阅读说明：本技术 重建血管造影数据中的心搏频率现象 (Reconstruction of heart beat frequency phenomena in angiographic data ) 是由 威廉·E·巴特勒 于 2020-03-27 设计创作，主要内容包括：提供了一种用于从血管造影图像的序列(即以比心率快(大于两倍)的速度获取的二维投影图像)重建心搏频率现象的技术,并对其进行分析以根据该投影提供移动血管脉搏波的时空重建。在各方面中,可以将心搏频率带通滤波器和/或欧拉放大应用于血管造影数据以输出心搏频率血管造影现象的时空重建。(A technique is provided for reconstructing the heart beat frequency phenomenon from a sequence of angiographic images, i.e. two-dimensional projection images acquired at a speed faster than (more than twice) the heart rate, and analyzing them to provide a spatiotemporal reconstruction of the moving vessel pulse wave from the projections. In aspects, a heart beat frequency band pass filter and/or euler amplification may be applied to the angiographic data to output a spatiotemporal reconstruction of the heart beat frequency angiographic phenomena.)

1. A method for extracting heart beat frequency angiography phenomena from an angiography study obtained at a faster rate than heart beat frequency, the method comprising:

acquiring or receiving data from an angiographic study that is acquired at a faster rate than the heart beat frequency;

applying a heart beat frequency band pass filter to the angiographic data to generate a spatiotemporal reconstruction of a heart beat frequency angiographic phenomenon; and

displaying the spatiotemporal reconstruction of the heart beat frequency angiography phenomenon in one or more images.

2. The method of claim 1, wherein the heart beat frequency angiography phenomenon is extracted from a cine sequence of angiography images using the heart beat frequency band pass filter.

3. The method of claim 1, wherein applying the heart beat frequency band pass filter further comprises:

processing a time sample of each pixel in the angiographic image as a separate signal; and

applying the heartbeat frequency band pass filter to a pixel-by-pixel signal.

4. The method of claim 1, further comprising obtaining simultaneously measured cardiac signals and using the simultaneously measured cardiac signals as a cross-correlation target to provide a band-pass heart beat frequency filter defined within a frequency range of the measured cardiac signals.

5. The method of claim 1, wherein the heart beat frequency band pass filter comprises one of:

a real-valued filter that presents in image form using gray scale; or a complex-valued filter that is presented in an image based on the heart beat frequency amplitude and the heart beat frequency phase.

6. The method of claim 1, further comprising applying euler magnification to the angiographic data.

7. The method of claim 6, wherein applying the euler amplification comprises:

applying a spatial decomposition to the sequence of angiographic images;

applying a temporal filter to the sequence of spatially resolved angiographic images;

one or more of the sequence of dual spatially resolved and temporally filtered angiographic images are selectively magnified; and

the sequence of selectively magnified angiographic images and the sequence of angiographic images are reassembled into a combined sequence of angiographic images to allow visualization of the magnified spatiotemporal reconstruction.

8. The method of claim 7, wherein applying the spatial decomposition further comprises performing a multi-scale anisotropic filtering or applying a spatial transformation comprising one of shear waves or ridge waves.

9. The method of claim 7, further comprising selecting an angiographic image having temporal and spatial phenomena of interest, including temporal phenomena corresponding to heart beat frequency phenomena.

10. The method of claim 7, wherein applying the spatial decomposition comprises spatially decomposing an angiographic image into several images each having different spatial characteristics, including filtering spatial structures of a particular spatial frequency.

11. The method of claim 7, wherein for temporal phenomena outside the heartbeat band, the heartbeat frequency band pass filter is applied with a value of zero, and further comprising:

reconstructing an angiographic image comprising the heart beat frequency phenomenon using the amplified spatial translation.

12. The method of claim 11, wherein the reconstructed angiogram is provided as a movie video sequence.

13. An angiography system for extracting beat frequency angiography phenomena obtained at a rate faster than the beat frequency, the angiography system comprising:

an x-ray source and an x-ray detector for obtaining an angiographic image;

one or more computer processors;

one or more computer-readable storage media;

program instructions stored on the one or more computer-readable storage media for execution by at least one of the one or more computer processors, the program instructions comprising instructions for:

acquiring or receiving data from an angiographic study that is acquired at a faster rate than the heart beat frequency;

applying a heart beat frequency band pass filter to the angiographic data to generate a spatiotemporal reconstruction of a heart beat frequency angiographic phenomenon; and

displaying the spatiotemporal reconstruction of the heart beat frequency angiography phenomenon in one or more images.

14. The system of claim 13, wherein the program instructions further comprise applying the heart beat frequency band pass filter to extract the heart beat frequency angiography phenomenon from a cine sequence of angiography images.

15. The system of claim 13, wherein the program instructions further comprise instructions to:

processing a time sample of each pixel in the angiographic image as a separate signal; and

applying the heartbeat frequency band pass filter to a pixel-by-pixel signal.

16. The system of claim 13, further comprising using the simultaneously measured cardiac signals as a cross-correlation target to provide a band-pass heart beat frequency filter that is confined within a frequency range of the measured cardiac signals.

