A ) defined by the ultrasound probe  106 . For illustration purposes, the predefined target area  502  may be synonymous with an ultrasound image that may be portrayed on the display  104 . 
     In some embodiments, the system  100  may determine or otherwise define a region  503  of the predefined target area  502  that encompasses the blood vessel  506 . In some instances, the identity of the blood vessel  506  as a vein vs. an artery may be unknown. According to some embodiments, the system  100  is configured to determine the identity of the blood vessel  506  as a vein or alternatively as an artery. In other embodiments, the system  100  may also be configured to determine the identity of one or more other anatomical elements within the ultrasound image, such as one or more nerves, for example. In some instances, the blood vessel  506  may be one of a plurality of the blood vessels (not shown) located within the predefined target area  502 . As such, the system  100  may be configured to determine the identity of more than one blood vessel within the ultrasound image. 
     The image plane  353  as defined by the ultrasound probe  106  may be oriented to be perpendicular to the blood vessel  506 . In other words, the clinician may adjust the position and/or orientation of the ultrasound probe  106  to establish an orientation of the image plane that is perpendicular to the blood vessel  506 . 
     In some embodiments, the identity of the blood vessel  506  may be at least partially determined by a proximity of the blood vessel  506  with respect to the ultrasound probe  106 . In other words, for some patients, the identity of the blood vessel  506  may be readily apparent due to a clinician awareness of the target area. For example, in some instances, the clinician may easily identify a basilic vein within a patient&#39;s arm. However, in other instances, the identification of the blood vessel  506  may be difficult to assess based on anatomical structure. 
     Typically, a blood pressure within an artery is greater than a blood pressure within a vein. Similarly, the structure of an artery may include a thicker wall than a vein. As such, a cross-sectional shape of an artery may often be rounder than a cross-section shape of a vein. More specifically, the cross-sectional shape of a vein may be more elliptical, or otherwise elongated, in contrast to the cross-sectional shape of an artery. In some embodiments, a length  510 A and a width  510 B of the blood vessel  506  may be obtained from ultrasound image data and processed according to the logic  120  to assess the shape of the blood vessel  506 . Accordingly, the identity of the blood vessel  506  may be determined based on the cross-sectional shape as further describe below. 
     With reference to  FIG.  5 B , the identity of the blood vessel  506  may be determined based on a direction of blood flow within the blood vessel  506 . As the direction of the blood flow is in opposite directions in veins vs. arteries, an assessment of the blood flow direction may assist in identifying the blood vessel  506 . As the ultrasound probe  106  is configured to perform doppler ultrasound, the ultrasound probe  106  may obtain doppler ultrasound data. Therefrom, the logic  120  may determine a direction of the blood flow within the blood vessel  506  with respect to the image plane  353  (i.e., an orientation of the ultrasound probe  106 ). In other words, in an instance where the clinician has oriented ultrasound probe  106  on the patient&#39;s arm so that a front side  501  of the ultrasound probe faces the patient&#39;s hand, a blood flow direction  507  (illustrated as going into the page) within the blood vessel  506  extending from the front side  501  of the ultrasound probe  106  toward the back side of the ultrasound probe  106  may be consistent with blood flow through a vein. Alternatively, a blood flow direction  507  within the blood vessel  506  extending from the back side of the ultrasound probe  106  toward the front side  501  (i.e., an opposite direction from the blood flow direction  507 ) may be consistent with blood flow through an artery. As such, the logic  120 , upon determining direction of blood flow within blood vessel  506 , may identify the blood vessel  506  as a vein or alternatively an artery based on doppler ultrasound data. 
     In some instances, the anatomy of the patient and/or a vasculature operation of the patient may introduce some error in the determination of the blood flow direction within the blood vessel  506 . Such an instance may include a partially occluded or totally occluded blood vessel  506 . In some embodiments, the logic  120  may determine a confidence for the identification of the blood vessel  506  based on the direction of blood flow as further described below. 
     In some embodiments, the identification of the blood vessel may be determined via a magnitude (e.g., a velocity or flow rate) of blood flow within the blood vessel  506 . In some instances, a medical procedure may include identifying one blood vessel in relation to an adjacent blood vessel. For example, in some instances, a blood flow rate through an artery may generally be greater than a blood flow through an adjacent vein. As such, the identification of the blood vessel  506  may be determined in accordance with a magnitude of blood flow with the blood vessel  506  as further described below. In some embodiments, the logic  120  may also determine a confidence for the identification of the blood vessel  506  based on the magnitude of blood flow as further described below. 
