Radiofrequency imaging of the brain with an apparatus which can be worn by the patient

Abstract

The invention relates to a portable apparatus (1) for capturing imaging data for imaging the brain of a patient, comprising a helmet (4) formed of at least two movable arches (2a, 2b, 2c), each movable arch (2a, 2b, 2c) being configured to move, in use, on the head of a patient along at least one of: a trajectory from one temporal lobe to the other and a trajectory from the frontal lobe to the occipital lobe, each movable arch (2a, 2b, 2c) carrying at least one radiofrequency imaging device, the helmet (4) further comprising a motor assembly (3) connected to one of the ends of the movable arches in order to move the movable arches (2a, 2b, 2c) along their trajectories, and a control device that is connected to the helmet (4), controls the motor assembly (3) and each imaging device, and is configured to receive the signals from each radiofrequency imaging device.

Description

RADIOFREQUENCY BRAIN IMAGING WITH A PATIENT-WEARABLE DEVICE

[0001] The present invention relates to the technical field of medical imaging, in particular brain imaging, and relates to an imaging apparatus, an imaging assembly and an associated imaging method.

[0002] Clinical information extracted from cerebral arteries can be classified into three levels.

[0003] At the first level, the spread or blockage of blood in the tissues causes tissue changes that are sufficient to diagnose the stroke and determine its type (hemorrhagic or ischemic).

[0004] At the second level, endovascular information, such as the presence of an internal lesion in the artery, alters the flow and velocity of blood in the artery, which is necessary to diagnose the risk of a future stroke or the risk of an embolic stroke.

[0005] At the third level, we find neurovascular coupling: neuronal activity causes changes in blood vessels. This information is manifested by changes in blood flow or an increase in the volume of blood vessels (dilation) in a specific area of ​​the brain that is involved in the neuronal activities of the selected area.

[0006] From a technological point of view, information related to the first level can be extracted by static imaging, while information related to the second level can be extracted by dynamic imaging.

[0007] However, for third-level information, functional imaging is necessary.

[0008] Spatial and temporal resolutions are of great importance for functional imaging. Currently, existing technologies do not meet the required spatial and temporal resolutions.

[0009] Moreover, most of these technologies, such as functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), and positron emission tomography (PETSCAN) devices, are very large, room-sized, and so expensive that they have no clinical value for various applications, such as patient monitoring during surgery or patient monitoring at home.

[0010] US patent application US2023 / 014769A1 describes an imaging data capture apparatus according to the state of the art.

[0011] The publication “Pattern-Reconfigurable Metasurface-Antenna Array for Functional Brain Imaging Applications”, Mohammad Ojaroudi, Stéphane Bila. 2021 15th European Conference on Antennas and Propagation (EuCAP), March 22, 2021, Dusseldorf, Germany, pp.1-5, (XP033907593), also describes a state-of-the-art imaging data capture device.

[0012] The present invention aims to overcome the disadvantages of the prior art, and provides a portable and non-invasive imaging apparatus based on emerging electromagnetic wave technology for creating functional images containing physiological information, such as increased blood flow in arteries or detection of lesions within blood vessels. The portable brain imaging apparatus of the invention is provided with an adjustable and flexible scanning mode and finds application for functional neurovascular imaging.

[0013] The present invention therefore relates to a portable imaging data capture apparatus for performing imaging of a patient's brain, characterized in that it comprises a headset formed of at least two movable hoops, each movable hoop being configured to move in use on a patient's head along at least one of a trajectory from one temporal lobe to the other and a trajectory from the frontal lobe to the occipital lobe, each movable hoop carrying at least one radiofrequency imaging device, the headset further comprising a motor assembly connected to one of the ends of the movable hoops to move the movable hoops along their trajectories, and a control device connected to the headset and controlling the motor assembly and each imaging device and configured to receive the signals from each radiofrequency imaging device.

[0014] Thus, the flexible structure comprising a series of movable semicircular arches, each carrying an antenna array, can be moved around the hemisphere formed by a patient's head. The proposed device is capable of detecting neurovascular dilation movements of the order of a millimeter on the surface of the cerebral cortex.