17. The system of claim 13, wherein the heart beat frequency band pass filter comprises one of: a real-valued filter that presents in image form using gray scale; or a complex-valued filter that is presented in an image based on the heart beat frequency amplitude and the heart beat frequency phase.

18. The system of claim 13, wherein the program instructions further comprise instructions to:

euler magnification is applied to the angiographic data.

19. The system of claim 18, wherein the program instructions further comprise instructions to:

applying a spatial decomposition to the sequence of angiographic images;

applying a temporal filter to the sequence of spatially resolved angiographic images;

one or more of the sequence of dual spatially resolved and temporally filtered angiographic images are selectively magnified; and

the sequence of selectively magnified angiographic images and the sequence of angiographic images are reassembled into a combined sequence of angiographic images to allow visualization of the magnified spatiotemporal reconstruction.

20. The system of claim 19, wherein the program instructions further comprise instructions to perform multi-scale anisotropic filtering or apply a spatial transformation using shear waves or ridge waves.

21. The system of claim 19, wherein the program instructions further comprise instructions to:

an angiographic image is selected having temporal and spatial phenomena of interest including temporal phenomena corresponding to heart beat frequency phenomena.

22. The system of claim 19, wherein the program instructions further comprise instructions to:

the angiographic image is spatially decomposed into several images each having different spatial characteristics, including filtering spatial structures of a particular spatial frequency.

23. The system of claim 19, wherein for temporal phenomena outside the heartbeat band, the heartbeat frequency band pass filter is applied with a value of zero, and the program instructions further comprise instructions to:

reconstructing an angiographic image comprising the heart beat frequency phenomenon using the amplified spatial translation.

24. A computer program product for determining semantic analysis, the computer program product comprising one or more computer-readable storage media having program instructions embodied therewith, the program instructions executable by a computer to cause the computer to:

acquiring or receiving data from an angiographic study that is acquired at a faster rate than the heart beat frequency;

applying a heart beat frequency band pass filter to the angiographic data to generate a spatiotemporal reconstruction of a heart beat frequency angiographic phenomenon; and

displaying the spatiotemporal reconstruction of the heart beat frequency angiography phenomenon in one or more images.

25. The system of claim 24, wherein the program instructions executable by the computer further cause the computer to apply euler magnification to the angiographic data.

Technical Field

The field relates generally to techniques for reconstructing heart beat frequency phenomena in angiographic studies, and more particularly to techniques for separating and/or amplifying heart beat frequency phenomena in angiographic studies using band-pass filters and/or amplification.

Background

To obtain an angiogram, a bolus of a chemical contrast agent is injected intravascularly into the patient and a sequence or time series of x-rays is obtained. A two-dimensional projection of the anatomy of the vascular system is captured as a chemical contrast agent blocking the x-ray passage through the vascular system in the x-ray projection path. The aggregation of these images, ordered according to the time of acquisition, comprises an angiogram.

Fluorescence angiography (fluorography) imaging captures and quantifies the heart beat frequency phenomenon allowing the spatiotemporal reconstruction of moving vascular pulse waves in the brain and other organs using wavelet processed angiography data, as described in U.S. patent No. 10,123,761 (hereinafter the' 761 patent), the entire contents of which are incorporated herein by reference in its entirety. This technique can show blood flow as a sequence of arterial volume and venous volume of reverse cardiac phase through the capillary bed. Thus, the spatial and temporal distribution of heart beat frequency phenomena in the blood flow provides physiological, diagnostic and medical information that can be shown in angiographic cine images.

While the above-described techniques provide spatio-temporal reconstruction of moving vascular pulse waves in the brain and other organs, it is desirable to develop other methods for reconstructing heart beat frequency phenomena in angiographic studies in order to provide greater flexibility to the prior art.

Disclosure of Invention

Embodiments of the present invention relate to methods, systems, and computer readable media for reconstructing heart beat frequency phenomena in angiographic data that does not utilize wavelets, particularly Gabor wavelets, for processing the angiographic data.

A system, method, and computer readable medium are provided for extracting heart beat frequency angiography phenomena from an angiography study obtained at a faster rate than heart beat frequency. Data is acquired or received from an angiography study obtained at a faster rate than heart beat frequency, and a heart beat frequency band pass filter is applied to the angiography data to output a spatiotemporal reconstruction of heart beat frequency angiography phenomena, which is displayed in one or more images.

According to another aspect, Euler magnification is applied to the angiographic data to produce a magnification effect. Euler's magnification may be applied to the angiographic images to select images with temporal and spatial phenomena of interest, including temporal phenomena corresponding to the heart beat frequency bands.

According to another aspect, a heart beat frequency band pass filter is applied to extract heart beat frequency angiography phenomena from a cine sequence of angiographic images.

According to another aspect, applying the heart beat frequency band pass filter further comprises processing the time samples of each pixel in the angiographic image as separate signals; and applying a heartbeat frequency band pass filter to the pixel-by-pixel signal.

According to another aspect, simultaneously measured cardiac signals are obtained and used as cross-correlation targets to provide a band-pass heart beat frequency filter defined within the frequency range of the measured cardiac signals.

