RECEIVE COIL UNIT WITH INTEGRATED NOISE ANTENNAS AND MAGNETIC RESONANCE IMAGING SYSTEM WITH SUCH A RECEIVE COIL UNIT

Abstract

The present invention provides a receive coil unit (140) comprising a receive coil array (142) for use in a magnetic resonance imaging system (110) with multiple antenna units (144) sensitive to magnetic resonance signals, i.e. antenna units (144) sensitive to B-field signals, whereby each antenna unit (144) comprises a coil element (146) sensitive to B-field signals, and each antenna unit (144) comprises an E-field antenna (148) sensitive to E-field signals. The present invention also provides a magnetic resonance imaging system (110) comprising a receive coil unit (140) with a receive coil array (142) having multiple antenna units (144) sensitive to magnetic resonance signals, i.e. antenna units (144) sensitive to B-field signals, whereby the receive coil unit (140) is provided as a receive coil unit (140) as specified above. Still further, the present invention provides a method for magnetic resonance imaging comprising the steps of providing a receive coil unit (140) comprising a receive coil array (142) for use in a magnetic resonance imaging system (110) with multiple antenna units (144) sensitive to magnetic resonance signals, i.e. antenna units (144) sensitive to B-field signals, whereby each antenna unit (144) comprises a coil element (146) sensitive to B-field signals, and each antenna unit (144) comprises an E-field antenna (148) sensitive to E-field signals, and performing de-noising of the B-field signals received from the coil elements (146) of the receive coil unit (140) by filtering noise signals, as received from the E-field antenna (148), from the B-field signals.

Claims

1. A receive coil unit comprising: a receive coil array for use in a magnetic resonance imaging system with multiple antenna units sensitive to magnetic resonance signals, wherein each antenna unit includes a coil element sensitive to B-field signals, and each antenna unit includes an E-field antenna sensitive to E-field signals and wherein the E-field antenna is embedded in the coil element for each antenna unit.

2. The receive coil unit according to claim 1, wherein the receive coil unit comprises multiple de-noising units for filtering noise signals as received from the E-field antennas from the B-field signals received from the respective coil element, whereby one de-noising unit is associated to each antenna unit, and each de-noising unit is adapted to perform de-noising based on the E-field signals of the E-field antennas of the respective antenna unit.

3. The receive coil unit according to claim 1, wherein the receive coil unit comprises one de-noising unit for filtering noise signals as received from the E-field antenna from the B-field signals received from the respective coil element, whereby the de-noising unit is connected to multiple antenna units, and the de-noising unit is adapted to perform de-noising for each connected antenna unit based on the E-field signals of the E-field antennas of the connected antenna units.

4. The receive coil unit according to claim 1, wherein the de-noising unit is adapted to perform de-noising based on antiphase operation and/or based on an independent component analysis.

5. The receive coil unit according to claim 1, wherein at least one analog-to-digital converter is provided for converting analog signals from the antenna unit into digital signals fed to the de-noising unit.

6. The receive coil unit according to claim 1, wherein the coil element is provided as an essentially planar loop, and the E-field antenna is located in the plane of the coil element as defined by the planar loop.

7. The receive coil unit according to claim 1, wherein the E-field antenna of each antenna unit is connected via at least one of a diversity switch, a balun, an impedance matching unit or a pre-amplifier to the respective de-noising unit.

8. The receive coil unit according to claim 1, wherein the antenna unit comprises local RF screen, and the E-field antennas of the antenna units are connected to the local RF screen.

9. The receive coil unit according to claim 1, wherein the receive coil unit comprises a RF screen, which is provided as a circumferential screen in the receive coil unit or as a circumferential outer surface thereof, the coil element is provided as a TEM coil element, which is coupled to the RF screen, and the coil element, the E-field antenna and the RF screen are arranged in this order in a direction radially outward of the receive coil unit.

10. A magnetic resonance imaging system comprising a receive coil unit with a receive coil array having multiple antenna units sensitive to magnetic resonance signals, i.e. antenna units sensitive to B-field signals, wherein the receive coil unit is provided as a receive coil unit according to claim 1.

11. The magnetic resonance imaging system according to preceding claim 10, wherein the magnetic resonance imaging system comprises a de-noising unit for filtering noise signals as received from the E-field antenna from the B-field signals received from the respective coil element, whereby the de-noising unit (152) is connected to multiple antenna units of the receive coil unit, and the de-noising unit is adapted to perform de-noising for each connected antenna unit based on the E-field signals of the E-field antennas of the connected antenna units.

