System and method of multispectral decomposition of dynamic signals for lung ventilation

Abstract

Computer implemented methods include adjusting respiration of a subject with either input oscillating pressure or changes in expiratory resistance that are applied with at least one selected frequency to breathing airways of the subject and inducing corresponding oscillations on the caliber of breathing airways. A series of radiological images of the breathing airways allow for identifying respective signal intensities for discrete portions of the images. The respective signal intensities include a magnitude corresponding to each of the selected frequencies present in the respective discrete portions of the radiological images. Converting the radiological images into respective frequency sequences shows the signal intensities as corresponding frequencies of sections of the breathing airways. Frequency components filtered from the signal intensities are used for generating the ventilation map showing respective magnitudes of signal oscillation of the respective breathing airways within the subject.

Description

[0001] SYSTEM AND METHOD OF MULTISPECTRAL DECOMPOSITION OF DYNAMIC SIGNALS FOR LUNG VENTILATION CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and incorporates by reference United States Provisional Patent Application Serial No. 63 / 710,956 filed on October 23, 2024, and entitled System and Method of Multispectral Decomposition of Dynamic Signals for Lung Ventilation.

[0003] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0004] None.

[0005] FIELD

[0006] The disclosed technology generally relates to methods and systems for diagnosing lung airway health with a ventilation map showing respective magnitudes of signal oscillation of the respective breathing airways within the subject.

[0007] BACKGROUND

[0008] Evaluating lung function involves assessment of both airway ventilation and blood perfusion. Prior disclosures have described a ventilation / perfusion (V / Q) scan that is a well-studied robust method to image overall lung health that detects radioactivity injected intravenously that is trapped in the capillary system and radioactivity inhaled through the airways. The V / Q scan is clinically useful for patients with acute or chronic thromboembolic pulmonary disease as well as those undergoing evaluation for lung transplantation, however, it requires an injection of contrast, time under the gamma camera, and non-negligible cost. In addition, only large centers capable of handling radioactive materials can offer this technique. Other methods to image perfusion (dual energy CT) and ventilation (4D Medical XV scanner) have different reference systems and would require registration in computer systems that are expensive and time consuming.

[0009] Other previously utilized techniques to analyze fluoroscopic images have used spectral analysis to make a map of blood perfusion by exploiting an oscillating x-ray signal that is attenuated by vessel caliber oscillation throughout the heart beating. One example of this technique is shown in U. S. Patent Application Serial No. 18 / 278,582, published as US Pat. Pub. No. 20240138795A1, the content of which is incorporated herein by reference. In the prior ait, when the blood fills a blood vessel during systole, less x-ray signal is received at an output image, and vice versa when the blood pressure changes from systolic to diastolic. The pulse pressure from cardiac motion (difference between systolic and diastolic pressures) causes an oscillation in the cross-sectional area of the blood vessels. For example, during systole, the cardiac ventricles contract and force blood to the lungs through the pulmonary vasculature. Since the capillary network has a high resistance, the cardiac output distends the pulmonary arteries given the transient increase in relative pressure and vessel caliber. When the pulmonary arteries expand, the increase in cross sectional area increases and will attenuate more x-rays (blood is more dense than air). Therefore, there is a dynamic x-ray attenuation in the lungs that oscillates at the same rate as the heart rate.

[0010] Prior publications, therefore, show ways of evaluating pulmonary vasculature for poor or obstructed blood flow. Mapping the pulmonary vasculature includes obtaining, by dynamic radiography, imaging data for a dynamic series of a plurality of x-ray images that include areas of a subject corresponding to pulmonary vasculature. The method identifies, based on the imaging data, a dynamic signal corresponding to changing blood volume during the cardiac cycle of the subject and decomposes the dynamic signal into periodic components in frequency space. A blood perfusion analysis continues by identifying, from the periodic components in frequency space, signals oscillating at the heart rate of the subject and generating, based on the identified signals oscillating at the heart rate of the subject, a perfusion map representing the pulmonary tissue perfusion in the subject. A blood perfusion map, therefore, allows for detecting, based at least in part on the generated perfusion map representation, a perfusion abnormality of the subject.

[0011] In one example of blood perfusion analysis of prior systems, exploiting differential x-ray attenuation is a fundamental property using fluoroscopy (2D) or CT (3D) imaging. 'The following description may refer to numerous non-limiting techniques, such as fluoroscopy, but by extension this technique could be applied to dynamic CT (4DCT). In an example embodiment, a patient would hold their breath for 5- 10s while dynamic fluoroscopy would be acquired with a frame rate sufficient to sample the heart rate (typically >5 fps). All dynamic images are retrieved in DICOM format and processed offline using a custom written software package (MATLAB 2021b, Math Works, Cambridge, MA). Motion artifacts were minimized by cropping to a subset of continuous frames without visible diaphragm motion. The timedependent signal from each pixel was normalized to a mean value of 0. The normalized signal was zero padded then converted into the frequency domain via a Fast Fourier Transform (FFT). A band-pass filter was centered over the dominant peak with + / - 5 bpm bandwidth to isolate the primary peak and minimize off-peak contributions. The magnitude of the signal peak within the band-pass filter, hereafter referred to as x-ray pulsatility index (XPI), was displayed pixel-by-pixel in a parametric colormap (XPI map). Spatial filtering was applied to reduce noise.

[0012] A full analysis of pulmonary health, however, requires a corresponding ventilation map to analyze not only blood perfusion in the vasculature but also ventilation efficiency in the airway s of a subject. A need exists in the art of pulmonary care for systems and methods of evaluating ventilation health of a patient’s airways in addition to blood perfusion in the pulmonary vasculature.