     In some embodiments, the cross-section shape of the blood vessel  506 , such as the cross-section shape  508  of  FIG.  5 A  may be determined via ultrasound image data. In further embodiments, a blood flow related cross-section shape  509  of the blood vessel  506  may be determined via doppler ultrasound data as shown in the  FIG.  5 B . In some instances, the cross-section shape  509  may be more elongated than the cross-section shape  508 , which may enhance (e.g., increase the accuracy of) the determination of the identity of the blood vessel  506  based on the cross-section shape. In some embodiments, the logic  120  may also determine a confidence for the identification of the blood vessel  506  based on the shape of the blood vessel. 
     In some embodiments, the identification of the blood vessel  506  may include an assessment of a pulsatility of the blood flow. Typically, arterial blood flow is more pulsatile in accordance with the heartbeat than venous blood flow. As such, the pulsatility of the blood flow within the blood vessel  506  may be used to identify the blood vessel  506 . According to one embodiment, the ultrasound probe  106  may obtain pulsatility data (i.e., doppler ultrasound data pertaining to the pulsatility of the blood flow) and provide the pulsatility data to the console  102  for processing. The logic  120  may then determine the identity of the blood vessel  506  based on the pulsatility data as further described below. In some embodiments, the logic  120  may also determine a confidence for the identification of the blood vessel  506  based on the pulsatility of the blood flow. 
     In some instances, the blood flow within the blood vessel  506  may be uneven (i.e., pulsatile) due to factors other than the heartbeat. In such instances, it may be advantageous to isolate the pulsatility related to the heartbeat from uneven flow caused by other factors. So doing may enhance an accuracy of a pulsatility assessment/measurement. As stated above, the system  100  may include an ECG monitor  170  for providing an ECG signal to the console  102 . The logic  120  may in some embodiments, utilize the ECG signal to isolate the pulsatility of the heartbeat from the uneven flow caused by other factors as further described below. In other words, the assessment of the pulsatility of the blood flow may be performed in coordination with the ECG signal. 
     The doppler ultrasound data may be obtained within a defined doppler ultrasound window  504  defining a portion of the ultrasound image. In other words, the logic  120  may define a portion of the ultrasound image within which motion/movement of elements may be assessed via doppler ultrasound. The doppler ultrasound window  504  encompasses at least the blood vessel  506  but may also encompass more than one blood vessel and/or other anatomical elements, such as nerves, for example. 
     In some embodiments, the doppler ultrasound window  504  may be automatically defined in accordance with detecting the blood vessel  506  within the predefined target area  502 , i.e., the doppler ultrasound window  504  may be automatically defined upon detecting the one or more blood vessels. 
     In some embodiments, the clinician may define the doppler ultrasound window  504  via input to the system  100  through 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 . In some embodiments, the clinician may select the blood vessel  506  as a target blood vessel (or a blood vessel on interest) from among other blood vessel that may be included in the ultrasound image. 
       FIGS.  6 A- 6 B  illustrate a subcutaneous target area of a patient for ultrasound imaging (i.e., for display in an ultrasound image) in accordance with further embodiments of the system  100 . Similar to  FIGS.  5 A- 5 B ,  FIGS.  6 A- 6 B  illustrate a blood vessel  606  within a predefined target area  602  (i.e., ultrasound image). Further illustrated within the predefined target area  602  in an additional anatomical element  611  shown as a bundle of nerves. However, the anatomical element  611  is not limited to a bundle of nerves. As such, the anatomical element  611  may comprise a bone, a ligament, a tendon, or another blood vessel. In similar fashion, more than one additional anatomical element  611  may be included in the predefined target area  602 . As shown in  FIGS.  6 A- 6 B  notifications may be superimposed atop the ultrasound image when the ultrasound image is portrayed on the display  104 . In some embodiments, the notifications include an identity  612  of the blood vessel  606  (e.g., “V” indicating a vein). The notifications further include indications of confidence as further described below.  FIG.  6 A  illustrates a scenario where the identity of the blood vessel  606  is determined without utilizing doppler ultrasound. Conversely,  FIG.  6 B  illustrates a scenario, where determining the identity of the blood vessel  606  includes doppler ultrasound. 
     In the exemplary instance shown in  FIG.  6 A , the system  100  has determined that the blood vessel  606  is a vein at a confidence level  613  of 90%. Similarly, the system  100  as determined a confidence level  614  of 50% associated with the anatomical element  611 . In other words, as a result of the identity determination, the clinician may understand that the probability that the blood vessel  606  is a vein is 90%. Similarly, the clinician may understand that the probability that the anatomical element  611  is a vein is 50%. In other words, the probability that the anatomical element  611  is a vein is the same as the probability that the anatomical element  611  is not a vein. 
