System and method for organ specific surface excitation coil for a single-sided magnetic particle imaging

Abstract

A magnetic particle imaging (MPI) system and related methods employ an external excitation coil (EEC) having a void configured to receive at least a portion of an imaging object therein. The EEC may be positioned external to a system table having a plurality of MPI selection magnets therein that may provide a static magnetic field gradient for spatial encoding. A coupling device can enable an operator to electrically couple and decouple the EEC from the MPI system, allowing exchange with differently shaped EECs tailored to different organs, tissues, or anatomies. Methods of making such EECs and MPI systems are also disclosed.

Description

PCT Patent Application 67612-0076SYSTEM AND METHOD FOR ORGAN SPECIFIC SURFACE EXCITATION COIL FOR A SINGLE-SIDED MAGNETIC PARTICLE IMAGING CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Patent Application No. 63 / 771,324, filed on March 13, 2025, the contents of which are incorporated herein by reference in its entirety.GOVERNMENT LICENSE RIGHTS

[0002] This invention was made with U.S. government support under R15EB028535 awarded by the National Institute of Health (NIH). The U.S. government has certain rights in the invention.FIELD OF TECHNOLOGY

[0003] Exemplary fields of technology for the present disclosure may relate to Magnetic Particle Imaging (MPI).BACKGROUND

[0004] Magnetic Particle Imaging (MPI) is a burgeoning field. In implementations of MPI, nanoparticles (e.g„ superparamagnetic iron oxide nanoparticles (SPIONs)) are employed as a tracer. The tracer may be placed (e.g., injected) into target tissue(s) and / or cell(s). Once injected, for example, a static gradient field (i.e., a selection field) is applied along with an alternating magnetic field (i.e., an excitation field), and the tracer’s response to the alternating magnetic field is detected via a receive coil. The response detected from the tracer allows for the spatial distribution of the tracer (i.e., superparamagnetic nanoparticles) to be determined / imaged.

[0005] Often an MPI system includes a static magnetic field coil (a.k.a. a set of selection coils), an excitation field coil (a.k.a. a drive or transmit coil), and one or more receive coils. Other magnetic coils or configurations may also be employed. For example, the static or gradient magnetic field system (selection system) may employ permanent magnetics, the electromagnetic (EM) coils discussed above, or a hybrid system that employs one or more permanent magnets and one or more EM coils.

[0006] Like magnetic resonance imaging (MRI), MPI also does not employ ionizing radiation. In contrast to MRI, however, MPI images or detects a tracer, not the tissue. That is, while MPI detects the magnetization oscillation of the nanoparticles, MRI detects the resonance of the nuclearPCT Patent Application 67612-0076spins of tissue / cells. Though MPI detects the tracer, inferences can be made about tissue and or cells based on the gathered data. For example, based on the data gathered, blood flow properties can be visualized.

[0007] From a structural perspective, there are generally three types of MPI systems: cylindrical-bore systems, open-sided, and single-sided systems (a.k.a. one-sided or asymmetric geometry systems). Cylindrical-bore systems generally have a closed geometry, where the hardware surrounds or rotates around an imaging volume. An open-sided system refers to the system with hardware located from two opposite sides from the imaging volume. A single-sided system, in contrast, has an asymmetric geometry, where the hardware is generally on one side of an imaging volume.

[0008] MPI systems can also be differentiated by the manner in which the spatial distribution of the tracer is encoded. For example, the spatial distribution of the tracer may be encoded using a magnetic field free point (FFP) or a magnetic field free line (FFL). With an FFP, the magnetic field vanishes at a point region, and with an FFL, the magnetic field vanishes on a line region. The encoded signal is received from this field free point or line.

[0009] Cylindrical-bore systems, whether implementing FFL or FFP, have their advantages. For example, since the hardware generally surrounds the imaging volume, they provide uniform sensitivity and spatial resolution throughout the imaging volume. Nonetheless, such systems can be complex and costly since the imaging hardware needs to surround and / or rotate around very large volume of the object / subject during imaging.

[0010] Single or one-side MPI systems, on the other hand, are often less costly and complex compared to cylindrical-bore or other closed-geometry MPI systems. Envisioned clinical onesided MPI systems employ a table that encloses the imaging hardware. For example, the selection coils, excitation coil(s), and receive coil(s) are enclosed in a system table of a one-sided MPI system. The object being imaged rests on or slightly above the system table during an imaging session.

[0011] Due to constraints of one-sided systems, however, it can be difficult to achieve sufficiently homogenous excitation field above the system table over an FFL or FFP region on or within an object / subject being imaged. As such, sensitivity and image resolution may suffer. Further, it can be difficult to create a large enough homogeneous excitation field, adequatePCT Patent Application 67612-0076boosting, and / or uniform sensitivity across the field of view (FOV) above the system table in single-sided MPI systems.

[0012] Accordingly, there is a need for systems and methods that overcome the aforementioned drawbacks of single- sided MPI systems.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A illustrates an exemplary magnetic particle imaging (MPI) system;

[0014] Figures IB illustrates the selection coils of the MPI system of Figure 1A from a perspective of the MPI system shown in Figure 1A;

[0015] Figure 1C illustrates the selection coils of Figure IB without the system table of Figure IB;

[0016] Figure ID illustrates the MPI system of Figure 1A with an object maneuvering support / table;

[0017] Figure IE is a planar view of the exemplary external excitation coil (EEC) of Figure 1A;

[0018] Figure 2 illustrates another exemplary MPI system with another exemplary EEC;

[0019] Figure 3 illustrates yet another exemplary MPI system with yet another exemplary EEC;

[0020] Figure 4 illustrates an exemplary technique for manufacturing an EEC;

[0021] Figure 5 illustrates an exemplary technique for manufacturing an MPI system employing replaceable or exchangeable EECs;

[0022] Figure 6 illustrates an exemplary graph representing a simulation of coil efficiency vs distance for an exemplary single-sided MPI system;

[0023] Figure 7 illustrates another exemplary MPI system having an exemplary EEC;

[0024] Figure 8 illustrates yet another exemplary MPI system with yet another exemplary EEC;

[0025] Figure 9 illustrates another exemplary selection field system that may be employed with an MPI system; and

[0026] Figure 10 illustrates yet another exemplary selection field system that may be employed with an MPI system.PCT Patent Application 67612-0076DETAILED DESCRIPTION

[0027] Figure 1A illustrates an exemplary single-sided field free line (FFL) magnetic particle imaging (MPI) system 100 (hereinafter the MPI system 100). The MPI system 100 includes an exemplary system table 102 and an exemplary external excitation coil (EEC) 104. The MPI system 100 may also include a receive coil 106 and a cancellation coil 108 (e.g., a gradiometer coil) that may be positioned on a top surface 110 of the system table 102. Alternatively, one or more of the receive coil 106 and the cancelation coil 108 may be integrated into the top surface 110, or positioned below the top surface of the system table 102. As yet another alternative, the receive coil 106 and / or cancelation coil 108 may be integrated / coupled to the EEC 104 or positioned / attached to an imaging object.