According to another aspect, the heart beat frequency band pass filter comprises one of: a real-valued filter using gray scale in image form, or a complex-valued filter based on heart beat frequency amplitude and heart beat frequency phase in image form.

According to another aspect, applying euler magnification includes applying a spatial decomposition to the sequence of angiographic images, applying a temporal filter to the sequence of spatially decomposed angiographic images, selectively magnifying one or more of the sequence of dual spatially decomposed and temporally filtered angiographic images, and reassembling the sequence of selectively magnified angiographic images and the sequence of angiographic images into a combined sequence of angiographic images to allow visualization of the magnified spatiotemporal reconstruction.

According to another aspect, applying the spatial decomposition further comprises performing a multi-scale anisotropic filtering or applying a spatial transformation comprising one of shear waves or ridge waves.

According to another aspect, an angiographic image is selected having temporal and spatial phenomena of interest including temporal phenomena corresponding to heart beat frequency phenomena.

According to another aspect, applying spatial decomposition includes spatially decomposing the angiographic image into several images each having different spatial characteristics, including filtering spatial structures of particular spatial frequencies.

According to another aspect, for temporal phenomena outside the heart beat frequency band, a heart beat frequency band pass filter with a value of zero is applied and an angiographic image comprising the heart beat frequency phenomena is reconstructed with the amplified spatial translation.

Other objects and advantages of these techniques will be apparent from the specification and drawings.

Drawings

The drawings illustrate preferred embodiments presently contemplated for carrying out various aspects of the invention. In the drawings:

fig. 1A and 1B illustrate a rotational x-ray system that may be used with aspects of the present disclosure to acquire angiographic data.

FIG. 2 is a block diagram of a computer system or information processing device that may be used with aspects of the present disclosure.

Fig. 3 is a perspective view of a pulse oximeter coupled to a multi-parameter patient monitor and sensor that may be used with aspects of the present disclosure to acquire cardiac signals.

Fig. 4 is a block diagram of an Electrocardiogram (EKG) device that may be used with aspects of the present disclosure to acquire cardiac signals.

Fig. 5 illustrates a luminance-hue-color model for rendering complex-valued numbers in accordance with aspects of the present disclosure.

FIG. 6 illustrates a generalized method for amplifying spatiotemporal angiography phenomena according to aspects of the present disclosure.

Fig. 7 is a detailed flow diagram illustrating a technique for reconstructing heart beat frequency phenomena in angiographic data according to aspects of the present disclosure.

Fig. 8 illustrates a fourier-based approach for amplifying spatiotemporal angiography phenomena according to aspects of the present disclosure.

Fig. 9 illustrates an example implementation of reconstructing heart beat frequency phenomena according to aspects of the present disclosure.

Fig. 10 is a high-level flow diagram illustrating a technique for reconstructing heart beat frequency phenomena in angiographic data according to aspects of the present disclosure.

Detailed Description

Methods, systems, and computer readable media are provided for reconstructing heart beat frequency phenomena in angiographic data that does not rely on wavelets for spatiotemporal reconstruction. A sequence of angiographic images (i.e., two-dimensional projection images) is acquired at a faster frequency than the heart rate and processed to provide a spatiotemporal reconstruction of the moving vessel pulse wave. To generate a spatiotemporal reconstruction of moving vessel pulse waves, in some aspects, a heart rate band pass filter may be applied to the angiography data using euler amplification and amplifiers to generate a spatiotemporal reconstruction of heart rate angiography phenomena. These techniques will be described in detail below.

Referring to fig. 1-4, exemplary systems or devices are shown that may be used to implement embodiments of the present invention. It should be understood that such systems and devices are merely examples of representative systems and devices and that other hardware and software configurations are suitable for use with the present technology. Accordingly, the present technology is not intended to be limited to the particular systems and devices illustrated herein, and it is to be understood that other suitable systems and devices may be employed without departing from the spirit and scope of the subject matter provided herein.

To reconstruct the moving vessel pulse wave, raw data is acquired via a fluorescence angiography imaging system at a higher rate than the heart beat frequency (e.g., images may be acquired at a frequency of up to 30 Hz). In various aspects, the system acquires images at a frequency that is twice as fast as the highest frequency component of the cardiac signal, according to the nyquist sampling theorem. For angiograms acquired at a faster rate than heart rate, the images may be processed according to the techniques provided herein to generate a time-varying spatial reconstruction of the heart beat frequency angiographic phenomena.

Referring first to fig. 1A and 1B, a rotational x-ray system 28 is shown, which rotational x-ray system 28 may be used to obtain angiograms at a faster rate than the heart rate (such as via fluorescence angiography). As previously described, in acquiring an angiogram, a chemical contrast agent is injected into a patient positioned between an x-ray source and a detector, and x-ray projections are captured by the x-ray detector as two-dimensional images. A sequence of two-dimensional projection images is acquired, the sequence of two-dimensional projection images comprising an angiographic study in which angiographic image frames are acquired at a faster frequency than heart beat frequency to allow spatiotemporal reconstruction of heart beat frequency phenomena into a heart beat space angiogram.

