Intravascular flow with electromagnetic interference filtering, and associated systems, devices, and methods

Abstract

An intravascular blood flow sensing system includes an intravascular catheter or guidewire configured to be positioned within a blood vessel and comprising a flow sensor; a display; and a processor circuit configured for communication with the display and the intravascular catheter or guidewire. The processor circuit controls the flow sensor to obtain flow data representative of blood flow within the blood vessel, wherein the flow data comprises electromagnetic interference (EMI). The processor circuit applies an EMI filter to the flow data to generate filtered flow data. The processor circuit provides, to an output device, a representation of the filtered flow data.

Description

2024PF00523INTRAVASCULAR FLOW WITH ELECTROMAGNETIC INTERFERENCE FILTERING, AND ASSOCIATED SYSTEMS, DEVICES, AND METHODSTECHNICAL FIELD

[0001] The present disclosure relates generally to intravascular flow using an intravascular device (e.g. catheter or guidewire) positioned inside of a blood vessel and, in particular, to filtering electromagnetic interference (EMI) in intravascular flow.BACKGROUND

[0002] Assessing the hemodynamic significance of cardiovascular and peripheral vascular disease by intravascular flow measurement is used to guide the treatment of circulatory disease. In the coronary arteries, large clinical trials have proven that decision-making based on pressure and flow measurements improves clinical outcomes compared to angiography alone. Flow measurements are particularly valuable in the case of non-obstructive coronary artery disease, i.e., angina complaints without visible obstructions in the coronary arteries. Additionally, beyond diagnostics, blood flow monitoring during embolization interventions is potentially helpful in assessing the degree of embolization and guiding when to stop to prevent embolization of healthy tissue, e.g., in transarterial chemoembolization (TACE).

[0003] In intravascular flow, Doppler ultrasound sensors are used to assess blood flow velocity. With these devices, an ultrasound pulse can be sent and received. By analysis of the difference between the sent and received signals, the blood velocity in a specific sampling area can be deduced as in ultrasound pulsed Doppler measurements. However, with the increase in various kinds of equipment and electronically tagged items, e.g., RF ID tags, electromagnetic interference (EMI) in Doppler measurements has increased. EMI may come to the flow system through its components, including guidewires, where the EMI could be close to the frequency of operation of the ultrasound sensor on the guidewire. Interference may not be stationary, and it may change over time in both phase and amplitude and not synchronized with the medical system (e.g. asynchronously). Consequently, EMI gets lumped into frequency bands of the Doppler ultrasound measurements.

[0004] EMI degrades the quality of the Doppler image and disturbs the estimation of the instantaneous peak velocity (IPV) and average peak velocity (APV) in the flow signal measured Therefore, EMI could influence clinical outcomes or decisions based on Doppler flow2024PF00523measurements. For the intravascular Doppler flow measurement, this is especially problematic because of at least two factors. First, the disposable guidewire and connector cable act as a receiving antenna. Second, the desired signal is quite small in nature, e.g., in the nV to pV range, and thus easily dominated by interference sources.

[0005] The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded as subject matter by which the scope of the disclosure is to be bound.SUMMARY

[0006] Disclosed herein are systems, devices, and methods of filtering EMI for intravascular flow measured with, for example, an intravascular blood flow sensing system and in particular a Doppler ultrasound sensing system. EMI is the result of electromagnetic waves impinging on various components of the intravascular flow system. Consequently, EMI will be present in Doppler ultrasound data and affect measurements derived from the ultrasound data. Creating an EMI filter may include several steps. A spectrogram buffer may be generated from the ultrasound data in the form of spectral A-lines. A threshold intensity value may be determined for each of the frequency components in the spectrogram buffer. The threshold intensity values may be used to generate an EMI filter. The EMI filter may be applied to the ultrasound data to remove EMI. Intravascular flow with EMI filtering advantageously improves Doppler ultrasound data quality and flow measurements derived from the Doppler ultrasound data, allowing improved displays to medical professionals and diagnoses.

[0007] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities, and advantages of the intravascular flow system, as defined in the claims, is provided in the following written description of various instances of the disclosure and illustrated in the accompanying drawingsBRIEF DESCRIPTION OF THE DRAWINGS

[0008] Illustrative instances of the present disclosure will be described with reference to the accompanying drawings, of which:2024PF00523

[0009] Figure 1 is a diagrammatic side view of an intravascular sensing system that includes an intravascular device, according to aspects of the present disclosure.

[0010] Figure 2 is side cross-sectional view of an example sensor assembly, according to aspects of the present disclosure.

[0011] Figure 3A is a schematic view of an intravascular device during measurement of a flow inside a blood vessel, according to aspects of the present disclosure.

[0012] Figure 3B is a schematic view of an intravascular device during measurement of a flow inside a sample volume, according to aspects of the present disclosure.

[0013] Figure 4 is a schematic overview of a measurement of intravascular flow using Doppler ultrasound, according to aspects of the present disclosure.

[0014] Figure 5 is a schematic contribution of a flowing particle p within a blood vessel to the Doppler signal matrix, according to aspects of the present disclosure.

[0015] Figure 6 is an example workflow screen, according to aspects of the present disclosure.

[0016] Figure 7 is a waveform display with electromagnetic interference artifacts, according to aspects of the present disclosure.

[0017] Figure 8 is a spectrogram of blood flow along a vessel, according to aspects of the present disclosure.

[0018] Figure 9A is a spectrogram buffer, according to aspects of the present disclosure.

[0019] Figure 9B is threshold intensity values plot for different frequency components of a spectrogram buffer, according to aspects of the present disclosure.

[0020] Figure 9C is plot of a smoothed filter, according to aspects of the present disclosure.

[0021] Figure 9D is a plot of an electromagnetic interference (EMI) filter, according to aspects of the present disclosure.

[0022] Figure 10 is an example workflow screen displaying flow velocity with electromagnetic interference artifacts removed, according to aspects of the present disclosure.

[0023] Figure 11 is a schematic diagram of a processor circuit, according to aspects of the present disclosure.

[0024] Figure 12 is a flow diagram for a method of filtering EMI from flow data, according to aspects of the present disclosure.2024PF00523

[0025] Figure 13 is a flow diagram for a method for generating an EMI filter, according to aspects of the present disclosure.DETAILED DESCRIPTION

[0026] These descriptions are provided for exemplary purposes only and should not be considered to limit the scope of the disclosure. Certain features may be added, removed, or modified without departing from the spirit of the claimed subject matter. In particular, it is expressly contemplated that aspects described herein may be implemented together, including in ways other than what is specifically described herein.

[0027] Coronary artery disease (CAD) is among the world's leading causes of death. To address this problem, imaging systems (for e.g. coronary angiography) as well as in-body diagnostic devices (e.g. pressure-sensing guidewires or intravascular ultrasound catheters) have been developed. One such diagnostic device is the blood flow velocity sensing guidewire, which can be used for example to assess Non-Obstructive Coronary Artery Disease (NOCAD) and MicroVascular Disease (MVD). These guidewires are equipped with a single-element ultrasound transducer that is located at its tip. The transducer can emit ultrasound waves in a forwardlooking direction and receive the corresponding pulse-echo signals. By pulsed-wave (PW) Doppler analysis, the blood flow velocity distribution in a specific sampling volume can be deduced. Several intravascular flow measurements are determined from the flow velocity distribution such as the instantaneous peak velocity (IPV) and average peak velocity (APV).

[0028] In some aspects, a blood flow velocity sensing guidewire may be a 14 / 1000 inch guidewire. Guidewires may come in different sizes, e.g., in the 14 / 1000 to 35 / 1000 inch range. In some aspects, catheters are typically 1 mm (254 / 1000 inch) diameter or larger (i.e., 3 French size or larger). Catheters and / or guidewires may be utilized in arteries of various sizes. For example, arteries in the region of the heart are typically 3-5 mm, while the aorta is >20 mm up to around 40 mm. Aspects of the present disclosure may be implemented using a blood flow sensing guidewire (e.g., a guidewire including a blood flow sensor, such as an ultrasound transducer that does not generate an image of the vessel) or a blood flow sensing catheter (e.g., a catheter including a blood flow sensor, such as an ultrasound transducer, which may or not may not generate an image of the vessel).2024PF00523

[0029] The present disclosure aids substantially in the measurement of intravascular flow by improving quality of flow measurements. Implemented on an ultrasound guidewire in communication with a processor, the flow measurement system disclosed herein filters electromagnetic interference from flow data used to generate flow velocity distributions and flow measurements. This unconventional approach improves the functioning of the flow measurement system by improving the quality of outputs to the clinician.

