Three-dimensional color doppler for ultrasonic volume flow measurement

Abstract

An ultrasonic diagnostic imaging system measures volume flow. An ultrasound probe operating in biplane mode is used to acquire a blood vessel in a long axis view in a first Doppler image and simultaneously in a transverse view in a second Doppler image. Volume flow is calculated from the transverse view of the blood vessel. The plane of the second image is aligned with the Doppler angle of the first image so that angle correction determined for the first image can be used for angle correction in the volume flow calculation.

Description

Technical Field

[0001] This invention relates to medical diagnostic ultrasound systems, and more particularly to ultrasound systems that generate quantitative measurements of the volumetric flow rate of blood passing through the heart or blood vessels. Background Technology

[0002] Ultrasound has long been used to assess various blood flow parameters in the heart and vascular system using the Doppler principle. The basic Doppler response is flow velocity, which can be used to further determine additional characteristics of blood flow. One characteristic of interest to cardiologists is the volumetric flow rate of blood through a vessel. Early efforts to estimate volumetric flow rate involved multiplying a measurement of the average velocity of the blood flow by the nominal cross-sectional area of ​​the vessel. However, these early efforts had limitations due to the need for certain estimations. One limitation was the circularity of the vessel lumen. Another limitation was estimating the average velocity based on a single Doppler measurement or a qualitative assessment of spectral Doppler data. Velocity measurements also had to be corrected for the angle between the ultrasound beam direction and the flow direction. Yet another factor to consider was the laminar flow profile in the presence of stenosis.

[0003] The pulsation of arterial blood flow further complicates matters. While venous flow is generally constant, arterial flow varies throughout the cardiac cycle. Therefore, standard techniques often lack user independence and repeatability. The advent of 3D ultrasound alleviates some of these needs for assessing flow conditions, particularly its ability to acquire volumetric flow information. With 3D imaging, the entire vascular lumen can be imaged, and sequences of 3D image datasets can be acquired for later playback and diagnosis. When complete volumetric flow data within the vessel is acquired in the dataset, the image data can be examined during post-acquisition diagnostics to assess flow profile. In multiplanar reconstruction (MPR), different 2D image planes can be extracted from the 3D data, allowing examination of image planes with desired orientations through the vessel. Thus, 3D imaging addresses many of the static imaging challenges problematic for 2D flow estimation. However, acquiring 3D Doppler data can be time-consuming, reducing the temporal accuracy of volumetric flow analysis. Therefore, there is a desire to develop more robust techniques to accurately assess volumetric flow in the presence of pulsation and irregular heartbeats. It is also hoped that the accuracy and reliability of Doppler angle measurement can be improved, thereby improving the accuracy of Doppler flow velocity values. Summary of the Invention

[0004] According to the principles of the present invention, a diagnostic ultrasound system for measuring volumetric flow rate using a 3D imaging probe is described. The probe is preferably a two-dimensional matrix array probe operating in a dual-plane mode. One imaging plane is manipulated to acquire a long-axis view of the blood vessel in which the volumetric flow rate is to be measured. The plane of the other dual-plane image is aligned with the beam direction of the first image and the target blood vessel is imaged in an oblique manner in the transverse view. The beam direction of the longitudinal view image and the flow direction seen in the long-axis view thus determine the Doppler angle used for Doppler angle correction of the velocity values ​​obtained from the transverse image. The Doppler data acquisition rate is relatively high because only two planar images need to be acquired instead of the complete 3D volume. Furthermore, the Doppler angle correction is performed directly from the Doppler angle found for the longitudinal image. Therefore, known volumetric flow rate measurement methods, such as the Gaussian surface integral method, can be used with high accuracy and repeatability.

[0005] In the method of this invention, an ultrasound diagnostic imaging system is used to perform an ultrasound examination to measure volumetric flow rate. A scan is performed using an ultrasound probe adapted to operate in dual-plane mode to acquire a first Doppler image of the target vessel in a long-axis view. A scan is then performed using the ultrasound probe in dual-plane mode to simultaneously acquire a second Doppler image of the target vessel in a lateral view in an image plane aligned with the Doppler angle of the first image. Both images are displayed simultaneously. Angle correction is performed based on the Doppler beam direction and the flow direction of the first Doppler image. The volumetric flow rate is calculated based on data from the second Doppler image using the angle correction determined based on the first Doppler image. Attached Figure Description

[0006] In the attached diagram:

[0007] Figure 1 The illustration shows the use of pulsed Doppler with uniform acoustic processing to acquire Doppler data for volumetric flow rate assessment.

[0008] Figure 2a and Figure 2b The illustration shows the use of the Gaussian surface integration method to acquire Doppler data for volumetric flow rate assessment.

[0009] Figure 3 The illustration shows the projection of Doppler data acquired from a Gaussian surface onto a two-dimensional image plane for quantification of volumetric flow rate.