12. A method for magnetic resonance imaging comprising the steps of: providing a receive coil unit comprising a receive coil array for use in a magnetic resonance imaging system with multiple antenna units sensitive to magnetic resonance signals, i.e. antenna units sensitive to B-field signals, whereby each antenna unit comprises a coil element sensitive to B-field signals, and each antenna unit comprises an E-field antenna sensitive to E-field signals, whereithe E-field antenna is embedded in the coil element for each antenna unit and performing de-noising of the B-field signals received from the coil elements of the receive coil unit by filtering noise signals, as received from the E-field antenna, from the B-field signals.

13. A software package for upgrading a MR imaging system, whereby the software package contains instructions stored on a non-transitory computer readable medium for controlling the MR imaging system according to the method of method claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. Such an embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.

[0032] In the drawings:

[0033] FIG. 1 is a schematic illustration of a part of an embodiment of a magnetic resonance (MR) imaging system in accordance with the invention,

[0034] FIG. 2 is a schematic illustration of a receive coil unit of the MR imaging system of FIG. 1 according to a first, preferred embodiment,

[0035] FIG. 3 is a schematic illustration of a receive coil unit of the MR imaging system of FIG. 1 according to a second embodiment,

[0036] FIG. 4 is a schematic illustration of a receive coil unit of the MR imaging system of FIG. 1 according to a third embodiment in a sectional side view within a bore of the MR imaging system of FIG. 1,

[0037] FIG. 5 is a schematic illustration of a receive coil unit of the MR imaging system of FIG. 1 according to a fourth embodiment in a sectional side view within a bore of the MR imaging system of FIG. 1,

[0038] FIG. 6 is a detailed schematic illustration of a receive coil unit of the MR imaging system of FIG. 1 according to a fifth embodiment,

[0039] FIG. 7 is a schematic illustration of an antenna unit of any of the above receive coil units according to a sixth embodiment,

[0040] FIG. 8 is a schematic illustration of an antenna unit of any of the above receive coil units according to a seventh embodiment,

[0041] FIG. 9 is a schematic illustration of an antenna unit according to an eights embodiment,

[0042] FIG. 10 is a schematic illustration of an antenna unit according to a ninth embodiment,

[0043] FIG. 11 is a schematic illustration of an antenna unit according to a tenth embodiment,

[0044] FIG. 12 is a schematic illustration of an antenna unit according to a eleventh embodiment, and

[0045] FIG. 13 is a schematic illustration of an antenna unit according to a twelfth embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0046] FIG. 1 shows a schematic illustration of a part of an embodiment of a magnetic resonance (MR) imaging system 110 comprising an MR scanner 112. The MR imaging system 110 includes a main magnet 114 provided for generating a static magnetic field. The main magnet 114 has a central bore that provides an examination space 116 around a center axis 118 for a subject of interest 120, usually a patient, to be positioned within. In this embodiment, the central bore and therefore the static magnetic field of the main magnet 114 have a horizontal orientation in accordance with the center axis 118. In an alternative embodiment, the orientation of the main magnet 114 can be different, e.g. to provide the static magnetic field with a vertical orientation. Further, the MR imaging system 110 comprises a magnetic gradient coil system 122 provided for generating gradient magnetic fields superimposed to the static magnetic field. The magnetic gradient coil system 122 is concentrically arranged within the bore of the main magnet 114, as known in the art.

[0047] Further, the MR imaging system 110 includes a radio frequency (RF) antenna device 140 designed as a whole-body coil having a tubular body. In an alternative embodiment, the RF antenna device 140 is designed as a head coil or any other suitable coil type for use in MR imaging systems 110. The RF antenna device 140 is provided for applying an RF magnetic field to the examination space 116 during RF transmit phases to excite nuclei of the subject of interest 120, which shall be covered by MR images. The RF antenna device 140 is also provided to receive MR signals from the excited nuclei during RF receive phases. In a state of operation of the MR imaging system 110, RF transmit phases and RF receive phases are taking place in a consecutive manner. The RF antenna device 140 is arranged concentrically within the bore of the main magnet 114. As is known in the art, a cylindrical metal RF screen 124 is arranged concentrically between the magnetic gradient coil system 122 and the RF antenna device 140.