[0030] For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the aspects illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation to the scope of the disclosure is intended. Any alterations and further modifications to the described devices, systems, and methods, and any further application of the principles of the present disclosure are fully contemplated and included within the present disclosure as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and / or steps described with respect to one embodiment may be combined with the features, components, and / or steps described with respect to other aspects of the present disclosure. Additionally, while the description below may refer to blood vessels, it will be understood that the present disclosure is not limited to such applications. For example, the devices, systems, and methods described herein may be used in any body chamber or body lumen, including coronary vasculature, peripheral vasculature, an esophagus, veins, arteries, intestines, ventricles, atria, or any other body lumen and / or chamber. For the sake of brevity, however, the numerous iterations of these combinations will not be described separately.

[0031] Figure 1 is a diagrammatic side view of an intravascular sensing system 100 that includes an intravascular device 102 according to aspects of the present disclosure. The intravascular device 102 can be an intravascular guidewire sized and shaped for positioning within a vessel of a patient. The intravascular device 102 can include a distal tip 108 and a sensing component 112. The sensing component 112 can be an electronic, electromechanical, mechanical, optical, and / or other suitable type of sensor. For example, the sensing component 112 can be a flow sensor configured to measure the velocity of blood flow within a blood vessel of a patient, a pressure sensor configured to measure a pressure of blood flowing within the vessel, or another type of sensor including but not limited to a temperature or imaging sensor. In2024PF00523some cases, the intravascular device 102 may comprise multiple sensing components 112. In such cases, the sensing components 112 may be different and may be disposed at different locations along the intravascular device 102. For example, a first sensing component 112 may be a flow sensor disposed at the distal tip 108 and a second sensing component 112 may be a pressure sensor disposed proximal to the distal tip 108. Flow data obtained by a flow sensor can be used to calculate physiological variables such as coronary flow reserve (CFR). Pressure data obtained by a pressure sensor may for example be used to calculate a physiological pressure ratio (e.g., FFR, iFR, Pd / Pa, or any other suitable pressure ratio). Flow and pressure data can be used together to calculate other diagnostic indices or to measure dynamic responses such as pressurevolume loops (P-V loops). An imaging sensor may include an intravascular ultrasound (IVUS), intracardiac echocardiography (ICE), optical coherence tomography (OCT), or intravascular photoacoustic (IVPA) imaging sensor. For example, the imaging sensor can include one or more ultrasound transducer elements, including an array of ultrasound transducer elements.

[0032] The intravascular device 102 includes a flexible elongate member 106. The sensing component 112 is disposed at the distal portion 107 of the flexible elongate member 106. The sensing component 112 can be mounted at the distal portion 107 within a housing 280 in some aspects. A flexible tip coil 290 extends distally from the housing 280 at the distal portion 107 of the flexible elongate member 106. A connection portion 114 located at a proximal end of the flexible elongate member 106 includes conductive portions 132, 134. In some aspects, the conductive portions 132, 134 can be conductive ink that is printed and / or deposited around the connection portion 114 of the flexible elongate member 106. In some aspects, the conductive portions 132, 134 are conductive, metallic rings that are positioned around the flexible elongate member. A locking section is formed by collar 118 and knob 120 are disposed at the proximal portion 109 of the flexible elongate member 106.

[0033] The intravascular device 102 in Figure 1 includes a distal core 210 and a proximal core 220. The distal core 210 and the proximal core 220 are metallic components forming part of the body of the intravascular device 102. For example, the distal core 210 and the proximal core 220 are flexible metallic rods that provide structure for the flexible elongate member 106. The diameter of the distal core 210 and the proximal core 220 can vary along its length. A joint between the distal core 210 and proximal core 220 may be surrounded and contained by a hypotube 215.2024PF00523

[0034] In some aspects, the intravascular device 102 comprises a distal assembly and a proximal assembly that are electrically and mechanically joined together, which provides for electrical communication between the sensing component 112 and the conductive portions 132, 134. For example, flow data obtained by the sensing component 112 (in this example, sensing component 112 is a flow sensor) can be transmitted to the conductive portions 132, 134. Control signals (e.g., operating voltage, start / stop commands, etc.) from a processing system 306 in communication with the intravascular device 102 can be transmitted to the sensing component 112 via a connector 314 that is attached to the conductive portions 132, 134. In some aspects, connector 314 may be replaced with a wireless connection. The wireless connection may be accomplished using any suitable wireless communication technology, including but not limited to one or more of: Bluetooth, Wi-Fi, ZigBee, Li-Fi, or cellular data connections such as 2G / GSM, 3G / UMTS, 4G / LTE / WiMax, or 5G. The distal subassembly can include the distal core 210. The distal subassembly can also include the sensing component 112, a conductor bundle 230, and / or one or more layers of insulative polymer / plastic 240 surrounding the conductive members 230 and the core 210. For example, the polymer / plastic layer(s) can insulate and protect the conductive members of the multi -filar cable or conductor bundle 230. The proximal subassembly can include the proximal core 220. The proximal subassembly can also include one or more layers of polymer layer(s) 250 (hereinafter polymer layer 250) surrounding the proximal core 220 and / or conductive ribbons 260 embedded within the one or more insulative and / or protective polymer layer(s) 250. In some aspects, the proximal subassembly and the distal subassembly can be separately manufactured. During the assembly process for the intravascular device 102, the proximal subassembly and the distal subassembly can be electrically and mechanically joined together. As used herein, flexible elongate member can refer to one or more components along the entire length of the intravascular device 102, one or more components of the proximal subassembly (e.g., including the proximal core 220, etc.), and / or one or more components the distal subassembly 210 (e.g., including the distal core 210, etc.). The joint between the proximal core 220 and distal core 210 is surrounded by the hypotube 215.

[0035] In various aspects, the intravascular device 102 can include one, two, three, or more core wires extending along its length. In some aspects, the intravascular device includes two core wire: one at the proximal portion and one at the distal portion. In some aspects, a single2024PF00523core wire extends substantially along the entire length of the flexible elongate member 106. In either aspect, a locking section 118 and a section 120 can be integrally formed in the core wire present at the proximal portion of the intravascular device 120. The sensing component 112 can be secured to the core wire at the distal portion of the intravascular device 120. In other aspects, such as the embodiment illustrated in Figure 1 , the locking section 118 and the section 120 can be integrally formed at the proximal portion of the proximal core 220. The sensing component 112 can be secured at the distal portion of the distal core 210.

[0036] As described herein, electrical communication between the conductive members 230 and the conductive ribbons 260 can be established at the connection portion 114 of the flexible elongate member 106. By establishing electrical communication between the conductor bundle 230 and the conductive ribbons 260, the conductive portions 132, 134 can be in electrically communication with the sensing component 112.

[0037] In some aspects, represented by Figure 1, intravascular device 102 includes a locking section 118 and a section 120. To form locking section 118, a machining process is necessary to remove polymer layer 250 and conductive ribbons 260 in locking section 118 and to shape proximal core 220 in locking section 118 to the desired shape. As shown in Figure 1, locking section 118 includes a reduced diameter while section 120 has a diameter substantially similar to that of proximal core 220 in the connection portion 114. In some instances, because the machining process removes conductive ribbons in locking section 118, proximal ends of the conductive ribbons 260 would be exposed to moisture and / or liquids, such as blood, saline solutions, disinfectants, and / or enzyme cleaner solutions, an insulation layer 158 is formed over the proximal end portion of the connection portion 114 to insulate the exposed conductive ribbons.

[0038] In some aspects, a connector 314 provides electrical connectivity between the conductive portions 132, 134 and a patient interface module or patient interface monitor 304. The patient interface module (PIM) 304 may in some cases connect to a console or processing system 306, which includes or is in communication with a display 308. In some aspects, the patient interface module 304 includes signal processing circuitry, such as an analog-to-digital converter (ADC), analog and / or digital filters, signal conditioning circuitry, and any other suitable signal processing circuitry for processing the signals provided by the sensing component 112 for use by the processing system 306.2024PF00523

[0039] The system 100 may be deployed in a catheterization laboratory having a control room. The processing system 306 may be located in the control room. Optionally, the processing system 306 may be located elsewhere, such as in the catheterization laboratory itself. The catheterization laboratory may include a sterile field while its associated control room may or may not be sterile depending on the procedure to be performed and / or on the health care facility. In some aspects, intravascular device 102 may be controlled from a remote location such as the control room, such that an operator is not required to be in close proximity to the patient.

[0040] The intravascular device 102, PIM 304, and display 308 may be communicatively coupled directly or indirectly to the processing system 306. These elements may be communicatively coupled to the processing system 306 via a wired connection such as via conductor bundle 230. The processing system 306 may be communicatively coupled to one or more data networks, e.g., a TCP / IP-based local area network (LAN). In other aspects, different protocols may be utilized such as Synchronous Optical Networking (SONET). In some cases, the processing system 306 may be communicatively coupled to a wide area network (WAN).