[0013] SUMMARY

[0014] In accordance with the purposes of the disclosed devices and methods, as embodied and broadly described herein, the disclosed subject matter relates to methods and systems of assessing lung ventilation by gathering and analyzing signal intensities based on changes in oscillation of the caliber of breathing airways. In disclosed embodiments, a computer implemented method allows for creating a ventilation map of a subject’s breathing airways. The systems and methods include adjusting respiration of the subject with either input oscillating pressure or changes in expiratory resistance that are applied with at least one selected frequency to breathing airways of the subject and inducing corresponding oscillations on the caliber of breathing airways in response to adjusting the respiration, wherein the corresponding oscillations include at least one selected frequency over a selected time period. The method includes obtaining, during the selected time period, a series of radiological images of the breathing airways of the subject and identifying, for each of the radiological images obtained over the selected time period, respective signal intensities for discrete portions of the radiological images. The respective signal intensities include a magnitude corresponding to each of the selected frequencies present in the respective discrete portions of the radiological images. Using a computer software program disclosed herein, the method and systems include converting the radiological images into respective frequency sequences showing the respective signal intensities as corresponding oscillation frequencies of sections of the breathing airways for each of the discrete portions of the radiological images. Additional steps for assessing ventilation include identifying, from the respective frequency sequences, respective frequency components present within the discrete portion of the images; identifying, from the frequency components, at least one selected frequency to illustrate in the ventilation map for each discrete portion of the images; and generating, based on the at least one selected frequency, the ventilation map showing respective magnitudes of signal oscillation of the respective breathing airways within the subject.

[0015] Additional advantages of the disclosed devices and methods will be set forth in part in the description which follows, and in part will be obvious from the description. The advantages of the disclosed devices will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed devices and methods, as claimed.

[0016] Additional embodiments include obtaining the series of radiological images further comprises, using an imaging system, directing a radiologically active signal to the breathing airways of the subject during the selected time period and forming the radiological images.

[0017] Additional embodiments include methods wherein the radiologically active signal at the output of the imaging system has a variable intensity oscillation response for breathing airways expanded by ventilation as compared to other portions of the image with lower ventilation due to obstruction or constriction.

[0018] Additional embodiments include methods wherein the respective signal intensities comprise signal intensities of respective magnitudes that encompass the at least one selected frequency present within the discrete portion of the radiological images.

[0019] Additional embodiments include methods wherein portions of the radiologically active signal received at the output of the imaging system correspond to the respective signal intensities for each of the discrete portions of the radiological images.

[0020] Additional embodiments include methods wherein the imaging system is an X-ray system.

[0021] Additional embodiments include methods wherein the imaging system is a fluoroscopy imaging system.

[0022] Additional embodiments include methods wherein the imaging system is a CT scanning system.

[0023] Additional embodiments include methods wherein the imaging system is selected from the group consisting of a 3D CT scanning system, a 4D CT' scanning system, a multispectral CT scanning system, and a multi-energy CT scanning system.

[0024] Additional embodiments include methods wherein adjusting the variable expiratory resistance comprises utilizing a flutter valve device during respiration of the patient.

[0025] Additional embodiments include methods wherein applying the oscillating pressure or adjusting the end expiratory resistance comprises utilizing a diaphragm device, a ball valve device, or a vibrating device during respiration of the patient.

[0026] Additional embodiments include methods wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying a pressure signal at a selected magnitude using a forced oscillatory technique (FOT) to the subject during respiration. Additional embodiments include methods wherein applying the oscillating pressure at different amplitudes as well as different frequencies.

[0027] Additional embodiments include methods wherein the generated ventilation maps using different applied pressures are combined to a parametric map that represents the response of the airway caliber to different applied pressures.

[0028] Additional embodiments include methods wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying the oscillating pressure or varying the expiratory resistance at a single selected frequency.

[0029] Additional embodiments include methods wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying the oscillating pressure or the variable expiratory resistance 'ithat least one selected frequency that is different from a heartbeat frequency of the subject.

[0030] Additional embodiments include methods further comprising adjusting the caliber of the airways with more than one oscillation frequency within the subject simultaneously while gathering the radiological images.

[0031] Additional embodiments include methods wherein showing the respective signal intensities for each of the discrete portions of the radiological image comprises showing the respective signal intensities on a pixel by pixel basis or on a voxel by voxel basis or on a video frame by frame basis.

[0032] Additional embodiments include methods wherein showing the respective showing respective magnitudes of oscillation frequencies comprises simultaneously showing changes of an oscillating caliber of the airways subject to the selected frequency adjusting the respiration of the subject.

[0033] Additional embodiments include methods further comprising filtering the respective images to show a single selected frequency response for a single frequency present in the frequency images.

[0034] Additional embodiments include methods further comprising filtering the respective images to show a frequency response for a range of frequencies present in the frequency space images.

[0035] Additional embodiments include methods further comprising detecting, based at least in part on the ventilation map representation, a ventilation abnormality of the subject.

[0036] Additional embodiments include methods wherein generating the ventilation map comprises generating a colormap that represents the respective signal intensities oscillating at the at least one selected frequency, based on filtering signals in frequency space. Additional embodiments include methods wherein generating the ventilation map comprises generating a colormap that represents the respective magnitudes of signal oscillating at a heart rate of the subject.

[0037] Additional embodiments include methods further comprising generating a perfusion map representation of the subject simultaneously with generating the ventilation map.

[0038] Additional embodiments include methods further comprising calculating the phase portion of the oscillating signal and creating a map representation of signal time delay.

[0039] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which are incorporated and constitute apart of this specification, illustrate several aspects of the disclosure, and together with the description, serve to explain the principles of the disclosure.

[0042] FIG. 1 is a flow chart illustrating a computer implemented method of this disclosure FIG. 2 is a computer environment that may be used to implement the method of FIG. 1 and be used in related s stems.

[0043] FIG. 3 is a computer environment that may be used to implement the method of FIG. 1 and be used in related systems.

[0044] FIG. 4 is a schematic drawing of example medical devices that can induce oscillations in breathing airways of a subject.

[0045] FIG. 5 is a schematic drawing of additional medical devices that can induce oscillations in breathing airways of a subject.