[0010] Figure 4 The illustration shows the acquisition of Doppler data using the transverse color Doppler method for volumetric flow rate assessment.

[0011] Figure 5 The illustration shows the projection of a dual-plane image plane from a 2D array transducer.

[0012] Figure 6 The illustration shows the acquisition of Doppler data from blood vessels for volumetric flow rate assessment according to the principles of the present invention.

[0013] Figure 7 The illustration shows side-by-side biplane ultrasound images during volumetric flow rate Doppler data acquisition according to the present invention.

[0014] Figure 7a The diagram shows... Figure 7 A horizontal view image in which the lumen of a blood vessel is segmented by a circular template.

[0015] Figure 8 An ultrasound diagnostic imaging system constructed according to the principles of the present invention is illustrated in block diagram form.

[0016] Figure 8a The diagram shows... Figure 8 Detailed instructions on how to use the volumetric flow rate calculator.

[0017] Figure 9 This is a flowchart of a method for measuring volumetric flow rate according to the principles of the present invention. Detailed Implementation

[0018] First refer to Figure 1 An ultrasound image was shown. Figure 1 This paper describes the use of pulsed Doppler ultrasound with uniform acoustic processing to acquire Doppler data for volumetric flow rate assessment. This is likely the most widely accepted method in clinical use because it is available in most commercial ultrasound systems and requires only a one-dimensional (1D) array transducer. The probe alternately acquires B-mode echoes (for generating structural images of tissues and vessels) and Doppler echoes (for depicting spatial flow velocities within colored boxes). This method uses pulsed Doppler ultrasound, thereby positioning long Doppler samples at an angle to the vessel of interest and calculating volumetric flow rate based on the time-averaged average velocity of blood flow. Figure 1 The ultrasound image of this method is illustrated. Figure 1 The target blood vessel 70 in which the volumetric flow rate is to be measured is shown. Doppler acquisition is performed within a colored frame 80 tilted from the upper left to the lower right (in the direction of Doppler beam propagation), with the Doppler gate line 82 aligned with this beam direction. A Doppler scan is performed on the colored frame at an angle shown by parallel scan lines; this technique is called a steerable linear scan. The distance of the break in the Doppler gate line 82 (wherein the break spans blood vessel 70) establishes a long Doppler sample through the lumen of the vessel. An adjustable flow cursor 84 is positioned above the blood vessel, with the top and bottom of the cursor positioned at the vessel wall and the middle horizontal line aligned with the flow direction. The angle between the Doppler gate line 82 and the horizontal line of the flow cursor 84 is the angle used for Doppler angle correction.

[0019] However, although still widely used clinically, this method is considered imprecise and inaccurate due to several incorrect assumptions and measurement dependencies. See, for example, R.G. W. Hill’s “Measurement of blood flow by ultrasound: accuracy and sources of error” (Ultrasound in Medicine and Biology, Vol. 11, No. 4, pp. 625-641, 1985). One implicit assumption in this method is that the blood vessel is uniformly acoustically processed by the ultrasound beam. This assumption is generally invalid because the ultrasound beam is typically smaller than the blood vessel at elevation angles. If uniform acoustic processing cannot be assumed, a simplified assumption must be made that the cross-section of the blood vessel is circular. This generally applies only to large arteries and not typically to veins. Another implicit assumption is that the time sampling rate of the flow is fast enough to capture changes in flow velocity (and therefore volume) throughout the cardiac cycle. This assumption is generally valid for the pulsed Doppler method because the time sampling rate of a 1D array probe is usually sufficient, even for very pulsating flow.

[0020] Furthermore, the accuracy of the measurement heavily depends on accurately determining the Doppler angle and the vessel diameter. The accuracy of the vessel diameter is crucial because the diameter is used in the formula Area = πr². 2 The cross-sectional area of ​​the blood vessel is calculated to determine its volumetric flow rate. This area is then multiplied by the flow velocity corrected for the Doppler angle. For straight, superficial vessels, accurately determining the Doppler angle is relatively easy, but it is more difficult for tortuous or deeper vessels. Volumetric measurements are particularly sensitive to vessel diameter measurements, as the diameter is used to determine the cross-sectional area using the aforementioned square law.