[0041] Processing system 306 may also be connected to one or more user input devices, such as a mouse or keyboard, which allow the user update various parameters used for displaying data, processing data, etc. Input provided by a user through a user input device may be displayed on a display 308.

[0042] The PIM 304 transfers the received signals to the processing system 306 where the information is processed and displayed on the display 308. The console or processing system 306 can include a processor and a memory. The processing system 306 may be operable to facilitate the features of the intravascular sensing system 100 described herein. For example, the processor can execute computer readable instructions stored on the non-transitory tangible computer readable medium. These instructions can then implement any one of the methods as described herein for example to configure the processor system and or system comprising the processor system as defined herein.

[0043] The PIM 304 facilitates communication of signals between the processing system 306 and the intraluminal device 102. In some aspects, the PIM 304 performs preliminary processing of data prior to relaying the data to the processing system 306. In examples of such aspects, the PIM 304 performs amplification, filtering, and / or aggregating of the data. In an embodiment, the2024PF00523PIM 304 also supplies high- and low-voltage DC power to support operation of the intraluminal device 102 via the multi-filar conductor bundle 230.

[0044] The display or monitor 308 may be a display device such as a computer monitor, a touch-screen display, a television screen, or any other suitable type of display. The monitor 308 may be used to display selectable prompts, instructions, and visualizations of flow data to a user. In some aspects, the monitor 308 may be used to provide a procedure-specific workflow to a user to complete an intraluminal flow procedure. The display or monitor 308 is an example of an output device.

[0045] Another example of an output device is an audio device (e.g., a speaker, headphones, earbuds, etc.), may be connected to processing system 306. The audio device may be used to output audio representing the flow data. For example, the a- / rhythmic pulsations of the blood represented in the flow data may be output through speakers or headphones as audio to a user. In some aspects, the user can use clarity of the pulsatile audio (representative of the cardiac cycle / heartbeat cycle) to determine that the flow sensor is properly positioned (e.g., lateral position, angle, etc.) within the blood vessel (e.g., more laterally centered, where the maximum velocity is expected to be; more straight down lumen, less angled towards vessel wall).

[0046] Before continuing, it should be noted that the examples described above are provided for purposes of illustration and are not intended to be limiting. Other devices and / or device configurations may be utilized to carry out the operations described herein.

[0047] Figure 2 is a diagrammatic cross-sectional view of an example sensor assembly 251, which may for example be included in the intravascular device 102 of Figure 1. More specifically, Figure 2 illustrates a sensor assembly 251 that includes sensing component 112, housing 280, and an acoustic matching layer 252. As indicated by the positions of the sensing component 112 and the housing 280 illustrated in Figure 1, the sensor assembly 251 may be included in a distal portion of the intravascular device 102 such that the surface 272 of the sensing component 112 faces distally.

[0048] As illustrated in Figure 2, the sensing component 112 is positioned within the housing 280 and includes a proximal surface 270, an opposite, distal surface 272, and a side surface 274. In some aspects, one or more of the proximal surface 270, the distal surface 272, or the side surface 274 may be coated in an insulating layer 276. The insulating layer 276 may be formed from parylene, which may be deposited on the one or more surfaces, for example. The insulating2024PF00523layer 276 may additionally or alternatively be formed from any other suitable insulating material. In some aspects, the insulating layer 276 may prevent a short (e.g., an electrical failure), which may otherwise be caused by contact between a conductive portion of the sensing component 112 and the housing 280, which may be formed with a metal. As used herein, references to the distal surface 272 encompass the insulating layer 276 in aspects where a distal end of the sensing component 112 is covered by the insulating layer 276, references to the proximal surface 270 encompass the insulating layer in aspects where a proximal end of the sensing component 112 is covered by the insulating layer 276, and references to the side surface 274 encompass the insulating layer in aspects where the side of the sensing component 112 is covered by the insulating layer 276 unless indicated otherwise.

[0049] In some aspects, the sensing component 112 may include a transducer element, such as an ultrasound transducer element on the distal surface 272 such that the transducer element faces distally and may be used by the sensing component 112 to obtain sensor data corresponding to a structure distal of the sensing component 112. The sensing component 112 may additionally or alternatively include a transducer element on the proximal surface 270 such that the transducer faces proximally and may be used to obtain sensor data corresponding to a structure proximal of the sensing component. A transducer element may additionally or alternatively be positioned on a side surface 274 (e.g., on a perimeter or circumference) of the sensing component 112 in some aspects.

[0050] As further illustrated, the sensing component 112 is coupled to the conductor bundle 230, and at least a portion (e.g., a distal portion) of the conductor bundle 230 extends through the housing 280. In particular, conductor bundle 230 may couple to an element, such as a transducer (e.g., an ultrasound transducer), of the sensing component 112 and may provide power, control signals, an electrical ground or signal return, and / or the like to the element. As described above, such an element may be positioned on the distal surface 272 of the sensor.

[0051] In some aspects, the acoustic matching layer 252 may be positioned on (e.g., over) the distal surface 272 of the sensing component 112. In particular, the acoustic matching layer 252 may be disposed directly on the sensing component 112, or the acoustic matching layer 252 may be disposed on the insulating layer 276 coating the sensing component 112. Further, the acoustic matching layer 252 may be disposed on a transducer element (e.g., an ultrasound transducer element) positioned on the sensing component (e.g., the distal surface 272) and / or at least a2024PF00523portion of the conductor bundle 230 that is in communication with the transducer element. Moreover, the acoustic matching layer 252 may provide acoustic matching to the sensing component 112 (e.g., to an ultrasound transducer of the sensing component 112). For instance, the acoustic matching layer 252 may minimize acoustic impedance mismatch between the ultrasound transducer and a sensed medium, such as a fluid and / or a lumen that the intravascular device 102 is positioned within. In that regard, the acoustic matching layer 252 may be formed from any suitable material, such as a polymer or an adhesive, to provide acoustic matching with the sensing component 112. The portion of the acoustic matching layer 252 positioned on the distal surface 272 may include and / or be formed from the same material as a portion of the acoustic matching layer positioned on the side surface 274 and / or the proximal surface 270. Further, the acoustic matching layer 252 may be applied to the sensing component 112 before or after the sensing component 112 is positioned within the housing 280 during assembly of the sensor assembly 251. In this regard, the portion of the acoustic matching layer 252 positioned on the distal surface 272 and the portion of the acoustic matching layer positioned on the side surface 274 and / or the proximal surface 270 may be included in the sensor assembly 251 in the same or different steps. Further, in addition to the one or more materials the acoustic matching layer 252 is formed from, the acoustic matching layer 252 may provide acoustic matching with the sensing component 112 via one or more dimensions of the acoustic matching layer 252.

[0052] In some aspects, the sensor assembly 251 may include an atraumatic tip, such as the distal tip 108 illustrated in Figure 1. In some aspects, the distal tip 108 may include the same material as the acoustic matching layer 252. In some aspects, the distal tip may include a different material than the acoustic matching layer 252. Additionally or alternatively the distal tip 108 may be formed from one or more layers of materials. The layers may include different materials and / or different configurations (e.g., shape and / or profile, thickness, and / or the like). Further, the distal tip 108 may be arranged to cover the distal surface 272 of the sensing component 112. In some aspects, the distal tip 108 may also cover a distal end 272 of the housing 280. Moreover, while the distal tip 108 is illustrated as having a domed shape, aspects are not limited thereto. In this regard, the distal tip 108 may include a flattened profile or any suitable shape. In some aspects, the entire sensing component 112 may be positioned within (e.g., surrounded by the continuous surface of) the housing 280.2024PF00523

[0053] Figure 3A is a schematic view of intravascular device 102 (e.g., a flow-sensing guidewire 350) during measurement of a flow 380 inside a blood vessel 320 with blood vessel walls 340, in accordance with at least one embodiment of the present disclosure. In the example shown in Figure 3A, the sensing component 112 (e.g., an ultrasound transducer 360) at the tip is shown to emit ultrasound waves 370 that are backscattered as reflections 375 by flowing cells 390 in the blood and sensed by the transducer 360.

[0054] Figure 3B is a schematic view of intravascular device 102 (e.g., a flow-sensing guidewire 350) during measurement of a flow velocity 380 inside a sample volume 379, in accordance with at least one embodiment of the present disclosure. In the example shown in Figure 3B, the beam profile or viewing cone 378 of the transducer 360 is schematically shown, along with an example of the sample volume 379 over which the distribution of the flow 380 is measured. This sample volume 379 results from the transducer beam profile or viewing cone 378 as well as the selected measurement distance range, as described below.