[0028] Figure IB illustrates the system table 102 of the MPI system 100 of Figure 1A from a first perspective 112 shown in Figure 1A. For clarity, the system table 102 of Figure IB does not include the top surface 110 shown in Figure 1 A. As such, a plurality of exemplary selection coils 114 (a.k.a. selection field system) can be seen. In the example represented, the MPI system 100 includes three selection coils 114: a first selection coil 116. a second selection coil 118, and a third selection coil 120. In other examples, however, two (2) selection coils or more than three (3) selection coils may instead be employed. Further, instead of employing the EM selection coils 114 shown, a system could employ a permanent magnet system to serve as the magnetic selection system, or a hybrid system (see, e.g., Figures 9 and 10) that employs one or more permanent magnetics and one or more EM coils to serve as the magnetic selection system.

[0029] To provide further clarity on the configuration of the exemplary selection coils 114 of Figure IB, Figure 1C illustrates these selection coils 116-120 without the system table 102 of Figure IB.

[0030] The first selection coil 116 of Figure 1C is offset from the second selection coil 118 in a horizontal direction 122, while the third selection coil 120 is offset from both the first and second selection coils 116, 118 in a vertical direction 124.

[0031] With reference to Figures 1A-1C, the MPI system 100 includes the system table 102 (or table-like structure) having the plurality of selection coils 114 under or near the surface 110 of the system table 102. Accordingly, the selection coils 114 may be integrated into the system tablePCT Patent Application 67612-0076102. As used herein, the terms “table” or “system table” may refer to a table, a table-like structure, or other support structure that can serve a similar function.

[0032] The shape of the coils 104-108, 116-120 are merely exemplary. That is, other shapes and sizes may be employed depending on the object being imaged. For example, the shape of the EEC 104 shown in Figure 1A may have advantages when carrying out breast imaging. If, however, a clinician would like to image a different tissue, organ, and / or anatomy, the EEC 104 may be replaced or exchanged with a different EEC (see, e.g., Figure 2) having a shape, size, and construction that is tailored to that tissue, organ, and / or anatomy.

[0033] Accordingly, a benefit of the MPI system 100 is that the EEC 104 may be replaceable or exchanged. As such, instead of needing specific MPI systems, each tailored to different tissues, organs, and / or anatomies, one MPI system may be used that allows for different EECs to be employed. Such a system may bring significant cost savings since the cost of purchasing different EECs may be significantly less than the cost of purchasing multiple MPI systems.

[0034] In light of the possibility that the EEC 104 may be removed and replaced or exchanged with a different EEC, the MPI system 100 may also include a coupling device or system 126, as shown in Figure 1A, which electrically couples the EEC 104 to the MPI system 100. As such, a clinician or user may couple an EEC (e.g., the EEC 104 of Figure 1A) to the MPI system 100 via the coupling device or system 126. They user may also decouple the EEC and replace or exchange it with a different EEC, which may be tailored to a different tissue, organ, and / or anatomy. A variety of coupling systems could be employed that would enable a user or clinician to readily electrically couple and uncouple an EEC from the MPI system 100 as needed.

[0035] In addition to the EEC 104 being replaceable or exchangeable, the MPI system 100 may be configured to enable the receive coil 106 and / or the cancellation coil 108 to be replaced or exchanged with coils of different shapes and / or dimensions if desired as well. The clinical application (e.g., breast imaging vs. head imaging) may determine the shape and / or dimensions of one or more of the coils 104-108.

[0036] In light of the replaceability or exchangeability of the EEC 104, the receive coil 106, and / or the cancellation coil 108, a clinician may, for example, use the system table 102 with its selection coils 104 for a variety of different purposes. As mentioned above, instead of purchasing a variety of different MPI systems that are each tailored to imaging, for example, different organs,PCT Patent Application 67612-0076a clinician may simply purchase one system table having at least the selection coils integrated therein, and augment the system with a variety of EECs (and / or receive coils or cancel coils), each having a shape tailored to different organs, tissues, and / or anatomies.

[0037] With reference now to Figure ID, the MPI system 100 of Figure 1A is shown with an exemplary object maneuvering support / table 128 that may be substantially transparent to magnetic fields. As such, the maneuvering support / table 128 may be configured to move an object 130 around during imaging. For example, the maneuvering support / table 128 may move up and down along a vertical axis 132 substantially perpendicular to the system table 102, move in directions 134 substantially parallel to the system table 102, and / or rotated 136 about a vertical axis 132. As such, the maneuvering support / table 128 may be able to move the object 130 in a variety of directions. The shape and size of the maneuvering support / table 128 of Figure ID is merely exemplary, and other shapes and sizes may instead be employed. For example, a maneuvering table could be configured to accommodate moving a person around. Further, there may be one or more voids in the table, where one or more parts of a subject may protrude therethrough. For example, if a breast imaging session is to be carried out, the maneuvering may include a void for a breast (or a void for each breast) to protrude therethrough, thus allowing the breast(s) to get even closer to the excitation coils 116, 118,-120. Voids may be configured for other anatomies as well.

[0038] While the exemplary MPI system 100 of Figure ID employs the maneuvering support / table 128 to move the object / subject around, other systems may instead employ a magnet system (e.g., the selection coils 114 of Figures IB and 1C) that moves. For example, and as will be discussed in further detail below with respect to Figure 7, a subject / object may rest upon a support table, and the selection magnet system may rotate instead of the support table.

[0039] With continued reference to Figures 1A-1D, during operation, the selection coils 114 provide a static magnetic field gradient to enable spatial encoding for the MPI system 100. The interaction of the magnetic fields from, for example, the first, second, and third selection coils 116, 118, 120 determine the position of the FFL region of those coils 116, 118, 120. As such, the position of the FFL region may be determined by manipulating the magnetic fields of one or more of the selection coils 116-120. For example, by manipulating the magnetic field(s) of the first and second selection coils 116, 118, the position of the FFL region may be manipulated in a directionPCT Patent Application 67612-0076generally parallel to the surface 110 of the system table 102, as well as in a direction above the surface 110 of the system table 102.