[0046] FIG. 6 is a schematic drawing of a system by which breathing airways of a subject are subject to oscillatory inputs from medical devices, subject to radiographic imaging, and processed according to signal analysis described herein.

[0047] FIG. 7 A is a schematic drawing of signal analysis procedures used in the embodiments of this disclosure to assess breathing airway ventilation.

[0048] FIG. 7B is a schematic drawing of signal analysis procedures used in the embodiments of this disclosure to assess breathing airway ventilation.

[0049] FIG. 8 is a schematic illustration of using systems and methods of this disclosure to develop co-registered blood perfusion maps and breathing airway ventilation maps. FIG. 9 is a schematic illustration of using systems and methods of this disclosure to develop co-registered blood perfusion maps and breathing airway ventilation maps.

[0050] FIG. 10 is a schematic illustration of using systems and methods of this disclosure to develop co-registered blood perfusion maps and breathing airway ventilation maps.

[0051] FIG. 11 is a schematic illustration of a computer display showing the co-registered perfusion maps and ventilation maps in addition to the signal analysis developed from the embodiments of tills disclosure.

[0052] DETAILED DESCRIPTION

[0053] The devices and methods described herein may be understood more readily by reference to the following detailed description of specific aspects of the disclosed subject matter and the Examples included therein.

[0054] Before the present devices and methods are disclosed and described, it is to be understood that the aspects described below are not limited to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The disclosed technology is capable of other embodiments and of being practiced or carried out in various ways.

[0055] In the following description, references are made to the accompanying drawings that form a part hereof and that show, by way of illustration, specific embodiments or examples.

[0056] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. In describing example embodiments, terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. It is also to be understood that the men ion of one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Steps of a method may be performed in a different order than those described herein without departing from the scope of the disclosed technology. Similarly, it is also to be understood that the mention of one or more components in a device or system does not preclude the presence of additional components or intervening components between those components expressly identified.

[0057] Also, throughout this specification, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which the disclosed matter pertains. 'The references disclosed are also individually and specifically incorporated by reference herein for the material contained in them that is discussed in the sentence in which the reference is relied upon.

[0058] The specification makes references to numerous electrical charges of opposite polarity along with collection of certain positive and negative charges on identified hardware. Nothing in this specification limits the disclosure to any one arrangement of positive or negative polarity in circumstances where an opposite polarity may also be arranged.

[0059] The specification further references peaks and troughs of a freestanding membrane subject to rippling effects due to outside energy forces, and whether a certain structure of the membrane is a peak or a trough depends up perspective as well as the membrane’s position relative to another structure. Accordingly, nothing in this detailed specification requires any particular orientation of structures or hardware, and the terms “peaks,” “troughs,” and “ripples” are not limited to any one orientation but are for description purposes only.

[0060] Definitions

[0061] In this specification and in the claims that follow, reference will be made to a number of terms, which shall be defined to have the following meanings:

[0062] Throughout the description and claims of this specification the word “comprise” and other forms of the word, such as “comprising” and “comprises,” means including but not limited to, and is not intended to exclude, for example, other additives, components, integers, or steps.

[0063] As used in the description and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a composition” includes mixtures of two or more such compositions, reference to “the compound” includes mixtures of two or more such compounds, reference to “an agent” includes mixture of two or more such agents, and the like.

[0064] It is understood that throughout this specification the identifiers “first” and “second” are used solely to aid the reader in distinguishing the various components, features, or steps of the disclosed subject matter. The identifiers “first” and “second” are not intended to imply any particular order, amount, preference, or importance to the components or steps modified by these terms.

[0065] FIG. 1 is a flow chart that illustrates one non-limiting embodiment of this disclosure as a computer implemented method that can be practiced with the hardware and other components of FIG. 2 and FIG. 3.

[0066] Figure 2 is a block diagram that illustrates a system 130 including a computer system 140 and the associated Internet 11 connection upon which an embodiment may be implemented. Such configuration is typically used for computers (hosts) connected to the Internet 11 and executing a server or a client (or a combination) software. A source computer such as laptop, an ultimate destination computer and relay servers, for example, as well as any computer or processor described herein, may use the computer system configuration and the Internet connection shown in Figure 4. The system 140 may be used as a portable electronic device such as a notebook / laptop computer, a media player (e.g., MP3 based or video player), a cellular phone, a Personal Digital Assistant (PDA), a glucose monitor device, an artificial pancreas, an insulin delivery device (or other interventional or diagnostic device), an image processing device (e.g., a digital camera or video recorder), and / or any other handheld computing devices, or a combination of any of these devices. Note that while FIG. 4 illustrates various components of a computer system, it is not intended to represent any particular architecture or manner of interconnecting the components; as such details are not germane to the present disclosure. It will also be appreciated that network computers, handheld computers, cell phones and other data processing systems which have fewer components or perhaps more components may also be used. The computer system of Figure 4 may, for example, be an Apple Macintosh computer or Power Book, or an IBM compatible PC. Computer system 140 includes a bus 137, an interconnect, or other communication mechanism for communicating information, and a processor 138, commonly in the form of an integrated circuit, coupled with bus 137 for processing information and for executing the computer executable instructions. Computer system 140 also includes a main memory 134, such as a Random Access Memory (RAM) or other dynamic storage device, coupled to bus 137 for storing information and instructions to be executed by processor 138.

[0067] Main memory 134 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 138. Computer system 140 further includes a Read Only Memory (ROM) 136 (or other non-volatile memory) or other static storage device coupled to bus 137 for storing static information and instructions for processor 138. A storage device 135, such as a magnetic disk or optical disk, a hard disk drive for reading from and writing to a hard disk, a magnetic disk drive for reading from and writing to a magnetic disk, and / or an optical disk drive (such as DVD) for reading from and writing to a removable optical disk, is coupled to bus 137 for storing information and instructions. The hard disk drive, magnetic disk drive, and optical disk drive may be connected to the system bus by a hard disk drive interface, a magnetic disk drive interface, and an optical disk drive interface, respectively. The drives and their associated computer-readable media provide non-volatile storage of computer readable instructions, data structures, program modules and other data for the general purpose computing devices. Typically computer system 140 includes an Operating System (OS) stored in a non-volatile storage for managing the computer resources and provides the applications and programs with an access to the computer resources and interfaces. An operating system commonly processes system data and user input, and responds by allocating and managing tasks and internal system resources, such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating networking and managing files. Non-limiting examples of operating systems are Microsoft Windows, Mac OS X, and Linux.

