Wearable thin film magnetic resonance imaging (MRI) receive coil integrated with MRI guided transcranial focused ultrasound (tFUS) therapy system

Abstract

A magnetic resonance imaging (MRI) receiver coil apparatus and a method of manufacture are provided. The MRI receiver coil apparatus includes a thin film substrate layer configured in a dome shape and a coil array positioned around a circumference of an outer surface of the thin film substrate layer. The thin film cover layer is positioned over an outer surface of the thin film substrate layer such that the coil array is positioned between the thin film cover layer and the thin film substrate layer. The MRI receiver coil apparatus also includes an end ring joining the thin film substrate layer and the thin film cover layer such that a waterproof seal is formed around the coil array between the thin film substrate layer, the thin film cover layer, and the end ring. The coil array includes a plurality of coil elements, each coil element including a loop of conductive trace material having at least one capacitive section.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of priority to U.S. patent application No. 18 / 119,833, filed on March 10, 2023, which claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 322,069, filed on March 21, 2022, and the disclosures of each patent application are incorporated by reference into this patent application. Technical Field

[0003] The present disclosure relates to magnetic resonance imaging (MRI)-guided transcranial focused ultrasound (tFUS) therapy systems and methods, and more particularly to an MRI receive coil array tightly integrated with a tFUS therapy transducer device. Background Art

[0004] High-intensity focused ultrasound (HIFU) was proposed and demonstrated as early as 1957 to deliver focused ultrasound energy from outside the body to a focal point in a target area inside the body for thermal treatment. The temperature of the target lesion can rise to more than 60 degrees Celsius (°C) within a few seconds, causing tissue necrosis. As a result, HIFU has been used as one of several thermal ablation modes for various tumors, even though it was originally applied to the brain to treat neurological disorders. Compared with other traditional surgical procedures, HIFU provides a minimally invasive outpatient alternative with no incisions or exposure to ionizing radiation, minimal side effects, and therefore a fast recovery. However, the application of HIFU was not widely accepted in the clinic until the use of magnetic resonance imaging (MRI) to guide and monitor tissue temperature and extent of damage. Summary of the invention

[0005] A magnetic resonance imaging (MRI) receiver coil device for use in an MRI-guided transcranial focused ultrasound (tFUS) system and a method for manufacturing the same are disclosed. The receiver coil device described is wearable, hydrophobic and ultrasonically transparent, and includes an MRI receiver coil or an MRI receiver coil array. In one embodiment, the MRI receiver coil device includes a first inner layer of a flexible substrate, which is made of a hydrophobic and ultrasonically transparent film and is manufactured to be conformable to a certain 3D shape, such as the shape of a subject or an individual patient's head. A pattern of conductive material can be formed on a first surface of the first inner layer. The pattern can include at least one receiver coil and at least one capacitor, and the conductive traces so formed can include multiple conductive layers and at least one layer of dielectric plastic material. A second thin film outer layer of the same material as the first inner layer is formed above the conductive pattern. The three-dimensional (3D) geometric configuration of the receiver coil device can be conformal to the 3D geometric configuration of a head model rendered from a 3D image data set of an individual patient. In an alternative embodiment, the thin film coil device is manufactured in a fixed 3D shape, and a gel-like ultrasonic transparent material is used to manufacture a thin layer of a separately shaped gel pad liner that conforms to the individual patient's head on the inside and to the fixed shape thin film coil device on the outside. The described method can utilize three to up to six dimensional printing technology or other precision multi-dimensional manufacturing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Various embodiments are described and illustrated herein with reference to the accompanying drawings, in which like items are indicated by the same reference numerals, and in which:

[0007] Figure 1A and Figure 1B An example transcranial focused ultrasound (tFUS) device is illustrated in accordance with one or more embodiments.

[0008] Figure 2A and Figure 2B An example thin film coil array assembly with an associated tFUS transducer is illustrated in accordance with one or more embodiments.

[0009] Figure 3 An example process for constructing a customized thin film coil array assembly in accordance with one or more embodiments is illustrated.

[0010] Figure 4 An example 3D MRI image dataset and resulting surface rendering are illustrated in accordance with one or more embodiments.

[0011] Figure 5A , Figure 5B , Figure 5C and Figure 5DAn example 3D printed head mold and film layers fabricated thereon are illustrated in accordance with one or more embodiments.

[0012] Figure 6 Illustrated are cross-sectional layered views of successive layers of individual coil elements of an example coil array in accordance with one or more embodiments.

[0013] Figure 7 Illustrated is a top view of an example coil array configuration having adjacent overlapping coil loop elements in accordance with one or more embodiments.

[0014] Fig. 8A A closed end ring for holding a tuning / matching circuit board is illustrated in accordance with one or more embodiments.

[0015] Figure 8B A typical tuning / matching circuit board for illustrating only one channel of a receive coil array element is illustrated in accordance with one or more embodiments.

[0016] Figure 8C An example thin film coil array assembly having end rings secured to a coil array cap is shown in accordance with one or more embodiments.

[0017] Fig.8D Illustrated is a cross-sectional view of an interface configuration between an end ring and a coil array cap in accordance with one or more embodiments.

[0018] Fig. 9 An interface between a customized thin film coil array assembly and a frame of a tFUS transducer device is illustrated in accordance with one or more embodiments.

[0019] Fig.10 An example process for constructing a universal thin film coil array assembly in accordance with one or more embodiments is illustrated.

[0020] Fig.11A and Fig. 11B An example generic thin film coil array constructed on a fixed shape mold according to one or more embodiments is illustrated.

[0021] Fig.12 An example concave mold for forming a wearable customized liner is illustrated in accordance with one or more embodiments.

[0022] Fig.13 An example process for placing a universal thin film coil array assembly onto a patient's head is illustrated in accordance with one or more embodiments.

[0023] Fig.14 The interface between a generic thin film coil array assembly and a frame of a tFUS transducer device according to one or more embodiments is illustrated. DETAILED DESCRIPTION

[0024] In the following description, many specific details are set forth in order to provide a thorough understanding of the present disclosure. The present disclosure can be practiced without some or all of these specific details. In order to clearly describe the present disclosure, the known process operations commonly practiced in the art are not described in detail to avoid unnecessarily obscuring the described concepts. Although some concepts will be described in conjunction with specific embodiments, it should be understood that these embodiments are not intended to be limiting. On the contrary, it is intended to cover alternatives, modifications and equivalents that may be included in the spirit and scope of the present disclosure defined by the appended claims.

[0025] For example, the techniques of the present disclosure will be described in the context of focused ultrasound treatment of various body parts, such as the head and brain. However, it should be noted that the techniques and mechanisms of the present disclosure are applicable to various other body parts, such as the abdomen or torso. For clarity, the various techniques and mechanisms of the present disclosure will sometimes be described in singular form. However, it should be noted that, unless otherwise stated, some embodiments include multiple iterations of the techniques or multiple instantiations of the mechanisms.