[0055] Figure 4 is a schematic overview of a measurement of intravascular flow using Doppler ultrasound, in accordance with at least one embodiment of the present disclosure. A red blood cell velocity distribution is derived by sending an ultrasound wave or pulse 370 from the transducer 360 into the blood vessel 320. The propagating ultrasound wave or pulse 370 is backscattered by red blood cells 390. The backscattered ultrasound wave is received by the same transducer 360, which converts it into a corresponding electrical signal. In this simplified model, we only consider the axial dimension, Z. At Z=0, the transducer 360 is positioned, and creates ultrasound waves 370 that propagate in the positive Z direction. As the waves travel along the vessel, they are backscattered by cells or particles 390 in the blood. Measurement of low velocity is performed over a distance range [Zmin - Zmax] in M separate packets 410 (also known as range gates), each covering a distance range of AZ from a minimum range Zmto a maximum range Zm+AZ. All particles p have a position Zpand travel along the Z direction with a velocity Vp(which is usually positive but may also be negative).

[0056] Figure 5 is a schematic contribution of a flowing particle p within a blood vessel 320 to the Doppler signal matrix, in accordance with at least one embodiment of the present disclosure. So far, this disclosure has only considered a single pulse-echo acquisition. However, in a flow-sensing modality, typically an ensemble of subsequent ultrasound pulse-echo acquisitions may be considered. The pulse-echo acquisitions may for example be repeated at a2024PF00523constant pulse repetition interval (PRI). In order to assess velocity, an algorithm considers the displacement of scattering particles between subsequent acquisitions, considering the effect that particles have moved in-between subsequent acquisitions as opposed to moving during a single acquisition. In other words, an algorithm may neglect the ‘true’ Doppler effect that would cause the frequency fcof the ultrasound wave in a single pulse-echo acquisition to change as a result of movement of the particles. Doppler analysis may be performed within so-called packets 410, which facilitates the analysis of velocity as a function of the distance Z by a suitable choice of packets with length AZ along the total distance range [Zmin - Zmax]. Graphically, this procedure is displayed in Figure 5, which shows the pulse-echo acquisitions 510 for a single moving scattering particle as a function of slow time, whereby the slow time ts is the time covered between subsequent pulse-echo acquisitions. On the left, a particle p is shown in three successive positions as it is moving away from the transducer 360 with velocity Vp. In the middle, its pulse-echo contribution 510 to the received signal is shown. In the top case (Zp<Zm), the particle is already contributing to the Doppler signal at position Zmowing to the duration of the transmitted pulse. In the middle case (Zm<Zp<Zm+AZ), the particle has moved further but is still contributing to the Doppler signal within packet m. In the bottom case (Zp>Zm+AZ), the particle p has moved completely out of the packet 410 and is no longer contributing to the Doppler signal 520, 530. Further to the right, this particle’s contribution is shown as a 2D image with the fast time tf on the horizontal axis and the slow time ts on the vertical axis. On the right, the resulting signal 530 along one particular distance / fast-time sample is displayed. The resulting signal 530 is a windowed sinusoid whose frequency (the Doppler frequency) is determined by the velocity of the particle p.

[0057] Figure 6 is an example workflow screen 600, in accordance with at least one embodiment of the present disclosure. The example workflow screen 600 includes a control tab area 610, a control button area 650, a blood flow statistics area 620, and a waveform display area 630 that contains a waveform 640. Waveform 640 may be representative of a velocity envelope. As shown by the waveform 640, a complete red blood cell velocity distribution is acquired at regular intervals in a certain predetermined packet (volume at a certain distance from the guidewire tip). The flow velocity distribution (in the selected volume) can be graphically shown by plotting the flow velocity along the y-axis at each moment in time (x-axis), as shown by the example velocity waveform 640, and a second waveform 641 showing the instantaneous peak2024PF00523velocity (IPV) of the velocity waveform 640. The brightness or grey scale of the waveforms is indicative of relative incidence of a red blood cell velocity at a particular point in time.

[0058] In the example shown in Figure 6, the blood flow statistics area 620 includes a coronary flow reserve measurement 621, an average peak velocity measurement 622, an average peak velocity baseline measurement 623, an average peak velocity hyperaemia measurement 624, a heart rate measurement 625, and an aortic pressure measurement 626.

[0059] For the clinical application the maximum blood cell velocity at each point in time is determined (instantaneous peak velocity = IPV). This IPV value is averaged over a period of time to provide the average peak velocity (APV). For example, the IPV value may be averaged over a single cardiac cycle, two cardiac cycles, three cardiac cycles, four cardiac cycles, five cardiac cycles, or may be averaged over more than five cardiac cycles. The number of cardiac cycles used in calculating the APV may be manually set by a user. This APV is measured during baseline (resting) conditions (APV-B, with B for baseline) as well as during hyperaemia (APV-P, with P for peak). The hyperaemia condition is induced by injecting, e.g., adenosine into the blood. The ratio of the two provides the so-called coronary flow reserve (CFR=APV-P / APV-B). The CFR is a clinically relevant parameter. A CFR value above 2 may be clinically accepted as a healthy coronary flow reserve which does not need treatment. A value below 2 may indicate a need for intervention or follow up. The flow velocity information is shown as a grayscale waveform image 630, 640 in a display format known as a spectral Doppler visualization. The horizontal axis represents time and the vertical axis represents velocity. The grey scale is indicative of relative incidence of a particular velocity measurement at a particular point in time. In practice, as the velocity is measured over a sample volume, a distribution of velocities is measured; each vertical line in the grayscale image 630, 640 represents this distribution, measured in the form of a Doppler spectrum. The spectrum may include an instantaneous peak velocity (IPV), which indicates the maximum velocity at any point in time. This tracing can be automatically determined from the Doppler spectrum and subsequently averaged across one or more cardiac cycles, e.g., between 1 and 5 cardiac cycles, to provide the average peak velocity (APV), which is numerically shown on the left-hand side in the flow statistics area 620. The APV is measured during baseline (resting) condition (APV-B) as well as during hyperaemia (in this case after intra-arterial injection of adenosine, APV-P); the ratio of the two provides the coronary flow reserve (CFR) value. In this case, the example CFR value of 2.6 above an2024PF00523exemplary clinically accepted threshold of 2, which may indicate a sufficiently healthy coronary flow reserve that would generally not require intervention.

[0060] Since flow velocity and frequency are proportional, they can be used interchangeably. The following discussion will refer primarily to frequencies, and, in particular, to spectral A-lines that include intensity values of the flow data as a function frequency.

[0061] Figure 7 is a waveform display 700 with electromagnetic interference (EMI) artifacts 710A-I, according to aspects of the present disclosure. Waveform display 700 includes a plot depicting flow velocity. Waveform 720 may be representative of a velocity envelope. As shown by the waveform 720, a complete red blood cell velocity distribution is acquired at regular intervals in a certain predetermined packet (volume at a certain distance from the guidewire tip). The flow velocity distribution (in the selected volume) can be graphically shown by plotting the flow velocity along the y-axis 702 at each moment in time (x-axis 704), as shown by the example velocity waveform 720. The brightness or grey scale may be a histogram and provide the total percentage of blood cells at a particular point in time that are moving at each velocity within the measurement velocity range the system is set up for. In some aspects, velocities from -100 to + 300 cm / sec may be detected, but other velocity ranges may be detected, e.g., in coronary or peripheral vessel velocity ranges. For example, the flow in the aorta is around 110-140 cm / sec velocity and aside form turbulence and major obstructions is highest velocity seen in humans. Some of the data displayed in the display 700 is indicative of background noise, wall motion, and electromagnetic interference (EMI). The EMI is shown by the artifacts 710A-I. These artifacts may interfere not only with the visualization of blood flow velocity but also background processes that determine other informative quantities, such as the IPV. If EMI artifacts 710A-I are not filtered or otherwise removed from the ultrasound data, the system may erroneously determine the location of the IPV. For example, the method of searching for the IPV may identify the EMI artifact as the IPV instead of the correct IPV based on the waveform 720. This disclosure is directed to systems and processes for the removal of EMI from the flow data.Further visualizations of EMI artifacts are shown in Figures 8-10.