[0068] The term "processor" is meant to include any integrated circuit or other electronic device (or collection of devices) capable of performing an operation on at least one instruction including, without limitation, Reduced Instruction Set Core (RISC) processors, CISC microprocessors, Microcontroller Units (MCUs), CISC-based Central Processing Units (CPUs), and Digital Signal Processors (DSPs). The hardware of such devices may be integrated onto a single substrate (e.g., silicon "die"), or distributed among two or more substrates. Furthermore, various functional aspects of the processor may be implemented solely as software or firmware associated with the processor.

[0069] Computer system 140 may be coupled via bus 137 to a display 131, such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), a flat screen monitor, a touch screen monitor or similar means for displaying text and graphical data to a user. The display may be connected via a video adapter for supporting the display. The display allows a user to view, enter, and / or edit information that is relevant to the operation of the system. An input device 1 2, including alphanumeric and other keys, is coupled to bus 137 for communicating information and command selections to processor 138. Another type of user input device is cursor control 133, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor 1 8 and for controlling cursor movement on display 131. Tills input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane.

[0070] The computer system 140 may be used for implementing the methods and techniques described herein. According to one embodiment, those methods and techniques are performed by computer system 140 in response to processor 138 executing one or more sequences of one or more instructions contained in main memory 134. Such instructions may be read into main memory 134 from another computer-readable medium, such as storage device 135. Execution of the sequences of instructions contained in main memory 134 causes processor 138 to perform the process steps described herein. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the arrangement. Thus, embodiments of the disclosure are not limited to any specific combination of hardware circuitry and software. The term "computer-readable medium" (or "machine-readable medium") as used herein is an extensible term that refers to any medium or any memory, that participates in providing instructions to a processor, (such as processor 138) for execution, or any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). Such a medium may store computer-executable instructions to be executed by a processing element and / or control logic, and data which is manipulated by a processing element and / or control logic, and may take many forms, including but not limited to, non-volatile medium, volatile medium, and transmission medium. Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise bus 137. Transmission media can also take the form of acoustic or light waves, such as those generated during radio-wave and infrared data communications, or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.). Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other optical medium, punch-cards, paper-tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read.

[0071] Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to processor 138 for execution. For example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system 140 can receive the data on the telephone line and use an infra-red transmitter to convert the data to an infra-red signal. An infra-red detector can receive the data carried in the infra-red signal and appropriate circuitry can place the data on bus 137. Bus 137 carries the data to main memory 134, from which processor 138 retrieves and executes the instructions. The instructions received by main memory 134 may optionally be stored on storage device 135 either before or after execution by processor 138.

[0072] Computer system 140 also includes a communication interface 141 coupled to bus 137. Communication interface 141 provides a two-way data communication coupling to a network link 139 that is connected to a local network 111. For example, communication interface 141 may be an Integrated Services Digital Network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another non-limiting example, communication interface 141 may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. For example, Ethernet based connection based on IEEE802.3 standard may be used such as 10 / 100BaseT, lOOOBaseT (gigabit Ethernet), 10 gigabit Ethernet (10 GE or 10 GbE or 10 GigE per IEEE Std 802.3ae-2002 as standard), 40 Gigabit Ethernet (40 GbE), or 100 Gigabit Ethernet (100 GbE as per Ethernet standard IEEE P802.3ba), as described in Cisco Systems, Inc. Publication number 1-587005-001-3 (6 / 99), "Internetworking Technologies Handbook", Chapter 7: "Ethernet Technologies", pages 7-1 to 7-38, which is incorporated in its entirety for all purposes as if fully set forth herein. In such a case, the communication interface 141 typically include a LAN transceiver or a modem, such as Standard Microsystems Corporation (SMSC) LAN91C111 10 / 100 Ethernet transceiver described in the Standard Microsystems Corporation (SMSC) data-sheet "LAN91C111 10 / 100 Non-PCI Ethernet Single Chip MAC+PHY" Data-Sheet, Rev. 15 (02-20-04), which is incorporated in its entirety for all purposes as if fully set forth herein.

[0073] FIG. 3 is a block diagram illustrating an example of a machine upon which one or more aspects of embodiments of the present disclosure can be implemented.

[0074] Examples of machine 400 can include logic, one or more components, circuits (e.g., modules), or mechanisms. Circuits are tangible entities configured to perform certain operations. In an example, circuits can be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner. In an example, one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware processors (processors) can be configured by software (e.g., instructions, an application portion, or an application) as a circuit that operates to perform certain operations as described herein. In an example, the software can reside (1) on a non -transitory machine readable medium or (2) in a transmission signal. In an example, the software, when executed by the underlying hardware of the circuit, causes the circuit to perform the certain operations.

[0075] In an example, a circuit can be implemented mechanically or electronically. For example, a circuit can comprise dedicated circuitry or logic that is specifically configured to perform one or more techniques such as discussed above, such as including a special-purpose processor, a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). In an example, a circuit can comprise programmable logic (e.g., circuitry, as encompassed within a general-purpose processor or other programmable processor) that can be temporarily configured (e.g., by software) to perform the certain operations. It will be appreciated that the decision to implement a circuit mechanically (e.g., in dedicated and permanently configured circuitry), or in temporarily configured circuitry (e.g., configured by software) can be driven by cost and time considerations.