[0040] The third selection coil 120 enables further control of the position of the FFL region. That is. an artisan will appreciate that the magnetic field of the third selection coil 120 may offer more control of the position of the FFL region in the horizontal direction 122 as well as the vertical direction 124.

[0041] Accordingly, by manipulating the magnetic field(s) of the selection coils 116-120, the FFL region may be placed at different positions above the surface 110 of the system table 102, as well as at different positions along the system table 102.

[0042] Due to the implementation of the selection coils 116-120, the location of the desired imaging volume in or one the object 130 may be determined by manipulating the location of FFL region, without having to move the object 130 via the maneuvering support / table 128. For example, the FFL region of the selection coils 116-120 may be positioned along a first region 138 of the object 130 and imaging may be carried out. Similarly, the FFL region of the selection coils 116-120 may be positioned along a second region 140 of the object 130 so that another round of imaging may be carried out. The first and second regions 138, 140 are merely exemplary, and other regions may be selected or determined. Nonetheless, since the position of the FFL region may be manipulated, the need to reorient the object 130 via the maneuvering support / table 128 may be minimized or avoided. That said, the maneuvering support / table 128 may still be moved and / or oriented to help position the FFL region in the object 130, if needed.

[0043] The EEC 104 provides an alternating magnetic field that excites superparamagnetic nanoparticles (hereinafter nanoparticles) in the FFL region (e.g., the first or second FFL regions respectively at the first and second positions 138, 140). That is, the field of the EEC 104 overlaps with the motion of the FFL along the encoding trajectory to excite the nanoparticles. It will be appreciated that these nanoparticles (e.g., tracer) may have been previously injected or otherwise placed or introduced in the object 130.

[0044] Upon excitation of the nanoparticles via the EEC 104, the receive coil 106 receives signals from the nanoparticles that were elicited by the EEC 104. The receive coil 106 continues to receive signals elicited as the FFL region moves through or on the object 130.PCT Patent Application 67612-0076

[0045] While the EEC 104 is intended to elicit signals from the nanoparticles in the FFL region (e.g., at first or second positions 138, 140), in some instances the magnetic field of the EEC 104 may interact with the receive coil 106 and cause unwanted background signals. These unwanted background signals are often referred to as “feed-through.” To counteract or minimize feed-through, the cancel coil 108, which may be a gradiometric coil, may be employed to provide an alternating magnetic field that helps to suppress the feed-through. In such instances, the sensitivity and / or signal-to-noise ratio (SNR) of the MPI system 100 may be improved.

[0046] The EEC 104 of Figures 1A and ID has a depth 142. As such, by moving the maneuvering support / table 128, the object 130 may be positioned at least partially within the EEC 104 at different depths. Since the magnetic field of the EEC 104 is more homogenous and flatter within the EEC 104 (i.e., within the void of the EEC 104), the MPI system 100 may achieve better sensitivity (e.g., 5 pg of iron) and / or better image quality (e.g.. a spatial resolution of 4 mm with a gradient of G=1 T / m) when an object 130 is placed at least partially within the void of the EEC 104. A more homogeneous field within the EEC 104 may also allow for superior feed-through cancellation or minimization. Still further, increased homogeneity of the excitation magnetic field within the EEC 104 may also provide an increased field of view (FOV) (e.g., 8 cm X 8 cm), a flatter (less curved) FOV, and / or decreased imaging time (e.g., around three minutes per two-dimensional slice).

[0047] Referring now to the planar view of the exemplary EEC 104 shown in Figure IE, the EEC 104 has a racetrack-like shape (a.k.a. stadium shape) having two substantially parallel portions 144, 146 and two semicircle (or semicircle-like) ends 148, 150. The EEC 104 has an inner diameter 152 between its two substantially parallel portions 144, 146 (i.e., the distance 152 between the two substantially parallel portions 144, 146). Further, the two substantially parallel portions 144, 146 may each have a substantially same length 154.

[0048] The inner diameter 152 of the EEC 104 could be, for example, 195 mm, while the length 154 of the substantially parallel portions 144, 146 could be, for example, 70 mm. A thickness or width 156 of the EEC 104 may be, for example, 25 mm. The two semicircle-like ends 148, 150 of the EEC 104 may have a “radius” length 158 of, for example, 97.5 mm. Again, the shape of the EEC 104 shown, and the dimensions listed, are merely exemplary.PCT Patent Application 67612-0076

[0049] In one example, the EEC 104 may be comprised of 14 AWG Litz wire, forming eight (8) layers of ten (10) turns each layer. The layers may, for example, be connected in series or in parallel depending on the current source. Other materials, differing amount of layers, and / or differing number of turns could also be employed. Regardless of the number of turns and / or layers employed, the EEC 104 may include at least one wire forming turns around a void 160 (e.g., the interior of the racetrack shape) such that an object (e.g., the object 130 of Figure ID) can fit at least partially within the void 160.

[0050] Once again, the shapes and dimensions of the EECs discussed herein are merely exemplary. A variety of shapes and dimensions may be employed, in which each configuration may be tailored to a specific organ, tissue, and / or anatomy.

[0051] Referring now to Figure 2, another exemplary single-sided FFL MPI system 200 is shown, where an exemplary EEC 202, an exemplary receive coil 204, and an exemplary system table 206 of the MPI system 200 are illustrated. For clarity, the two or more selection coils, which may be integrated into the system table 206, are not shown. Further, though a cancel coil is not shown, one could be employed in the MPI system 200 of Figure 2 if desired.

[0052] The illustrated shape of the exemplary EEC 202 (i.e., the bowl-like shape), and / or the shape of receive coil 204, is configured to be beneficial for head imaging. That is, the EEC 202 is comprised of at least one wire forming a plurality of turns 207 that surrounds a void 208 such that at least a portion of an imaging object (e.g., head) may fit within the void 208 for imaging. Since the magnetic field within or in proximity to the void 208 of the EEC 202 is generally more homogenous, better imaging may be obtained from portions of the object within or near the void 208 of the EEC 202.

[0053] While it is envisioned that the EEC 202 is part of the MPI system 200, the EEC 202 may instead be an add-on to the MPI system 200. For example, the EEC 202 may be one of many different shaped EECs that may be purchased to augment the MPI system 200. That is, EECs tailored to specific tissue, organs, and / or anatomies could be purchased.

