SYSTEM FOR POSITIONING AND MAINTAINING THE POSITION OF A REFERENCE SENSOR AROUND A MAGNETOENCEPHALOGRAPHY HELMET

Abstract

A system for positioning and maintaining a position of a reference sensor around a magnetoencephalography helmet. The system includes an arch comprising at least one fixing branch for fixing the arch to an MEG helmet, a support plate on which the branch is fixed, a sensor support post fixed to the support plate of the arch; and a locking component for fixing the reference sensor to the post in at least one position defining the position with respect to an MEG helmet.

Claims

1. A system for positioning and maintaining a position of a reference sensor on a magnetoencephalography (MEG) helmet, comprising: an arch including at least one fixing branch to fix the arch to the MEG helmet, and a support plate to which the branch is fixed, a sensor support post fixed to the support plate of the arch; and a locking piece to fix the reference sensor to the post in at least one position defining the position with respect to the MEG helmet.

2. The system as claimed in claim 1, wherein the arch comprises two branches arranged symmetrically to one another with respect to the support plate.

3. The system as claimed in claim 1, wherein the post is a hollow post extending on a longitudinal axis in which the reference sensor can be inserted according to several longitudinal positions.

4. The system as claimed in claim 3, wherein the hollow of the post comprises a plurality of wedging slits, spaced apart longitudinally, each forming a support for a positioning wedge for positioning the sensor according to a longitudinal position.

5. The system as claimed in claim 3, wherein the locking piece is a locking ring to be tightened around the hollow post.

6. The system as claimed in claim 1, wherein the arch comprises shutes to position cables of OPM sensors fixed to the MEG helmet.

7. The system as claimed in claim 1, wherein each fixing branch comprises, at a free end thereof, a plate to be screwed onto the MEG helmet by means of a tightening thumbwheel.

8. The system as claimed in claim 1, wherein the arch, the post, and the locking piece are made of plastic material.

9. An assembly comprising the magnetoencephalography (MEG) helmet to which is fixed the system for positioning and maintaining the position as claimed in claim 1.

10. The assembly as claimed in claim 9, wherein the helmet further comprises at least one anchor point to which the fixing branch is fixed by means of a tightening thumbwheel, the anchor point being an inclined flat provided with a drilled and tapped hole into which the tightening thumbwheel is screwed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is a perspective view of an arch of a positioning system according to the invention.

[0038] FIG. 2 is another perspective view of the arch according to FIG. 1.

[0039] FIG. 3 is a view of a fixing thumbwheel of the system with an MEG helmet according to the invention.

[0040] FIG. 4 is a perspective view showing a fixing piece of an MEG helmet for fixing of the arch.

[0041] FIG. 5 is a perspective view of a post of the positioning system according to the invention.

[0042] FIG. 6 is a perspective view of a locking ring of the reference sensor.

[0043] FIG. 7 is a perspective view of a wedging piece in the longitudinal positioning of the reference sensor in the post.

[0044] FIG. 8 is a perspective view of the positioning system according to the invention fixed to the MEG helmet.

[0045] FIG. 9 is another perspective view of the positioning system according to the invention fixed to the MEG helmet, with a reference sensor positioned and fixed.

[0046] FIG. 10 is a perspective view of the positioning system according to the invention with a reference sensor fixed by means of a tightening ring on the support post.

[0047] FIG. 11 reprises FIG. 10 but with the additional presence of a piece for wedging the reference sensor heightwise in the post.

DETAILED DESCRIPTION

[0048] FIGS. 1 and 2 show an arch 10 of the system for positioning and maintaining the position of the reference sensor according to the invention.

[0049] The arch 10 is designed as to be flexible enough to be able to adapt to different head morphologies: based on the morphology, the arch must be able more or less to bend and be sufficiently rigid to allow a sensor support post 2 to be held well as detailed hereinbelow.

[0050] The arch 10 can be produced in a plastic material, typically in PLA.

[0051] This arch 10 comprises two fixing branches 10 arranged symmetrically on either side of a support plate 11.

[0052] Each branch 10 is preferably a branch arranged laterally with respect to the support plate 11.

[0053] Each branch 10 has a free end 100 that is drilled for fixing to an anchor point 3.

[0054] Each free end 100 can be fixed by means of a tightening thumbwheel 40 shown in FIG. 3 on an anchor point provided on an MEG helmet.

[0055] FIG. 4 shows an example of anchor point 3 as it can be arranged in an MEG helmet.

[0056] The anchor point 3 is an inclined flat provided with a drilled and tapped hole 30 at its center in which the tightening thumbwheel is screwed. An anchor point 3 is preferably arranged in the MEG helmet, on either side of the head, behind the ears and facing the zones of the cranium called mastoids.

[0057] The inclination of the flat 3 is designed to adapt to the fixing zone situated at each end 100 of the lateral branches 10 of the arch.