[0015] The motor assembly may include at least one stepper motor, each stepper motor preferably, but not necessarily, being calibrated prior to a measurement to accommodate the particular head morphology of each patient.

[0016] The motor assembly may include a stepper motor to control the movement of each movable hoop, or several stepper motors each controlling the drive of a dedicated movable hoop.

[0017] The movable arches may be configured to all move along the same trajectory, for example from one temporal lobe to another or from the frontal lobe to the occipital lobe, or to move along different trajectories, with one part of the movable arches moving from one temporal lobe to the other while the other part moves from the frontal lobe to the occipital lobe, without the invention being limited in this respect.

[0018] The control device may comprise a power supply for powering the motor assembly and each imaging device, and an electronic unit comprising at least one computing device such as a processor, microprocessor, microcontroller, digital signal processor (DSP), field programmable gate array (FPGA), application specific component (ASIC), associated with the RAM or ROM, and one or more input / output ports or a wireless or wired communication means, for controlling the operation of the motor assembly and each imaging device via an embedded program or via an external command, for example from a computer connected to the data capture device, and transmitting the data to an external device, which may be the computer sending the external command, which will produce an image from the data captured by the data capture device.

[0019] The controller includes a fully automatic algorithm to extract static anatomical information and time-varying philological information is updated at each scan by one of the movable C-arms. In order to reconstruct the functional image, different types of information are extracted from the full diffusion parameters, such as: head surface boundaries from phase information, brain layer boundaries from the amplitude of monostatic signals, blood vessel detection and localization by confocal images as structural information, blood flow from micro-Doppler information and blood dilation from MathWorks® two-dimensional constant false alarm rate (2D-CFAR) detector results.

[0020] The helmet may also include one or more fixed hoops, in addition to the at least one movable hoop, to stiffen the structure of the helmet, each fixed hoop optionally carrying at least one imaging device controlled by the control device.

[0021] An advantage of the imaging data capture apparatus according to the invention is that it is based on non-invasive electromagnetic waves. Another important technical problem that this invention solves is the improvement of the spatio-temporal resolution of functional images of neuronal activities. The nature of electromagnetic waves makes it possible to generate images at high speed in a few seconds and to obtain a spatial resolution of the order of a millimeter, with a cost and size compatible with uses such as patient monitoring during surgery or patient monitoring at home.

[0022] According to one embodiment, the movable arches are configured to move along the path from the frontal lobe to the occipital lobe.

[0023] This makes it possible to use a motor assembly comprising a single stepper motor to drive the movement of each of the movable hoops, which simplifies and lightens the structure of the helmet.

[0024] The movable C-arms can move, within the same trajectory from the frontal lobe to the occipital lobe or from one temporal lobe to the other, either over the entire trajectory, in which case the movable C-arms are nestable, meaning they are different radii to be able to overlap when they cross while carrying the imaging device(s), or over a part of the trajectory, in which case the movable C-arms can have the same radius. However, it is preferable that each movable C-arm can travel the entire trajectory for better imaging quality and to avoid uncovered areas at the interface of two partial trajectories in the case where the movable C-arms are only part of the trajectory.

[0025] Another advantage is that the data capture device has a shape close to a classic headgear.

[0026] According to one embodiment, the helmet comprises three interlocking movable hoops.

[0027] The term "interlocking" means that the mobile arches, equipped with their imaging device(s), can intersect on a given trajectory.

[0028] According to one embodiment, each mobile arch comprises between five and ten, preferably eight, radiofrequency imaging devices, uniformly distributed on the surface of the mobile arch oriented in use towards the patient's head.

[0029] Optimal imaging, in terms of image quality obtained relative to the number of imaging devices used, is thus achieved. The imaging devices are thus arranged linearly on each movable C-arm surface, called the inner surface, facing the patient's head in use.