[0054] The EEC 202 of Figure 2 may have a diameter 210 of 160 mm, or some other diameter. Since an object may be placed, at least partially, within the EEC 202, imaging can benefit from increased excitation field strengths within or near the EEC 202. For example, with a field per unit current of 1.25 mT / A at the surface 212 of the system table 206, 16 mT may be obtainable withinPCT Patent Application 67612-0076the EEC 202 at 17 mm above the top surface 212 if the EEC 202 employs a single-layer coil, and 32 mT may be obtainable if the EEC 202 employs a double-layer coil. Other field strengths, depending on the EEC configuration, are also obtainable.

[0055] With reference now to Figure 3, another exemplary EEC 300 is shown. The EEC 300 is coupled to an exemplary single-sided FFL MPI system 302. The MPI system 302 may employ an EM shield 304 to reduce EM noise, a receive coil 306, and a system table 308. For clarity, the system table 308 is generally shown in a cross-sectional perspective. If the EM shield 304 is employed, the MPI system 302 may also include cooling mechanism(s) to at least partially offset any heating the EM shield 304 may cause.

[0056] Integrated into the system table 308 is a plurality of selection coils 310 (a.k.a. selection field system), which includes a first selection coil 312, a second selection coil 314, a third selection coil 316, and a fourth selection coil 318. While four selection coils 312-318 are shown, other examples may employ two (2), three (3), or more than four (4) selection coils.

[0057] The magnetic field of the selection coils 312-318 may be manipulated such that the position of the FFL region associated with the plurality of selection coils 310 may be manipulated. In an example represented in Figure 3, the FFL region of the selection coils 310 is shown at a first position 320 in an object 322 (represented as an exemplary mouse).

[0058] If desired, the system table 308 may be rotated 324, while the EEC 300 and the receive coil 306 remain stationary. Accordingly, data acquisition can occur when the table is at a variety of positions. Alternatively, the object 132 could instead be rotated through multiple positions. Regardless of whether the object 322 is rotated or the system table 308 is rotated, an artisan will appreciate that multiple data acquisitions are often employed during image reconstruction.

[0059] Since the position of the selection coils’ FFL region can be manipulated, the MPI system 302 is able to image other portions of the object 322 without the need to move the object 322 (though the object 322 may be moved if needed). For example, the FFL region may be placed at a second position 326 that passes through the object, thus allowing imaging thereof. While Figure 3 only represents two positions 320, 326 for placement of the FFL region, the MPI system 302 is able to select other positions on / in the object 322 for imaging.

[0060] The EEC 300 is comprised of at least one wire forming a plurality of turns around a void 328 (e.g., the interior of the bowl-like shape). Since the EEC 300 surrounds the void 328, at leastPCT Patent Application 67612-0076a portion of the object 322 is able to fit into or within the EEC 300 (i.e., within the void 328 of the EEC 300). The magnetic field of the EEC 300 within or near at least a portion of the void 328 is generally more homogenous than the magnetic field outside the void 328. As such, better sensitivity and / or resolution may be obtained when imaging in these regions.

[0061] Referring now to Figure 4, an exemplary technique 400 for manufacturing an EEC is shown. Process control begins at block 402, where forming a plurality of turns of at least one wire around a void to create an external MPI excitation coil occurs. The void is configured to receive at least a portion of an imaging object therein. As such, the excitation coil is configured to receive at least a portion of the imaging object therein. Since the EEC is configured to receive at least a portion of the imaging object therein, more homogenous imaging fields can be obtained.

[0062] The EEC may also be configured to rest upon an MPI system table. Alternatively, the EEC may be formed into the system table in such a manner that still allows at least a portion of the imaging object to be placed within the EEC. That is, the EEC may be integrated into the MPI system table in such a manner as to allow at least a portion of an imaging object to be placed therein.

[0063] After creating the excitation coil, process control proceeds to block 404, where attaching a coupler to the excitation coil is earned out. The coupler is configured to electrically couple the excitation coil to an MPI system, where the MPI system may have at least a system table and two or more selection coils within the system table. After attaching the coupler to the excitation coil, the exemplary technique 400 may come to an END.

[0064] While the technique 400 illustrates creating the external excitation coil (EEC) at block 402 prior to attaching the coupler to the EEC at block 404, in other examples the coupler may be attached to the EEC as the EEC is being created.

[0065] Referring now to Figure 5, an exemplary technique 500 for manufacturing an MPI system employing replaceable or exchangeable EECs is shown. The technique includes placing at least two MPI selection coils into an MPI system table at block 502. The selection coils are configured to provide a static magnetic field gradient to an object being imaged.

[0066] The exemplary technique 500 also includes creating a coupling device or system that enables an EEC to be electrically coupled to the MPI system at block 504. In addition to enabling the EEC to be electrically coupled to the MPI system, the coupling device or system is configuredPCT Patent Application 67612-0076to enable a user (e.g., a clinician) to remove / decouple the EEC from the MPI system and replace or exchange the EEC with a similar or differently shaped EEC. Accordingly, the MPI system is able employ a variety of different EECs, where each EEC may be tailored to specific tissues, organs, and / or anatomies.

[0067] After creating the coupling system, process control may come to an END.

[0068] While the technique 500 of Figure 5 illustrates that the placement of the at least two MPI selection coils occurs before creating the coupling system, in another example, the placement of the excitation coils into the system table may occur after, or during, creation of the coupling system.

[0069] With reference to Figure 6, a graph 600 representing an EEC simulation of coil efficiency vs distance from system table surface is shown. An x-axis 602 of the graph 600 represents a height above the scanner or system table (in mm) in which the modulus of the magnetic field per current (in mT / A) was simulated. A y-axis 604 of the graph 600 represents the modulus of the magnetic field (in mT / A). As illustrated, results 606 for an EEC coil is shown compared to results 608 for a coil embedded in the system table (i.e., not an EEC). The improved effects of the EEC are visible.

[0070] Referring now to Figure 7, an exemplary single- sided breast scanning MPI system 700 (hereinafter the MPI system 700) employing an exemplary EEC 702 is shown. The MPI system 700 includes a system table 704 and a support table 706.

[0071] Incorporated into the system table 704 is a selection magnet system 708 (a.k.a. selection field system). For clarity, the selection magnets (e.g., EM selection coils, permanent selection magnets, or some combination of both) of the selection magnet system 708 are not shown. Some examples of selection magnets are discussed above with respect to Figures 1A-6.