[0062] Figure 8 is a spectrogram 800 of blood flow along a vessel, according to aspects of the present disclosure. Spectrogram 800 is a plot depicting the intensity (pixel intensity values) of the flow data as a function of time (x-axis) and frequency (y-axis). Each vertical slice of spectrogram 800 represents a spectral A-line, i.e., each time bin has an associated spectral A-2024PF00523line. Spectrogram 800 may be generated from time domain data, e.g., the Doppler signal 520 depicted in Figure 4. To generate a spectrogram from the time-domain Doppler signal, for each range gate packet the signal is Fourier transformed across multiple transmit-receive acquisition events. The time measured across the multiple transmit-receive events for a given range gate packet is known as the slow time variable. For example, 512 transmit receive acquisition events will have 512 samples at each range gate packet. The spectral A-line corresponding to the 512 transmit receive acquisition events will generate a spectral A-line of 512 frequency bins. In this way, the intensity of the Doppler signal for each frequency component is known, and this is referred to as the spectrogram. In some aspects, the spectrogram 800 represents an intermediate output of processing steps that take raw flow data and generate flow velocity distribution waveforms, e.g., as depicted in Figures 6-7. Further conditioning and processing may be performed to improve the final displayed spectrogram, and to condition the spectral A-lines to allow flow measurements to be performed on the spectrogram

[0063] Several horizontal cross-sections of the spectrogram at different frequencies (also referred to as frequency bins or frequency components) are identified in spectrogram 800 — Region 1 805 A, Region 2810A, Region 3 815A, Region 4820A, Region 5 825 A, Region 6 830A, Region 7835 A, Region 8 840A. A horizontal cross-section is representative of the variation in time of one frequency component of the flow data. As shown in Figure 8, each horizontal cross-section indicated in spectrogram 800 has an associated intensity plot, i.e., Region 1 plot 805B, Region 2 plot 810B, Region 3 plot 815B, Region 4 plot 820B, Region 5 plot 825B, Region 6 plot 830B, Region 7 plot 835B, Region 8 plot 840B. Each of the plots 805B-840B identifies several intensity values, including the mean of the intensity values, the 20th percentile value, and the 10th percentile value. In each of the plots 805B-840B it should be appreciated that each plot includes some background noise, even if not explicitly stated in the following.

[0064] Region 1 plot 805B depicts flow intensity data around 30 Hz with weak EMI. Region 2 plot 810B depicts flow intensity data around 330 Hz with strong EMI. Region 3 plot 815B depicts flow intensity data around 520 Hz and comprises primarily a sampling of the background noise without EMI. Region 4 plot 820B depicts flow intensity data around 660 Hz and comprises flow signal overlapping with an overlapping EMI band. Region 5 plot 825B depicts flow intensity data around 680 Hz and comprises true flow signal without an overlapping EMI band.2024PF00523Region 6 plot 830B depicts flow intensity data around 700 Hz and comprises true flow signal with an overlapping EMI band. Region 7 plot 835B depicts flow intensity data around 740 Hz and comprises true flow signal and small wall motion artifacts. Region 8 plot 840B depicts flow intensity data around 760 Hz and is dominated by wall motion artifacts.

[0065] The EMI bands depicted in Figure 8 are merely exemplary. Depending on the circumstances, e.g., the source of the EMI artifacts, the EMI bands can be spaces closer or farther apart and / or the EMI bands may be strongest in the region around the true flow signal indicated by the waveform 850, and the total number of EMI bands may be a greater or lesser number than depicted. Consequently, it is important for quality depiction of the waveform 850 and any flow measurements derived therefrom that the EMI artifacts be removed.

[0066] Figure 9A is a spectrogram buffer 900, according to aspects of the present disclosure. A spectrogram buffer 900 includes a subset of the flow data depicted in spectrogram 800 shown in Figure 8 and described above. By way of example, Figure 9 A includes 196 spectral A-lines, indicated by the time index along the x-axis, ranging between 1 and 196. Each time index is associated with one corresponding spectral A-line.

[0067] In some aspects, spectrogram buffer can be represented as a matrix, S, having dimensions m x n, where m is the number of rows that correspond to the frequency component and n is the number of columns that correspond to time. For example, for the spectrogram buffer 900, n = 196. The matrix, S, is written out in Equation 1, below. In this way, n spectral A-lines may be ordered sequentially in the spectrogram buffer 900, with the ordering indicated by the time index 902. Each spectral A-line includes an intensity value for each of the frequency components indicated by the y-axis in Figures 9A-9D. Spectral A-lines may be constructed and / or in real time as flow data is received from the flow sensor. To get a better estimate of the EMI, several (i.e., ri) spectral A-lines are buffered. In some aspects, a user may control, n, the number of spectral A-lines, also referred to as the buffer size. Control may be implemented through a data entry window or a clickable and draggable slider bar.•$11 *-*12 ■■■ $ln s = ^21 $22 ■■■ $2n (1) C C Cdm2 ■■■dmnJ2024PF00523

[0068] Figure 9B is a threshold intensity values plot 910 for different frequency components of a spectrogram buffer 900, according to aspects of the present disclosure. A vector of threshold intensity values may be determined based on the spectrogram buffer 900. As shown in Figure 8 with each of the horizontal cross-section plots 805B-840B, different characteristic threshold intensity values may be determined for each frequency components, e.g., one or more percentile values, mean values, etc. For example, the k-th percentile intensity value for each row of the buffered spectral A-lines matrix S is calculated. In some aspects, the k-th percentile may be between 5% and 40%, and, in particular, between 5% and 25%. The percentile value for each row forms a vector p of dimensions m x 1 and expressed as:p _ ^(^2) (2)AGSn)- Where Pk(Si is the k-th percentile intensity of the i-th row of matrix S, or equivalently, the i-th frequency component of spectrogram buffer 900. The vector p may be depicted as threshold intensity values plot 910. The y-axis of the threshold intensity values plot 910 indicates the row of matrix S or, equivalently, the frequency component, and the x-axis indicates the k-th percentile intensity level. As shown in Figure 9B, the threshold intensity values plot 910 includes the relatively flat background noise 912, EMI artifacts 914, and wall motion artifact 916.

[0069] A choice for the k-th percentile value may be made on the basis of empirical evidence gathered from the test datasets. Testing has shown that amplitudes value of less than or equal to 20thpercentile capture the background noise and EMI consistently regardless of whether they appear in the flow or non-flow region without negatively impacting the flow signal. However, various circumstances may dictate the effectiveness of other choices for the k-th percentile. In some aspects, a user may control the k-th percentile value through a data entry window or a clickable and draggable slider bar. In this way, a user may be able to determine the optimal percentile value through real-time control.

[0070] Due to the pulsatile nature of the flow signal, the intensity levels of flow signal region of the spectrogram drop to the background level during the diastolic phase. In some instances, under physiological or pathophysiological conditions, the flow signal amplitude value is usually found to be above 20thpercentile level for each frequency bin within the flow regions (e.g., around 650-750 Hz in spectrogram buffer 900), but the EMI and background noise may be2024PF00523relatively stable and weak and be below this 20thpercentile level on each frequency bin. In the higher velocity regions where the flow signal does not exist the background noise stays weak, and the mean EMI bands will increase, the choice of 20thpercentile level of each frequency bin still has reasonable performance in estimating the levels of background noise or EMI bands for each frequency bins. In some aspects, the k-th percentile level can be set between 5th percentile and 40th percentile. Some exemplary percentile values may be the 10th, 15th, and 20th percentile. In some aspects, the intensity of one or more EMI bands may be similar to or stronger than the flow signal. In this scenario, a 20th percentile level, or other percentile level, may successfully estimate the EMI intensity, but because the EMI intensity is equal to or higher than the flow signal, when the EMI is subtracted out, the flow signal is also removed at the same time, leaving a gap in the flow signal region. However, this gap does not affect the IPV tracing and / or the estimation of APV.

[0071] Threshold intensity values plot 910 may also be referred to as a threshold intensity values filter, which may be applied to each spectral A-line of the flow data in the spectrogram 800, e.g., by subtracting the vector p from each of the spectral A-line in the spectrogram 800. However, if we subtract this threshold intensity values filter 910 from the original spectrogram 800, the EMI bands, the noise estimate, a portion of the wall motion artifact and a portion of the flow signal would be removed, which is not ideal. The filter may be improved by processing it to include only the estimated EMI band levels. This process is shown in Figures 9C and 9D and described below.

[0072] Figure 9C is plot of a smoothed filter, according to aspects of the present disclosure. A median filter with a window size of w is applied on the percentile values vector p to smooth it out. This results in a vector v with the same dimensions as p, i.e., m x 1. Because EMI bands are narrower (< 3 rows in some cases), they are smoothed out by the median filter, leaving only the estimated background noise level 922 and the estimated wall motion artifact level 926 in the smoothed filter 920, v. As an example, a window size of w = 15 was chosen for the smoothed filter 920. In some aspects, a user may control the window size w through a data entry window or a clickable and draggable slider bar.