[0026] Overview

[0027] The advantage of magnetic resonance imaging (MRI) guided thermal therapy is not only its ability to provide rapid and accurate temperature imaging of treatment targets inside the patient's body during ablation procedures. As a proven imaging modality with optimal soft tissue contrast, MRI scans are used to plan treatment, evaluate treatment outcomes immediately after treatment, and for long-term follow-up. In addition, MRI can provide a variety of additional contrast mechanisms, such as those for protein denaturation and lesion formation, to enable better control of treatment outcomes even during ablation procedures. Another MRI method, magnetic resonance acoustic radiation force imaging (MR-ARFI), can detect small focal displacements caused by low-power ultrasound pulses. Comprehensive MRI temperature measurement combined with other acoustic measurement techniques has been proven to be an ideal imaging modality for guiding and navigating various focused ultrasound (FUS) treatment procedures, including but not limited to high-intensity focused ultrasound (HIFU) ablation procedures.

[0028] Several MR-guided HIFU devices have been developed, primarily for abdominal target areas. Existing methods utilize general MRI-compatible robotic systems to move and operate therapeutic or diagnostic devices inside the MRI bore. Other methods utilize a three-axis motion table to position the HIFU transducer in an unsealed water tank that can be placed onto an MRI patient table. The arc-shaped structure can hold the HIFU transducer and allow mechanical motion control of up to 6 degrees of freedom while sitting on a patient table inside the bore of an existing MRI system. MRI receive-only phased array coils can be used to improve the MRI signal-to-noise ratio (SNR). Smaller coils achieve higher SNRs with smaller sensitive volumes, but, comparing the SNRs on the same region of interest, arrays combining multiple small coils show better SNRs than single large coils. Another advantage of a multi-channel coil array is that it can be used for parallel imaging to accelerate MRI scans. For example, a 32-channel head array coil arranged in a soccer ball pattern with overlapping loops can demonstrate the ability of higher SNRs and high acceleration factors in parallel imaging.

[0029] For abdominal HIFU applications under MRI guidance, it is necessary to integrate an MRI receive coil configuration with a HIFU transducer device that is closely positioned on the treated anatomy and can be moved during treatment to focus on successive sonication points in the target region of interest. An N+1 multi-channel configuration can be used to utilize a hollow annular coil that moves with the transducer HIFU device while allowing the ultrasound beam to pass through unimpeded and serves as an additional parallel imaging channel for a multi-channel (N) coil array that remains fixed in place.

[0030] However, the aforementioned systems are not designed for applications within the brain. In recent years, focused ultrasound in a transcranial focused ultrasound (tFUS) transducer array configuration has also been applied to treat various neurological and psychiatric diseases under MRI navigation. Such a tFUS transducer device is placed on the top of the patient's head and is equipped with multiple transducer elements that transmit multiple ultrasound beams through a water bath to penetrate the skull. In this transcranial configuration, the tight integration of the MRI head coil array with the tFUS transducer device is crucial for demanding treatment accuracy in order to fully utilize the image navigation capabilities of MRI, including: targeting, positioning, aiming, real-time monitoring and dose control, immediate prognosis and follow-up. Not only does advanced MRI technology play a key role in targeting defective neural circuits to be treated to support soft tissue contrast provided by conventional anatomical structure images, but temperature measurement and / or acoustic dose monitoring are also becoming increasingly demanding in terms of speed and sensitivity.

[0031] MRI-guided tFUS was approved by the FDA in 2016 for the treatment of essential tremor and in 2018 for Parkinson's disease with tremor as the primary symptom. However, during treatment, MRI scans can only be performed with a large-scale whole-body MRI coil or a simple dual-loop MRI coil inserted into the water bath of the tFUS transducer device. The typical MRI multi-channel head coil itself is a helmet-like structure and therefore cannot be placed simultaneously with the tFUS transducer helmet. Therefore, MRI images can be obtained before ultrasound treatment. However, when images used for targeting or treatment planning are acquired with a head coil before treatment, the actual position of the head when the tFUS transducer is in place during treatment may show misregistration on the images used for planning. A stereotactic frame is required and anchored to the patient's skull to ensure the accuracy of the treatment target location. In addition, once tFUS is in place, MRI sensitivity can no longer be fully achieved with a body coil or a simple dual-loop coil, not to mention the full signal-to-noise ratio (SNR) and acceleration performance.

[0032] Some approaches suggest using a soft 8-channel coil wrapped around the lower portion of the patient's head and face and positioned outside of a water bath of a tFUS transducer placed above the top of the head to minimize direct interference between the coil's magnetic field of view and the overlying acoustic field from the hemispherical tFUS transducer. Because the coil is placed outside the tFUS transducer, this configuration prevents complete imaging of certain substantial portions of the brain that may be treatment targets. Additionally, even though the fine-wire coil exhibits high acoustic transparency, the fabric-like material used to embed the fine-wire coil elements and wrap around the patient's face is breathable and, therefore, not hydrophobic or ultrasonically transparent. Therefore, the coil cannot be immersed in a water bath within the tFUS transducer, or otherwise placed within the tFUS transducer, to improve imaging of the treatment target.

[0033] However, by appropriately selecting sufficiently thin layers of conductive and dielectric materials for coil fabrication, the coil can be placed within a tFUS transducer and can produce low attenuation of the ultrasound beam passing through the coil traces for the tFUS transducer. The present disclosure provides a configuration for a thin film coil array positioned within a tFUS transducer device that provides improved signal-to-noise ratio (SNR) performance and allows for parallel imaging acceleration to enable high temporal resolution of navigated MRI scans. The described systems and methods enable tight integration of an MRI coil array into a tFUS transducer device while retaining or satisfying the following requirements:

[0034] Array of 8 to 16 or more MRI signal receiving channels

[0035] Positioning close to the head

[0036] Rigidly holds in place even in a water bath to ensure RF reception stability

[0037] Minimized sound attenuation to ensure sound beam penetration and adequate focus

[0038] Minimized interference from the transducer.

[0039] In brief, the described systems and devices may include or implement the following elements:

[0040] A physical 3D model constructed from a 3D head MRI image of the individual patient to provide the external surface shape of the head;

[0041] A thin film layer made of a hydrophobic and acoustically transparent material on top of the head mold, including but not limited to TPU (thermoplastic polyurethane), various ultrasound gel materials, etc.; wherein the manufacturing technology adopted in this step and subsequent steps is 3D or up to 6D printing technology;

[0042] A first layer of conductive material, which is fabricated on top of the film to form the base traces of the coil pattern, followed by a layer of dielectric sections for the capacitors, and then overlapping layers of conductive material;

[0043] A second thin film layer, fabricated over the first thin film layer and the conductive material, which forms an array of thin film coils that are elastic, hydrophobic, and ultrasonically transparent, much like a floppy hat;

[0044] End rings, solid structures that hold the circuitry of the coil elements and are attached to seal the conductive material within the thin film coil array cap;

[0045] The manufacturing technology used for this thin film layer and conductive material is not the screen printing typically used for flexible printed circuit boards on a flat substrate surface. Instead, it uses high-precision multi-dimensional (3D up to 6D) printing technology. The thin film coil array assembly can then be placed on the patient's head before being sealed to the frame of the tFUS device.