[0021] Other methods for assessing volumetric flow rate have been proposed that are less dependent on these assumptions and measurements. One such method is the Gaussian surface integral method, which uses 3D / 4D color Doppler and Gauss's law. Using this method, the flow rate is determined by integrating (summing) all color flow voxels on a coronal plane that intersects the target vessel and is perpendicular to the 3D (or 4D) color Doppler beam. See ODKripfgans et al., “Measurement of volumetric flow” (J. Ultrasound Med., Vol. 25, pp. 1305-1311, 2006). See also US Patent 6780155 (Li). Because the coronal plane intersects the entire vessel, there are no assumptions about uniform acoustic processing or that the vessel is circular. Furthermore, it is not necessary to measure the Doppler angle or vessel diameter, as the emitted ultrasound beam is perpendicular to every point on the surface. Figure 2aThe illustration shows a blood vessel 70 intersecting a Gaussian surface 50. A thin plane 52 of the surface is scanned by transmission of a Doppler beam from a 2D array transducer 54, which electronically directs the beam onto the surface 50 and intersects it with the blood vessel 70. A flow image 76 is thus plotted as a cross-sectional surface through a curved cross-section 58 of the blood vessel 70. As explained in the aforementioned '155 patent, the flow image 76 can be projected onto the flat surface 72 as a B-mode image 56. A circle 64 or other shape outside the vessel wall 60 can segment the vessel lumen 62 in the B-mode image, and then the color voxels within the segmented areas are summed to produce an estimate of the volumetric flow rate. The color voxels at the vessel wall where there may only be partial flow should be corrected, and one way to do this is to normalize the velocity estimate by using the power (intensity) in the Doppler signal (see the above-mentioned Kripfgans et al.), which is often referred to as partial volume correction.

[0022] While this is an excellent method for measuring volumetric flow rate, measuring pulsating flow rate is challenging due to the typically limited volumetric velocities achievable with 3D / 4D color Doppler, leading to insufficient temporal information sampling and flow rate calculation errors. Each point on the Gaussian surface must be sampled by an individual Doppler beam and multiple times via multiple transmissions to accurately estimate the Doppler velocity at each point on the Gaussian surface. To mitigate this limitation, related methods have been developed to acquire information over multiple cardiac cycles and then average it to obtain the average volumetric flow rate, or, if the cardiac cycle is precisely known, to reconstruct a single cardiac cycle from multiple cycles. However, these methods increase acquisition time and reduce the robustness of the method due to the required temporal sampling time.

[0023] Picot et al. have proposed another method similar to the Gaussian surface integral method. See Picot et al., “Rapid volume flow rate estimation using transverse colour Doppler imaging” (Ultrasound in Medicine and Biology, Vol. 21, No. 9, pp. 1199-1209, 1995). In this method, instead of extracting the coronal plane from the 3D color Doppler volume, a conventional 1D array transducer is tilted at an angle toward the blood vessel, such that its scanning plane and the 2D color image intersect the blood vessel at a tilted but lateral angle. Figure 4The illustration shows an ultrasound image of a blood vessel 70 scanned in this manner within a colored frame 80. Similar to the Gaussian surface integral method, all color Doppler pixels within the colored frame 80 are summed, with corrections applied to partially filled pixels at the vessel's edges. Again, no assumptions are made regarding flow profiles or vessel geometry. A major advantage over the Gaussian surface integral method is that the 2D color frame rate is typically much higher than the 3D / 4D color volume rate, thus significantly improving the time sampling of pulsatile flow. However, a disadvantage compared to the Gaussian surface integral method is the requirement to know the Doppler angle, which is difficult to obtain from lateral images. Picot et al. described a sophisticated probe holder that allows probing of the same vessel from two angles, thus eliminating Doppler angle dependence; however, such a probe holder is bulky and impractical for clinical use.

[0024] According to the principles of the present invention, an ultrasound probe with a two-dimensional matrix array transducer operates in a dual-plane mode to measure volumetric flow rate. In dual-plane mode, two image planes are scanned simultaneously in an interleaved manner. While dual-plane mode can be performed by a mechanical probe that moves a 1D transducer array to scan two image planes of a volumetric region, as described in U.S. Patent US 6443896 (Detmer), it is preferable to use a 2D matrix array probe that scans these planes electronically rather than mechanically, as described in U.S. Patent US 6709394 (Frisa et al.). Furthermore, color flow imaging can be performed in dual-plane mode, as described in U.S. Patent US 7645237 (Frisa et al.), wherein a color frame is scanned to acquire color Doppler data in each of the dual-plane image planes. Ultrasound systems and probes are commercially available and capable of performing color flow scanning of dual-plane images; for example, the xMATRIX series probes available on Philips Healthcare ultrasound systems. In one embodiment of the invention, a dual-plane scanning mode is performed to generate two real-time images, including mutually perpendicular color Doppler data. This allows for the simultaneous generation of a long-axis view and a lateral view of the blood vessel. The long-axis image can be used to accurately measure the Doppler angle, as described below. The lateral color image intersects the blood vessel at an angle in the same manner as Picot's method, thus enabling the estimation of volumetric flow rate using the same algorithm by summing all color pixels, but corrected using the accurate, known Doppler angles obtained from the long-axis image.