[0030] For any far-field imaging linear array (where plane wave propagation is assumed), the distance between imaging devices, called d, should not exceed 1 / 2λ to avoid array lobes (spatial aliasing), λ being the effective wavelength of the wave's center frequency in the propagation medium. In tissue, λ is a factor of √ ε r (with ε rdielectric constant (or relative permittivity with respect to vacuum)) smaller than in air. Simulations can be used to predict the point spread function (PSF) of an array design. In practice, in microwave imaging in the biomedical field, the array density is limited by the physical dimensions of the antenna and by the need to avoid crosstalk between antennas. An effective way to achieve high channel density is to use the multistatic scanning mode. Preferably, 24 imaging devices distributed in three rows can be considered, each row corresponding to a C-arm and therefore carrying eight uniformly distributed and spaced imaging devices.

[0031] According to one embodiment, each radiofrequency imaging device consists of a radiofrequency antenna.

[0032] Each radio frequency antenna may, for example but not exclusively, be a printed butterfly antenna which has physical characteristics of simple structure, small size and high gain.

[0033] For example, a square slot antenna fed by a 50 Ω microstrip line, printed on a 22×22 mm RT / duroid® 5880 substrate can be provided. 2 , dielectric constant 2.2 and loss tangent 0.001. The basic structure of the antenna consists of a radiating plate and a balun-type feed line. By shielding the antennas in the matching medium, it is possible to reduce mismatch effects between the antenna and the patient.

[0034] According to one embodiment, each antenna is mounted with an orientable metasurface facing the transmitting / receiving surface of the antenna, at least one diode being mounted on the metasurface.

[0035] The metasurface allows control of the propagation direction and return beam for adjacent imaging devices.

[0036] The metasurfaces may include an undercoat (e.g., Rogers RT / duroid® 6010) with microstrip lines on one side (head-facing side). These microstrip lines form a polygon, preferably a hexagon, by connecting several equilateral triangles with their apex at the center of the polygon. Thus, for a hexagon, six triangles are joined with their apex at the center of the hexagon. In addition, on at least one side of the microstrip lines, a small trapezoidal notch may be provided to accommodate a diode.

[0037] Each diode is an RF PIN diode, soldered between two pieces of a microstrip line on either side of the notch. RF PIN diodes have the sole role of turning on and off. When they turn on, they create a short connection between the two cut edges of the corresponding microstrip line on one of the triangles forming the metasurface polygon. By connecting the diode, the cut edge of the triangle is connected, causing electromagnetic excitation in this triangle and conducting the electromagnetic wave along its path, the different paths created forming different radiation patterns.

[0038] Preferably, each arch (mobile or fixed) is equipped with eight imaging devices. Each imaging device is composed of an antenna and a metasurface facing the antenna, in front of the head of the patient in use. Each metasurface, due to its constitution as a hexagon formed of six triangles, comprises six diodes placed in a rectangular notch on each side of the triangle opposite the apex in the center of the hexagon. Upon command from the control device, these diodes light up and make it possible to form different radiation patterns towards the patient's head.

[0039] According to one embodiment, each metasurface consists of six triangular microstrip lines mounted in a hexagon opposite the transmitting / receiving surface of the antenna, each triangular microstrip line carrying a diode.

[0040] According to one embodiment, the control device comprises a first switch connected to each radiofrequency imaging device, a vector network analyzer connected to each imaging device, a computing and memory unit, and a user interface.

[0041] According to one embodiment, the control device further comprises a second switch connected to each metasurface.

[0042] The invention also relates to an assembly comprising an imaging data capture apparatus as described above associated with a computing device for forming an image from the data received from the control device.

[0043] The extracted vascular parameters that can be collected with the imaging data capture apparatus according to the present invention include stroke volume, carotid flow and diameter, and vascular dilation.

[0044] Microwave technology offers the advantage of target ranging and temporal elimination of unwanted noise sources for sensing applications. More importantly, it allows for imaging in 2- or 3-dimensional space when spatially disparate radar data are combined. Operating a UWB radar in the time domain offers less flexibility regarding center frequency and pulse bandwidth, but has the advantage of potentially reducing scan times and thus increasing spatial resolution for dynamic imaging. The small form factor and low cost of microwave devices make them an attractive option for applications where mobility, availability, and ease of use are required.However, making a microwave device portable and even modular means that there is much less control over the clutter environment and more leakage (crosstalk, backscatter) is to be expected compared to a fully static imaging system. In the case of dynamic imaging, reduced scan times are required and microwave devices offer the possibility of receiving signals from multiple (spatially different) devices simultaneously. This means that the number of Rx reception channels can be increased (leading to better signal quality) without drawbacks in terms of scan time.