[0046] In an alternative embodiment, a convex mold is constructed based on a defined 3D shape, upon which a generic thin film coil array is fabricated, and its concave counterpart is used with a head mold to form a void space that is filled with an ultrasonically transparent gel-like material to fabricate a custom gel pad liner. As an alternative embodiment, a gel material layer of the liner can be fabricated on top of the head mold to conform externally to the defined 3D shape of the generic coil array.

[0047] Example Embodiments

[0048] Figure 1A and Figure 1BAn example transcranial FUS (tFUS) device 100 is illustrated in accordance with one or more embodiments. Figure 1A A perspective view of a tFUS device 100 is shown showing a cavity 102 in which a subject's head is placed. The tFUS device 100 also includes a frame 110 having an attachment mechanism 112 for docking with another frame that holds a docking membrane of the subject. Figure 1B A side view of a tFUS device 100 positioned on the head of a subject 130 is shown. As described herein, the subject of the described system and device may be referred to as a "patient" or "user". In order to fully utilize the image navigation capabilities of MRI for advanced transcranial focused ultrasound (tFUS) treatment of various neuropsychiatric diseases, especially for real-time monitoring of tissue temperature, degree of necrosis, or the effect of ultrasonic neuromodulation during treatment, the optimal performance of the received signal-to-noise ratio (SNR) becomes increasingly important for the required spatial and temporal resolution. This is typically achieved by equipping a clinical MRI system with a head-specific radio frequency (RF) receiving coil array. A specific coil array may include multiple elements or channels for head and / or brain scanning, up to 32 channels or more. However, in the presence of a tFUS transducer device, tight integration has always been challenging due to the complexity of the mutual compatibility of the two modes. The described coil array assembly solves such problems regarding the optimal position, stable support, waterproofing, and ultrasound transparency of a multi-channel coil array with minimal changes to the existing tFUS transducer configuration.

[0049] Since the coil needs to be placed inside the transducer device and close to the head, it has become a great challenge to solve the problems associated with the coil array being positioned in the path of the ultrasound beam emitted from the transducer device and therefore often inevitably immersed in a water bath, which serves as an ideal interface medium for the ultrasound beam emitted from the transducer elements to the patient's head.

[0050] refer to Figure 2A and Figure 2B , example thin film coil array assemblies 200 -A and 200 -B are shown according to one or more embodiments. Figure 2A A wearable thin film coil array assembly 200-A having a coil array 220-A arranged in a cylindrical configuration is illustrated. The assembly 200-A may be integrated with a conventional tFUS transducer array 100-A distributed on a hemispherical surface. As used herein, the thin film coil array assembly may be referred to as a "coil array assembly" or an "MRI receiver coil device". Figure 2AAs shown in , the coil array assembly 200-A is positioned or worn on the head of the subject 130. In various embodiments, the coil array assembly 200-A includes a thin film cap 202-A coupled to an end ring 204. In an embodiment, the thin film cap 202-A includes a coil array 220-A of one or more coil elements (including conductive loops and series capacitors) embedded between two thin film layers 210-A. In some embodiments, the thin film layers are made of a selected material such as a thermoplastic. For example, thermoplastic polyurethane (TPU) can be used, which is known to exhibit high hydrophobicity and minimal ultrasonic attenuation in a thin film form. In addition, the described systems and methods are not limited to the use of TPU, and other selected materials including polymers and fluoropolymers can be selected based on various properties including elasticity, hydrophobicity, ultrasonic transparency, and good dielectric properties. For example, the film material may include, but is not limited to, one or more of the following: polyimide (PI) film, polyethylene (PE) film, polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, polyetherimide (PEI) film, polyphenylene sulfide (PPS) film, polytetrafluoroethylene (PTFE) film, and polyetheretherketone (PEEK) film. In some embodiments, a conductive loop and a series capacitor are fabricated between two layers of film, as further described below.

[0051] In the example embodiment, the coil array assembly includes a minimum of 8 channels. The number of channels is not limited to 8, and the described coil array assembly may have fewer channels than 8 or more channels (such as 4 or 16 channels, depending on the specific application). Figure 2A As shown in , the element loops of the coil array can be arranged in a cylindrical configuration to be positioned around the side of the patient's head. When the tFUS transducer 100-A (which is also an array of transducer elements) is distributed in a hemispherical configuration covering the top of the head, the cylindrical configuration can maintain as much orthogonality as possible between the direction of the radio frequency (RF) magnetic field and the direction of the ultrasound beam. The transducer 100-A can be packaged inside the tFUS transducer device 100.

[0052] Figure 2B Another embodiment of a coil array assembly 200-B is shown having a coil array 220-B that includes a loop of elements within two layers of film 210-B placed in an overlapping configuration within a film cap 202-B. The coil array assembly 200-B also includes end rings 204 when fully assembled. The coil array assembly 200-B has a hemispherical configuration that can be optimized for MR imaging of human cortical structures and is implemented to function with a tFUS transducer array having elements distributed in an annular shape or cylindrical structure, such as the tFUS transducer 100-B. Figure 2A and Figure 2B In the present invention, the pairing of dual-mode arrays in a mutually orthogonal relative configuration is a way to minimize interference between the respective fields generated by each. For some applications, cylindrical ultrasound transducer arrays can also produce finer and sharper acoustic focus profiles.

[0053] However, as the technology moves into advanced MRI functional and structural studies of cortical areas of the brain near the top, coil arrays with 32 or more channels in a soccer ball-like configuration may demonstrate enhancements in sensitivity or acceleration. In this case, some of the element coil loops happen to be in the path of the ultrasound beam generated by the central transducer element, and minimizing ultrasound attenuation is a key issue to be addressed by integrating the two modes. Despite careful selection of film materials and maintaining the thinnest possible thickness of conductive traces and dielectric segments, as an alternative embodiment, an annular tFUS transducer array with elements distributed in cylindrical symmetry is disclosed herein, which is Figure 2B Shown as 200-B in order to be paired with a coil array having a hemispherical distribution.

[0054] The described coil array assembly also solves another key problem, minimizing eddy currents caused by coil loops that may exist on the conductive electrode surface of the transducer hemisphere. To reduce the eddy current effects, the common ground electrode plate of the tFUS transducer is cut or slotted into multiple thin radial strips on the inner side of the hemispherical transducer array. Figure 2A 100-A is shown in Figure 1. While maintaining the ground connection of all tFUS transducer elements, the radial strip-shaped grooves confine the eddy current loops to a narrow area, minimizing the impact. In the case of the annular tFUS transducer, the ground is grooved into a comb shape ( Figure 2B 100-B) in to achieve the same effect.