[0025] The embodiments of the present invention overcome many limitations and drawbacks of existing methods for measuring volumetric flow rate. Compared to pulsed Doppler methods, the embodiments of the present invention do not require uniform acoustic processing or assumptions about vessel geometry, and do not require measurement of vessel diameter (a major cause of inaccuracies in typical pulsed Doppler-based methods). Compared to Gaussian surface integral methods, the technique of the present invention provides much better temporal sampling because only two image planes need to be scanned, making it more suitable for the highly pulsating flows found in many arteries. Furthermore, no compromise is made in spatial sampling, as there is no need to attempt to increase the 3D volumetric frame rate. Better spatial sampling allows for a better representation of the flow profile and also reduces the reliance on partial volumetric corrections. Compared to the method of Picot et al., the embodiments of the present invention make it very easy to accurately measure the Doppler angles required for velocity correction.

[0026] The operation and use of the embodiments of the present invention can be found by referring to Figure 5 and Figure 6 To understand. Figure 5 A 2D matrix array transducer 54 is depicted, scanning two dual planes (denoted by L and T) in front of the transducer. When all scan lines transmitted and received for a plane are normal to the plane of the 2D array transducer, the plane extends normally to the transducer, as shown in the figure. When scan lines are transmitted and received at an angle relative to the plane of the array transducer, the scan plane will be angled in the shape of a parallelogram, caused by the turning linear operation. Figure 5 In the example, the two dual-plane normals extend towards the transducer because the scan lines are transmitted and received directly in front of the array. The L-plane and T-plane can be seen intersecting at a common intermediate scan line.

[0027] Figure 6 The invention illustrates two biplanes, L and T, which are redirected and intersecting to scan a blood vessel 70. The L plane is tilted from the upper left to the lower right and is aimed at the longitudinal center of the blood vessel 70 by probe manipulation, thereby producing a long-axis view of the vessel. The L scanning plane is tilted in a parallelogram orientation such that the scan lines of this plane will intersect the blood flow direction of the vessel at a non-orthogonal angle, since it is well known that a 90° angle between the Doppler beam and the blood flow direction will not produce a measurable Doppler signal because the cosine of 90° is zero. The T plane is aligned with one of the parallel scan lines of the L plane and intersects the blood vessel 70 in a tilted manner, thereby producing a transverse view of the vessel through which the T image plane cuts. Therefore, the Doppler angle of the T plane required for angular correction of the Doppler velocity measurement is the tilt angle of the L plane, which can be easily determined from the Doppler angle of the L plane and the flow direction easily observed in the long-axis view of the vessel.

[0028] When Figure 6As shown, when using a dual-plane probe to scan blood vessels, it is possible to simultaneously generate and display both the longitudinal and lateral views of the blood vessels, such as... Figure 7 As shown. In this example, dual-plane images are displayed side-by-side on a dual-sided monitor. Figure 90 on the left is... Figure 6 The image is a long axis view of the L-scan plane, showing the vessel 70 bisected in the long axis view. Within the grayscale (B-mode) image of the vessel and surrounding tissue is a colored frame 80, which is Doppler-beam scanned for Doppler visualization of the material within the frame. Figure 1 Similar to the colored frame, the colored frame 80 is tilted at a certain angle, which is determined by setting the tilt angle of the Doppler gate line 82. As with the previous... Figure 1 Similarly, the Doppler line has a motion cursor 84, which the user aligns with the flow direction in the blood vessel 70. The angle between the Doppler gate line 82 and the motion cursor 84 establishes the Doppler angle (the angle between the Doppler beam used to scan the colored frame 80 and the blood flow direction). The Doppler angle is typically automatically identified and recorded in standard ultrasound systems.

[0029] In an embodiment of the invention, an image 92 of a transverse view of a blood vessel 90 is scanned in a plane angularly aligned with the color frame 80. Typically, image planes 90 and 92 are spatially normal to each other. In this example, the plane of image 92 is aligned with the Doppler gate line 82 of image 90; the two images spatially share the common position of their Doppler lines 82. The result is that the Doppler angle correction required for the blood flow velocity values ​​in the transverse image 92 is the Doppler angle of the longitudinal view 90 (the angle between the Doppler gate line 82 and the flow cursor 84), which is readily identifiable in typical commercial ultrasound systems. The ultrasound system can then measure the volumetric flow rate using any of several known algorithms (e.g., the algorithm by Picot et al.), where the color pixel values ​​of the blood vessel in the transverse view are angularly corrected and then summed to calculate the volumetric flow rate. Mathematically, this can be expressed using Gauss's theorem, calculated as follows:

[0030] Q=∫ s v·dA

[0031] Where Q is the volumetric flow rate (e.g., in ml / s), v is the angle-corrected flow velocity, and surface S is the Doppler portion of the cross-section through the lumen of the blood vessel in the transverse view 92. Additionally, typical commercial ultrasound systems will allow users to segment (delineate) the portion of the image for which Doppler velocity pixels are to be integrated. Figure 7aAn example of such a tool is presented: a circular template 78, whose size can be appropriately adjusted by the user, who can then manipulate the template 78 on the ultrasound image to specify the image region where Doppler value integration will occur. For example, such segmentation of a blood vessel lumen will prevent the volumetric flow rate algorithm from incorrectly including pixel values ​​of adjacent vessels.