     Conversely, in the exemplary instance shown in  FIG.  6 B , the system  100  has determined that the blood vessel  606  is a vein at a confidence level  623  of 95% with doppler ultrasound vs. the confidence level  613  of 90% without doppler ultrasound. Similarly, the system  100  as determined a confidence level  624  of 0% associated with the anatomical element  611  with doppler ultrasound vs. the confidence level  614  of 50% without doppler ultrasound. By way of summary, the utilization of doppler ultrasound when determining the identity of the blood vessel  606  and/or the anatomical element  611  enhances the confidence of the identity determination. As such, when doppler ultrasound is utilized when determining the identity of the blood vessel  606 , the clinician may more reliably avoid a blood vessel identification error when performing an intravascular procedure. 
       FIG.  7    illustrates the console  102  portraying an ultrasound image  701  of the predefined target area on the display screen  104 . Depicted in the ultrasound image  701  is the blood vessel  606  (or more specifically an image of the blood vessel  606 ). Superimposed atop the ultrasound image  701  are the blood vessel identity  612  and the confidence for the identity  623 . In some embodiments, a direction indicator  715  of the blood flow direction within the blood vessel  606  may also be superimposed. 
     In some embodiments, an iconographic representation  712  of the medical device  112  ( FIG.  3 A ) may also be superimposed atop the atop the ultrasound image  701  to assist the clinician in inserting the medical device  112  into the blood vessel  606 . In some embodiments, the iconographic representation  712  of the medical device  112  may serve as a pointing device similar to a computer mouse. For example, the clinician may adjust a position and/or orientation of the medical device  112  in relation to the blood vessel  351  (see  FIG.  3 A ) and thereby adjust the position of the iconographic representation  712  with respect to the image of the blood vessel  606 . In some embodiments, the clinician may provide input to the logic  120  via the iconographic representation  712  to define the doppler ultrasound window  504  (see  FIG.  5 B ). In some embodiments, the clinical may also select the blood vessel  606  as the blood vessel of interest among other blood vessels (not shown) that may be included in the ultrasound image  701 . 
     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 . 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.  8    is a flow chart illustrating an exemplary method of the system  100 . The method  800  includes operations in accordance with a reference numbers  810 - 860 . Defining the ultrasound image (block  810 ) 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 . 
     The logic  120  may detect a blood vessel with the ultrasound image (block  820 ). More specifically, the ultrasound probe may identify color or contrast changes within an ultrasound image that indicate a difference in subcutaneous tissue structure. In some instances, a blood vessel may appear as a black hole in an ultrasound image as defined by ultrasound image data. The ultrasound probe may provide the ultrasound data to the console where the logic  120  may define the black hole as a blood vessel. 
     The method includes doppler ultrasound operations applied to all or a portion of the ultrasound image. The doppler ultrasound operations including defining a doppler ultrasound window (block  830 ). The doppler ultrasound window defines a portion of the ultrasound window for assessing motion of elements imaged within the doppler ultrasound window including blood flow within the blood vessel. In some embodiments, the logic  120  may automatically define the doppler ultrasound window to encompass one or more blood vessels upon detection of the one or more blood vessels within the ultrasound image. 
     In some embodiments, the logic  120  may automatically define the doppler ultrasound window  504  based on the comparison of the ultrasound image with the corresponding ultrasound images stored in memory  118 . For example, the corresponding ultrasound images in memory may include a predefined doppler ultrasound window. As such, the logic  120  may define the doppler ultrasound window  504  based on the predefined doppler ultrasound window of the corresponding ultrasound images in memory. 
     According to further embodiments, the logic  120  may receive an input as may be entered by a clinician via an input device, 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. In some embodiments, the clinician may select a portion of the ultrasound image via the GUI such as with a computer mouse or touch screen. In other embodiments, the clinician may select a portion of the ultrasound image via the control buttons of the ultrasound probe. 
     In still other embodiments, the clinician may select a portion of the ultrasound image via the medical device. More specifically, the medical device tracking operations may track the medical device with respect to the predefined target area and depict the iconographic representation of the medical device atop the ultrasound image in real time so that the clinician may select the portion of the ultrasound image based on positioning of the medical device. 
     After detecting a blood vessel, the logic  120  may determine an identity of the blood vessel (block  840 ). The determination of the identity of the blood vessel may include all or a subset of the logic operations described below. The logic  120  may determine a blood flow condition within the blood vessel by obtaining doppler ultrasound data. The blood flow condition may include a presence or absence of blood flow. The logic  120  may detect, via doppler ultrasound, a blood flow within the blood vessel and thereby further identify the detected black hole to be a blood vessel. The logic  120  may further determine a direction of the blood flow within the blood vessel 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 a vein or alternatively an artery. The logic  120  may also detect a non-flow condition of the blood vessel (i.e., absence of blood flow), and thereby, determine the blood vessel to be an anatomical element other than a blood vessel, such as a nerve or a bundle of nerves for example. 