[0055] To ensure that there is no or minimized ultrasonic obstruction, deflection, or attenuation, a thin film coil array assembly such as 200-A shown is manufactured to be "worn" on the head of an individual subject with a close fit and close contact. In some embodiments, the described coil array assembly such as 200-B is placed on a customized gel pad worn on the subject's head, or attached to the inside of a thin film cap with a close-fitting gel pad. The customized pad can allow a close fit to the subject's head while maintaining ultrasonic transparency. In addition, the coil array assembly must be placed inside the tFUS transducer device and immersed in a water bath that serves as an interface medium between the subject's head and the ultrasonic beam emitted by the transducer. Therefore, the coil array assembly requires hydrophobic and waterproof properties to protect the coil elements from water or other fluids. The present disclosure describes the configuration and method of manufacturing a coil array assembly that is positioned close to the patient's head to meet the proximity principle for achieving optimal SNR on the one hand, and the requirements of hydrophobicity and ultrasonic transparency on the other hand.

[0056] Custom Thin Film Coil Array Assemblies

[0057] In some embodiments, the coil array assembly is customized to fit the head of a specific subject. This ensures the closest overall positioning of the coil elements around the target area (i.e., the subject's head). Figure 3 , shows an example process for constructing a custom coil array assembly according to one or more embodiments. Figure 4 , Figure 5A , Figure 5B , Figure 5C , Figure 5D , Figure 6 , Figure 7 , Fig. 8A , Figure 8B , Figure 8C , Fig.8D and Fig. 9 describe Figure 3 , these figures illustrate the configuration of the described coil array assemblies and components at various stages of construction.

[0058] In some embodiments, a 3D model of the subject's head is obtained to construct such a customized coil array assembly. For example, at operation 302, a 3D model of the subject's head is constructed. The 3D model is customized for the subject's (or patient's) specific head and corresponding geometric configuration. Various techniques are implemented to generate the 3D model.

[0059] In one example, MRI image data is used to render a 3D model. Figure 4, shows an example 3D MRI image dataset 410 and a resulting surface rendering 420 according to one or more embodiments. Although the image dataset 410 shows eight (8) images of an axial view of the entire head of a user (such as subject 130), many more additional images are included in the dataset 410. For example, the 3D MRI image dataset 410 includes a total of 148 images, each corresponding to a 1.2 mm thick slice. Using these images, a binary threshold can be used to define MRI null signal regions, which include air cavities in the head region and the lateral region of the head. The null signal regions are then processed using a "connected component labeling" algorithm. By selecting the largest region, an image of only the outside of the head can be obtained. By collecting all images of only the outside of the head from top to bottom, a surface rendering of the patient's head is obtained by a "marching cubes" algorithm. The marching cubes algorithm calculates hundreds of thousands of triangles on the head surface and provides 3D coordinate data for these triangles to generate the surface rendering 420. It should be appreciated that various other techniques can be implemented to obtain a 3D model rendering of the subject's head, including 3D optical scanning.

[0060] The 3D surface rendering 420 is then used to generate a physical model that serves as a mold for the coil array assembly to be constructed. Figure 5A , Figure 5B , Figure 5C and Figure 5D An example 3D solid head mold 502 and thin film layers fabricated thereon are shown in accordance with one or more embodiments. Figure 5A A 3D head mold 502 is shown, which is constructed according to 3D coordinate data using a 3D printer. In various embodiments, the head mold 502 is constructed by using 3D manufacturing techniques, such as but not limited to stereolithography (SLA), selective laser sintering (SLS), fused deposition molding (FDM), digital light processing (DLP), multi-jet fusion (MJF), polymer jetting (PolyJet), direct metal laser sintering (DMLS) and electron beam melting (EBM). The head mold can be made of various materials suitable for the above-mentioned manufacturing techniques, such as, for example, polylactic acid (PLA). In some embodiments, the entire head mold is not constructed. Instead, only the relevant parts required for forming and constructing the coil array assembly in the head mold are constructed. Various printing techniques including stereolithography are implemented.

[0061] At operation 304, a first film layer is constructed on the head mold. Figure 5BThe first film layer 510 of the coil array assembly constructed on the head mold is shown. The first film layer is called the base layer or inner layer. As previously described, the first film layer 510 includes a material that is both hydrophobic and ultrasonically transparent, such as TPU. In some embodiments, the first base layer is uniformly manufactured on the head mold via various techniques including vacuum forming and printing with higher dimensional accuracy. In other embodiments, the head mold is coated with a layer of base material by immersing the head mold in a bath of material in liquid form and then drying. In some embodiments, the first film layer is applied to the head mold by spraying the material onto the desired portion of the head mold and then drying. Additional machining can be used to shape or form the material dipped or sprayed onto the mold. As such, the first film layer will closely conform to the geometric contours of the head mold and therefore conform to the subject's head.

[0062] Then, at operation 306, a coil array is constructed on the first thin film layer. Figure 5C A coil array 520 is shown constructed on a first film layer 510. In some embodiments, the coil array is fabricated on the first film layer 510 using a conductive ink and a selected dielectric material. The coil array 520 may include one or more layers of conductive material for coil traces and one or more dielectric layers for capacitors. In various embodiments, the coil array includes a pattern of conductive traces and distributed capacitors configured into one or more coil elements. The coil elements may include loops or other configurations of conductive traces. Figure 5C As shown in , the coil array 520 includes a plurality of overlapping conductive loops, each of which is a coil element. In the exemplary embodiment, the coil array includes eight overlapping coil elements uniformly positioned in a cylindrical pattern around the subject's head, such as Figure 5C As shown in FIG. A coil element 522 of the coil array is Figure 5C Outlined with dotted lines. Figure 6 and Figure 7 The configuration of the coil pattern is further described.

[0063] refer to Figure 6 , shows a cross-sectional layered view of successive layers of a single coil element 600 of an example coil array according to one or more embodiments. In various embodiments, the coil element 600 is Figure 5C An example of the coil element 522 in FIG. Figure 6 As shown in FIG. 6 , the coil element 600 is made of at least three layers 610, 620, and 630, wherein an intermediate layer 620 of dielectric material is sandwiched between two layers of conductive material 610 and 630. Various conductive materials and dielectric materials can be used. For example, the conductive material can include, but is not limited to, silver, copper, graphene, etc. For example, the dielectric material can include, but is not limited to, polytetrafluoroethylene (PTFE) or other ceramics, glass, mica, and plastic materials.

[0064] The three layers of coil element 600 (conductor traces and distributed series capacitors) are sandwiched between two layers of film 510 and 512. In various embodiments, conductive layer 610 includes a base conductive trace of the loop with one or more gaps at selected locations along the loop. Conductive layer 610 is fabricated onto a first or inner film layer. Dielectric layer 620 is fabricated on top of conductive layer 610. Dielectric layer 620 includes one or more dielectric segments that overlap the location of one or more gaps in layer 610. Subsequently, a second conductive layer 630 is fabricated on top of dielectric layer 620 that includes conductive segments that match the dielectric segments.