[0032] exist Figure 8 The diagram illustrates an ultrasonic system constructed according to the principles of the present invention. A transducer array 12 is provided in an ultrasonic probe 10 for transmitting ultrasonic waves and receiving echo information. The transducer array 12 is a two-dimensional array of transducer elements capable of scanning in three dimensions (both elevation and azimuth). Therefore, it is capable of simultaneously scanning two dual planes in a time-staggered manner. The transducer array 12 is coupled to a microwave beamformer 14 in the probe, which controls the transmission and reception of signals by the array elements. The microwave beamformer is capable of performing at least partial beamforming on the signals received by the group or “patch” of transducer elements, as described in U.S. Patents US 5,997,479 (Savord et al.), US 6,013,032 (Savord), and US 6,623,432 (Powers et al.). The microwave beamformer is coupled to a transmit / receive (T / R) switch 16 via a probe cable. The T / R switch 16 switches between transmit and receive modes and protects the main beamformer 18 from high-energy transmitted signals. The transmission operation of the ultrasonic beam from the transducer array 12, controlled by the microwave beamformer 14, is guided by a beamformer controller 17 coupled to the T / R switch and the main beamformer 18. The beamformer controller 17 receives input from the user interface or control panel 38. Transmission characteristics controlled by the transmit controller include the direction, quantity, spacing, amplitude, phase, angle, frequency, polarity, and diversity of the transmitted waveform. The beam formed in the pulse transmission direction can be redirected from directly in front of the transducer array, or redirected at different angles on either side of the unredirected beam to obtain a wider fan-shaped field of view, or transmitted at a selected Doppler angle.

[0033] Beamforming is performed by appropriately delaying and then combining the echoes received by adjacent groups of transducer elements. The partial beamforming signals generated from each patch by microwave beamformer 14 are coupled to a main beamformer 18, where the partial beamforming signals from individual patches of transducer elements are combined into a coherent echo signal of full beamforming. For example, the main beamformer 18 may have 128 channels, each receiving partial beamforming signals from patches of 12 transducer elements. In this way, signals received by more than 1500 transducer elements of a two-dimensional matrix array transducer can be effectively contributed to a single beamformed signal.

[0034] The coherent echo signal undergoes signal processing performed by signal processor 20, which includes filtering by digital filters and noise and speckle reduction through spatial or frequency recombination. For example, the digital filters of signal processor 20 can be of the type disclosed in U.S. Patent US 5833613 (Averkiou et al.). The echo signal is then coupled to a quadrature bandpass filter (QBP) 22. The QBP performs three functions: band-limiting the rf echo signal data, generating in-phase and quadrature pairs (I and Q) of the echo signal data, and decimating the digital sampling rate. The QBP comprises two separate filters, one generating in-phase samples and the other generating quadrature samples, wherein each filter is formed by multiple multiplier-accumulators (MACs) implementing FIR filters.

[0035] The coherent echo signal, after beamforming and processing, is coupled to a pair of image data processors. The B-mode processor 26 generates signal data for B-mode images of structures in the body (e.g., tissues and blood vessel walls). The B-mode processor transmits signal data via (I... 2 +Q 2 ) 1 / 2 The amplitude (envelope) of the I and Q signal components of the quadrature demodulated signal is calculated in the form of the echo signal amplitude to perform amplitude (envelope) detection. The quadrature echo signal components are also coupled to the Doppler processor 24. The Doppler processor 24 stores the set of echo signals from discrete points in the image field and then uses it to estimate the Doppler frequency shift at points in the image by a Fast Fourier Transform (FFT) processor. The Doppler processor is also capable of performing angle correction for Doppler velocity values, and in embodiments of the invention, angle correction as measured on the first (major axis) Doppler image is used to perform angle correction for Doppler data of the second (lateral) Doppler image used to determine volumetric flow rate. The rate of acquisition of the set determines the range of motion velocities that the system can accurately measure and depict in the image. The Doppler frequency shift is proportional to the motion (e.g., blood flow and tissue movement) at each point in the image field. For color Doppler image data, the estimated Doppler blood flow values ​​at each point in the blood vessel are wall-filtered, angle-corrected, and converted to color values ​​using a lookup table. The wall filter has an adjustable cutoff frequency; motion is rejected when the frequency is above or below this cutoff frequency. For example, when imaging flowing blood, low-frequency motion of the vessel wall will be rejected. B-mode image data and Doppler blood flow values ​​are coupled to a scan converter 32, which converts the B-mode and Doppler samples from their acquired R-θ coordinates to Cartesian (x, y) coordinates, thereby displaying them in the desired format (e.g., a linear display format or a sector display format, such as...). Figure 7 and Figure 7aThe image is displayed as shown. B-mode images or Doppler images can be displayed separately, or both can be displayed together in anatomical registration, where the color Doppler overlay shows blood flow in tissues and vessels processed in B-mode in the image, such as... Figure 7 and Figure 7a As shown in the figures. Another display possibility is to display side-by-side images of the same anatomical structures that have been processed differently, as illustrated in these figures. This side-by-side display format is useful when comparing images and is particularly useful for displaying two images from a dual-plane probe. The scan-converted image data (B-mode data and Doppler data) is coupled to and stored in image data memory 30, where the scan-converted image data (B-mode data and Doppler data) is stored in a memory location addressable according to the spatial location at the time of image data acquisition. The dual-plane image derived from the data generated by the scan converter 28 and stored in the image data memory is coupled to display processor 34 for further enhancement, buffering, and temporary storage for display on image display 36.