[0058] As illustrated in FIG. 4, each anchor point 3 forms part of a block of a number of three support studs 4 for OPM measurement sensors of the MEG helmet.

[0059] The arch 10 also comprises chutes 12 on each of its branches 10 and preferably on the support plate 11. These chutes 12 make it possible to position the cables of the measurement OPM sensors situated on the head of the patient, in order to keep them stable and avoid any pulling effect on the OPM measurement sensors. This makes it possible to guarantee a low measurement noise level.

[0060] FIG. 5 shows a hollow post 2 for supporting the reference sensor.

[0061] This post 2 is fixed to the support plate 11 of the arch 10 via a fixing plate 13.

[0062] This post 2 is of square section. It has an opening on one face and the other three faces are grooved at their center, in order to distance the material from certain sensitive elements of the reference sensor.

[0063] The post 2 comprises a central hollowed part 21. This hollowed part extends preferably only over a substantial part of its height, that is to say not to the bottom of the post 2 so as to have a rigid stable fixing on a probe location provided for this purpose on an MEG helmet. This hollowed part 21 makes it possible to insert the reference sensor. Wedging slits 22 are arranged along the post at different longitudinal positions. These slits 22 make it possible to position the reference sensor longitudinally at several different distances from the measurement OPM sensors placed on the scalp of the patient.

[0064] A wedge piece 5 shown in FIG. 6 makes it possible to set the chosen height by being inserted into the post 2 at one or other of the slits 22 for a given position.

[0065] A locking ring 6 shown in FIG. 7 is fixed around the post 2 to lock and maintain the reference sensor in fixed position with respect to the measurement OPM sensors, and do so regardless of the head movements of the patient.

[0066] More specifically, the wedge piece 5 is composed of a tongue 50 which is inserted into one of the two slits 22 of the post 2 at the chosen longitudinal position.

[0067] A reference sensor is slid into the post 2 and then rests on this wedge piece 5.

[0068] The locking ring 6 is then positioned facing the top part of the reference sensor, around the post 2, and it is tightened using a screw.

[0069] The positioning system according to the invention which has just been described is fixed to an MEG helmet 7 that can accommodate an OPM sensor for measuring the cerebral signal, as follows.

[0070] The base of the post 2 is fixed to a support stud, of the type of that referenced in FIG. 4, at the top of the MEG helmet.

[0071] The arch 1 is fixed at two lateral anchor points to the MEG helmet.

[0072] FIGS. 8 and 9 show an MEG helmet with its OPM sensor support studs 4 and the system for positioning and maintaining the position of a reference sensor 8 which is fixed to it.

[0073] In a concrete embodiment, the system for positioning and maintaining the position of the reference sensor described has been designed to adapt to an MEG flexible helmet 7 comprising a number of 97 support studs 4 for the OPM sensors for measuring the cerebral signal.

[0074] In FIG. 9, a reference sensor 8 linked to its cable 9 is inserted into the post 2 and is locked therein and maintained in fixed position by means of the ring 6 tightened by means of a tightening thumbwheel 61 screwed into the tightening eyelets 60.

[0075] FIG. 10 reprises FIG. 9, additionally showing the wedging piece 5 which, inserted into the wedging slits 22, supports and maintains the reference sensor 8, inserted into the post 2, in a given longitudinal position.

[0076] The invention is not limited to the examples which have just been described; it is notably possible to combine with one another the features of the examples illustrated in variants that are not illustrated.

[0077] Other variants and enhancements can be envisaged without in any way departing from the framework of the invention.

[0078] In the example illustrated in FIG. 8, the support post 2 is fixed to the support plate 11 of the arch 1 in such a way that it is substantially positioned at the top of the head of a person on which the magnetoencephalography is to be performed. Obviously, other fixing positions around the cranium of a person can be envisaged.

[0079] In the example illustrated in FIG. 4, the anchor points 3 are provided at the mastoids. In fetal and magnetocardiography (MCG) MEG variations, it is possible to envisage positioning these anchor points 3 respectively at the iliac crests (fetal MEG) or acromions (MCG).

LIST OF THE REFERENCES CITED

[0080] [1]: Boto et al., Moving magnetoencephalography towards real-world applications with a wearable system. Nature. 2018 Mar. 29; 555(7698):657-661 DOI: 10.1038/nature26147. [0081] [2]: Hill et al., Multi-Channel Whole Head OPM-MEG: Helmet design and a comparison with a conventional system Neurolmage Vol 219, 1 Oct. 2020, 116995https://doi.org/10.1016/j.neuroimage.2020.116995. [0082] [3]: Borna et al, Non-Invasive Functional-Brain-Imaging with an OPM-based Magnetoencephalography System PLoS ONE 15(1). 2020 https://doi.org/10.1371/journal.pone.0227684. [0083] [4]: A. A. FifeJ. Vrba, S. E. Robinson[ . . . ] W. Sutherling. Synthetic gradiometer systems for MEG. July 1999 IEEE Transactions on Applied Superconductivity.