[0048] In the context of the present invention, the RF antenna device 140 is discussed in respect to its receiving capabilities, Hence, the RF antenna device 140 is also referred to as receive coil unit 140.

[0049] Moreover, the MR imaging system 110 comprises an MR image reconstruction unit 130 provided for reconstructing MR images from the acquired MR signals and an MR imaging system control unit 126 with a monitor unit 128 provided to control functions of the MR scanner 112, as is commonly known in the art. Control lines 132 are installed between the MR imaging system control unit 126 and an RF transmitter unit 134 that is provided to feed RF power of an MR radio frequency to the RF antenna device 140 via an RF switching unit 136 during the RF transmit phases. The RF switching unit 136 in turn is also controlled by the MR imaging system control unit 126, and another control line 138 is installed between the MR imaging system control unit 126 and the RF switching unit 136 to serve that purpose. During RF receive phase, the RF switching unit 136 directs the MR signals from the RF antenna device 140 to the MR image reconstruction unit 130 after pre-amplification.

[0050] A receive coil unit 140 according to a first, preferred embodiment is shown in FIG. 2. The receive coil unit 140 comprises a receive coil array 142 for use in magnetic resonance imaging systems 110. The receive coil array 142 comprises multiple antenna units 144, which comprise a coil element 146 sensitive to magnetic resonance signals, i.e. sensitive to B-field signals, and an E-field antenna 148 sensitive to E-field signals. The E-field antenna 148 and the coil element 146 are decoupled, whereby the E-field antenna's 148 sensitivity for MR signal reception is strongly suppressed, in this embodiment up to −80 dB.

[0051] As can be seen in FIG. 2, the coil element 146 is provided as an essentially planar loop 147, and the E-field antenna 148 is embedded in the coil element 146 for each antenna unit 144. As can be further seen in FIG. 2, the E-field antenna 148 is located in the plane of the coil element 146 and within the coil element 146. In an alternative embodiment, the E-field antenna 148 is oriented at some angle with respect to the coil element 146. Providing the coil element 146 as a planar loop 147 comprises that the planar loop 147 may extended along an surface of the receive coil unit 140. Accordingly, the E-field antenna 148 is embedded in the coil element 146 for each antenna unit 144.

[0052] The antenna units 144 further comprise pre-amplifiers 150, which are connected with their inputs to the coil element 146 and the E-field antenna 148. The antenna units 144 comprise each a de-noising unit 152 for filtering noise signals as received from the E-field antennas 148 from the B-field signals received from the respective coil element 146. Each de-noising unit 152 is adapted to perform de-noising based on the E-field signals of the E-field antennas 148 of the respective antenna unit 144. Accordingly, the de-noising units 152 receive as input signals the pre-amplified signals from the coil element 146 and the E-field antenna 148 of each antenna unit 144 via the pre-amplifiers 150. As can be further seen in FIG. 2, the de-noising units 152 have an optical output 154 for transmission of the filtered B-field signals from the antenna units 144 to the control unit 126 of the MR imaging system 110.

[0053] The de-noising unit of the first embodiment is adapted to perform de-noising based on antiphase operation to cancel e.g. locally generated interferences. In antiphase operation, an interfering signal is detected and an antiphase signal is generated, whereby the antiphase signal is adjusted in its phase and magnitude, so that it matches the unwanted signal interference in the digital domain, i.e. the locally generated interferences, but it is 180 degrees out of phase, effectively cancelling the interference. In an alternative embodiment, the de-noising unit is adapted to perform de-noising based on an independent component analysis. Independent Component Analysis, also referred to as ICA, is a statistical technique for decomposing a complex dataset into independent sub-parts, which can then be utilized to determine noise compounds of the signal and cancel it by adding an inverted signal of equal amplitude.

[0054] A receive coil unit 140 according to a second embodiment is shown in FIG. 3. The receive coil unit 140 of the second embodiment is in major aspects identical to the receive coil unit 140 of the first embodiment. If not otherwise stated, principles of the receive coil unit 140 of the first embodiment also apply to the receive coil unit 140 of the second embodiment.