[0036] Doppler values ​​of the image (e.g., such as) Figure 7 The color Doppler pixel values ​​of the lateral view of the blood vessel shown in image 92 are coupled to the volumetric flow rate calculator 40. In the volumetric flow rate calculator 40, an algorithm for calculating the volumetric flow rate is run, for example, by integrating the pixel flow rate values ​​over the lumen area of ​​the blood vessel, as shown in the following expression:

[0037] Q=∫ s v·dA

[0038] The volumetric flow rate can be calculated individually for each frame in the color Doppler image to provide a volumetric flow rate as a function of time, or the volumetric flow rate can be summed over multiple frames to provide a time-averaged volumetric flow rate. The volumetric flow rate measurement results are coupled to a graphics generator 49, and the volumetric flow rate values ​​are coupled from the graphics generator 49 to a display processor 34 for display along with the ultrasound images. Alternatively or additionally, the graphics generator 49 is capable of generating flow profile curves for display on a display 36. The graphics generator also generates graphics for display along with the ultrasound images for items such as cursors, measurement dimensions, examination parameters, patient name, and the aforementioned Doppler gate line 82, flow cursor 84, and segmentation template 78.

[0039] exist Figure 8a It shows Figure 8The operation details of the volumetric flow rate calculator 40 are described below. In this embodiment, the angle correction of the transverse image 92 is performed by the volumetric flow rate calculator, not by the Doppler processor 24. The image segmentation processor 402 receives data from the image data storage 30 of the transverse image 92. Doppler data in the transverse view of the blood vessel 70 is identified (segmented) by the system operator placing a template, such as a circular template 78, on the lumen of the blood vessel 70. The Doppler data specified within the blood vessel 70 is then coupled to the angle correction processor 404, which calculates the angle correction performed on the Doppler data of the long-axis view 90 based on the long-axis Doppler gate line 82 and the long-axis flow cursor 84, the angle being the angle between the two graphics set by the user during the acquisition of the long-axis view 90. Thus, the Doppler values ​​of blood flow in the transverse image are angle-corrected based on the angle set by these graphics during the acquisition of the long-axis view 90. The angle-corrected Doppler values ​​are then integrated over the blood vessel region in the transverse image 92 to determine the volumetric flow rate. Figure 8a In one implementation, this operation is performed by summing angle-corrected Doppler flow values ​​from a transverse view image, as shown by processor 406, to generate a measure of volumetric flow rate Q. This value is coupled to a graphics generator 49 for display to the ultrasound system operator. In a typical implementation, the calculations performed by processors 402, 404, and 406 are performed by a software program configured to perform the illustrated functions.

[0040] Operable Figure 8 The ultrasound system is used to perform a typical ultrasound examination of the carotid artery, as described below. The user will first examine the carotid artery using ultrasound imaging (including B-mode imaging, color Doppler imaging, and pulsed Doppler imaging) according to standard clinical practice. Upon identification of significant stenosis, the user then takes the following steps to determine volumetric flow rate. First, the ultrasound probe is scanned to locate a segment of the artery upstream of the stenosis, minimizing turbulence in the blood flow. Next, dual-plane mode is activated. The probe is manipulated until the vessel appears extended in the long axis view of the left image 90. The probe is tilted at an elevation angle until the vessel is approximately centered in the right image 92. The color scale (pulse repetition frequency, PRF) is adjusted to prevent blood flow aliasing. The angle correction is adjusted to align with vessel 70 in the left image 90. Flow information for one or more cardiac cycles is then acquired. The region of interest is specified (segmented) by placing a template 78 over vessel 70 in the right image, defining which color pixels in the image should be included in the volumetric flow rate calculation. Then, Doppler data from the transverse image, which is angularly corrected according to the long axis view, is used to calculate and display the volumetric flow rate as an average value over time (a single number) or as a graph of the volumetric flow rate as a function of time.