[0065] To minimize the attenuation of transmembrane ultrasound, in example embodiments, the thickness of the single layer may be no thicker than 0.02 millimeters (mm) for the conductive material (layers 610 and 630), no thicker than 0.1 mm for the dielectric material (layer 620), and no thicker than 0.1 mm for the thin film layer material (layers 510 and 512). However, it should be appreciated that the thickness of each of the layers and components is not limited to the described ranges and may vary to achieve various conductive or wave transparency properties and various structural or mechanical properties. For example, the dielectric material may be provided at a thickness greater than 0.1 mm.

[0066] The described system can use multi-dimensional printing technology to manufacture both the multiple layers of the film layer and the coil array onto the film layer. As such, the layer is constructed to conform to the 3D shape of the head mold. Different from the solid head mold 502 that can be constructed by conventional 3D printing technology, each film layer (510 and 512) and the coil array trace (610, 620, 630) are constructed using a multi-dimensional printer (such as a 5-dimensional or up to 6-dimensional printer), which can perform three orthogonal translational dimensions on the physical 3D mold in combination with two to three dimensional rotational motions. This can be achieved by modifying a conventional 3D printer, adding an additional fixture for rotational control or utilizing a 6-axis robotic arm. This ensures that the thickness of a layer such as a film base layer is a uniform thickness throughout the entire layer on the 3D contour of the mold.

[0067] The described manufacturing techniques are significantly different from two-dimensional (2D) planar screen printing techniques and other planar manufacturing techniques that are commonly used to print traces onto thin, flat substrate sheets (i.e., flexible printed circuit boards), which are then folded into non-planar shapes after printing. Due to the flexible nature of such printed circuit boards, there is a lack of mechanical stability, especially when immersed in a water bath and subjected to water pressure. Such printed circuit boards also cannot conform precisely to the shape of a subject's head.

[0068] like Figure 6As shown in , the coil element 600 includes a loop configuration formed by four meandering trace structures 612 in layer 610, on which one or more gaps 614-A and 614-B are designed between the meandering trace structures to position distributed series capacitive elements so that the coil resonates electrically at the Larmor frequency of the MRI scanner. To form these series capacitive elements, a segment of overlapping conductor traces (in layer 630) is aligned with each gap to form the equivalent of two capacitors in series with the inductive loop at the location of the gap. As shown, overlapping traces 632-A (in layer 630) are aligned with gaps 614-A, wherein dielectric segments 622-A (in layer 620) are positioned between the overlapping traces in layer 630 and the meandering trace structures in layer 610. As also shown, overlapping trace 632-B (in layer 630) is aligned with gap 614-B, with dielectric segment 622-B (in layer 620) positioned between the overlapping trace in layer 630 and the meandering trace structure in layer 610. The capacitance of the distributed capacitive element required for resonance can be adjusted empirically by the choice and thickness of the dielectric material and the area of ​​the overlapping segment of the overlapping trace.

[0069] In some embodiments, the dimensions of meander trace structures 612 are the same. In some embodiments, the dimensions of gaps 614-A and 614-B are the same. In some embodiments, dielectric segments 622-A and 622-B are the same. In some embodiments, the dimensions of overlapping traces 632-A and 632-B are the same.

[0070] In arrays of multiple coil loop elements, adjacent loops typically overlap slightly to eliminate mutual inductance, which could interfere with resonance. Figure 7 A top view of an example coil array configuration with adjacent overlapping coil loop elements is shown in accordance with one or more embodiments. Figure 7 , wherein adjacent coil elements 710 and 730 overlap with coil element 600. Components located on layer 610 are shown in gray, while components located on layer 630 are shown in blue. Accordingly, the curved structure 612 of coil element 600 is shown in gray, while overlapping traces 632-A and 632-B are shown in blue. In one embodiment, opposite patterns are printed for adjacent coil elements to form an overlapping configuration. For example, the curved structure (612-C) of coil elements 710 and 730 is located within layer 630 and is shown in blue, while the overlapping traces (632-C) of coil elements 710 and 730 is located within layer 610 and is shown in gray. The pattern on dielectric layer 620 is shown in FIG. Figure 6The dielectric traces are printed at all the capacitive sections described in . The dielectric traces in layer 620 are also made at overlapping sections 760 (outlined in dotted lines) wherever the conductive traces of adjacent coil elements overlap. The described configuration minimizes the number of layers to three layers to achieve coil resonance without interfering mutual inductive coupling. Minimizing the number of layers also reduces the amount of material used and allows the construction of the coil array assembly to be as thin as possible in order to minimize ultrasonic attenuation.

[0071] Once the coil pattern is constructed on the first film layer, a second film layer is constructed over the coil element at operation 308 for additional dielectric isolation and waterproofing. Figure 5D A second film layer 512 positioned over the first film layer 510 (shown in dotted lines) and the coil element is shown to seal the coil element within the first film layer and the second film layer, thereby forming a thin film coil array cap 550. As used herein, the second film layer is referred to as a cover layer or outer layer. The second film layer can be manufactured using any of the described construction techniques for manufacturing the first film layer. In some embodiments, the techniques for manufacturing the first film layer and the second film layer can be the same or different.

[0072] The second film layer is directly manufactured on the first film layer and the coil element. In some embodiments, the air pocket or gap between the film layer and the coil element is eliminated or reduced to the greatest extent possible. Although the second film layer may include the same material as the first film layer, in some embodiments, different materials may be used for each film layer. Although the previously discussed operation constructs the film cap layer by layer on a physical head mold, in some embodiments, a physical 3D head mold may not be required. On the contrary, the film layer and the coil array can be constructed based on the merged 3D head rendering data with a 3D CAD (computer-aided design) model.

[0073] At operation 310, an end ring is attached to the thin film layer of the thin film coil array cap 550. In this way, the coil elements are completely sealed within the two thin film layers and the end ring. In addition, each coil element of the coil array is electrically connected or otherwise coupled to one channel of the signal receiving unit of the MRI system through a tuning and matching circuit board (TMCB) encapsulated or housed in the end ring. Fig. 8A An example end ring 800 that can be implemented using one or more embodiments of the present disclosure is shown. The end ring 800 includes a plurality of TMCBs 810 positioned along the inner circumference of the end ring. As illustrated, the structure of the end ring 800 is transparent to show eight (8) TMCBs 810, each TMCB 810 corresponding to a coil element of the coil array 520. The TMCBs are housed in the structure of the end ring 800, which is a rigid hollow annular structure. Each TMCB is positioned within the structure of the end ring at equal or approximately equal spacings.