[0055] The receive coil unit 140 of the second embodiment comprises a receive coil array 142 with multiple antenna units 144. The antenna units 144 each comprise a coil element 146 sensitive to magnetic resonance signals, i.e. B-field signals, and an E-field antenna 148 sensitive to E-field signals. The antenna units 144 further comprise pre-amplifiers 150, which are connected with their inputs to the coil element 146 and the E-field antenna 148. Furthermore, each pre-amplifier 150 is connected to an analog-to-digital converter 156, also referred to as ADC. The ADC 156 comprises a FPGA and performs a conversion of the pre-amplified signals of the coil elements 146 and the E-field antennas 148 into digital signals. Furthermore, the digital signals are provided as optical signals from the ADCs 156.

[0056] According to the second embodiment, the receive coil unit 140 comprises a de-noising unit 152 for filtering noise signals as received from the E-field antennas 148 from the B-field signals received from the respective coil element 146. The de-noising unit 152 is provided centrally in the receive coil unit 140. The de-noising unit 152 is adapted to perform de-noising based on the E-field signals of the E-field antennas 148 of the respective antenna unit 144. Accordingly, the de-noising unit 152 receive as input signals the pre-amplified signals from the coil elements 146 and the E-field antennas 148 of all antenna units 144 via the pre-amplifiers 150. As can be further seen in FIG. 3, the de-noising unit 152 has an optical output 154 for transmission of the filtered B-field signals from the receive unit 140 to the control unit 126 of the MR imaging system 110.

[0057] In an alternative embodiment, the de-noising unit 152 is adapted to perform a combined processing of data. Accordingly, the de-noising is performed in the de-noising unit 152 for the B-field signals of an antenna unit 144 based on the E-field signals of the same antenna unit 144 and under additional consideration of E-field signals of further antenna units 144.

[0058] A receive coil unit 140 according to a third embodiment is shown in FIG. 4. The receive coil unit 140 of the third embodiment is in major aspects identical to the receive coil unit 140 of the first embodiment. If not otherwise stated, principles of the receive coil unit 140 of the first embodiment also apply to the receive coil unit 140 of the third embodiment.

[0059] The receive coil unit 140 of the third embodiment is shown within the examination space 116 of the MR imaging system 110. The examination space 116 is also referred to as bore. The examination space 116 is limited by the main magnet 114 and the magnetic gradient coil system 122.

[0060] The receive coil unit 140 of the third embodiment comprises a receive coil array 142 with multiple antenna units 144. The antenna units 144 each comprise a coil element 146 sensitive to magnetic resonance signals, i.e. B-field signals, and an E-field antenna 148 sensitive to E-field signals. As can be seen in FIG. 4, the receive coil unit 140 comprises a local RF screen 158, and the E-field antennas 148 are connected to the local RF screen 158. In particular, the E-field antennas 148 located in a direction radially outward of the local RF screen 158, whereas the coil elements 146 are located in a direction radially inward of the local RF screen 158. The local RF screen 158 in this embodiment is provided as a circumferential screen in the receive coil unit.

[0061] According to the third embodiment, the antenna units 144 further comprise pre-amplifiers 150 in accordance with the receive coil unit of the first embodiment. Hence, the pre-amplifiers 150 are connected with their inputs to the coil element 146 and the E-field antenna 148. Furthermore, each antenna unit 144 comprises a de-noising unit 152, as described with reference to the first embodiment.

[0062] A receive coil unit 140 according to a fourth embodiment is shown in FIG. 5. The receive coil unit 140 of the fourth embodiment is in major aspects identical to the receive coil unit 140 of the first embodiment. If not otherwise stated, principles of the receive coil unit 140 of the first embodiment also apply to the receive coil unit 140 of the fourth embodiment.

[0063] The receive coil unit 140 of the fourth embodiment is shown within the examination space 116 of the MR imaging system 110. The examination space 116 is limited by the main magnet 114 and the magnetic gradient coil system 122.

[0064] The receive coil unit 140 of the fourth embodiment comprises a receive coil array 142 with multiple antenna units 144. The antenna units 144 each comprise a coil element 146 sensitive to magnetic resonance signals, i.e. B-field signals, and an E-field antenna 148 sensitive to E-field signals. The receive coil unit 140 comprises a local RF screen 158 in accordance with the third embodiment. As can be seen in FIG. 5, the E-field antennas 148 are connected to a circumferential cover 160 of the bore 116 of the MR imaging system 110, thereby providing a constructional separation of the coil element 146 and the E-filed antenna 148. With the receive coil unit 140 placed in the bore 116 in a specified way, the E-field antennas 148 and the coil elements 146 are aligned so that a coil element 146 and corresponding E-field antenna 148 form a distributed antenna unit 144.