[0041] The method for measuring volumetric flow rate according to the principle of the present invention can be as follows: Figure 9 Proceed as shown. At point 901, the ultrasound system is set to operate in dual-plane mode, thereby acquiring two images that intersect at a Doppler angle. At point 903, the first Doppler image is acquired, for example, Figure 7 The long axis view is 90. At 904, the Doppler acquisition direction of the first image is adjusted by adjusting the Doppler gate line 82. After the Doppler direction has been set, at 905, a second Doppler image is acquired at a plane in the Doppler line direction of the first image. At 907, both images are displayed simultaneously. At 909, the Doppler angle correction for the first image is determined based on the Doppler line direction and the direction of the flow cursor set by the user on the blood flow in the first image. At 911, the blood flow in the second Doppler image is segmented by placing a graphic circular template on the lumen of the second image. At 915, the volumetric flow rate is calculated as described above based on the Doppler value of the blood flow in the second image, which has been angle-corrected by the angle correction determined for the first image. At 920, the measured volumetric flow rate is displayed to the user or recorded in the ultrasound examination record.

[0042] Note that the scope of the invention described above also includes embodiments that do not necessarily include an ultrasound probe, but rather receive input Doppler image data acquired from two image planes (90, 92) intersecting along the Doppler beam direction, and are adapted to generate two Doppler images of blood flow. The invention also includes a display (36) adapted to simultaneously display the two Doppler images, and a graphics generator (49) responsive to user control and adapted to display Doppler lines (82) and a moving cursor (84) on the first Doppler image (90) of the Doppler images. A volumetric flow rate calculator (40) responds to Doppler image data from the second Doppler image (92) of the Doppler images and the Doppler angles established by the Doppler lines and the moving cursor, and is adapted to determine an angle-corrected measure of the volumetric flow rate.

[0043] It should also be noted that ultrasonic systems suitable for use in embodiments of the present invention (especially) Figure 8The component structure of an ultrasound system can be implemented using hardware, software, or a combination thereof. Various embodiments and / or components of the ultrasound system and its controller, or components and controllers therein, can also be implemented as part of one or more computers or microprocessors. The computer or processor may include computing devices, input devices, display units, and interfaces (e.g., for accessing the Internet). The computer or processor may include a microprocessor. The microprocessor may be connected to a communication bus to, for example, access a PACS system or data network to import training images and store the results of clinical examinations. The computer or processor may also include memory. Memory devices such as image data storage may include random access memory (RAM) and read-only memory (ROM). The computer or processor may also include storage devices, which may be hard disk drives or removable storage drives, such as floppy disk drives, optical disk drives, solid-state thumb drives, etc. The storage device may also be other similar devices for loading computer programs or instructions for volumetric flow analysis into the computer or processor.

[0044] As used herein, the terms “computer,” “module,” “processor,” or “workstation” can include any processor-based or microprocessor-based system (including systems using microcontrollers, reduced instruction set computers (RISC), ASICs, or logic circuits), as well as any other circuitry or processor capable of performing the functions described herein. The examples above are merely illustrative and are therefore not intended to limit the definition and / or meaning of these terms in any way.

[0045] A computer or processor runs a set of instructions stored in one or more storage elements to process input data. Storage elements may also store data or other information as desired or required. Storage elements can be in the form of information sources within the processing machine or physical storage elements. The set of instructions for an ultrasound system (including instructions controlling the acquisition, processing, and display of ultrasound images, as well as instructions for Doppler angle measurement and volumetric flow rate calculation as described above) can include various commands that instruct the computer or processor, acting as the processing machine, to perform specific operations, such as methods and procedures for Doppler blood flow data acquisition, line and cursor adjustment, and volumetric flow rate measurement. The set of instructions can be in the form of software programs. Software can take various forms, such as system software or application software, and can be embodied in tangible and non-transient computer-readable media. The formulas for volumetric flow rate calculation given above and Figure 8aThe sum of the Doppler data values ​​shown, and the calculation of the Doppler angle based on the cursor placed on the image, are typically calculated by or under the guidance of software routines. Alternatively, the software can be in the form of a larger program or a collection of individual programs or modules within a larger program module. The software can also include modular programming in the form of object-oriented programming. The processing machine's processing of the input data can be in response to operator commands issued from the control panel 38, or in response to the results of previous processing, or in response to requests from another processing machine.

[0046] Furthermore, the limitations of the claims are not written in the form of functional modules, nor are they intended to be interpreted based on paragraph 6 of 35 U.S.C. 112. This is unless such a claim explicitly uses the phrase "for a unit that is not further structured" to state a function without further construction.

Claims

1. An ultrasound diagnostic imaging system for analyzing blood volumetric flow rate, comprising: An ultrasonic probe (10) is adapted to acquire Doppler image data from two image planes (90, 92) that intersect along the direction of the Doppler beam; Image data processor (24) that responds to acquired Doppler image data and is adapted to generate two Doppler images of the flow; A display (36) adapted to simultaneously display the two Doppler images; A graphics generator (49) that responds to user control and is adapted to display Doppler lines (82) and a moving cursor (84) on a first Doppler image (90) in the Doppler image; as well as A volumetric flow rate calculator (40) responds to Doppler image data of a second Doppler image (92) in the Doppler image and the Doppler angle established by the Doppler lines and the moving cursor, and is adapted to determine an angle-corrected measure of the volumetric flow rate.