[0072] With continued reference to the example illustrated in Figure 7, to the selection magnet system 708 may be configured to rotate 710. The selection magnet system 708 may also be configured to move up and down 712. As such, in some examples, a subject 714 may only need to be positioned once during an imaging session. For example, the subject 714 may be positioned on the support table 706 such that a breast 716 of the subject 714 passes through a void 718 in the support table 706 and at least partially into the exemplary EEC 702. During an imaging session, the selection magnet system 708 may be rotated 710 to a variety of positions for positioning thePCT Patent Application 67612-0076FFL or FFP region. Imaging data may be gathered at each position, if needed. It is noted that the MPI system 700 may be configured to keep the EEC 702, and any receive coil or cancelation coil employed, stationary as the selection magnet system 708 moves.

[0073] Further, if the selection magnet system 708 is also configured to move up and down 712, the imaging positions may be further fine-tuned. Alternatively, or in addition, the support table 706 may be configured to move up and down 712, thus allowing further capabilities of positioning the FFL or FFP in or on the breast 716.

[0074] In addition to the selection magnet system 708, the system table 704 may also include a control system 720 housing electronics and a cooling system 722. The electronics may include, for example, a frequency generator 724, power suppl(ies) 726, amplifier(s) 728 for field creation, control unit(s) 730, low pass filter(s) 732, and high-pass filter(s) 734. Working together, these components 722-734 of the control system 720 enable operation of the MPI system 700.

[0075] The MPI system 700 may also include a compute system 736, which may be configured to. among other things, control movement of the selection magnet system 708 and / or control the magnetic fields of the magnets employed. For example, if the selection magnet system 708 employs one or more EM selection coils, the compute system 736 may manipulate the magnetic field(s) of the EM selection coil(s) to manipulate the position of the FFL or FFP region. The compute system 736 may also provide signals that cause movement (e.g., rotation 710 and / or vertical orientation 712 ) of the selection magnet system 708.

[0076] To carry out its tasks, the compute system 736 may include one or more processors 738, one or more memory 740, and a program 742 saved on at least one of the one or more memory 740. Based on the program 742 and / or external inputs, the compute system 736 provides signals to the magnetic imaging system (e.g., the selection magnet system 708. a receive coil, and a cancelation coil) to carry out imaging. Any resulting imaging data may then be, at least temporarily, stored on the memory 740.

[0077] With reference now to Figure 8, another exemplary single-sided MPI system 800 is shown. The MPI system 800 includes a system table 802, where a portion 804 of the system table 802 is not shown so that an exemplary selection field system 806 is visible.

[0078] Incorporated into the system table 802 is a receive coil 808, a cancelation coil 810, and the above-mentioned selection field system 806. In some examples, the receive coil 808 and / orPCT Patent Application 67612-0076the cancelation coil 810 are moveable to different positions. The receive coil 808 and / or the cancelation coil 810 and may also simply rest upon the system table 802, or be coupled to a subject or imaging object.

[0079] In addition to the magnets discussed above, the MPI system 800 may also include an EEC system 812. Alternatively, the EEC 812 may be an “add-on” to the MPI system 800. In some examples, the selection coil 808 and / or the cancelation coil 810 can be coupled to the EEC 812. In yet another example, the EEC system 812, receive coil 808, and cancelation coil 810 may form a system or unit. That is, a user could purchase these coils 808-810 as a package, where the coils 808-810 are permanently coupled together, or need assembly.

[0080] The selection field system 806, the EEC system 812, the receive coil 808, and / or the cancelation coil 810 may include cooling component(s) therein or thereon. For example, tubing for coolant (e.g., water) could be incorporated into the selection field system 806 and / or the EEC system 812.

[0081] In addition to the MPI system 800 of Figure 8 being able to employ a cooling system, other MPI systems discussed herein (e.g., see discussions with respect to Figure 1 A-7) may employ cooling system(s) to cool magnets (whether permanent and / or EM magnets) or other components thereof.

[0082] Referring now to Figures 9 and 10, two additional exemplary hybrid selection field systems 900, 1000 are shown, where each may be employed with MPI systems discussed herein. That is, each could be used to supply the static magnetic field gradient to the object being imaged. The exemplary hybrid selection field system 900 of Figure 9 includes a plurality of EM coils 902 as well as a plurality of permanent magnets 904, which is in contrast to the selection field systems of Figures 1C and 3 that employ EM coils (114 and 310 respectively), but not permanent magnets. Despite the differences, the magnets 902, 904 of the selection field system 900 of Figure 9 also determines the position of the FFL.

[0083] Similarly, the exemplary hybrid selection field system 1000 of Figure 10 also includes a plurality of EM coils 1002 and a plurality of permanent magnets 1004. Like the other selection field systems discussed, the selection field system 1000 of Figure 10 may also be employed to provide the static magnetic field gradient to the object being imaged.PCT Patent Application 67612-0076

[0084] In light of the selection field systems 900, 1000 of Figures 9 and 10, respectively, it is clear that a selection field system may employ both permanent magnets as well as EM coils. Further, there are a variety of configurations that may be employed. For example, a comparison of the configuration of magnets 902, 904 of Figure 9 with the configuration of magnets 10002, 1004 of Figure 10 makes clear that a selection field system may implement a variety of form factors, as well as implement differing quantities of magnets.

[0085] It is again noted that the selection field systems discussed herein (e.g., the selection field systems 900, 1000 of Figures 9 and 10, respectively) are merely exemplary. Further, selection field systems employing permanent magnets and not EM coils are also envisioned. Still further, while examples have been presented herein of selection field systems configured to provide FFE regions, the EECs discussed herein could also be employed with selection field systems that provide FFP regions.

[0086] The MPI coils and / or permanent magnets illustrated and discussed herein may be beneficial for a variety of diagnostics, therapies, and / or treatments. For example, the unique EECs and / or receive coils may be employed for molecular imaging and cell labeling, visualizing blood flow, cancer detection and / or staging (e.g., to aid in a sentinel lymph node biopsy used for identifying, removing, and / or examining breast cancer tumors), cancer treatment / therapy (e.g., employing hyperthermia to heat nanoparticles at a cancer site), brain imaging (e.g., functional or stroke detection), real-time tracking of interventional instruments (e.g., tracking of ballooncatheters in cardiovascular procedures), and / or drug delivery to a site to name a few.

[0087] Further, the EECs discussed herein may provide a plurality of advantages. For example, since the excitation coils (a.k.a., transmits coils) discussed herein are external excitation coils able to receive at least a portion of an imaging object therein, the excitation coils may be able to provide a higher strength, more homogenous magnetic field to the imaging object. Accordingly, the EECs may provide increased sensitivity and better image quality, while having decreased sensitivity to noise. The more homogenous field of the EECs also allows for a flat or flatter FFL trajectory, thus reducing artifacts that are associated with curved trajectories, while at the same time enabling expansion of the FOV in at least the horizontal plane.PCT Patent Application 67612-0076

[0088] Also, since the EECs allow at least a portion of an imaging object therein, deeper imaging depths into the imaging object may be obtained, along with greater excitation strengths at those distances or depths.