[0073] Figure 9D is a plot of an EMI filter 930, according to aspects of the present disclosure. An EMI filter 930 may be generated by subtracting the vector v from p, elementwise. Said another way, the EMI filter 930 may be generated by subtracting the smoothed filter 9202024PF00523from the threshold intensity values filter 910, leaving EMI filter 930. The final EMI filter 930 contains mostly the estimated EMI band levels 934 and negligible levels of residual wall motion artifact 936. The EMI filter may be scaled by a configurable parameter, a. In some aspects, a user may control the configurable parameter a through a data entry window or a clickable and draggable slider bar. As an example, a = 1 (i.e., unsealed) for the EMI filter 930 depicted in Figure 9D. In some aspects, the EMI filter may be scaled by other factors, e.g., between 0.5-1.5.

[0074] As new spectral A-lines are generated, the EMI filter is re-calibrated to account for changes in the EMI profile. The buffer 900 is updated to take in new spectral A-lines and remove old ones. The filters depicted in Figures 9B-9D and described above may be reconstructed using the buffer 900 with new spectral A-lines. Initially, flow data may be gathered until there is enough data to fill the buffer for a selected buffer size. Once enough sample spectral A-lines are buffered, the EMI filter is created. And thereafter the new spectral A-line values are adjusted by subtracting the EMI filter from spectral A-lines. The adjusted values below zero are set to a small value such as 1x1 O'4, though other values may be used.

[0075] Figure 10 is an example workflow screen 1000 displaying flow velocity with electromagnetic interference artifacts removed, according to aspects of the present disclosure. Workflow screen includes a plot of the velocity flow distribution. Workflow screen 1000 is similar to the workflow screen 600 of Figure 6 but with the adjustable parameter interface 1010 that allows a user to set various parameters, such as the scale factor “a” for the EMI filter 930, the window size “w” of the median filter, the buffer size “n”, and the k-th percentile threshold “Percentile,” as described above. Workflow screen also shows the initial flow velocity distribution 1020, which includes EMI because the spectrogram buffer for generating the EMI filter is accumulating sufficient spectral A-lines to generate the EMI. Around time 0.01, the spectrogram buffer 900 is filled (i.e., it includes 196 spectral A-lines) and an EMI filter is generated and applied to the flow data as described above in Figures 9A-9D. Consequently, the later flow velocity distribution 1030 has EMI artifacts removed by the EMI filter 930. A user may, using a keyboard or other input device, change the parameters in the parameter interface 1010.

[0076] In some aspects, the waveform 1050 may scroll across the screen as new flow data is generated and filtered. In other words, the waveform 1050 may translate to the left as new data is added to the right side of the waveform in workflow screen 1000.2024PF00523

[0077] In some aspects, an EMI filter as described herein may be used in the context of blood flow imaging. In that regard, the EMI filter may be used to remove EMI in blood flow image processing. For example, the EMI filter can be used for blood flow visualization in intravascular ultrasound (e.g., ChromaFlo) to reduce the amount of EMI associated with the relative intensity of flow in the IVUS image. In some aspects, an EMI filter may be applied to reduce EMI in color doppler processing. In this way, an EMI filter advantageously improves the visual quality of the blood flow overlay (e.g., colored relative flow intensity overlay in ChromaFlo, colored blood flow velocity in color doppler overlay) that is overlaid on intravascular image(s) and / or external image(s), provided on a display (e.g., display 308 of Fig.1). For example, the intravascular image can be an IVUS image or an OCT image. The external image can be, e.g., an ultrasound image, an x-ray / x-ray based image, etc.

[0078] In some aspects, applying EMI filter to flow data may improve the quality of audio (e.g., provided to an audio output device, such as a speaker) generated from the flow data. For example, the clarity of the pulsatile audio (representative of the cardiac cycle / heartbeat cycle) can be improved by the removal of the EMI, thereby improving the user’s ability to rely on the audio to determine proper positioning (e.g., lateral position, angle, etc.) of the flow sensor.

[0079] Figure 11 is a schematic diagram of a processor circuit 1150, according to aspects of the present disclosure. The processor circuit 1150 may be implemented in intravascular sensing system 100, or other devices or workstations (e.g., third-party workstations, network routers, etc.), or on a cloud processor or other remote processing unit, as necessary to implement the method. As shown, the processor circuit 1150 may include a processor 1160, a memory 1164, and a communication module 1168. These elements may be in direct or indirect communication with each other, for example via one or more buses. The processor circuit can be comprised in the processing system 306, in the patient interface module or both.

[0080] The processor 1160 may include a central processing unit (CPU), a digital signal processor (DSP), an ASIC, a controller, or any combination of general-purpose computing devices, reduced instruction set computing (RISC) devices, application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other related logic devices, including mechanical and quantum computers. The processor 1160 may also comprise another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 1160 may also be implemented as a combination of2024PF00523computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0081] The memory 1164 may include a cache memory (e.g., a cache memory of the processor 1160), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an instance, the memory 1164 includes a non-transitory computer-readable medium. The memory 1164 may store instructions 1166. The instructions 1166 may include instructions that, when executed by the processor 1160, cause the processor 1160 to perform the operations described herein. Instructions 1166 may also be referred to as code. The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement(s). For example, the terms “instructions” and “code” may refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” may include a single computer-readable statement or many computer-readable statements.

[0082] The communication module 1168 can include any electronic circuitry and / or logic circuitry to facilitate direct or indirect communication of data between the processor circuit 1150, and other processors or devices. In that regard, the communication module 1168 can be an input / output (I / O) device. In some instances, the communication module 1168 facilitates direct or indirect communication between various elements of the processor circuit 1150 and / or the intravascular sensing system 100. The communication module 1168 may communicate within the processor circuit 1150 through numerous methods or protocols. Serial communication protocols may include but are not limited to United States Serial Protocol Interface (US SPI), Inter-Integrated Circuit (I2C), Recommended Standard 232 (RS-232), RS-485, Controller Area Network (CAN), Ethernet, Aeronautical Radio, Incorporated 429 (ARINC 429), MODBUS, Military Standard 1553 (MIL-STD-1553), or any other suitable method or protocol. Parallel protocols include but are not limited to Industry Standard Architecture (ISA), Advanced Technology Attachment (ATA), Small Computer System Interface (SCSI), Peripheral Component Interconnect (PCI), Institute of Electrical and Electronics Engineers 488 (IEEE-488),2024PF00523IEEE- 1284, and other suitable protocols. Where appropriate, serial and parallel communications may be bridged by a Universal Asynchronous Receiver Transmitter (UART), Universal Synchronous Receiver Transmitter (US ART), or other appropriate subsystem.

[0083] External communication (including but not limited to software updates, firmware updates, preset sharing between the processor and central server, or readings from the sensor(s) of the intraluminal device) may be accomplished using any suitable wireless or wired communication technology, such as a cable interface such as a universal serial bus (USB), micro USB, Lightning, or FireWire interface, Bluetooth, Wi-Fi, ZigBee, Li-Fi, or cellular data connections such as 2G / GSM (global system for mobiles) , 3G / UMTS (universal mobile telecommunications system), 4G, long term evolution (LTE), WiMax, or 5G. For example, a Bluetooth Low Energy (BLE) radio can be used to establish connectivity with a cloud service, for transmission of data, and for receipt of software patches. The controller may be configured to communicate with a remote server, or a local device such as a laptop, tablet, or handheld device, or may include a display capable of showing status variables and other information. Information may also be transferred on physical media such as a USB flash drive or memory stick.

[0084] Figure 12 is a flow diagram for a method of filtering electromagnetic interference from flow data, according to aspects of the present disclosure. It is understood that the steps of method 1200 may be performed in a different order than shown in Figure 12, additional steps can be provided before, during, and after the steps, and / or some of the steps described can be replaced or eliminated in other aspects. One or more of steps of the method 1200 can be carried by one or more devices and / or systems described herein, such as components of the intravascular sensing system 100 and / or processor circuit 1150.

[0085] At step 1210, a flow sensor (e.g., sensing component 112 in Figure 1) is controlled to obtain flow data (e.g., spectrogram 800 in Figure 8) representative of blood flow within a blood vessel. In some aspects, the flow data includes a plurality of spectral A-lines, e.g., as depicted in spectrogram 800 of Figure 8 and described above. In some aspects, the flow data may include different types of noise and artifacts, such as background noise, EMI artifacts, and / or wall motion artifacts, e.g., as described above in Figures 9A-9D. In some instances, it is advantageous to only remove EMI artifacts from the flow data, while leaving the background noise and wall2024PF00523motion artifact minimally affected (other methods may be used removing background noise and wall motion artifacts, if desired).