[0076] Accordingly, the term “circuit” is understood to encompass a tangible entity, be that an entity that is physically constructed, permanently configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform specified operations. In an example, given a plurality of temporarily configured circuits, each of the circuits need not be configured or instantiated at any one instance in time. For example, where the circuits comprise a general-purpose processor configured via software, the general-purpose processor can be configured as respective different circuits at different times. Software can accordingly configure a processor, for example, to constitute a particular circuit at one instance of time and to constitute a different circuit at a different instance of time.

[0077] In an example, circuits can provide information to, and receive information from, other circuits. In this example, the circuits can be regarded as being communicatively coupled to one or more other circuits. Where multiple of such circuits exist contemporaneously, communications can be achieved through signal transmission (e.g., over appropriate circuits and buses) that connect the circuits. In embodiments in which multiple circuits are configured or instantiated at different times, communications between such circuits can be achieved, for example, through the storage and retrieval of information in memory structures to which the multiple circuits have access. For example, one circuit can perform an operation and store the output of that operation in a memory device to which it is communicatively coupled. A further circuit can then, at a later time, access the memory device to retrieve and process the stored output. In an example, circuits can be configured to initiate or receive communications with input or output devices and can operate on a resource (e.g., a collection of information).

[0078] The various operations of method examples described herein can be performed, at least partially, by one or more processors that are temporarily configured (e.g., by software) or permanently configured to perform the relevant operations. Whether temporarily or permanently configured, such processors can constitute processor-implemented circuits that operate to perform one or more operations or functions. In an example, the circuits referred to herein can comprise processor-implemented circuits.

[0079] Similarly, the methods described herein can be at least partially processor-implemented. For example, at least some of the operations of a method can be performed by one or processors or processor-implemented circuits. The performance of certain of the operations can be distributed among the one or more processors, not only residing within a single machine, but deployed across a number of machines. In an example, the processor or processors can be located in a single location (e.g., within a home environment, an office environment or as a server farm), while in other examples the processors can be distributed across a number of locations.

[0080] The one or more processors can also operate to support performance of the relevant operations in a "cloud computing" environment or as a "software as a service” (SaaS). For example, at least some of the operations can be performed by a group of computers (as examples of machines including processors), with these operations being accessible via a network (e.g., the Internet) and via one or more appropriate interfaces (e.g., Application Program Interfaces (APIs).)

[0081] Example embodiments (e.g., apparatus, systems, or methods) can be implemented in digital electronic circuitry, in computer hardware, in firmware, in software, or in any combination thereof. Example embodiments can be implemented using a computer program product (e.g., a computer program, tangibly embodied in an information carrier or in a machine readable medium, for execution by, or to control the operation of, data processing apparatus such as a programmable processor, a computer, or multiple computers).

[0082] A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a standalone program or as a software module, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[0083] In an example, operations can be performed by one or more programmable processors executing a computer program to perform functions by operating on input data and generating output. Examples of method operations can also be performed by, and example apparatus can be implemented as, special purpose logic circuitry (e.g., a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC)).

[0084] The computing system can include clients and servers. A client and server are generally remote from each other and generally interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. In embodiments deploying a programmable computing system, it will be appreciated that both hardware and software architectures require consideration. Specifically, it will be appreciated that the choice of whether to implement certain functionality in permanently configured hardware (e.g., an ASIC), in temporarily configured hardware (e.g., a combination of software and a programmable processor), or a combination of permanently and temporarily configured hardware can be a design choice. Below are set out hardware (e.g., machine 400) and software architectures that can be deployed in example embodiments.

[0085] In an example, the machine 400 can operate as a standalone device or the machine 400 can be connected (e.g., networked) to other machines.

[0086] In a networked deployment, the machine 400 can operate in the capacity of either a server or a client machine in server-client network environments. In an example, machine 400 can act as a peer machine in peer-to-peer (or other distributed) network environments. The machine 400 can be a personal computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a mobile telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing instructions (sequential or otherwise) specifying actions to be taken (e.g., performed) by the machine 400. Further, while only a single machine 400 is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets ) of instructions to perform any one or more of the methodologies discussed herein.

[0087] Example machine (e.g., computer system) 400 can include a processor 402 (e.g., a central processing unit (CPU), a graphics processing unit (GPU) or both), a main memory 404 and a static memory 406, some or all of which can communicate with each other via a bus 408. The machine 400 can further include a display unit 410, an alphanumeric input device 412 (e.g., a keyboard), and a user interface (UI) navigation device 411 (e.g., a mouse). In an example, the display unit 410, input device 412 and UI navigation device 414 can be a touch screen display. The machine 400 can additionally include a storage device (e.g., drive unit) 416, a signal generation device 418 (e.g., a speaker), a network interface device 420, and one or more sensors 421, such as a global positioning system (GPS) sensor, compass, accelerometer, or other sensor.

[0088] The storage device 416 can include a machine readable medium 422 on which is stored one or more sets of data structures or instructions 424 (e.g., software) embodying or utilized by any one or more of the methodologies or functions described herein. The instructions 424 can also reside, completely or at least partially, within the main memory 404, within static memory 406, or within the processor 402 during execution thereof by the machine 400. In an example, one or any combination of the processor 402, the main memory 404, the static memory 406, or the storage device 416 can constitute machine readable media.

[0089] While the machine readable medium 422 is illustrated as a single medium, the term "machine readable medium" can include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) that configured to store the one or more instructions 424. The term “machine readable medium” can also be taken to include any tangible medium that is capable of storing, encoding, or carrying instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present disclosure or that is capable of storing, encoding or carrying data structures utilized by or associated with such instructions. The term “machine readable medium” can accordingly be taken to include, but not be limited to, solid-state memories, and optical and magnetic media. Specific examples of machine readable media can include non-volatile memory, including, by way of example, semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices; magnetic disks such as internal hard disks and removable disks; magnetooptical disks; and CD-ROM and DVD-ROM disks.