As shown in FIG. 1A, an example of an angiographic imaging system is shown in the form of a rotational x-ray system 28, the rotational x-ray system 28 including a gantry having a C-arm 30, the C-arm 30 carrying an x-ray source assembly 32 at one of its ends and an x-ray detector array assembly 34 at the other end of the C-arm. The gantry enables the x-ray source 32 and detector 34 to be oriented in different positions and angles around a patient placed on a table 36, while enabling access to the patient by a physician. The frame includes a base 38, the base 38 having a horizontal leg 40 extending below the table 36, and a vertical leg 42 extending upwardly at the end of the horizontal leg 40, the horizontal leg 40 being spaced from the table 36. A support arm 44 is rotatably secured to the upper end of the vertical leg 42 for rotation about a horizontal pivot 46.

Pivot 46 is aligned with the centerline of table 36 and arm 44 extends radially outward from pivot 46 to support a C-arm drive assembly 47 on its outer end. The C-arm 30 is slidably secured to the drive assembly 47 and is coupled to a drive motor (not shown) that slides the C-arm 30 to rotate about the C-axis 48, as indicated by arrow 50. Pivot 46 and C-axis 48 intersect each other at an isocenter 56 located above table 36 and are perpendicular to each other.

An x-ray source assembly 32 is mounted at one end of the C-arm 30 and a detector array assembly 34 is mounted at the other end thereof. The x-ray source assembly 32 emits an x-ray beam directed toward the detector array assembly 34. Both assemblies 32 and 34 extend radially inward to pivot 46 so that the central ray of the beam passes through the system isocenter 56. Thus, during acquisition of x-ray attenuation data from a subject placed on table 36, the central ray of the beam may be rotated about the system isocenter about pivot 46 or C-axis 48, or both.

The x-ray source assembly 32 contains an x-ray source that emits a beam of x-rays when energized. The central ray passes through the system isocenter 56 and strikes a two-dimensional flat-panel digital detector 58 housed in the detector assembly 34. The detector 58 may be, for example, a 2048 x 2048 element two-dimensional array of detector elements. Each element produces an electrical signal that represents the intensity of impinging x-rays, and thus the attenuation of the x-rays as they pass through the patient. During a scan, the x-ray source assembly 32 and the detector array assembly 34 are rotated about the system isocenter 56 to acquire x-ray attenuation projection data from different angles. In some aspects, the detector array is capable of acquiring 50 projections or views per second, which is a limiting factor in determining how many views can be acquired at a given scan path and speed.

Referring to FIG. 1B, the rotation of the assemblies 32 and 34 and the operation of the x-ray source are governed by a control mechanism 60 of the x-ray system. Control mechanism 60 includes an x-ray controller 62 that provides power and timing signals to x-ray source 52. A Data Acquisition System (DAS)64 in control mechanism 60 samples data from the detector elements and passes the data to an image reconstructor 65. An image reconstructor 65 receives digitized x-ray data from DAS64 and performs high speed image reconstruction in accordance with the methods of the present disclosure. The reconstructed image is used as an input to a computer 66, which computer 66 stores the image in a mass storage device 69 or further processes the image.

The control mechanism 60 also includes a frame motor controller 67 and a C-axis motor controller 68. In response to motion commands from computer 66, motor controllers 67 and 68 provide power to motors in the x-ray system that produce rotation about respective pivots 46 and C-axis 48. The computer 66 also receives commands and scanning parameters from an operator via a console 70 having a keyboard and other manually operable controls. An associated display 72 allows the operator to observe the reconstructed image and other data from computer 66. The operator supplied commands are used by computer 66 under stored program guidance to provide control signals and information to DAS64, x-ray controller 62, and motor controllers 67 and 68. In addition, the computer 66 operates a table motor controller 74, which table motor controller 74 controls the motorized table 36 to position the patient relative to the system isocenter 56.

Referring now to fig. 2, there is shown a block diagram of a computer system or information processing device 80 (e.g., computer 66 in fig. 1B), which computer system or information processing device 80 may incorporate an angiographic imaging system, such as rotational x-ray system 28 of fig. 1A and 1B, to provide enhanced functionality or to serve as a stand-alone device for extracting heart beat frequency angiographic phenomena from angiographic data, according to embodiments of the present invention. In one embodiment, computer system 80 includes a monitor or display 82, a computer 84 (which includes processor(s) 86, a bus subsystem 88, a memory subsystem 90, and a disk subsystem 92), a user output device 94, a user input device 96, and a communication interface 98. The monitor 82 may include hardware and/or software elements configured to generate a visual representation or display of information. Some examples of monitor 82 may include familiar display devices such as television monitors, Cathode Ray Tubes (CRTs), Liquid Crystal Displays (LCDs), and so forth. In some embodiments, the monitor 82 may provide an input interface, such as in conjunction with touch screen technology.

The computer 84 may include familiar computer components such as one or more Central Processing Units (CPUs), memory or storage devices, Graphics Processing Units (GPUs), communication systems, interface cards, and the like. As shown in FIG. 2, computer 84 may include one or more processors 86, with the one or more processors 86 communicating with a plurality of peripheral devices via a bus subsystem 88. The processor(s) 86 may include commercially available central processing units or the like. Bus subsystem 88 may include mechanisms for communicating the various components and subsystems of computer 84 with one another as desired. Although bus subsystem 88 is shown schematically as a single bus, alternative embodiments of the bus subsystem may utilize multiple bus subsystems. The peripheral devices in communication with the processor(s) 86 may include a memory subsystem 90, a disk subsystem 92, user output devices 94, user input devices 96, a communication interface 98, and the like.