[0074] Figure 8B An example tuning and matching circuit board (TMCB) 810 is shown in accordance with one or more embodiments. Figure 8B The TMCB shown in the figure includes an input connected to a coil element and an output connected to a preamplifier with low input impedance. The circuit board includes a ceramic capacitor 812, a copper strip 814, variable capacitors 821 and 822, a PIN diode 816 and a printed circuit board 830. Example circuit boards include flexible circuit boards and FR4 circuit boards. The TMCB produces parallel resonance with the inductive coil element loop, produces high impedance for the coil element, and thus reduces the current in the coil element to eliminate the mutual inductance effect between non-adjacent coil elements. For adjacent coil elements, an overlapping method is used to eliminate the mutual inductance effect. The PIN diode 816 is used to perform active decoupling to protect the receiving coil element from the high RF power emitted by the transmitting coil of the MRI system during transmission. On the printed circuit board 830, the circuit resonance can be tuned to the Larmor frequency of the MRI magnetic field by adjusting the capacitance of the variable capacitors 821 and 822 to achieve optimal pickup of the magnetic resonance signal.

[0075] The magnetic resonance signals picked up by the coil elements are amplified by multi-stage amplifiers including low input impedance preamplifiers, intermediate amplifiers, and various gain amplifiers. The signals from each coil element are then transmitted to the receiver's channel, where the magnetic resonance signals are processed by analog-to-digital sampling and digital down-converters before being reordered to form time domain data. Finally, the time domain data is Fourier transformed to reconstruct the MR imaging. The above MRI signal processing chain can be independent for each channel.

[0076] End rings are coupled to the membrane cap at a lip or edge structure of each membrane layer. Figure 8C End rings 800 are shown attached to a thin film coil cap 550 that forms a coil array assembly 500 customized for a particular subject's head. Fig.8D Illustrated is a cross-sectional side view of a coil array assembly in accordance with one or more embodiments. Fig.8D The interface between the end ring 800 and the thin film coil cap 550 is shown. In various embodiments, the end ring 800 can be attached to the thin film coil cap 550 at the edge structures 530 and 532 extending from the thin film layers 510 and 512, respectively. The edge structure can extend around the entirety of the thin film cap, forming a brim-like structure. In some embodiments, the edge structure can be constructed together with the thin film layer, such as during operations 304 and 306. In some embodiments, the edge structure can be an extension or portion of the corresponding thin film layer.

[0077] Each TMCB in the end ring can be electrically coupled to the coil element by an additional conductive trace 850 embedded in the thin film layer extending from the close-fitting coil array. Such conductive traces can be fabricated on the thin film layer in a similar manner as the coil element. The other terminal of the TCMB is connected to a corresponding low input impedance preamplifier, such as a 1 / 2 wavelength, 50 ohm impedance coaxial cable. Figure 8B as shown in .

[0078] In some embodiments, the end ring can be fully sealed to the edge structure to form a watertight seal. In some embodiments, the end ring is clamped against the flexible material of the film layer with sufficient pressure to prevent water or other liquids from passing through the interface of the end ring and the edge structure. In turn, the end ring is configured to engage and fully sealably dock with the tFUS transducer using a watertight seal. As such, water can be contained within a cavity formed between at least the outer film layer, the tFUS transducer device, and the edge ring. Fig. 9 A customized coil array assembly, such as 200-A, is shown having an end ring 800 that interfaces with a tFUS transducer 100. In various embodiments, the attachment mechanism 112 of the transducer 100 can be configured to engage and fully seal with the end ring 800. Once fully sealed, the cavity 102 within the transducer is fully sealed between the tFUS transducer and the coil array assembly. As such, a water bath or other liquid can be contained within the cavity 102 without damaging or interfering with the coil elements and other components of the coil array assembly.

[0079] As described, the example customized thin film coil array assembly 200-A (or 500) is wearable and manufactured to conform to the head of a specific patient. The coil array assembly 200-A provides the tightest fit to minimize ultrasound attenuation, is best mechanically supported by the head, and meets the MRI requirements of close proximity and multi-channel parallel acceleration. It can also be reused by the same patient for subsequent or follow-up treatments. As an alternative embodiment, the thin film coil array assembly can be manufactured in conjunction with a customized gel pad liner thin layer to conform to one or more universally defined shapes.

[0080] Common Thin Film Coil Array Assembly Configuration

[0081] In another embodiment, the thin film coil array assembly is not customized for a specific subject's head, but is manufactured on a fixed mold having a defined geometry of one or more dimensions to fit the specific subject as closely as possible. This method of universal coil array assembly configuration is facilitated by a customized gel pad liner that is manufactured to form a close fit with the subject's head to ensure that no void space is formed between the subject's head and the thin film coil array cap to avoid ultrasound deflection or reflection. Fig.10An example process for constructing a universal coil array assembly according to one or more embodiments is shown. Fig.11A , Fig. 11B , Fig.12 , Fig.13 and Fig.14 describe Fig.10 , these figures illustrate the configuration of the described coil array assemblies and components at various stages of construction.

[0082] At operation 1002, a male mold defining a shape such as Fig.11A The convex mold 1102 shown in . Fig.11A An example convex mold 1102 and a thin film layer manufactured thereon are shown according to one or more embodiments. Thus, the thin film coil array assembly is manufactured to conform to the outer surface of the fixed geometry of the convex mold 1102. In various embodiments, the convex mold can be constructed together with a concave counterpart (1202) further described below. The defined geometry of the convex mold can have a size that is slightly larger than the size of an average human head while being small enough to fit inside a tFUS transducer device. In some cases, the convex mold can be constructed with additional dimensions to accommodate heads of different sizes. The convex mold can be constructed of various materials, including polylactic acid (PLA) and other materials suitable for the various 3D printing techniques described herein.

[0083] At operation 1004, a first film layer is constructed on the male mold. Similar to operation 304, a first layer or inner layer of material is manufactured on the male mold to form a first film layer 1110. As described, such material can include a TPU film. Next, at operation 1006, a coil array is constructed on the first film layer. Coil array 1120 is shown positioned at Fig.11A On the first film layer 1110 in.

[0084] As previously described with reference to operation 306, the coil array may include one or more layers of conductive material for coil traces and one or more dielectric layers for distributed capacitors. In various embodiments, the coil pattern includes a pattern of conductive traces and distributed capacitors configured into one or more coil elements. Coil array 1120 is shown as a configuration of overlapping circular element loops in overlapping rows, similar to Figure 2B However, various patterns of conductive elements may be constructed in operation 1006, including but not limited to coil arrays. Figure 2A and Figure 5C Similarly, the customized thin film coil array assembly constructed via method 300 may include: Fig.11A The coil array of overlapping element loops shown in FIG. 5A to FIG. 5D An alternative to the cylindrical configuration shown in .

[0085] As Fig.11A In one example embodiment shown in FIG. 1 , coil array 1120 includes up to 16 elements distributed in a hemispherical configuration positioned to cover or surround the top of the subject's head. There are two ascending rows of overlapping elements. However, the number of elements is not limited to 16. Additional rows of overlapping elements may also be implemented. The coil pattern of coil array 1120 may include three layers of conductive traces-dielectric-conductive traces printed one after another on top of a first film layer (similar to Figure 6 and Figure 7 610, 620 and 630 shown in FIG. 1 ). Similar to Figure 7 Adjacent coil loop elements may also overlap (positioned in different layers) to eliminate mutual inductance of the coil array 1120, except that the overlap may be repeated in more than one direction of the example configuration.