[0045] The imaging data capture apparatus according to the present invention can therefore find various applications in the diagnosis, treatment and post-treatment monitoring of strokes. One of these applications is the monitoring of large vessels, such as the carotid artery. This apparatus will then be mainly used for endovascular detection of blood flow in the carotid artery, which makes it possible to monitor the blood flow and extract endovascular information such as the presence of atherosclerotic lesions in order to predict the risk of stroke in any situation, such as driving a vehicle. Atherosclerotic lesions in the carotid artery cause embolic strokes. In addition, during surgery, the risk of embolic stroke is high.The second application is to measure the dilation of the surface pial artery and blood flow in the process of neurovascular coupling to extract neuronal activity. This application is used to monitor the functional activities of the brain, which is essential for post-stroke treatment monitoring for effective physiotherapy. In this case, by measuring the diameter of the arteries and the blood flow inside the arteries, the activity of the neuronal part of the brain can be monitored. According to the principle of neurovascular coupling, neuronal activity changes the vessel diameter and flow rate. In other words, if the changes in flow rate inside the vessel as well as the changes in vessel diameter at certain points are monitored, it is possible to deduce that this point in the brain is the site of neuronal activity.

[0046] The invention also relates to an imaging method implementing an imaging data capture apparatus as described above, characterized in that it comprises taking an image in several positions of the mobile arches and forming an image by a computing device connected to the imaging data capture apparatus from the data received from the imaging data capture apparatus.

[0047] Embodiments of the invention will now be described in more detail, by way of illustration and not limitation, in conjunction with the accompanying drawings.

[0048] On these drawings:

[0049] is a schematic view of an imaging data capture apparatus according to the present invention.

[0050] is a schematic view of an imaging assembly according to the present invention.

[0051] is another schematic sectional view of an imaging data capture apparatus according to the invention.

[0052] is a schematic view of an antenna of an imaging data capture device according to the.

[0053] is a schematic view of a metasurface of an antenna of the.

[0054] is a view of several radiation patterns that can be generated by an antenna of the.

[0055] Referring to the, it can be seen that there is shown an imaging data capture apparatus 1 according to the present invention, placed on a patient U.

[0056] The apparatus 1 comprises, in the non-limiting embodiment shown, three arches 2a, 2b and 2c, extending from one temporal lobe to the other of the patient U.

[0057] A stepper motor 3 is arranged at each temporal lobe of patient U, each stepper motor being connected to one end of the three arches 2a, 2b and 2c of the apparatus 1 in order to make the three arches 2a, 2b and 2c movable between the frontal lobe and the occipital lobe of patient U in use.

[0058] It is understood that the invention is not limited to the embodiment shown and that:

[0059] - device 1 could include a stepper motor per arch,

[0060] - device 1 could include a single stepper motor for all the arches, then located on one of the temporal lobes, in which case the other temporal lobe would only consist of guide bearings,

[0061] - the device 1 could comprise one fixed arch out of three, or a single mobile arch out of three arches, the fixed arch(s) then preferably being located at the level of the frontal and / or occipital lobe,

[0062] - the device 1 could comprise movable arches from one temporal lobe to the other, in which case the stepper motor(s) would be located at the level of the frontal lobe and / or the occipital lobe,

[0063] - device 1 could include movable arches from one temporal lobe to the other and from the occipital lobe to the frontal lobe, with stepper motors arranged in correspondence,

[0064] - the movable hoop(s) may be of different diameters, so that they can overlap on a common stroke, or may be of the same diameter, in which case the strokes of the hoops are limited by the positions of the other hoops.

[0065] Preferably, as in the embodiment shown, a casing 4 envelops the device 1 and allows easier placement on the patient U. Such a casing 4 is however not obligatory.