[0089] Further, due to the EEC configuration, less power may be needed and heating issues may be reduced. Still further, the EECs allow for electromagnetic (EM) shielding to be employed to further reduce noise. That is. since the EEC may be placed on top of (or above) an MPI system table or selection coils, an EM shield may be easily placed between the EEC and the selection coils without much complexity (see, e.g., the EM shield 304 of Figure 3).

[0090] While the single or one-sided MPI systems discussed above are generally FFL one-sided MPI systems, EECs discussed herein could also be employed in one-sided FFP systems, thus providing the same or similar advantages thereto.

[0091] The disclosure includes, without limitation, the following embodiments:

[0092] 1. A magnetic particle imaging (MPI) system comprising: a first external excitation coil (EEC) having a void therein, the first EEC is configured to be employed external from a system table having at least two MPI selection magnets therein, wherein the first EEC is further configured to receive at least a portion of an imaging object within the void.

[0093] 2. The MPI system of embodiment 1, further comprising the system table, wherein the at least two MPI selection magnets are configured to provide a static magnetic field gradient to the imaging object.

[0094] 3. The MPI system of any of the preceding embodiments, wherein at least one of the at least two MPI selection magnets is an electromagnet or a permanent magnet, and wherein the first EEC is configured to have a bowl-like shape to create a generally homogenous field within its void when in operation.

[0095] 4. The MPI system of any of the preceding embodiments, wherein the at least two MPI selection magnets are configured to be maneuverable in a vertical direction.

[0096] 5. The MPI system of any of the preceding embodiments, further comprising a coupling device configured to enable an operator to electrically couple and electrically decouple the first EEC to the MPI system, wherein the MPI system is a single-sided MPI system.PCT Patent Application 67612-0076

[0097] 6. The MPI system of any of the preceding embodiments, further comprising a second EEC having a void configured to receive at least a portion of an imaging object therein, wherein the second EEC is formed for or tailored to a different organ, tissue, or anatomy than the first EEC.

[0098] 7. The MPI system of any of the preceding embodiments, further comprising a receive coil configured to receive signals from nanoparticles in or on a region of the imaging object, wherein the first EEC is configured to elicit the signals from the nanoparticles when operating, and wherein the region is one of a field free line (FFL) region and a field free point (FFP) region.

[0099] 8. The MPI system of any of the preceding embodiments, further comprising a cancel coil configured to suppress feed-through signals generated via an interaction of a magnetic field of the first EEC with the receive coil.

[0100] 9. A magnetic particle imaging (MPI) system comprising a system table having at least two MPI selection magnets therein, wherein the at least two MPI selection magnets are configured to apply a static magnetic field gradient to an imaging object; and a first external excitation coil (EEC) having a void therein, the first EEC is configured to be employed external from the system table having at least two MPI selection magnets therein, wherein the first EEC is further configured to receive at least a portion of the imaging object within the void.

[0101] 10. The MPI system of embodiment 9, wherein at least one of the at least two MPI selection magnets is configured to be maneuverable in a vertical direction to adjust a vertical position of one of a field free line (FFL) region and a field free point (FFP) region in the imaging object.

[0102] 11. The MPI system of any of the preceding embodiments, further comprising a second EEC having a different shape than the first EEC, wherein the MPI system is configured to enable the first EEC to be decoupled from the MPI system by an operator so that the second EEC can be coupled to the MPI system.

[0103] 12. The MPI system of any of the preceding embodiments, wherein at least one of the at least two MPI selection magnets is an electromagnet or a permanent magnet, and wherein the first EEC is further configured to have a bowl-like shape to create a generally homogenous field within its void when in operation.

[0104] 13. The MPI system of any of the preceding embodiments, further comprising a receive coil configured to receive signals from nanoparticles in or on a region of the imaging object,PCT Patent Application 67612-0076wherein the first EEC elicits the signals from the nanoparticles when operating, and wherein the region is one of a field free line (FFL) region and a field free point (FFP) region.

[0105] 14. The MPI system of any of the preceding embodiments, further comprising a cancel coil configured to suppress feed-through signals generated via an interaction of a magnetic field of the first EEC with the receive coil.

[0106] 15. The MPI system of any of the preceding embodiments, further comprising an electromagnetic (EM) shield configured to be positioned between the first EEC and the at least two MPI selection magnets, the EM shield configured to reduce electromagnetic noise.

[0107] 16. The MPI system of any of the preceding embodiments, further comprising an object maneuvering support table that is substantially transparent to magnetic fields and configured to support the imaging object above the system table, the object maneuvering support table being movable relative to the system table in at least one of: a direction substantially perpendicular to the system table, a direction substantially parallel to the system table, or rotationally about an axis substantially perpendicular to the system table.

[0108] 17. The MPI system of any of the preceding embodiments, wherein the object maneuvering support table includes at least one void configured to allow at least a portion of the imaging object to protrude therethrough and into at least a portion of the void of the first EEC.

[0109] 18. The MPI system of any of the preceding embodiments, wherein the system table is configured to rotate the at least two selection magnets relative to the first EEC.

[0110] 19. The MPI system of any of the preceding embodiments, further comprising a compute system comprising at least one processor, at least one memory, and a program stored in the at least one memory and executable by the at least one processor, the program configured to generate control signals for at least one of: the at least two MPI selection magnets, the first EEC, a receive coil, or a cancellation coil.

[0111] 20. A method comprising: forming a plurality of turns of at least one wire around a void to create a first excitation coil for magnetic particle imaging (MPI), wherein the first excitation coil is configured to receive at least a portion of an imaging object in the void for MPI; and attaching a coupler to the first excitation coil so that the first excitation coil can be electrically coupled to a system table having at least two MPI selection magnets.PCT Patent Application 67612-0076

[0112] 21. The method of embodiment 20, wherein the first excitation coil is a first external excitation coil (EEC) configured to be employed externally to the system table having the MPI selection magnets therein, and wherein the coupler is configured to enable an operator to electrically decouple the first EEC from the system table so that a second EEC can be electrically coupled via the coupler to the system table by the operator.