[0065] A receive coil unit 140 according to a fifth embodiment is shown in FIG. 6. The receive coil unit 140 of the fifth embodiment is in major aspects identical to the receive coil unit 140 of the first embodiment. If not otherwise stated, principles of the receive coil unit 140 of the first embodiment also apply to the receive coil unit 140 of the fifth embodiment.

[0066] The receive coil unit 140 of the fifth embodiment is shown in FIG. 6 by way of example with three antenna units 144. ADCs 156, de-noising units 152 and further signal processing components are for reasons of simplicity not shown in FIG. 6.

[0067] Each antenna unit 144 of the fifth embodiment comprises a coil element 146, a local RF screen 158 and an E-field antenna 148. The E-field antenna 148 is coupled via a coupling element 162, which is an inductivity in this embodiment, to the local RF screen 158. To optimize impedance match and noise pick-up, lumped element components are combined with the E-field antenna 148.

[0068] FIG. 7 refers to an antenna unit 144 according to a sixth embodiment. The antenna unit 144 of the sixth embodiment can substitute any of the previously described antenna units 144. If not otherwise stated, principles of the antenna units 144 of the first to fifth embodiment also apply to the antenna unit 144 of the sixth embodiment.

[0069] The antenna unit 144 according to the sixth embodiment comprises a coil element 146 sensitive to magnetic resonance signals, i.e. sensitive to B-field signals, and an E-field antenna 148 sensitive to E-field signals. The E-field antenna 148 and the coil element 146 are decoupled, as described above.

[0070] As can be seen in FIG. 7, the coil element 146 is provided as an essentially planar loop 147, and the E-field antenna 148 is embedded in the coil element 146. As can be further seen in FIG. 7, the E-field antenna 148 is located in the plane of the coil element 146 and within the coil element 146. In an alternative embodiment, the E-field antenna 148 is oriented at some angle with respect to the coil element 146.

[0071] The E-field antenna 148 of the sixth embodiment is provided as orthogonal dipole antenna with four connections 164. In this embodiment, the connections 164 are connected via a diversity switch 166, balun filter 168, and impedance matching unit 170 to pre-amplifier 150. The diversity switch 166 provides an optimum receive pattern of individual segments 172 of the E-field antenna 148. The coil element 146 is provided with coupling capacitors 174 within the planar loop 147. Furthermore, the coil element 146 is provided with connections 176, which are connected to a pre-amplifier 150 in accordance with the description of the first embodiment.

[0072] ADCs 156, de-noising units 152 and further signal processing components of the antenna unit 144 are for reasons of simplicity not shown in FIG. 7.

[0073] FIG. 8 refers to an antenna unit 144 according to a seventh embodiment. The antenna unit 144 of the seventh embodiment can substitute any of the previously described antenna units 144. If not otherwise stated, principles of the antenna units 144 of the first to sixth embodiment also apply to the antenna unit 144 of the seventh embodiment.

[0074] The antenna unit 144 according to the seventh embodiment comprises a coil element 146 sensitive to magnetic resonance signals, i.e. sensitive to B-field signals, and an E-field antenna 148 sensitive to E-field signals. The E-field antenna 148 and the coil element 146 are decoupled, as described above.

[0075] As can be seen in FIG. 8, the coil element 146 is provided as an essentially planar loop 147, and the E-field antenna 148 is embedded in the coil element 146. As can be further seen in FIG. 8, the E-field antenna 148 is located in the plane of the coil element 146 and within the coil element 146. In an alternative embodiment, the E-field antenna 148 is oriented at some angle with respect to the coil element 146.

[0076] The E-field antenna 148 of the seventh embodiment is provided as dipole antenna with two connections 164, which are connected via balun filter 168 and impedance matching unit 170 to pre-amplifier 150. The coil element 146 is provided with coupling capacitors 174 within the planar loop 147. Furthermore, the coil element 146 is provided with connections 176, which are connected to a preamplifier in accordance with the description of the first embodiment. The E-field antenna 148 in this embodiment is symmetrically matched using the balun filter. The impedance matching unit 170 transforms the impedance to the optimum noise impedance of the pre-amplifier 150.