Memory subsystem 90 and disk subsystem 92 are examples of physical storage media configured to store data. Memory subsystem 90 may include a number of memories including a Random Access Memory (RAM) for volatile storage of program code, instructions, and data during program execution and a Read Only Memory (ROM) that stores fixed program code, instructions, and data. The disk subsystem 92 may include a plurality of file storage systems that provide persistent (non-volatile) storage for programs and data. Other types of physical storage media include floppy disks, removable hard disks, optical storage media such as CD-ROMs, DVDs, and bar codes, semiconductor memories such as flash memories, read-only memories (ROMs), battery-backed volatile memories, network storage devices, etc. The memory subsystem 90 and the disk subsystem 92 may be configured to store programming and data constructs that provide the functionality or features of the techniques discussed herein. Software code modules and/or processor instructions that when executed by the processor(s) 86 perform or otherwise provide the functions may be stored in the memory subsystem 90 and the disk subsystem 92.

User input device 94 may include hardware and/or software elements configured to receive input from a user for processing by components of computer system 80. The user input devices may include all possible types of devices and mechanisms for inputting information to the computer system 84. These may include keyboards, keypads, touch screens, touch interfaces incorporating a display, audio input devices (such as microphones and voice recognition systems), and other types of input devices. In various embodiments, the user input device 94 may be implemented as a computer mouse, trackball, track pad, joystick, wireless remote control, drawing pad, voice command system, eye tracking system, or the like. In some embodiments, the user input device 94 is configured to allow a user to select or otherwise interact with objects, icons, text, etc., that may appear on the monitor 82 via commands, motions, or gestures (such as clicking buttons, etc.).

User output device 96 may include hardware and/or software elements configured to output information from components of computer system 80 to a user. User output devices may include all possible types of devices and mechanisms for outputting information from computer 84. These may include a display (e.g., monitor 82), a printer, a touch or force feedback device, an audio output device, and so forth.

Communication interface 98 may include hardware and/or software elements configured to provide one-way or two-way communication with other devices.

For example, communication interface 98 may provide an interface between computer 84 and other communication networks and devices (such as via an internet connection).

In accordance with embodiments of the present invention, it should be appreciated that in addition to acquiring angiographic images, additional cardiac signals/data may be acquired simultaneously to serve as a cross-correlation target to perform spatio-temporal reconstruction of vessel pulse waves based on the techniques provided herein. For example, the cardiac signal/data may be used as a reference cardiac signal for phase indexed pixels in an angiographic projection. Fig. 3 and 4 illustrate exemplary devices for acquiring/providing reference cardiac signals using such devices/systems in the form of pulse oximetry and/or Echocardiography (EKG) systems or devices.

Fig. 3 is a perspective view of an example of a suitable pulse oximetry system 100 that includes a sensor 102 and a pulse oximetry monitor 104. The sensor 102 includes an emitter 106 for emitting light of a particular wavelength toward the patient's tissue and a detector 108 for detecting the light after it is reflected and/or absorbed by the patient's tissue. The monitor 104 is capable of calculating physiological characteristics related to the emission and detection of light received from the sensor 102. In addition, the monitor 104 includes a display 110 that is capable of displaying physiological characteristics and/or other information about the system. Sensor 102 is shown communicatively coupled via cable 112To the monitor 104, but may alternatively be communicatively coupled via a wireless transmission device or the like. In the illustrated embodiment, the pulse oximetry system 100 also includes a multi-parameter patient monitor 114. In addition to the monitor 104, or alternatively, the multi-parameter patient monitor 114 may be capable of calculating physiological characteristics and providing a central display 116 for information from the monitor 104 and other medical monitoring devices or systems. For example, the multi-parameter patient monitor 114 may display the patient SpO from the monitor 104 on the display 116₂And pulse rate information and blood pressure from a blood pressure monitor. In another embodiment, the computer system 80 may be configured to include hardware and software for communicating with a pulse oximetry sensor (such as sensor 102 shown in fig. 3), as well as hardware and software for calculating physiological characteristics received from the pulse oximetry sensor and utilizing such characteristics to extract and display heart beat frequency phenomena in accordance with the techniques described herein.