[0086] At operation 1008 , a second or outer film layer is constructed over the coil elements and the first film layer to complete the thin film coil array cap 1150 . Fig.11A In the lower left figure, a second film layer 1112 positioned on the first film layer 1110 (shown in dotted lines) is shown. As such, the coil array can be completely or mostly sealed between the first film layer and the second film layer. As previously described, the first film layer and the second film layer can be constructed by the multi-dimensional printing equipment discussed above. As previously explained, air pockets or gaps between the film layers and the coil elements are eliminated or reduced as much as possible.

[0087] Then, at operation 1010, the completed thin film coil array cap can be removed from the male mold and end rings (such as end ring 800) attached to the thin film layer of the thin film coil array cap, as previously described with reference to FIG. Fig.8D The end rings housing the tuning / matching plates inside are connected and sealed to the thin film coil array cap 1150. Fig. 11B End rings 800 are shown attached to thin film coil array cap 1150 forming coil array assembly 1100 .

[0088] The coil array assembly 1100 can be used universally for any user whose head has an appropriate size to fit within the assembly 1100. However, because the universal coil array assembly is constructed to have a configuration corresponding to a mold 1102 of a predetermined size and geometry, such an assembly may not precisely fit the head of any one particular subject or patient to allow for sufficient elimination of any air gap that may deflect the ultrasound beam or cause skin burns at the location of the air gap. Therefore, the additional structures described herein can be constructed and implemented within such a universal coil array assembly. For example, before the assembly is placed on the top of the patient's head, a personalized lining layer can be constructed and worn on the patient's head, or otherwise placed on the inside of the thin film coil array cap to provide and maintain as close a fit as possible without affecting the ultrasound emitted by the transducer. The construction of the personalized lining layer can be faster and more economical than the construction of a personalized thin film coil array cap containing complex conductive traces. As such, creating a personalized lining layer allows multiple patients to cost-effectively use a single universal thin film coil array assembly and a corresponding personalized lining.

[0089] In some embodiments, an ultrasound clear gel material is used to fill the patient's head mold ( Figure 5A 502) and a concave fixed shape mold ( Fig.12 The void space formed between the inner surfaces of 1202) and allows the formation of Fig.12 A semi-rigid thin layer of personalized gel pad liner 1220 in the thin film coil array assembly. Referring again to process 1000, additional operations for manufacturing a patient-specific lining layer to fit onto a specific patient's head and serve as an effective interface between the patient's head and the thin film cap portion of the thin film coil array assembly are described. In operation 1012, a 3D model of the subject's head is constructed. As previously discussed with reference to operation 302, a physical model (such as mold 502) can be constructed from 3D image data. However, only relevant portions of the 3D model can be used to create a physical mold to reduce materials, costs, and manufacturing time. In operation 1014, a concave mold is constructed. Fig.12 An example concave mold 1202 for constructing a personalized lining layer according to one or more embodiments is shown. Fig.12 As shown in , the female mold 1202 can include a geometric inner surface shape that is the same as the predetermined outer shape of the male mold 1102. In other words, the outer surface of the male mold 1102 can be seamlessly connected to the inner surface of the female mold 1202.

[0090] In various embodiments, at operation 1016, a concave mold 1202 and a patient-specific head mold 502 are used together to form a customized cushion. Since the concave mold 1202 is a counterpart to the convex mold 1102, the inner surface of the mold 1202 should precisely correspond to the surface of the convex mold 1102. When the patient-specific head mold is placed inside the fixed-shape concave mold, a void space is formed. In some embodiments, the head mold 502 can be positioned within the concave mold at a specific distance to maintain a minimum distance from the surface of the concave mold at each point along the head mold 502. In some embodiments, the head mold 502 can be positioned within the concave mold to minimize the distance between all points of the head mold 502 and the surface of the concave mold while maintaining the minimum distance requirement. In some embodiments, landmarks can be designed on the head mold to align the molds.

[0091] The custom pad can be formed by filling the void space with an ultrasonically transparent material that will cure into a flexible or semi-rigid structure. For example, a selected ultrasonic gel material can be filled into the void space and allowed to form into a semi-rigid thin gel pad or custom pad 1220. In various embodiments, the material can cure at room temperature or under heat. Once the custom pad has been formed, the head mold 502 can be removed to allow access to remove the custom pad, such as Fig.12 Once formed, the custom pad should include an outer surface that corresponds to the inner surface of the mold 1202 and an inner surface that corresponds to the surface of the head mold. Some additional machining may be performed to shape or complete the custom pad.

[0092] Another way that custom pads can be manufactured is by constructing a padding layer directly onto a head mold. For example, the head mold can be coated with a padding material so that the inner surface of the pad conforms to the shape of the head mold. The excess padding material can then be formed or machined so that the outer surface conforms to the shape of a universal thin film coil array cap. As another example, the padding material can be directly 3D or higher dimensionally printed onto the head mold to have the desired external geometry. In some embodiments, in order to provide more structural support for the padding layer during manufacturing, additional film layers can be implemented. For example, very similar to the first film layer, an inner film layer such as TPU can first be constructed on the head mold. The padding material can then be constructed on the inner film layer as discussed above. In some embodiments, an additional outer film layer can be constructed on the formed padding layer to seal the padding layer within the inner film layer and the outer film layer.

[0093] At operation 1020 , a custom gasket is attached to the coil array assembly. Fig.13An example process for placing a universal thin film coil array assembly on a patient's head is illustrated in accordance with one or more embodiments. Fig.13 As shown in , the customized pad is first placed or worn on the patient's head 130. The universal thin film coil array assembly 1100 can then be placed on the outer surface of the pad having a complementary geometric profile. However, in some embodiments, the customized pad can first be docked with the inner surface of the first (inner) film layer of the coil array assembly 1100 before being placed on the subject's head. In some embodiments, the customized pad can be fixed and / or sealed with the assembly by an end ring. Therefore, the universal thin film coil array assembly can be used for multiple patients, each patient having their own customized pad as a consumable.

[0094] refer to Fig.14 , illustrates an interface between a generic thin film coil array assembly 1100 and a frame of a tFUS transducer device 100 according to one or more embodiments. In some embodiments, the assembly 1100 may alternatively interface with a tFUS transducer having an array of transducers distributed in a ring configuration (e.g., as described with respect to FIG. 1 ). Figure 2B 100-B) to minimize interference with the specific configuration of the coil elements of the assembly 1100. In various embodiments, the attachment mechanism 112 of the transducer 100 can be configured to fully seal to the end ring 800. Once fully sealed, the cavity 102 within the transducer is fully sealed between the tFUS transducer and the coil array assembly. In this way, a water bath or other liquid can be contained within the cavity 102 without damaging or interfering with the coil elements and other components of the coil array assembly.