[0090] The instructions 424 can further be transmitted or received over a communications network 426 using a transmission medium via the network interface device 420 utilizing any one of a number of transfer protocols (e.g., frame relay, IP, TCP, UDP, HTTP, etc.). Example communication networks can include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., IEEE 802.11 standards family known as Wi-Fi®, IEEE 802.16 standards family known as WiMax®), peer-to-peer (P2P) networks, among others. The term “transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

[0091] Overview

[0092] As noted above, oscillation of blood vessels has been used to evaluate pulmonary perfusion, and this disclosure pursues another important aspect of pulmonary health — airway ventilation. Oscillation of a patient’s lung airways would also produce an oscillatory x-ray signal. Using the techniques disclosed below, both blood perfusion and airway ventilation signals could be decomposed using spectral analysis, yielding inherently registered distinct maps of ventilation and blood perfusion with one short breath-hold fluoroscopic acquisition. When extended to CT, a 3D map of ventilation and blood perfusion is possible and can be viewed in numerous formats for side-by-side comparison, images matched in the time domain, or even overlays of images as necessary for diagnosing pulmonary health of a subject. Embodiments of this disclosure incorporate computer implemented methods to conduct a spectral analysis to identify oscillations related to airway caliber change when the airway is subject to airway pressure oscillations using an external mechanical device. The embodiments herein allow for multispectral decomposition of ventilation and perfusion from a single dataset if the perfusion response and the ventilation response of the lungs are analyzed at distinct frequencies. Another advantage of this disclosure lies in the possibility of free breathing acquisition while tracking the position of diaphragm either prospectively (to acquire only at certain points of the respiratory cycle) or retrospectively (to bin the images). Finally, another aspect of this disclosure lies in the phase of the signals being used to infer resistance / impedance similar to forced oscillation technique but in a spatial map.

[0093] In non-limiting embodiments, medical devices and machinery can be used to adjust the caliber of airways of the subject. The medical devices, such as those of FIGS. 4- 6 provide oscillating input signals (such as but not limited to variable pressure signals) to ventilation airways of a subject and induce corresponding oscillations in the ventilation airways. Non-limiting examples of the medical devices that may be applicable to this disclosure include a flutter valve, which is a hand-held device that causes a vibration during exhalation through it in order to loosen mucous in the airways for patients with airway disease such as cystic fibrosis. Two product designs include a oscillating diaphragm and ball-valve mechanism as shown in FIGS. 4 and 5. A different non-limiting medical technique for consideration here is a second currently used method to apply oscillating pressure waves by use of a forced oscillation technique (FOT) as shown in FIG. 6. FOT is a non-invasive method to measure respiratory mechanics using small-amplitude pressure oscillations through a mouthpiece and measuring the amplitude and phase lag of the returning pressure waves. The frequency for the ventilation analysis technique would be similar but likely higher amplitude to distend the airways more than needed in FOT. FOT is a 1D technique, whereas the method described herein would provide a spatial MAP of the ventilation.

[0094] In addition, the methods and systems of this disclosure can look at the delay in pressure waves using the phase of the x-ray signal and provide similar metrics to FOT like resistance / impedance but in a spatial map rather than a ID metric.

[0095] As mentioned, fluoroscopy is a widely available dynamic imaging modality that produces 2D images. CT is essentially an x-ray tube that rotates around the patient and reconstructs slices of data (ie. tomographic data) in 3D. Therefore, the properties that are useful here apply to CT. Dynamic CT (4DCT) is become increasingly more popular and led mainly by the cardiac imaging community but also in radiation therapy to track respiratory motion.

[0096] Assuming a sufficient frame rate of dynamic CT data, this method could result in a 3D map of ventilation. Moreover, if the airway oscillation frequency is distinct from the heart rate, both ventilation and perfusion maps could be generated from the same dataset using our method, which can spectrally decompose the complex signal into distinct signals. This would be an inherent registered map of ventilation and perfusion. FIG. 8 shows how X-ray attenuation can be useful in both blood perfusion and ventilation perfusion analyses.

[0097] In the embodiments of the disclosure illustrated in FIGS. 7-11, a method for creating a ventilation map of a subject includes adjusting respiration of the subject with either input oscillating pressure or change in expiratory resistance, applied to breathing airways of the subject at at least one selected frequency. The mechanically input adjustments to ventilation induces corresponding oscillations on the caliber of breathing airways in response to adjusting the respiration. The corresponding oscillations occur at the at least one selected frequency over a selected time period. The method continues by obtaining, during the selected time period, a series of radiological images of the breathing airways of the subject and identifying, for each of the radiological images obtained over the selected time period, respective signal intensities for discrete portions of the radiological images, wherein the respective signal intensities comprise a magnitude corresponding to each of the selected frequencies present in the respective discrete portions of the radiological images. A computer implemented method includes converting the radiological images into respective frequency sequences showing the respective signal intensities as corresponding oscillation frequencies of sections of the breathing airways for each of the discrete portions of the radiological images and identifying, from the respective frequency sequences, respective frequency components present within the discrete portion of the images. Next, the method includes identifying, from the frequency components, at least one selected frequency to illustrate in the ventilation map for each discrete portion of the images and generating, based on the at least one selected frequency, the ventilation map showing respective magnitudes of signal oscillation of the respective breathing airways within the subject.

[0098] During the process of obtaining the series of radiological images, practitioners use an imaging system, directing a radiologically active signal to the breathing airways of the subject during the selected time period and forming the radiological images. The radiologically active signal at the output of the imaging system has a variable intensity oscillation response for breathing airways expanded by ventilation as compared to other portions of the image with lower ventilation due to obstruction or constriction. The respective signal intensities received at the output will be signal intensities of respective magnitudes that encompass the at least one selected frequency present within the discrete portion of the radiological images. The generated ventilation maps using different applied pressures are combined with a parametric map that represents the response of the airway caliber to different applied pressures.