Fig. 4 is a schematic diagram of an electrocardiogram ("EKG") device 120, the electrocardiogram ("EKG") device 120 being shown connected to an information management system 122, optionally through a communication link 124. A common device for obtaining EKG is a 12-lead electrocardiograph. The EKG device 120 and the information management system 122 receive power 126 from an external source. The information management system 122 includes, among other things, a central processing unit 128 connected to a memory unit or database 130 via a data link 132. The CPU 128 processes the data and connects to output, such as a printer 134 and/or a display 136. Alternatively, if the optional information management system 122 is not utilized, the Electrocardiogram (EKG) device 120 may be directly connected to the printer 134 or display 136 through the communication link 124. The software program according to embodiments provided herein may reside in the EKG device 120, the information management system 122, or another device associated with receiving signals from the EKG device 120. The EKG device 120 is connected to a plurality of patient leads 138, each patient lead 138 having electrodes 140 for receiving EKG signals from a patient 142 in a known manner. The EKG device 120 has a signal conditioner 144 that receives the EKG signal and filters out noise, sets a threshold, isolates the signal, and provides an appropriate number of EKG signals for the number of leads 138 to an a/D converter 146, which a/D converter 146 converts the analog signal to a digital signal for processing by a microcontroller 148 or any other type of processing unit. Microcontroller 148 is connected to memory unit 150 (similar to memory unit 130) or any other computer-readable storage medium. In another embodiment, the computer system 80 may be configured to include hardware and software for communicating with EKG electrodes (such as the electrodes 140 shown in fig. 4), as well as hardware and software for calculating physiological characteristics received from the electrodes and utilizing such characteristics to extract and display heart beat frequency phenomena in accordance with the techniques described herein.

As indicated previously, the present embodiments relate to systems, methods, and computer readable media for reconstructing heart beat frequency phenomena in angiographic data. A sequence of angiographic images (i.e., two-dimensional projection images) is acquired (such as via the system of fig. 1A, 1B) at a faster rate than heart rate and analyzed (such as via the system of fig. 2) to provide a spatiotemporal reconstruction of moving vessel pulse waves (e.g., as described in the' 761 patent) utilizing band-pass filtering and magnification techniques provided herein.

In some aspects, the spatio-temporal reconstruction is complex valued data having the same dimensions as the projections, and each pixel at each point in time has complex valued data. It can be expressed as real and imaginary numbers. However, for physiological interpretation, it is expressed in polar form with amplitude and phase. In aspects, the amplitude represents the change in contrast of a given pixel at the heart beat frequency, and the phase represents the phase relative to the heart beat cycle.

While the' 761 patent uses a wavelet transform to produce a time-varying extraction of heart rate angiography phenomena (i.e., a wavelet transform is applied to each of the pixel-by-pixel time signals of the angiography), it should be understood that other methods may be utilized to produce a time-varying extraction of heart rate angiography phenomena.

Fig. 6-9 are flow diagrams corresponding to operation of techniques provided herein. It should be appreciated that the operations described herein may be implemented in an angiographic imaging system or in a stand-alone computer system to improve angiographic image processing and display techniques. According to an embodiment, a heart beat frequency band pass filter may be applied to angiographic data acquired at a faster frequency than the heart beat frequency to output a spatiotemporal reconstruction of heart beat frequency angiographic phenomena (e.g., moving vessel pulse waves). To extract the heart beat frequency phenomenon from a cine sequence of angiographic images, a heart beat frequency band pass filter is applied to the angiographic images. In aspects, a simultaneously measured cardiac signal (such as acquired from the pulse oximetry system of fig. 3 or the electrocardiography device of fig. 4) may be used as a reference cardiac signal for phase indexing.

FIG. 6 illustrates a high-level implementation of the techniques provided herein. Although operations are shown separately, it should be understood that certain operations (e.g., temporal processing, bandpass filtering, and amplification) may be combined and/or performed in a different order than shown in the present figure. At operation 610, the image is spatially decomposed. In one embodiment, the image may be decomposed into pixels, with subsequent calculations performed on a pixel-by-pixel basis. In other aspects, the pixels may be grouped into different frequency bands, and the calculations may be performed on a band-by-band basis.

Spatial decomposition is the segmentation of an image into several images with different spatial characteristics. For example, the images may be divided into groups corresponding to the spatial structure of a particular spatial frequency. Examples of methods for generating the spatial decomposition include, but are not limited to, a laplacian pyramid, a complex steerable pyramid, and a Reisz pyramid. In other aspects, the spatial decomposition may include multi-scale anisotropic filtering, or a shear wave or ridge wave based transformation. Any of which may be selected to extract heart beat frequency phenomena in a sequence of angiographic images, as heart beat frequency tissue may occur in one or more specific dimensions of the spatial structure. In aspects, the spatial frequency decomposition may be real-valued or complex-valued.

At operation 620, temporal processing may be performed to correlate the observed intensity of the pixels as a function of time with the translational motion signal. The temporal processing allows to extract the translational motion signal when the vessel pulse wave passes through the vascular system. At operation 630, the translational motion signal may be band-pass filtered, for example, at the heart beat frequency. In aspects, each pixel in an angiographic image may be considered a separate signal as a function of time, and a heart beat frequency band pass filter may be applied on a pixel-by-pixel basis. In other aspects, the heartbeat frequency band pass filter may be applied to groups corresponding to spatial structures. Within the limitations, instead of a frequency band pass filter, the simultaneously measured cardiac signal (e.g., obtained from the pulse oximetry system of fig. 3 or the electrocardiography device of fig. 4) may be used as a cross-correlation target, thereby providing an ultra-narrow band pass heart beat frequency filter. In aspects, the simultaneously measured cardiac signals are used as reference cardiac signals for phase indexing.