[0066] Although not shown, the apparatus 1 is connected by wires to a power supply to power the stepper motor(s) 3 and the imaging devices described below.

[0067] Furthermore, the apparatus 1 is connected wired or wirelessly to control means allowing the operation of the apparatus 1 by controlling each of the imaging devices and the stepper motor(s) 3.

[0068] As can be seen in the figure, the travel of the arches 2a, 2b, 2c covers the spatial extent of the brain of the patient U when the latter wears the device 1.

[0069] Referring now to Figures 3 to 5, it can be seen that each hoop 2a, 2b, 2c carries a plurality of imaging devices 5, shown for illustrative purposes on one of the hoops 2b, the imaging devices 5 being fixed on the surface of the hoop facing the head of the patient U in use, facing radially towards the head of the patient U in use to radiate towards the head of the patient U in use.

[0070] Although only five imaging devices 5 are shown so as not to make the drawing cumbersome, the imaging data capture apparatus 1 according to the present invention comprises, for each arch 2a, 2b, 2c, between 5 and 10 imaging devices 5, preferably between 6 and 8 imaging devices 5, more preferably 8 imaging devices 5.

[0071] Each imaging device 5 consists of a radiofrequency antenna 6, preferably a printed butterfly antenna which has physical characteristics of simple structure, small size and high gain (schematically represented by a rectangle), with which is associated a metasurface 7 (also represented by a rectangle, thinner and elongated), with an air gap 10 between the two. Each antenna 6 comprises a socket 6a for connection to a control device described below, a rod 6b connecting the socket 6a to a base plate 6c in which two conductive patterns 6e are formed in a triangle to form the butterfly pattern, the socket 6a and the two conductive patterns 6e being connected by a conductive wire 6d.The rod 6b may be formed perpendicular to the plane of the antenna 6 as shown in Figures 3 and 4, for clarity, but will however preferably be formed extending over the plane of the printed antenna 6, for reasons of less space requirement.

[0072] In practice, the antenna sub-layer 6 and the metasurface sub-layer 7 are built larger to allow for the creation of holes. Since the antenna sub-layer 6 and the metasurface sub-layer 7 are square or rectangular, this allows for the connection of four plastic screws at the four corners (not shown). In addition, these screws can be extended to connect to an arc-shaped mold, thus attaching the entire antenna-metasurface structure to this mold, which in turn attaches to the corresponding hoop. This configuration allows for movement in conjunction with the rotation of the corresponding hoop.

[0073] The radiofrequency antennas 6 can thus be fixed to the corresponding hoop 2a, 2b, 2c, while the metasurfaces 7 are arranged on a supporting structure (not shown) opposite the corresponding hoop 2a, 2b, 2c, with an air space between the two, the supporting structure preferably allowing the orientation of the metasurfaces 7 relative to the radiofrequency antennas 6.

[0074] Preferably, the distance between imaging devices 5, called d, should not exceed 1 / 2λ in order to avoid grating lobes (spatial aliasing), λ being the effective wavelength of the center frequency of the wave in the propagation medium. In tissues, λ is a factor of √ ε r (with ε rdielectric constant (or relative permittivity with respect to vacuum)) smaller than in air. Simulations can be used to predict the point spread function (PSF) of an array design. In practice, in microwave imaging in the biomedical field, the array density is limited by the physical dimensions of the antenna and by the need to avoid crosstalk between antennas. An effective way to achieve high channel density is to use the multistatic scanning mode. Preferably, 24 antennas distributed in three rows can be considered, each row corresponding to a hoop.

[0075] For example, a square slot antenna powered by a 50 Ω micro-strip line, printed on a 22×22 mm RT / duroid® 5880 substrate can be provided. 2, dielectric constant 2.2 and loss tangent 0.001. By shielding the antennas in the matching medium, it is possible to reduce the mismatch effects between the antenna and the patient.

[0076] Preferably, each radio frequency antenna 6 may have a radiation range of between 1 and 3 GHz.