[0095] in conclusion

[0096] The present disclosure is not limited by the design of the coil array, the number of coil elements or loops, the shape or traces of the loops, or their spatial distribution. Figure 8C The 8-channel array shown in Fig. 11B The 16-channel array in is only an example of a possible configuration. Since one of the main considerations in the tight integration of the head coil array and the tFUS transducer device is the mutual interference between the two modes, a simple principle is to maintain the orthogonality of the two fields (the ultrasound field in the direction of the beam and the magnetic field perpendicular to the coil loop). Since conventional tFUS transducer arrays consist of hundreds of transducer elements that are typically distributed on a hemispherical shell, the ideal placement of the coil loops is to arrange the loops along the sides of a cylinder, such as Figure 2A Configuration in and Figure 5C As shown in the example given in .

[0097] Different examples of the apparatus and methods disclosed herein include various components, features, and functions. It should be understood that the various examples of the apparatus and methods disclosed herein may include any of the components, features, and functions of any other examples of the apparatus and methods disclosed herein in any combination, and all possible variations are intended to be within the spirit and scope of the present disclosure. With the benefit of the teachings presented in the foregoing description and the associated drawings, those skilled in the art to which the present disclosure relates will appreciate many modifications of the examples set forth herein.

[0098] Therefore, it should be understood that the present disclosure is not limited to the specific examples illustrated, and modifications and other examples are intended to be included within the scope of the appended claims. In addition, although the foregoing description and associated drawings describe examples of the present disclosure in the context of certain illustrative combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the appended claims. Therefore, the bracketed reference numerals in the appended claims are presented for illustrative purposes only and are not intended to limit the scope of the claimed subject matter to the specific examples provided in the present disclosure.

Claims

1. A magnetic resonance imaging (MRI) receiver coil apparatus, comprising: a thin film base layer configured in a dome shape; an array of coils positioned around a circumference of an outer surface of the thin film substrate layer; a thin film cover layer positioned on the outer surface of the thin film base layer such that the coil array is positioned between the thin film cover layer and the thin film base layer; and An end ring engages the thin film base layer and the thin film cover layer such that a watertight seal is formed between the thin film base layer, the thin film cover layer and the end ring around the coil array.

2. The MRI receiver coil apparatus according to claim 1, wherein: The dome shape conforms to the geometry of the particular subject's head.

3. The MRI receiver coil apparatus according to claim 1, wherein: The dome shape conforms to a predetermined geometric contour.

4. The MRI receiver coil apparatus according to claim 3, wherein: The MRI receiver coil apparatus also includes a backing layer configured to conform to the geometric contours of a particular subject's head.

5. The MRI receiver coil apparatus according to claim 1, wherein: The film base layer or the film cover layer includes thermoplastic polyurethane.

6. The MRI receiver coil apparatus according to claim 1, wherein: The film base layer has a thickness of no greater than 0.1 mm.

7. The MRI receiver coil apparatus according to claim 1, wherein: The coil array includes a plurality of coil elements, each coil element including a loop of conductive trace material having at least one capacitive segment.

8. The MRI receiver coil apparatus according to claim 7, wherein: Adjacent coil elements overlap at an overlap section, wherein the coil array further comprises a dielectric trace positioned within the overlap section to electrically isolate the adjacent coil elements.

9. The MRI receiver coil apparatus according to claim 8, wherein: The coil array comprises: A first conductive material layer, which is disposed on the outer surface of the film base layer, wherein the first conductive material layer has a first pattern; a second conductive material layer on the outer surface of the thin film substrate above the first conductive material layer, the second conductive material layer having a second pattern, wherein the first pattern and the second pattern overlap at the overlapping section and the capacitor section; and A dielectric material layer having the overlapping section and the capacitive section positioned between the first conductive material layer and the second conductive material layer, wherein a portion of the overlapping section forms one or more capacitors.

10. The MRI receiver coil apparatus according to claim 8, wherein: The conductive material includes conductive ink, and the conductive ink includes one or more of the following: gold, copper, silver, graphene, and metal flakes.

11. A method of constructing a magnetic resonance imaging (MRI) receiver coil apparatus, the method comprising: manufacturing a film substrate layer on a mold having a dome shape; fabricating a coil array around the circumference of the outer surface of the thin film substrate layer; manufacturing a thin film cover layer positioned on the outer surface of the thin film base layer such that the coil array is positioned between the thin film cover layer and the thin film base layer; and End rings are bonded to the thin film base layer and the thin film cover layer to form a watertight seal around the coil array between the thin film base layer, the thin film cover layer and the end rings.

12. The method of claim 11, further comprising forming the dome shape to conform to the geometry of a particular patient's head.

13. The method of claim 11, further comprising forming the dome shape to conform to a predetermined geometric contour.

14. The method of claim 13, further comprising configuring a backing layer of the MRI receiver coil apparatus to conform to the geometry of a particular patient's head.

15. The method according to claim 11, wherein: The film base layer or the film cover layer is produced as a thermoplastic polyurethane layer.

16. The method according to claim 11, wherein: The manufacturing of the thin film base layer includes manufacturing the thin film base layer to have a thickness of no greater than 0.1 mm.

17. The method according to claim 11, wherein: The manufacturing of the coil array further includes manufacturing a plurality of coil elements, each coil element comprising a loop of conductive trace material having at least one capacitive segment.

18. The method according to claim 17, wherein: Fabricating the coil array includes overlapping adjacent coil elements at an overlap section and positioning dielectric traces within the overlap section to electrically isolate the adjacent coil elements.

19. The method according to claim 18, wherein: Manufacturing the coil array comprises: Producing a first conductive material layer on the outer surface of the film substrate layer, the first conductive material layer having a first pattern; fabricating a second conductive material layer on the outer surface of the thin film substrate above the first conductive material layer, the second conductive material layer having a second pattern, wherein the first pattern and the second pattern overlap at the overlap section and the capacitor section; and A dielectric material layer is fabricated between the first conductive material layer and the second conductive material layer at the overlap section and the capacitive section, wherein a portion of the overlap section forms one or more capacitors.

20. A system comprising: a transcranial focused ultrasound (tFUS) transducer device comprising a plurality of transducer elements for transmitting a plurality of ultrasound beams; A magnetic resonance imaging (MRI) receiver coil apparatus comprising: a thin film base layer having a coil array disposed on an outer surface of the thin film base layer and covered by a thin film cover layer, and an end ring engaging the thin film base layer and the thin film cover layer such that a watertight seal is formed around the coil array between the thin film base layer, the thin film cover layer and the end ring; and wherein the coil array is electrically connected to transmit received signals to an MRI receiver via a tuning and matching circuit board (TMCB) encapsulated in the end ring; wherein the MRI receiver coil apparatus is configured to be worn on the subject's head with a tight and airtight fit; wherein the transcranial focused ultrasound (tFUS) transducer device is configured to be sealed to and form a watertight fit therewith the MRI receiver coil device; and Wherein, the system is configured to simultaneously operate the MRI receiver coil device and the tFUS transducer device to provide real-time image navigation, including targeting, positioning, aiming, real-time dose monitoring and control operations of the tFUS treatment procedure.

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