2. The ultrasound diagnostic imaging system according to claim 1, wherein, The Doppler lines are aligned with the direction of the Doppler beam that scans the first Doppler image; and The image plane of the second Doppler image is aligned with the direction of the Doppler beam of the first Doppler image.

3. The ultrasound diagnostic imaging system according to claim 1, wherein, The ultrasound probe is also adapted to simultaneously acquire a long-axis view of the blood vessel in the first Doppler image and a lateral view of the blood vessel in the second Doppler image.

4. The ultrasound diagnostic imaging system according to claim 1, wherein, The first Doppler image is acquired by scanning an image plane using multiple parallel Doppler beams emitted in a given direction. The Doppler lines are aligned with the direction of the Doppler beam.

5. The ultrasound diagnostic imaging system according to claim 4, wherein, The image plane of the second Doppler image is aligned with the direction of the Doppler beam of the first Doppler image.

6. The ultrasound diagnostic imaging system according to claim 1, wherein, The ultrasonic probe also includes a two-dimensional matrix array transducer.

7. The ultrasound diagnostic imaging system according to claim 6, wherein, The ultrasound probe is also adapted to operate in a dual-plane mode, thereby scanning two image planes in a time-staggered manner.

8. The ultrasound diagnostic imaging system according to claim 7, wherein, The ultrasound probe is also adapted to scan two image planes at a selected non-orthogonal angle to the plane of the matrix array transducer.

9. The ultrasound diagnostic imaging system according to claim 7, wherein, The ultrasonic probe is also adapted to scan the image plane at a selected non-orthogonal angle to the direction of flow.

10. The ultrasound diagnostic imaging system according to claim 1, wherein, The volumetric flow rate calculator is also adapted to calculate algorithms of the following forms: Q=∫ s v·dA Where Q is the volumetric flow rate, v is the angle-corrected flow velocity, and surface S is a cross-section of a blood vessel containing Doppler data.

11. The ultrasound diagnostic imaging system according to claim 10, wherein, The volumetric flow rate calculator is also adapted to sum the values ​​of angle-corrected Doppler data within the blood vessel lumen.

12. A method for measuring volumetric flow rate using an ultrasound diagnostic imaging system, comprising: A scanning (903) was performed using an ultrasound probe suitable for operation in dual-plane mode to acquire a first Doppler image of the target blood vessel in a long-axis view; The ultrasound probe in the dual-plane mode is used to scan (905) to simultaneously acquire a second Doppler image in a lateral view of the target blood vessel in an image plane aligned with the Doppler angle of the first Doppler image; Display both images (907) simultaneously; Angle correction (909) is determined based on the Doppler beam direction and the flow direction of the first Doppler image; and The volumetric flow rate (915) is calculated based on the data from the second Doppler image using an angle correction determined based on the first Doppler image.

13. The method of claim 12, further comprising adjusting the Doppler beam direction for the first Doppler image to intersect the flow direction at a non-orthogonal angle.

14. The method of claim 13, further comprising segmenting the flow in the second Doppler image using a template.

15. The method according to claim 12, wherein, Calculating volumetric flow rate also includes integrating the flow rate value pixels of the target blood vessel in the second Doppler image.

16. An ultrasound diagnostic imaging system for analyzing blood volumetric flow rate, comprising: An image data processor (24) that responds to inputs of Doppler image data acquired from two image planes (90, 92) intersecting along the Doppler beam direction and is adapted to generate two Doppler images of the flow; A display (36) adapted to simultaneously display the two Doppler images; A graphics generator (49) that responds to user control and is adapted to display Doppler lines (82) and a moving cursor (84) on a first Doppler image (90) in the Doppler image; as well as A volumetric flow rate calculator (40) responds to Doppler image data of a second Doppler image (92) in the Doppler image and the Doppler angle established by the Doppler lines and the moving cursor, and is adapted to determine an angle-corrected measure of the volumetric flow rate.

17. The ultrasound diagnostic imaging system according to claim 16, wherein, The Doppler lines are aligned with the direction of the Doppler beam scanning the first Doppler image; and The image plane of the second Doppler image is aligned with the direction of the Doppler beam of the first Doppler image.

18. The ultrasound diagnostic imaging system according to claim 16, wherein, The volumetric flow rate calculator is also adapted to calculate algorithms of the following forms: Q=∫ s v·dA Where Q is the volumetric flow rate, v is the angle-corrected flow velocity, and surface S is a cross-section of a blood vessel containing Doppler data.

19. The ultrasound diagnostic imaging system according to claim 18, wherein, The volumetric flow rate calculator is also adapted to sum the values ​​of angle-corrected Doppler data within the blood vessel lumen.

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