[0077] Each metasurface 7, described in more detail in, comprises a surface, hexagonal in shape in the embodiment shown, divided into six triangles 8, each formed from three microstrip lines conducting electromagnetic waves, one of the microstrip lines oriented towards the edge of the surface carrying a cutout into which is inserted an RF PIN diode 9, connecting (for example by soldering) the two parts of the microstrip lines on either side of the RF PIN diode 9. Each RF PIN diode 9 is controlled by a microcontroller or other electronic control device (not shown in the). With the commands of said electronic control device, the RF PIN diodes 9 light up and connect the two parts of the microstrip lines on either side of each RF PIN diode 9. The RF PIN diodes 9 have the sole role of turning on and off.When they light up, they create a short connection between the two cut edges of the corresponding microstrip line on the surface of the metasurface 7 to conduct an electromagnetic wave along the corresponding microstrip line 7. By separately controlling each of the RF PIN diodes 9, it is therefore understood that it is possible to modify the radiation emitted by each imaging device 5, as shown schematically in the, in the case where the metasurface has a pentagonal shape. Indeed, the radiation from the antenna 6 passing through the metasurface 7 will be modified according to the different electromagnetic wave paths formed by the different triangles 8 on the metasurface 7, depending on the RF PIN diodes 9 lit. As can be seen in the, the actuations of the different RF PIN diodes 9 make it possible to modify the radiation emitted by each imaging device, and therefore by each arch, towards the brain of the patient U.

[0078] As suggested by the, the shape of each of the metasurfaces is not limited to the hexagonal or pentagonal shape of the. Thus, each metasurface can adopt any polygonal shape.

[0079] Also, the shape of each of the microstrip lines arranged on the metasurface is not limited to a triangle shape.

[0080] Also, the position of each of the RF PIN diodes on the microstrip line is not limited to the side delimiting the edge of the metasurface.

[0081] Finally, it would be possible to have several independently controlled RF PIN diodes on each microstrip line with more complex shapes, to create several electromagnetic wave paths for a single microstrip line and thus increase the possibilities of modifying the electromagnetic field initially radiated by the antenna 6.

[0082] The metasurfaces 7 may comprise an underlayer (e.g., Rogers RT / duroid® 6010 type) with the microstrip lines 8 formed on one side (head-facing side).

[0083] Preferably, the metasurfaces 7 are orientable relative to the antenna.

[0084] Furthermore, it is possible to provide, between the metasurfaces 7 and the head of the patient U, a layer of adaptation material 11 intended to reduce the reflection effects of the skin of the skull of the patient U.

[0085] An additional protective layer 12, between the adaptation layer 11 and the head of the patient U, may also be provided, for better comfort of the patient U and protection of the adaptation material layer 11.

[0086] Referring now to the, it can be seen that an imaging assembly 20 according to the present invention has been shown.

[0087] The imaging assembly 20 according to the present invention comprises an imaging data capture apparatus 1 as described above, equipped with nine imaging devices 5 in this non-limiting embodiment shown.

[0088] The antennas of each imaging device 5 are connected to an antenna switch 21 which controls the activation of the antennas of each imaging device 5, while the metasurfaces of imaging device 5 are connected to a metasurface switch 22 which controls the activation of the metasurfaces of each imaging device 5.

[0089] The two switches 21 and 22 are themselves controlled by a control switch 23 controlled by a user interface 24, comprising a display device (screen) 25 and an input device such as a keyboard and / or mouse 26.

[0090] Stepper motor 3 is controlled by a motor switch 27.

[0091] The user interface 24 allows a scanning mode to be selected for the imaging data capture apparatus 1, which will control both the control switch 23, to activate the antennas and metasurfaces of the imaging devices 5, and the motor switch 27 to control the stepper motor 3 to move the arches of the imaging data capture apparatus 1.

[0092] The data captured by the imaging devices 5 are then transmitted to a vector network analyzer 28, acting for the imaging devices 5 as both a transmitter and a receiver, and which processes them and sends them to a computing device 29, comprising one or more processors (or microcontrollers, microprocessors, DSPs, field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs)) associated with memory, which will reconstruct images from the signals captured by the imaging devices 5.