[0086] At step 1220, an electromagnetic interference (EMI) filter 930 is applied to the flow data (e.g., spectrogram 800 in Figure 8) to generate filtered flow data. Filtered flow data is generated by subtracting the EMI filter 930 from each spectral A-line in spectrogram 800. In this way, the EMI filter is applied by subtracting it, in frequency space, from each spectral A-line in the spectrogram 800. In some aspects, an EMI filter 930 is generated from one or more of the spectral A-lines included in the flow data.

[0087] At step 1230, a representation of the filtered flow data is output. In some aspects, the representation may be a plot, image, or audio representative of the filtered flow data (e.g., as shown in Figures 6-10). For example, filtered flow data is shown in the flow velocity distribution portion 1030 in workflow screen 1000. In some aspects, as shown in Figure 10, flow data may be displayed as a moving window over time. Along with the moving window, audio may be generated representing the flow over time, e.g., the characteristic beats of the blood flow as a result of the heart pumping.

[0088] It is noted that flow diagrams are provided herein for exemplary purposes; a person of ordinary skill in the art will recognize myriad variations that nonetheless fall within the scope of the present disclosure. For example, the logic of flow diagrams may be shown as sequential. However, similar logic could be parallel, massively parallel, object oriented, real-time, event-driven, cellular automaton, or otherwise, while accomplishing the same or similar functions. To perform the methods described herein, a processor may divide each of the steps described herein into a plurality of machine instructions, and may execute these instructions at the rate of several hundred, several thousand, several million, or several billion per second, in a single processor or across a plurality of processors.

[0089] Figure 13 is a flow diagram for a method for generating an electromagnetic interference filter, according to aspects of the present disclosure. It is understood that the steps of method 1300 may be performed in a different order than shown in Figure 13, additional steps can be provided before, during, and after the steps, and / or some of the steps described can be replaced or eliminated in other aspects. One or more of steps of the method 1300 can be carried by one or more devices and / or systems described herein, such as components of the intravascular sensing system 100 and / or processor circuit 1150.2024PF00523

[0090] At step 1310, a spectrogram buffer 900 including a second plurality of spectral A-lines (i.e., the vertical cross-section of spectrogram buffer 900) is generated. In some aspects, spectrogram buffer 900 includes a subset of the spectral A-lines in the spectrogram 800. In some aspects, a user may control the number of spectral A-lines in the buffer, e.g., through workflow screen 1000 shown in Figure 10 and described above.

[0091] At step 1320, a plurality of threshold intensity values for a plurality of frequency components are determined based on a percentile value and the second plurality of spectral A-lines. For example, the plurality of threshold intensity values may be calculated from the horizontal cross-sections of spectrogram buffer 900 shown in Figure 9A and 9B and described above.

[0092] At step 1330, a first filter (e.g., threshold intensity values filter 910) comprising the plurality of threshold intensity values is generated. A first filter may be the threshold intensity values filter 910, also represented by vector, p, of intensity values shown in Figure 9B and described above. In some aspects, the threshold intensity may be determined using the k-th percentile, e.g., the 20thpercentile. In some aspects, a user may control the percentile value through workflow screen 1000 shown in Figure 10 and described above.

[0093] At step 1340, a median filter is applied to the first filter (e.g., threshold intensity values filter 910) to generate a smoothed filter 920. For example, applying the median filter to the first filter may generate the smoothed filter 920 shown in Figure 9C and described above. In some aspects, the medial filter includes a window size (e.g., w = 15) which may be controlled by a user through workflow screen 1000 shown in Figure 10 and described above. The median filter may include the background noise and / or vessel wall motion artifacts but not include the EMI. In other words, the median filter isolated the background noise and vessel wall motion artifacts from the EMI.

[0094] At step 1350, the smoothed filter 920 and the first filter (e.g., threshold intensity values filter 910) are combined to generate an EMI filter 930. In some aspects, a scale factor may be applied to EMI filter 930 (e.g., a scale factor a = 1 would correspond to no scaling). In some aspects, a user may control the scale factor of the EMI filter through workflow screen 1000 shown in Figure 10 and described above.

[0095] In some aspects, further steps may include updating the spectrogram buffer 900 as new flow data is received and processed by the sensing component 112. For example, if a new2024PF00523spectral A-line has been generated, then the oldest A-line in the spectrogram buffer 900 may be removed and the new spectral A-line added. In some instances, the flow system may wait for 1, 2, 3, or any number of new spectral A-lines to be available before updating the buffer 900. For example, every 5 new spectral A-lines may trigger the buffer to have the oldest 5 spectral A-lines removed and the 5 new spectral A-lines added.

[0096] It is noted that flow diagrams are provided herein for exemplary purposes; a person of ordinary skill in the art will recognize myriad variations that nonetheless fall within the scope of the present disclosure. For example, the logic of flow diagrams may be shown as sequential. However, similar logic could be parallel, massively parallel, object oriented, real-time, event-driven, cellular automaton, or otherwise, while accomplishing the same or similar functions. To perform the methods described herein, a processor may divide each of the steps described herein into a plurality of machine instructions and may execute these instructions at the rate of several hundred, several thousand, several million, or several billion per second, in a single processor or across a plurality of processors. Such rapid execution may be necessary to execute the method in real time or near-real time as described herein.

[0097] A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions. Aspects can include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0098] In one general aspect, the present disclosure is directed to an intravascular blood flow sensing system. The intravascular blood flow sensing system also includes an intravascular catheter or guidewire configured to be positioned within a blood vessel and that may include a flow sensor; a display; and a processor circuit configured for communication with the display and the intravascular catheter or guidewire, where the processor circuit is configured to: control the flow sensor to obtain flow data representative of blood flow within the blood vessel, where the flow data that may include electromagnetic interference (EMI); apply an EMI filter to the2024PF00523flow data to generate filtered flow data; and provide, to an output device, a representation of the filtered flow data a.In some aspects, implementations may include one or more of the following features. The flow data may include a first plurality of spectral A-lines, where each spectral A-line may include an intensity value for each of a plurality of frequency components of the flow data. The processor circuit is configured to generate, based on the flow data, the EMI filter. To generate the EMI filter, the processor circuit is further configured to: generate a spectrogram buffer that may include a second plurality of spectral A-lines, where the second plurality of spectral A-lines is a subset of the first plurality of spectral A-lines, and where the second plurality of spectral A-line are sequentially ordered in time; determine, based on a percentile value and the second plurality of spectral A-lines, a plurality of threshold intensity values for the plurality of frequency components; generate a first filter that may include the plurality of threshold intensity values; apply a median filter to the first filter to generate a smoothed filter; and combine the smoothed filter and the first filter to generate the EMI filter. The processor circuit is configured to: update the spectrogram buffer in real time as new flow data is obtained by the flow sensor, where the new flow data includes new spectral A-lines. To update the spectrogram buffer, the processor circuit is further configured to: remove one or more spectral A-lines corresponding to the flow data; and add one or more new spectral A-lines corresponding to the new flow data. The number of spectral A-lines in the spectrogram buffer is configurable by a user. The percentile value is configurable by a user. The processor circuit is configured to: apply a scale factor to the EMI filter. The system where the scale factor is configurable by a user. The median filter is characterized by a window size, where the window size is configurable by a user. The median filter isolates background noise or a vessel wall motion artifact. The EMI filter is generated after a minimum amount of flow data is obtained by the flow sensor. The flow data that may include background noise, and where applying the EMI filter to flow data preserves the background noise. The flow data that may include a vessel wall motion artifact, and where applying the EMI filter to flow data preserves the vessel wall motion artifact. The EMI filter is applied to the flow data in a frequency domain associated with a fast time variable. The output device can be a display and / or a speaker, and the representation can be a plot, a blood flow overlay on an image, and / or audio.2024PF00523

[0099] It is noted that block diagrams are provided herein for exemplary purposes; a person of ordinary skill in the art will recognize myriad variations that nonetheless fall within the scope of the present disclosure. For example, block diagrams may show a particular arrangement of components, modules, services, steps, processes, or layers, resulting in a particular data flow. It is understood that some instances of the systems disclosed herein may include additional components, that some components shown may be absent from some instances, and that the arrangement of components may be different than shown, resulting in different data flows while still performing the methods described herein.

[0100] The logical operations making up the instances of the technology described herein are referred to variously as operations, steps, objects, elements, components, modules, etc.Furthermore, it should be understood that these may occur or be performed or arranged in any order, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.