[0113] 22. The method of any of the preceding embodiments, further comprising placing at least two MPI selection magnets in a system table of the MPI system, wherein the at least two MPI selection magnets are configured to provide a static field gradient to the imaging object so that at least one of a field free line (FFL) region and a field free point (FFP) region in the imaging object can be created.

[0114] 23. The method of any of the preceding embodiments, further comprising integrating the first excitation coil into the system table having MPI selection magnets.

[0115] 24. The method of any of the preceding embodiments, further comprising creating a receive coil, wherein the receive coil is configured to receive signals elicited by the first excitation coil.

[0116] 25. The method of any of the preceding embodiments, further comprising creating a cancellation coil configured to minimize feed-through signals generated via an interaction of a magnetic field of the first excitation coil with the receive coil.

[0117] 26. An external excitation coil (EEC) for a magnetic particle imaging (MPI) system, the EEC comprising: at least one wire forming a plurality of turns around a void, the void being shaped and dimensioned to receive at least a portion of an imaging object therein during MPI; and a coupler electrically connected to the at least one wire and configured to enable an operator to electrically couple and electrically decouple the EEC to and from an MPI system having at least two MPI selection magnets in a system table, wherein, when the EEC is coupled to the MPI system and driven with an excitation current, the plurality of turns are configured to provide an alternating magnetic field having greater homogeneity within at least a portion of the void than outside the void.

[0118] 27. The EEC of embodiment 26, wherein the void has a racetrack shape comprising two substantially parallel portions and two semicircular or semicircular-like ends.PCT Patent Application 67612-0076

[0119] 28. The EEC of any of the preceding embodiments, wherein the at least one wire comprises at least two wires, the at least two wires comprising Litz wires, and wherein the plurality of turns comprises at least two layers, each layer comprising a plurality of turns and one of the two wires, the layers being connected in at least one of series or parallel.

[0120] 29. The EEC of any of the preceding embodiments, further comprising at least one cooling component incorporated therein or thereon, the at least one cooling component configured to remove heat from the EEC during operation.

[0121] 30. The EEC of any of the preceding embodiments, wherein the EEC is configured to be employed external to the system table such that at least the portion of the imaging object is positionable within the void while the at least two MPI selection magnets remain in the system table.

[0122] 31. The EEC of any of the preceding embodiments, wherein the EEC is configured to be integrated into the system table such that at least the portion of the imaging object may be placed in the system table.

[0123] With regard to the processes, techniques, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain examples, and should in no way be construed so as to limit the claims.

[0124] Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope should be determined, not with reference to the above description or Abstract below, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the technologies discussed herein, and that the disclosed systems and methods will be incorporated into such futurePCT Patent Application 67612-0076embodiments. In sum, it should be understood that the application is capable of modification and variation.

[0125] All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary. Further, the use of terms such as “first,” “second,” “third,” and the like that immediately precede an element(s) do not necessarily indicate sequence unless set forth otherwise, either explicitly or inferred through context.

[0126] With reference now back to Figures 1-8 discussed above, exemplary compute system(s) and devices may be any computing system and / or device that includes a processor and a memory (e.g., the processor(s) 738 and memory 740 of Figure 7). Compute systems and / or devices generally include computer-executable instructions (e.g., the program 742 of Figure 7), where the instructions may be executable by one or more computing devices such as those listed above and below. The computer-executable instructions may be compiled or interpreted from computer programs created using a variety of programming languages and / or technologies, including, without limitation, and either alone or in combination, Java™, C, C++, Visual Basic, Java Script, Perl, etc. The exemplary system(s), device(s), and items therein may take many different forms and include multiple and / or alternate components. While exemplary systems, devices, and modules are shown in the Figures, the exemplary components illustrated in the Figures are not intended to be limiting. Indeed, additional or alternative components and / or implementations may be used, and thus the above examples should not be construed as limiting.

[0127] In general, compute systems and / or devices may employ any of a number of computer operating systems, including, but by no means limited to, versions and / or varieties of the Microsoft Windows® operating system, the Unix operating system (e.g., the Solaris® operating system distributed by Oracle Corporation of Redwood Shores, California), the AIX UNIX operating system distributed by International Business Machines of Armonk, New York, the Uinux operating system, the Mac OS X and iOS operating systems distributed by Apple Inc. of Cupertino, California, the BlackBerry OS distributed by Research In Motion of Waterloo, Canada, and thePCT Patent Application 67612-0076Android operating system developed by the Open Handset Alliance. Examples of computing systems and / or devices include, without limitation, personal computers, tablet computers, next generation portable devices, handheld computers, secure voice communication equipment, or some other computing system and / or device.

[0128] Further, the processor or the microprocessor (e.g., the processor(s) 738 of Figure 7) of computing systems and / or devices receives instructions from the memory and executes these instructions, thereby performing one or more processes, including one or more of the processes described herein. Such instructions and other data may be stored and transmitted using a variety of computer-readable mediums (e.g., the memory 740 of Figure 7).

[0129] A CPU or processor may include processes comprised from any hardware, software, or combination of hardware or software that carries out instructions of a computer programs by performing logical and arithmetical calculations, such as adding or subtracting two or more numbers, comparing numbers, or jumping to a different part of the instructions. For example, the compute system 736 of Figure 7 may include any one of, but not limited to single, dual, triple, or quad core processors (on one single chip), graphics processing units, visual processing units, and virtual processors.

[0130] Memory (e.g., the memory 740 of Figure 7) may be, in general, any computer-readable medium (also referred to as a processor-readable medium) that may include any non-transitory (e.g., tangible) medium that participates in providing data (e.g., instructions) that may be read by a computer. Such a medium may take many forms, including, but not limited to. non-volatile media and volatile media. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Volatile media may include, for example, dynamic random access memory (DRAM), which typically constitutes a main memory. Such instructions may be transmitted by one or more transmission media, including radio waves, metal wire, fiber optics, and the like, including the wires that comprise a system bus coupled to a processor of a computer. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any other memory chip or cartridge, or any other medium from which a computer can read.

Claims

PCT Patent Application 67612-0076CLAIMSWhat is claimed is:

1. A magnetic particle imaging (MPI) system comprising:a first external excitation coil (EEC) having a void therein, the first EEC is configured to be employed external from a system table having at least two MPI selection magnets therein, wherein the first EEC is further configured to receive at least a portion of an imaging object within the void.

2. The MPI system of claim 1, further comprising the system table, wherein the at least two MPI selection magnets are configured to provide a static magnetic field gradient to the imaging object.