[0093] From the vector network analyzer 28, a diffusion tensor 30 is created, which is analyzed by the computing device 29 into monostatic signals 31, bistatic signals 32 and time domain signals 33.

[0094] The monostatic signals 31 are used to reconstruct the surface 34 and an anatomical layer 35.

[0095] The bistatic signals 32 are used to reconstruct differential images 36.

[0096] Time domain signals 33 allow Doppler information 37 to be collected.

[0097] The different information is used to reconstruct an image 38 by merging the different information 39.

[0098] All stages of scanning are controlled by the computing device 29, which also records the signals supplied to it. After processing the data, the extracted information is displayed on the display device 25.

[0099] The different stages of image acquisition on a patient by the imaging assembly 20 are as follows.

[0100] First, an MRI image of the patient is loaded into the imaging suite to determine the rotation angle and spatial position of the C-arm based on anatomical information from the brain.

[0101] A. Patient preparation for examination: First, the imaging data capture device 1 is placed on the patient's head. The zero calibration point is an arbitrary reference mark located at the top of the patient's head, corresponding to the brow line, i.e., the glabella and supraorbital margin, which the physician can easily identify. The end point to which the imaging data capture device 1 moves is also a reference mark at the back of the skull, the inion.

[0102] B. Focusing the device on the area targeted by the physician: In functional imaging examinations, the physician prepares a series of tests such as displaying images for vision tests, creating sounds for hearing tests, or presenting questions to elicit responses from the patient in order to assess the patient's concentration and attention, as well as the manipulation of an object. According to each test, the C-arms of the imaging data capture device 1 must focus on the corresponding specific brain region.

[0103] C. Moving the C-arms: To do this, the user interface 24 is made available to the physician, who starts scanning by pressing the button and selecting the test area. Then, the device moves to this area using geometric calculations to find the distance between the targeted region and the zero calibration point, bringing one or more C-arms of the imaging data capture device 1 to this region. After placing at least one C-arm in the desired area, scanning starts.

[0104] D. Scanning Process:

[0105] After pressing the scan start button, the vector network analyzer 28 is turned on, and the antenna switch 21, which is a monostatic switch, is activated sequentially, activating each transmission path to the antennas one after the other. At each command, only one of the antennas is active in the switch. This antenna acts as both transmitter and receiver. Then, the command is sent to the metasurface switch 22 of the respective antenna to activate or deactivate the diodes sequentially. Due to the presence of several diodes in front of each antenna, a pulse is emitted for each antenna by keeping the selection path active in the antenna switch 21, and the return signal is measured and recorded.Each time a pulse is sent, the metasurface switch 22 activates one of the diodes so that the corresponding antenna scans an area of ​​space in front of it, recording 6 signals. This process is then repeated.

[0106] sequentially for the other antennas. Once all antennas and diodes are activated sequentially, the signals corresponding to one scan are completed, and the next scan is repeated in the same order as before.

[0107] E. Signal Processing for Detection of Physiological Changes: From the signals returned and stored in the computing device 29 from successive scans, factors indicating the presence of physiological changes are extracted using three distinct processes. These factors are as follows:

[0108] 1. The first factor is based on the calculation of the diameter change: by calculating the difference in size between two time signals from two successive scans, the diameter variations are highlighted. This difference reflects the changes in the reflection coefficients of brain tissue due to changes in the diameter of blood vessels induced by neuronal activity.

[0109] 2. The second factor is based on calculating the pressure change in blood vessels: in the event of an obstruction in the blood vessels, changes in blood pressure occur along the vessels. By extracting Doppler information, it is possible to detect changes in the blood flow velocity in the vessels.

[0110] 3. The third factor is based on the calculation of permittivity variations: neuronal activity causes an increase in blood flow in the blood vessels, which changes the permittivity and conductivity of the blood. This results in changes in the size and phase of the reflected signals.

[0111] F. Display of functional images:

[0112] After extracting these factors, they are finally merged to create changes in the distance graphs and scan slices. Finally, these variations are overlaid on the patient's MRI image, which was previously loaded into the computer system, at the precise moment these changes took place.