[0101] All directional references e.g., upper, lower, inner, outer, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, proximal, and distal are only used for identification purposes to aid the reader’s understanding of the claimed subject matter, and do not create limitations, particularly as to the position, orientation, or use of the system. Connection references, e.g., attached, coupled, connected, joined, or “in communication with” are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily imply that two elements are directly connected and in fixed relation to each other. The term “or” shall be interpreted to mean “and / or” rather than “exclusive or.” The word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. Unless otherwise noted in the claims, stated values shall be interpreted as illustrative only and shall not be taken to be limiting.

[0102] The above specification, examples and data provide a complete description of the structure and use of exemplary instances of the system as defined in the claims. Although various instances of the claimed subject matter have been described above with a certain degree of particularity, or with reference to one or more individual instances, those skilled in the art2024PF00523could make numerous alterations to the disclosed instances without departing from the spirit or scope of the claimed subject matter.

[0103] Still other instances are contemplated. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular instances and not limiting. Changes in detail or structure may be made without departing from the basic elements of the subject matter as defined in the following claims.

[0104] Additional embodiments:Embodiment 1. An intravascular blood flow sensing system, comprising:an intravascular catheter or guidewire configured to be positioned within a blood vessel and comprising a flow sensor;a display; anda processor circuit configured for communication with the display and the intravascular catheter or guidewire, wherein the processor circuit is configured to:control the flow sensor to obtain flow data representative of blood flow within the blood vessel, wherein the flow data comprises electromagnetic interference (EMI);apply an EMI filter to the flow data to generate filtered flow data; and provide, to an output device, a representation of the filtered flow data.Embodiment 2. The system of Embodiment 1, wherein the flow data comprises a first plurality of spectral A-lines, wherein each spectral A-line comprises an intensity value for each of a plurality of frequency components of the flow data.Embodiment 3. The system of Embodiment 2, wherein the processor circuit is configured to:generate, based on the flow data, the EMI filter.Embodiment 4. The system of Embodiment 3, wherein, to generate the EMI filter, the processor circuit is further configured to:generate a spectrogram buffer comprising a second plurality of spectral A-lines,2024PF00523wherein the second plurality of spectral A-lines is a subset of the first plurality of spectral A-lines, andwherein the second plurality of spectral A-line are sequentially ordered in time;determine, based on a percentile value and the second plurality of spectral A-lines, a plurality of threshold intensity values for the plurality of frequency components;generate a first filter comprising the plurality of threshold intensity values;apply a median filter to the first filter to generate a smoothed filter; andcombine the smoothed filter and the first filter to generate the EMI filter.Embodiment 5. The system of Embodiment 4, wherein the processor circuit is configured to:update the spectrogram buffer in real time as new flow data is obtained by the flow sensor, wherein the new flow data includes new spectral A-lines.Embodiment 6. The system of Embodiment 5, wherein, to update the spectrogram buffer, the processor circuit is further configured to:remove one or more spectral A-lines corresponding to the flow data; andadd one or more new spectral A-lines corresponding to the new flow data.Embodiment 7. The system of Embodiment 3, wherein the EMI filter is generated after a minimum amount of flow data is obtained by the flow sensor.Embodiment 8. The system of Embodiment 1 ,wherein the flow data comprises background noise, andwherein applying the EMI filter to flow data preserves the background noise.Embodiment 9. The system of Embodiment 1 ,wherein the flow data comprises a vessel wall motion artifact, andwherein applying the EMI filter to flow data preserves the vessel wall motion artifact.2024PF00523Embodiment 10. The system of Embodiment 4, wherein the number of spectral A-lines in the spectrogram buffer is configurable by a user.Embodiment 11. The system of Embodiment 4, wherein the percentile value is configurable by a user.Embodiment 12. The system of Embodiment 4, wherein the processor circuit is configured to:apply a scale factor to the EMI filter.Embodiment 13. The system of Embodiment 12, where the scale factor is configurable by a user.Embodiment 14. The system of Embodiment 4, wherein the median filter is characterized by a window size, wherein the window size is configurable by a user.Embodiment 15. The system of Embodiment 1, wherein the EMI filter is applied to the flow data in a frequency domain associated with a fast time variable.Embodiment 16. The system of Embodiment 4, wherein the median filter isolates background noise or a vessel wall motion artifact.Embodiment 17. The system of Embodiment 1 ,wherein the output device comprises a display or a speaker, andwherein the representation comprises a plot, a blood flow overlay on an image, or audio.Embodiment 18. A computer program comprising instructions readable by a processor of a processor circuit as disclosed herein, which instructions, when executed by the processor cause the method of any method as described or claimed herein to be performed.2024PF00523Embodiment 19. The computer program of Embodiment 18, wherein the method is performed by the processor circuit or the system comprising the processor circuit.

Claims

2024PF00523CLAIMSWhat is claimed is:

1. A processor circuit for an intravascular blood flow sensing system, the processor circuit configured to:communicate with an intravascular device configured to be positioned within a blood vessel and comprising a flow sensor:control the flow sensor to obtain flow data representative of blood flow within the blood vessel;apply an electromagnetic interference (EMI) filter to the flow data to generate filtered flow data; andprovide, to an output device, a representation of the filtered flow data.

2. The processor circuit of claim 1 ,wherein the flow data comprises a first plurality of spectral A-lines,wherein each spectral A-line comprises an intensity value for each of a plurality of frequency components of the flow data.

3. The processor circuit of claim 1 or 2, wherein the processor circuit is configured to: generate, based on the flow data, the electromagnetic interference (EMI) filter.

4. The processor circuit of claim 2 or 3, wherein, to generate the electromagnetic interference (EMI) filter, the processor circuit is further configured to:generate a spectrogram buffer comprising a second plurality of spectral A-lines, wherein the second plurality of spectral A-lines is a subset of the first plurality of spectral A-lines, andwherein the second plurality of spectral A-line are sequentially ordered in time; determine, based on a percentile value and the second plurality of spectral A-lines, a plurality of threshold intensity values for the plurality of frequency components;generate a first filter comprising the plurality of threshold intensity values;2024PF00523apply a median filter to the first filter to generate a smoothed filter; andcombine the smoothed filter and the first filter to generate the electromagnetic interference (EMI) filter.

5. The processor circuit of any one of claims 1 to 4, wherein the processor circuit is configured to:generate the spectrogram buffer of claim 4; andupdate the spectrogram buffer in real time as new flow data is obtained by the flow sensor, wherein the new flow data includes new spectral A-lines.

6. The processor circuit of claim 5, wherein, to update the spectrogram buffer, the processor circuit is further configured to:remove one or more spectral A-lines corresponding to the flow data; andadd one or more new spectral A-lines corresponding to the new flow data.

7. The processor circuit of any one of claims 3 to 6, when dependent on claim 3, wherein the electromagnetic interference (EMI) filter is generated after a minimum amount of flow data is obtained by the flow sensor.

8. The processor circuit of any one of claims 1 to 7,wherein the flow data comprises background noise, andwherein applying the electromagnetic interference (EMI) filter to flow data preserves the background noise.

9. The processor circuit of any one of claims 1 to 8,wherein the flow data comprises a vessel wall motion artifact, andwherein applying the electromagnetic interference (EMI) filter to flow data preserves the vessel wall motion artifact.2024PF0052310. The processor of any one of claims 4 to 9, when dependent on claim 4, wherein the number of spectral A-lines in the spectrogram buffer is configurable by a user, and optionally, wherein the percentile value is configurable by a user.

11. The processor of any one of claims 4 to 10, when dependent on claim 4, wherein the processor circuit is configured to:apply a scale factor to the electromagnetic interference (EMI) filter, and optionally, where the scale factor is configurable by a user.

12. The processor of any one of claims 4 to 11, when dependent on claim 4, wherein the median filter is characterized by a window size, wherein the window size is configurable by a user.

13. The processor of any one of claims 1 to 12, wherein the electromagnetic interference (EMI) filter is applied to the flow data in a frequency domain associated with a fast time variable.

14. A system comprising:a processor circuit of any one of claims 1 to 13.

15. The system of claim 14, wherein the system is an Doppler ultrasound system and the flow sensor is a Doppler ultrasound sensor.

16. The system of claim 14 or 15, further comprising the intravascular device wherein when the system is the system of claim 15, the intravascular device is an intravascular Doppler ultrasound device.

17. A method performed by a processor circuit, the method comprising:receiving flow data from a flow sensor, the flow data being representative of blood flow within a blood vessel;2024PF00523applying an electromagnetic interference (EMI) filter to the flow data to generate filtered flow data; andproviding, to an output device, a representation of the filtered flow data.

18. The method of claim 17, wherein the method is a method of processing, such as for example filtering, EMI from intravascular blood flow data.

19. A computer program comprising computer readable code which, when run on a processor, causes the method of any one of the claims 17 and 18 to be executed.

20. The computer program of claim 19, wherein the processor is comprised within the processor circuit.

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