At operation 640, the signal (e.g., extracted from the image using band pass filtering, which corresponds to motion on the scale of the heart) may undergo magnification. In aspects, amplification may be achieved by multiplying a signal by a constant. In other aspects, euler magnification may be used. In some aspects, the amplification may be performed by isolating and then amplifying the heart beat frequency signal. In such a case, the amplified signal may be recombined with the original signal, for example, by aligning the amplified signal with the original signal (e.g., based on time-varying intensity, based on a timestamp, etc.). In some aspects, the amplified signal may be additively combined with the original signal. In other aspects, the amplified signal may be superimposed on the original signal. Thus, at operation 650, the original signal may be combined or superimposed with the amplified band-pass signal to form a reconstructed signal. For example, optionally, at operation 660, the reconstructed signal may undergo noise suppression (e.g., bilateral filtering or other suitable techniques). These techniques take as output a spatiotemporal reconstruction of the heart beat frequency angiography phenomenon, which is shown as a moving vessel pulse wave that can be amplified.

In other aspects, the heart beat frequency band pass filter may be real or complex valued, according to embodiments. If the heart beat frequency band pass filter is real valued, the resulting heart beat frequency phenomenon will be re-evaluated and may be presented in the form of an image using any suitable visualization format including grayscale, chrominance and/or luminance. Alternatively, if the heart beat frequency band pass filter is complex valued with real and imaginary parts, it can be represented in polar form including amplitude and phase. After passing through the heart beat frequency band pass filter, this amplitude can be interpreted as heart beat frequency amplitude, such as "intensity of heart action". The phase can be interpreted as a temporal position within the cardiac cycle. The amplitude and phase may be rendered using a luma-hue-color model, where the brightness of a pixel represents heart beat frequency amplitude and the hue represents heart beat frequency phase.

The heart beat frequency band pass filter and the magnified image may be presented in grayscale or in color scale (referring back to fig. 5), where optionally, color brightness may represent heart beat frequency amplitude or spatial motion velocity, and color hue may represent heart beat frequency phase or spatial motion direction, depending on whether the user chooses to emphasize temporal or spatial characteristics in the heart beat frequency band of the reconstructed result. Although the image is presented in grayscale, one of ordinary skill in the art will recognize that grayscale images include a spectrum of hues. A color model for rendering a complex-valued number in a pixel is depicted in fig. 5, and fig. 5 may show a spectrum of color tones including green, yellow, red and blue regions. For example, a sequence of such images may be animated across a time index to represent a movie video sequence of the motion of a list of vessel pulse waves (such as in the brain or heart or other vessel regions).

Referring now to fig. 7, examples for a given spatially filtered image and for only one spatial dimension x and time t dimension t are provided below for illustrative purposes. The representation corresponds to a continuous form of the signal. It should be understood, however, that these continuity equations may be applied to process digitized images in accordance with techniques known in the art.

In operation 710, a spatially filtered image is generated. As provided herein, the image I (x, t) may undergo spatial decomposition. For example, the spatial decomposition may include a pyramidal decomposition, where coarse filtering is used to separate regions into different frequency bands and fine filtering is used to refine the image. The spatially decomposed or spatially filtered image I (x, t) may be represented as:

f(x)＝I(x，t)

at operation 720, a time-dependent translation (or temporal filter) is applied to x to determine motion from the vessel and extract the heart beat frequency, where x is a translation functionAnd (3) modifying the original shape of the original shape,is a function of t:

at operation 730, the time-dependent translation used to extract heart beat frequency motion is amplified by an amplification factor α, which is applied to the translation functionTo give:

in various aspects, itemsExpansion to a first order Taylor expansion with respect to x:

in aspects, higher order terms (e.g., second order, third order, etc.) from the taylor expansion may be included. The equation corresponds to the reconstructed signal including the amplified time-dependent translation. For example, an itemActing as a heart beat frequency band pass filterThe filter (with time window) is such that the value of this term is zero for temporal phenomena outside the heartbeat band. The time dependent translation is (1+ α) amplified (if α is chosen to be greater than zero) and combined with the original image f (x). The reconstruction may be shown as a cine video sequence to account for spatio-temporal angiography phenomena. Thus, by combining this strategy with spatial decomposition, an image can be synthesized from the pyramid of the spatially decomposed image. In aspects, the amplification technique may be optional, and only band pass filtering may be performed.

In another aspect, the fourier transform may act as a bandpass filter. At operation 810, spatial decomposition is performed on the image. At operation 810, the image may be subjected to a cardiac scale band pass filter and then transformed pixel by pixel into the frequency domain using a fourier transform. In other aspects, a time windowed fourier transform may be applied. At operation 830, the cardiac scale may be enlarged in the frequency domain. At operation 840, the enlarged frequency domain image may be inverse transformed into the time domain and a spatiotemporal angiography phenomenon having an enlarged cardiac range may be displayed.

In another aspect, the euler magnification technique may be modified and extended to allow for customized magnification of cardiac angiographic phenomena. For example, current methods extend these techniques to angiography, which involves the injection of a bolus of contrast agent intravascularly into the vascular system at a faster frequency than the heart beat frequency, and a time series of images obtained during the entry of the bolus into the vascular system. In this case, the magnification factor α may be chosen to magnify the spatiotemporal angiography phenomenon, allowing reproducibility by limiting and normalizing the range of the factor. Additionally, the euler method may select a band pass filter for the angiographic data, and may include higher order terms (e.g., second or third order terms as needed) to estimate the heartbeat band, which may be narrowly estimated and/or limited to independent data (such as a heartbeat monitor).