[0099] Non-limiting embodiments of this disclosure include applying the oscillating pressure or adjusting the variable expiratory resistance at a single selected frequency. This frequency may be distinct from a heartbeat frequency so that a spectral analysis can include a perfusion study at the heartbeat frequency and a ventilation study at the selected frequency of the oscillating inputs from the medical devices. In other non-limiting embodiments, adjusting the caliber of the airways may include using more than one oscillation frequency within the subject simultaneously while gathering the radiological images.

[0100] Output images of the embodiments, include showing the respective signal intensities for each of the discrete portions of the radiological image by showing the respective signal intensities on a pixel by pixel basis or on a voxel by voxel basis or on a video frame by frame basis. Showing respective magnitudes of oscillation frequencies include simultaneously showing changes of an oscillating caliber of the airways subject to the selected frequency adjusting the respiration of the subject and filtering the respective images to show a single selected frequency response for a single frequency present in the frequency images. In other embodiments, filtering the respective images shows a frequency response for a range of frequencies present in the frequency space images. The images allow for detecting, based at least in part on the ventilation map representation, a ventilation abnormality of the subject. In non-limiting embodiments, displaying the ventilation map includes generating a colormap that represents the respective signal intensities oscillating at the at least one selected frequency, based on filtering signals in frequency space and may include generating a colormap that represents the respective magnitudes of filtered signals oscillating at the selected input frequency applied to the subject. A perfusion map representation of the subject may be simultaneously displayed with generating the ventilation map. As noted above, the method and the display system may include calculating the phase portion of the oscillating signal and creating a map representation of signal time delay.

[0101] Methods and systems of assessing lung ventilation by gathering and analyzing signal intensities based on changes in oscillation of the caliber of breathing airways. In disclosed embodiments, a computer implemented method 100 allows for creating a ventilation map of a subject’s breathing airways. The systems and methods include adjusting 105 respiration of the subject with either input oscillating pressure or changes in expiratory resistance that are applied with at least one selected frequency to breathing airways of the subject and inducing 110 corresponding oscillations on the caliber of breathing airways in response to adjusting the respiration, wherein the corresponding oscillations include at least one selected frequency over a selected time period. The method includes obtaining 115 during the selected time period, a series of radiological images of the breathing airways of the subject and identifying 120, for each of the radiological images obtained over the selected time period, respective signal intensities for discrete portions of the radiological images. The respective signal intensities include a magnitude corresponding to each of the selected frequencies present in the respective discrete portions of the radiological images. Using a computer software program disclosed herein, the method and systems include converting 125 the radiological images into respective frequency sequences showing the respective signal intensities as corresponding oscillation frequencies of sections of the breathing airways for each of the discrete portions of the radiological images. Additional steps for assessing ventilation include identifying 130, from the respective frequency sequences, respective frequency components present within the discrete portion of the images; identifying 135, from the frequency components, at least one selected frequency to illustrate in the ventilation map for each discrete portion of the images; and generating 140, based on the at least one selected frequency, the ventilation map showing respective magnitudes of signal oscillation of the respective breathing airways within the subject.

[0102] Additional advantages of the disclosed devices and methods will be set forth in part in the description which follows, and in part will be obvious from the description. The advantages of the disclosed devices will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed devices and methods, as claimed.

[0103] Additional embodiments include obtaining the series of radiological images further comprises, using an imaging system, directing a radiologically active signal to the breathing airways of the subject during the selected time period and forming the radiological images.

[0104] Additional embodiments include methods wherein the radiologically active signal at the output of the imaging system has a variable intensity oscillation response for breathing airways expanded by ventilation as compared to other portions of the image with lower ventilation due to obstruction or constriction.

[0105] Additional embodiments include methods wherein the respective signal intensities comprise signal intensities of respective magnitudes that encompass the at least one selected frequency present within the discrete portion of the radiological images.

[0106] Additional embodiments include methods wherein portions of the radiologically active signal received at the output of the imaging system correspond to the respective signal intensities for each of the discrete portions of the radiological images.

[0107] Additional embodiments include methods wherein the imaging system is an X-ray system.

[0108] Additional embodiments include methods wherein the imaging system is a fluoroscopy imaging system.

[0109] Additional embodiments include methods wherein the imaging system is a CT scanning system.

[0110] Additional embodiments include methods wherein the imaging system is selected from the group consisting of a 3D CT scanning system, a 4D CT scanning system, a multispectral CT scanning system, and a multi-energy CT scanning system.

[0111] Additional embodiments include methods wherein adjusting the variable expiratory-resistance comprises utilizing a flutter valve device during respiration of the patient.

[0112] Additional embodiments include methods wherein applying the oscillating pressure or adjusting the end expiratory resistance comprises utilizing a diaphragm device, a ball valve device, or a vibrating device during respiration of the patient. Additional embodiments include methods wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying a pressure signal at a selected magnitude using a forced oscillatory technique (FOT) to the subject during respiration.

[0113] Additional embodiments include methods wherein applying the oscillating pressure at different amplitudes as well as different frequencies.

[0114] Additional embodiments include methods wherein the generated ventilation maps using different applied pressures are combined to a parametric map that represents the response of the airway caliber to different applied pressures.

[0115] Additional embodiments include methods wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying the oscillating pressure or varying the expiratory resistance at a single selected frequency.

[0116] Additional embodiments include methods wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying the oscillating pressure or the variable expiratory resistance with at least one selected frequency that is different from a heartbeat frequency of the subject.

[0117] Additional embodiments include methods further comprising adjusting the caliber of the airways with more than one oscillation frequency within the subject simultaneously while gathering the radiological images.

[0118] Additional embodiments include methods wherein showing the respective signal intensities for each of the discrete portions of the radiological image comprises showing the respective signal intensities on a pixel by pixel basis or on a voxel by voxel basis or on a video frame by frame basis.

[0119] Additional embodiments include methods wherein showing the respective showing respective magnitudes of oscillation frequencies comprises simultaneously showing changes of an oscillating caliber of the airways subject to the selected frequency adjusting the respiration of the subject.