[0113] The imaging assembly of the invention therefore extracts the anatomical and physiological information necessary for mapping to the patient's MRI image. To do this, as indicated above, it will use methods such as confocal images and 2D CFAR.

[0114] In general, imaging can be performed with a single C-arm equipped with a monostatic switch. However, it is better to consider the option of three C-arms with a multistatic switch. Since the coils require a change of direction to improve spatial resolution and a path must be established between the receiver and the transmitter, the side C-arms can serve as receivers. Furthermore, for simultaneous imaging of two or more regions, it is preferable to have more than one C-arm, so that, for example, both the visual and motor regions can be scanned simultaneously. The number of coils in each C-arm can vary, but a minimum of three coils is preferably required to cover a rectangular area of ​​the cortex surface with three coils in each C-arm.

[0115] Optionally, after each scan, the signals broadcast at each step can be stored in a separate matrix and displayed in 3D in the final image.

[0116] In-situ calibration can be performed to remove clutter and artifacts from a calibrated signal while preserving cerebrovascular target information. For example, connectome theory can be used to remove similar parts from signal pairs that share the same trajectory based on brain symmetry. This technique can isolate target information from clutter.

Claims

– A portable imaging data capture apparatus (1) for imaging a patient's brain, characterized in that it comprises a headset (4) formed of at least two movable hoops (2a, 2b, 2c), each movable hoop (2a, 2b, 2c) being configured to move in use on a patient's head along at least one of a trajectory from one temporal lobe to the other and a trajectory from the frontal lobe to the occipital lobe, each movable hoop (2a, 2b, 2c) carrying at least one radiofrequency imaging device (5), the headset (4) further comprising a motor assembly (3) connected to one of the ends of the movable hoops (2a, 2b, 2c) for moving the movable hoops (2a, 2b, 2c) along their trajectories, and a control device (24) connected to the headset (4) and controlling the motor assembly (3) and each device imaging device (5) and configured to receive signals from each radiofrequency imaging device (5). – Imaging data capture apparatus (1) according to claim 1, characterized in that the movable arches (2a, 2b, 2c) are configured to move on the trajectory going from the frontal lobe to the occipital lobe. – Imaging data capture apparatus (1) according to claim 1 or claim 2, characterized in that the helmet (4) comprises three nestable movable hoops (2a, 2b, 2c). – Imaging data capture apparatus (1) according to one of claims 1 to 3, characterized in that each movable arch (2a, 2b, 2c) comprises between five and ten, preferably eight, radiofrequency imaging devices (5), uniformly distributed over the surface of the movable arch (2a, 2b, 2c) oriented in use towards the patient's head. – Imaging data capture apparatus (1) according to one of claims 1 to 4, characterized in that each radiofrequency imaging device (5) consists of a radiofrequency antenna. – Imaging data capture apparatus (1) according to claim 5, characterized in that each antenna (6) is mounted with an orientable metasurface (7) opposite the transmission / reception surface of the antenna (6), at least one diode (9) being mounted on the metasurface. – Imaging data capture apparatus (1) according to claim 6, characterized in that each metasurface (7) consists of six triangular microstrip lines (8) mounted in a hexagon opposite the transmission / reception surface of the antenna (6), each triangular microstrip line (8) carrying a diode (9). - Imaging data capture apparatus (1) according to one of claims 1 to 7, characterized in that the control device (24) comprises a first switch (23) connected to each imaging device (5), a vector network analyzer connected to each radiofrequency imaging device, a computing and memory unit, and a user interface (24). – Imaging data capture apparatus (1) according to claim 8 taken in dependence on claim 6 or claim 7, characterized in that the control device (24) further comprises a second switch (22) connected to each metasurface. – Assembly (20) comprising an imaging data capture apparatus (1) according to one of claims 1 to 9 associated with a computing device (29) for forming an image from the data received from the control device (24). – Imaging method implementing an imaging data capture apparatus (1) according to any one of claims 1 to 9, characterized in that it comprises taking an image in several positions of the movable arches and forming an image by a computing device (29) connected to the imaging data capture apparatus (1) from the data received from the imaging data capture apparatus (1).

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