For example, the amplification may be performed using an euler amplification method. In the method, a spatial filter is applied to a time-aligned sequence of two or more images. A temporal filter is applied to the plurality of results of the spatial filter. One or more of the results of the dual spatial and temporal filtering are selectively magnified and then reassembled into a sequence of images in order to produce a magnification effect corresponding to the reconstruction of the spatio-temporal phenomenon. These techniques may be applied to angiographic images to select images with temporal and spatial phenomena of interest, including temporal phenomena corresponding to heart beat frequency phenomena.

According to additional embodiments of the present invention, shear wave or ridge wave transformations may be used to extract heart beat frequency phenomena in angiographic data. The shear or ridge wave transformation accommodates multivariate functions controlled by anisotropic features, such as edges in the image. As an object of isotropy, wavelets cannot capture such phenomena. While wavelet transforms may be used for temporal resolution, shear wave and ridge wave transforms may be used for spatial resolution, allowing multi-resolution (e.g., two-dimensional spatial and temporal) analysis to be performed on the angiographic data.

An example implementation is provided in fig. 9. In this example, a band pass filter with a magnification factor is applied to visualize the heart beat frequency phenomenon. The left part of the figure shows a patient 910 undergoing angiography while cardiac signals are recorded from a finger pulse oximeter 102, also known as a photoplethysmogram.

Angiography is obtained by injecting a contrast agent into a patient and acquiring angiographic images at a frequency faster than the heart beat frequency. The heart beat frequency can be obtained from a cardiac signal of the patient. In some aspects, the cardiac signal may vary over time. In this case, the instantaneous cardiac signal may be referenced with respect to the correspondingly acquired image.

In this example, a graphical user interface is shown having two primary display elements 920 and 930 and two visual control widgets 940 and 945. It will be appreciated that the graphical user interface may be displayed on a computer monitor, such as the monitor of computer system 80. The two main display elements are a cardiac angiographic image 920 without heartbeat frequency amplification (left on computer monitor labeled "raw") and a cardiac angiographic image 930 with heartbeat frequency amplification (right on computer monitor labeled "heartbeat frequency amplification", brightness-tone model with heartbeat frequency amplitude and phase). Other display methods including, but not limited to, grayscale, monochrome, etc. are contemplated for use with the present technology. In this example, a horizontally oriented slider control widget 940 (labeled "frame") located below the image may be moved left and right on the screen by the user (e.g., by dragging with a mouse) to control the image frame being displayed. A heart beat frequency filter (as described in fig. 6-8) is applied to all image frames of the angiographic image sequence and the clinician or radiologist can examine one frame at a time. Optionally, a three-dimensional representation of the image magnified by the heart beat frequency is provided, for example, using the technique described in co-pending U.S. patent application sequence 16/784,125 filed on 6.2.2020, which is incorporated herein by reference in its entirety.

The graphical user interface also includes a vertically oriented slider control 945 (labeled "zoom factor") on the right, which the user can adjust (e.g., by dragging with a mouse) to specify the degree of magnification of the heart beat frequency. By controlling these parameters while viewing the image, a user explaining the image may modify the magnification and spatial resolution of the image based on the techniques provided herein to customize these settings for a particular medical analysis. These techniques may provide medical insight into the frequency of heartbeat activity of the imaging subject.

FIG. 10 illustrates a high-level operation of the techniques provided herein. At operation 1010, data is acquired or received from an angiographic study that is acquired at a faster frequency than the heart beat frequency. At operation 1020, a heart beat frequency band pass filter is applied to the angiography data to output a spatiotemporal reconstruction of the heart beat frequency angiography phenomenon. At operation 1030, a spatiotemporal reconstruction of a heart beat frequency contrast phenomenon is displayed in one or more images.

Beneficially, embodiments provided herein include systems, methods, and computer readable media for spatio-temporal reconstruction of heart beat frequency phenomena in angiographic data applying a heart beat frequency band pass filter to the angiographic data with or without euler magnification for extracting and potentially magnifying the heart beat frequency phenomena. In some aspects, these techniques may be combined with the techniques provided in the' 761 patent to further amplify the heart beat frequency phenomenon.

These techniques may be applied with hardware systems designed to obtain angiographic images, particularly angiographic systems, to obtain images of a patient. These techniques provide an improvement in the art over existing angiographic methods, i.e. allow the superimposition of amplified spatiotemporal heart beat frequency phenomena on the angiographic signal. This enhancement can improve the visualization effect by amplifying the vessel pulse wave and the resolution of the fine details (based on spatial filtering techniques) compared to the prior art. In aspects, magnification may be custom controlled as described herein to allow for varying degrees of magnification and resolution, which may be customized to produce information for various medical analyses.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in carrying out the above method and in the construction(s) set forth without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

The techniques provided herein have been described in terms of preferred embodiments, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.