[0120] Additional embodiments include methods further comprising filtering the respective images to show a single selected frequency response for a single frequency present in the frequency images.

[0121] Additional embodiments include methods further comprising filtering the respective images to show a frequency response for a range of frequencies present in the frequency space images.

[0122] Additional embodiments include methods further comprising detecting, based at least in part on the ventilation map representation, a ventilation abnormality of the subject. Additional embodiments include methods wherein generating the ventilation map comprises generating a colormap that represents the respective signal intensities oscillating at the at least one selected frequency, based on filtering signals in frequency space.

[0123] Additional embodiments include methods wherein generating the ventilation map comprises generating a colormap that represents the respective magnitudes of signal oscillating at a heart rate of the subject.

[0124] Additional embodiments include methods further comprising generating a perfusion map representation of the subject simultaneously with generating the ventilation map.

[0125] Additional embodiments include methods further comprising calculating the phase portion of the oscillating signal and creating a map representation of signal time delay.

[0126] The detail s of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

[0127] These and other aspects of this disclosure are set forth in the claims below.

Claims

CLAIMS1. A method for creating a ventilation map of a subject, comprising:adjusting respiration of the subject with either input oscillating pressure or change in expiratory resistance, applied to breathing airways of the subject of at least one selected frequency;inducing corresponding oscillations on the caliber of breathing airways in response to adjusting the respiration, wherein the corresponding oscillations comprise the at least one selected frequency over a selected time period;obtaining, during the selected time period, a series of radiological images of the breathing airways of the subject;identifying, for each of the radiological images obtained over the selected time period, respective signal intensities for discrete portions of the radiological images, wherein the respective signal intensities comprise a magnitude corresponding to each of the selected frequencies present in the respective discrete portions of the radiological images;converting the radiological images into respective frequency sequences showing the respective signal intensities as corresponding oscillation frequencies of sections of the breathing airways for each of the discrete portions of the radiological images;identifying, from the respective frequency sequences, respective frequency components present within the discrete portion of the images;identifying, from the frequency components, at least one selected frequency to illustrate in the ventilation map for each discrete portion of the images; andgenerating, based on the at least one selected frequency, the ventilation map showing respective magnitudes of signal oscillation of the respective breathing airways within the subject.

2. The method of Claim 1, wherein obtaining the series of radiological images further comprises, using an imaging system, directing a radiologically active signal to the breathing airways of the subject during the selected time period and forming the radiological images.

3. The method of Claim 2, wherein the radiologically active signal at the output of the imaging system has a variable intensity oscillation response for breathing airways expandedby ventilation as compared to other portions of the image with lower ventilation due to obstruction or constriction.

4. The method of Claim 1, wherein the respective signal intensities comprise signal intensities of respective magnitudes that encompass the at least one selected frequency present within the discrete portion of the radiological images.

5. The method of Claim 4, wherein portions of the radiologically active signal received at the output of the imaging system correspond to the respective signal intensities for each of the discrete portions of the radiological images.

6. The method of Claim 3, wherein the imaging system is an X-ray system.

7. The method of Claim 3, wherein the imaging system is a fluoroscopy imaging system.

8. The method of Claim 3, wherein the imaging system is a CT scanning system.

9. The method of Claim 8, wherein the imaging system is selected from the group consisting of a 3D CT scanning system, a 4D CT scanning system, a multispectral CT scanning system, and a multi-energy CT scanning system.

10. The method of Claim 1, wherein adjusting the variable expiratory resistance comprises utilizing a flutter valve device during respiration of the patient.

11. The method of Claim 1, wherein applying the oscillating pressure or adjusting the end expiratory resistance comprises utilizing a diaphragm device, a ball valve device, or a vibrating device during respiration of the patient.

12. The method of Claim 1, wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying a pressure signal at a selected magnitude using a forced oscillatory technique (FOT) to the subject during respiration.

13. The method of Claim 1, wherein applying the oscillating pressure at different amplitudes as well as different frequencies.

14. The method of Claim 1, wherein the generated ventilation maps using different applied pressures are combined to a parametric map that represents the response of the airway caliber to different applied pressures.

15. The method of Claim 1, wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying the oscillating pressure or varying the expiratory resistance at a single selected frequency.

16. The method of Claim 1, wherein applying the oscillating pressure or adjusting the variable expiratory resistance comprises applying the oscillating pressure or the variable expiratory resistance with at least one selected frequency that is different from a heartbeat frequency of the subject.

17. The method of Claim 16, further comprising adjusting the caliber of the airways with more than one oscillation frequency within the subject simultaneously while gathering the radiological images.

18. The method of Claim 1, wherein showing the respective signal intensities for each of the discrete portions of the radiological image comprises showing the respective signal intensities on a pixel by pixel basis or on a voxel by voxel basis or on a video frame by frame basis.

19. The method of Claim 18, wherein showing the respective showing respective magnitudes of oscillation frequencies comprises simultaneously showing changes of an oscillating caliber of the airways subject to the selected frequency adjusting the respiration of the subject.

20. The method of Claim 17, further comprising filtering the respective images to show a single selected frequency response for a single frequency present in the frequency images.

21. The method of Claim 17, further comprising filtering the respective images to show a frequency response for a range of frequencies present in the frequency space images.

22. The method of Claim 1, further comprising detecting, based at least in part on the ventilation map representation, a ventilation abnormality of the subject.

23. The method of Claim 1, wherein generating the ventilation map comprises generating a colormap that represents the respective signal intensities oscillating at the at least one selected frequency, based on filtering signals in frequency space.

24. The method of Claim 1, wherein generating the ventilation map comprises generating a colormap that represents the respective magnitudes of signal oscillating at a heart rate of the subject.

25. The method of Claim 1, further comprising generating a perfusion map representation of the subject simultaneously with generating the ventilation map.

26. The method Claim 1, further comprising calculating the phase portion of the oscillating signal and creating a map representation of signal time delay.

Images