     The operations may include identifying the blood vessel as a vein or an artery based on a blood flow rate or velocity within the blood vessel. The operations may include determining a flow rate (i.e., magnitude of blood flow) with the blood vessel and thereby identify the blood vessel as vein or an artery. For example, in some instances, the blood flow within a defined artery may generally be greater than a blood within an adjacent vein. Accordingly, the logic  120  may obtain a blood flow rate or velocity within a first blood vessel and further obtain a blood flow rate or velocity within a second blood vessel adjacent the first blood vessel. The logic  120  may then compare the determined blood flow rates and identify the blood vessel with the greater flow rate as an artery. 
     The operations may include identifying the blood vessel as a vein or an artery based on a pulsatility of the blood flow within the blood vessel. The logic  120  may measure, via doppler ultrasound, a pulsatility of the blood flow within the blood vessel. 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 logic  120  obtain an ECG signal, and determine the pulsatility of the blood flow in coordination with the ECG signal. By so doing, logic  120  may filter out pulse noise within the blood vessel as may be caused by patient movement, patient contact, or other external sources, thereby enhancing an accuracy or reliability of the pulsatility measurement. 
     In some embodiments, the logic  120  may assess the timing blood flow pulses within blood vessels. More specifically, the logic  120  may determine a timing difference between a blood flow pulse within a first blood vessel and a corresponding blood flow pulse within a second blood vessel based on doppler ultrasound data. Based on the timing difference, the logic  120  may identify one or both of the first blood vessel or the second blood vessel as a vein or as an artery. By way of one example, a blood flow pulse as defined a heartbeat travels along an artery toward an extremity of the patient, such as a hand for example, passing through the predefined target area at a first point in time. The same pulse travels in the opposite direction (i.e., toward the heart) along a corresponding vein, passing back through the predefined target area at a second point in time. The logic  120  determines that the second point in time follows the first point in time by the pulse timing difference. The logic  120  may then determine that the blood flow pulse passing through the predefined target area at the first point in time emanates from an artery, and the blood flow pulse passing through the predefined target area at the second point in time emanates from a vein. In such a way, the logic  120  may identify a blood vessel as an artery or as a vein. In some embodiments, the logic  120  may obtain pulse timing data in coordination with the ECG signal. 
     In some embodiments, the operations may further include identifying the blood vessel as a vein or an artery based on a spatial positioning of the blood vessel within the ultrasound image. In some embodiments, 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 blood vessel within the ultrasound image with the spatial positioning of the corresponding blood vessel in the one or more corresponding ultrasound images, where in some embodiments, the spatial positioning includes a subcutaneous depth of the blood vessel. As a result of the comparison, the logic  120  may identify the blood vessel as a vein or alternatively as an artery. 
     In some embodiments, the operations may further include identifying the blood vessel as a vein or an artery based on a cross-sectional shape of the blood vessel. Typically, a blood pressure within an artery is greater than a blood pressure within a vein. Similarly, the structure of an artery may include a thicker wall than a vein. As such, a cross-sectional shape of the artery may often be rounder than a cross-section shape of a vein. More specifically, the cross-section shape of a vein may be more elliptical, or otherwise elongated, in contrast to the cross-section shape of an artery. In some embodiments, the logic  120  may determine a length and a width of the blood vessel from ultrasound image data. In some, the logic  120  may then determine an aspect ratio of the shape and compare the aspect ratio with an aspect ratio limit stored in memory. As a result of the comparison, the logic  120  may identify the blood vessel as (1) a vein when the aspect ratio exceeds the limit or (2) an artery when the aspect ratio is less than the limit. 
     The operations may include determining a confidence for the identification of the blood vessel (block  850 ). The logic  120  may determine the confidence based on all or a subset of the identification operations described above. For example, the logic  120  may determine an individual confidence for each of the identification operations described above and determine a composite confidence for the identification. The confidence determination operation may take several forms. For example, the confidence regarding the identification based on the shape may include assessing a magnitude of difference between the determined aspect ratio and the aspect ratio limit stored in memory. By way of another example, the confidence for the identification based on the blood flow direction within the blood vessel may be greater when the blood flow rate is relatively high vs. relatively low. 
     The displaying operations further include portraying the ultrasound image on the display screen coupled with the console (block  860 ). The displaying operations may further include superimposing a visual notification atop the ultrasound image. The notification may indicate the identification of the blood vessel. The notification may also include the confidence where the confidence includes a number (e.g., a percent probability) or other confidence indication such as a low, medium, or high-level indication of confidence. 
     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 so that the iconographic representation of the medical device may be portrayed on the display screen  104 . 
     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 to assist in superimposing the iconographic representation of a medical device on the display screen  104 . 
     Other method operations can include a data-providing operation that 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  where the tracking data pertains to the position and/or orientation of the ultrasound probe with respect to a trajectory of the one or more blood vessels. Such, operations may enhance an accuracy of the determining of the direction and/or magnitude of blood flow within the one or more blood vessels. 
     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.