3. The MPI system of claim 2, wherein at least one of the at least two MPI selection magnets is an electromagnet or a permanent magnet, and wherein the first EEC is configured to have a bowl-like shape to create a generally homogenous field within its void when in operation.

4. The MPI system of claim 2, wherein the at least two MPI selection magnets are configured to be maneuverable in a vertical direction.

5. The MPI system of claim 1 , further comprising a coupling device configured to enable an operator to electrically couple and electrically decouple the first EEC to the MPI system, wherein the MPI system is a single-sided MPI system.

6. The MPI system of claim 5, further comprising a second EEC having a void configured to receive at least a portion of an imaging object therein, wherein the second EEC is formed for or tailored to a different organ, tissue, or anatomy than the first EEC.PCT Patent Application 67612-00767. The MPI system of claim 1, further comprising a receive coil configured to receive signals from nanoparticles in or on a region of the imaging object, wherein the first EEC is configured to elicit the signals from the nanoparticles when operating, and wherein the region is one of a field free line (FFL) region and a field free point (FFP) region.

8. The MPI system of claim 7, further comprising a cancel coil configured to suppress feed-through signals generated via an interaction of a magnetic field of the first EEC with the receive coil.

9. A magnetic particle imaging (MPI) system comprising:a system table having at least two MPI selection magnets therein, wherein the at least two MPI selection magnets are configured to apply a static magnetic field gradient to an imaging object; anda first external excitation coil (EEC) having a void therein, the first EEC is configured to be employed external from the system table having at least two MPI selection magnets therein, wherein the first EEC is further configured to receive at least a portion of the imaging object within the void.

10. The MPI system of claim 9, wherein at least one of the at least two MPI selection magnets is configured to be maneuverable in a vertical direction to adjust a vertical position of one of a field free line (FFL) region and a field free point (FFP) region in the imaging object.

11. The MPI system of claim 9, further comprising a second EEC having a different shape than the first EEC, wherein the MPI system is configured to enable the first EEC to be decoupled from the MPI system by an operator so that the second EEC can be coupled to the MPI system.

12. The MPI system of claim 9, wherein at least one of the at least two MPI selection magnets is an electromagnet or a permanent magnet, and wherein the first EEC is further configured to have a bowl-like shape to create a generally homogenous field within its void when in operation.PCT Patent Application 67612-007613. The MPI system of claim 9, further comprising a receive coil configured to receive signals from nanoparticles in or on a region of the imaging object, wherein the first EEC elicits the signals from the nanoparticles when operating, and wherein the region is one of a field free line (FFL) region and a field free point (FFP) region.

14. The MPI system of claim 13, further comprising a cancel coil configured to suppress feed-through signals generated via an interaction of a magnetic field of the first EEC with the receive coil.

15. The MPI system of claim 9, further comprising an electromagnetic (EM) shield configured to be positioned between the first EEC and the at least two MPI selection magnets, the EM shield configured to reduce electromagnetic noise.

16. The MPI system of claim 9, further comprising an object maneuvering support table that is substantially transparent to magnetic fields and configured to support the imaging object above the system table, the object maneuvering support table being movable relative to the system table in at least one of: a direction substantially perpendicular to the system table, a direction substantially parallel to the system table, or rotationally about an axis substantially perpendicular to the system table.

17. The MPI system of claim 16, wherein the object maneuvering support table includes at least one void configured to allow at least the portion of the imaging object to protrude therethrough and into at least a portion of the void of the first EEC.

18. The MPI system of claim 9, wherein the system table is configured to rotate the at least two selection magnets relative to the first EEC.

19. The MPI system of claim 9, further comprising a compute system comprising at least one processor, at least one memory, and a program stored in the at least one memory and executablePCT Patent Application 67612-0076by the at least one processor, the program configured to generate control signals for at least one of: the at least two MPI selection magnets, the first EEC, a receive coil, and a cancellation coil.

20. A method comprising:forming a plurality of turns of at least one wire around a void to create a first excitation coil for magnetic particle imaging (MPI), wherein the first excitation coil is configured to receive at least a portion of an imaging object in the void for MPI; andattaching a coupler to the first excitation coil so that the first excitation coil can be electrically coupled to a system table having at least two MPI selection magnets.

21. The method of claim 20, wherein the first excitation coil is a first external excitation coil (EEC) configured to be employed externally to the system table having the MPI selection magnets therein, and wherein the coupler is configured to enable an operator to electrically decouple the first EEC from the system table so that a second EEC can be electrically coupled via the coupler to the system table by the operator.

22. The method of claim 20, further comprising placing the at least two MPI selection magnets in the system table, wherein the at least two MPI selection magnets are configured to provide a static field gradient to the imaging object so that at least one of a field free line (FFL) region and a field free point (FFP) region in the imaging object can be created.

23. The method of claim 22, further comprising integrating the first excitation coil into the system table having MPI selection magnets.

24. The method of claim 20, further comprising creating a receive coil, wherein the receive coil is configured to receive signals elicited by the first excitation coil.

25. The method of claim 24, further comprising creating a cancellation coil configured to minimize feed-through signals generated via an interaction of a magnetic field of the first excitation coil with the receive coil.PCT Patent Application 67612-007626. An external excitation coil (EEC) for a magnetic particle imaging (MPI) system, the EEC comprising:at least one wire forming a plurality of turns around a void, the void being shaped and dimensioned to receive at least a portion of an imaging object therein during MPI; anda coupler electrically connected to the at least one wire and configured to enable an operator to electrically couple and electrically decouple the EEC to and from an MPI system having at least two MPI selection magnets in a system table,wherein, when the EEC is coupled to the MPI system and driven with an excitation current, the plurality of turns are configured to provide an alternating magnetic field having greater homogeneity within at least a portion of the void than outside the void.

27. The EEC of claim 26, wherein the void has a racetrack shape comprising two substantially parallel portions and two semicircular or semicircular-like ends.

28. The EEC of claim 26, wherein the at least one wire comprises at least two wires, the at least two wires comprising Litz wires, and wherein the plurality of turns comprises at least two layers, each layer comprising a plurality of turns and one of the two wires, the layers being connected in at least one of series or parallel.

29. The EEC of claim 26, further comprising at least one cooling component incorporated therein or thereon, the at least one cooling component configured to remove heat from the EEC during operation.

30. The EEC of claim 26, wherein the EEC is configured to be employed external to the system table such that at least the portion of the imaging object is positionable within the void while the at least two MPI selection magnets remain in the system table.

31. The EEC of claim 26, wherein the EEC is configured to be integrated into the system table such that at least the portion of the imaging object may be placed in the system table.

Images