[0077] ADCs 156, de-noising units 152 and further signal processing components of the antenna unit 144 are for reasons of simplicity not shown in FIG. 8.

[0078] FIG. 9 shows an antenna unit 144 according to an eighth embodiment. The antenna unit 144 of the eighth embodiment can substitute any of the previously described antenna units 144. If not otherwise stated, principles of the antenna units 144 of the first to seventh embodiment also apply to the antenna unit 144 of the eighth embodiment.

[0079] The antenna unit 144 according to the eighth embodiment comprises a coil element 146 sensitive to magnetic resonance signals, i.e. sensitive to B-field signals, and an E-field antenna 148 sensitive to E-field signals. The E-field antenna 148 and the coil element 146 are decoupled, as described above.

[0080] As can be seen in FIG. 9, the coil element 146 is provided as an essentially planar loop 147, and the E-field antenna 148 is embedded in the coil element 146. As can be further seen in FIG. 9, the E-field antenna 148 is located in the plane of the coil element 146 and within the coil element 146. In an alternative embodiment, the E-field antenna 148 is oriented at some angle with respect to the coil element 146.

[0081] The E-field antenna 148 of the eighth embodiment is provided as dipole stripline antenna with two connections 164. The coil element 146 is provided with coupling capacitors 174 within the planar loop 147. Furthermore, the coil element 146 is provided with connections 176, which are connected to a preamplifier in accordance with the description of the first embodiment. To achieve a locally optimal dipole antenna, the conducting dipole antenna is embedded inside a ceramic substrate with high permittivity.

[0082] ADCs 156, pre-amplifiers 150, de-noising units 152 and further signal processing components of the antenna unit 144 are for reasons of simplicity not shown in FIG. 9.

[0083] FIG. 10 shows an antenna unit 144 according to a ninth embodiment. The antenna unit 144 of the ninth embodiment can substitute any of the previously described antenna units 144. If not otherwise stated, principles of the antenna units 144 of the first to eighth embodiment also apply to the antenna unit 144 of the ninth embodiment.

[0084] The antenna unit 144 according to the ninth embodiment comprises a coil element 146 sensitive to magnetic resonance signals, i.e. sensitive to B-field signals, and an E-field antenna 148 sensitive to E-field signals. The E-field antenna 148 and the coil element 146 are decoupled, as described above.

[0085] As can be seen in FIG. 10, the coil element 146 is provided as a TEM coil element, which is coupled using coupling capacitors 174 to a local RF screen 158 of the antenna unit 144. The local RF screen 158 in this embodiment is provided as a circumferential screen in the receive coil unit 140. The E-field antenna 148 is embedded radially between the TEM coil element and the local RF screen 158. The E-field antenna 148 is provided with connections 164, which extend through the local RF screen 158. Also feeding of the TEM coil element is provided in a way not shown through the local RF screen 158.

[0086] ADCs 156, pre-amplifiers 150, de-noising units 152 and further signal processing components of the antenna unit 144 are for reasons of simplicity not shown in FIG. 10.

[0087] FIG. 11 shows an antenna unit 144 according to a tenth embodiment. The antenna unit 144 of the tenth embodiment can substitute any of the previously described antenna units 144. If not otherwise stated, principles of the antenna units 144 of the first to ninth embodiment also apply to the antenna unit 144 of the tenth embodiment.

[0088] The antenna unit 144 according to the tenth embodiment comprises a coil element 146 sensitive to magnetic resonance signals, i.e. sensitive to B-field signals, and an E-field antenna 148 sensitive to E-field signals. The E-field antenna 148 and the coil element 146 are decoupled, as described above.

[0089] As can be seen in FIG. 11, the coil element 146 is provided as an essentially planar loop 147, and the E-field antenna 148 is embedded in the coil element 146. As can be further seen in FIG. 11, the E-field antenna 148 is located in the plane of the coil element 146 and within the coil element 146. In an alternative embodiment, the E-field antenna 148 is oriented at some angle with respect to the coil element 146.

[0090] The E-field antenna 148 of the tenth embodiment is provided as a spiral pick-up antenna. The coil element 146 is provided with coupling capacitors 174 within the planar loop 147. To reduce the size of the spiral pick-up antenna, the spiral pick-up antenna is mounted on a ceramic substrate with a high dielectric constant.

[0091] ADCs 156, pre-amplifiers 150, de-noising units 152 and further signal processing components of the antenna unit 144 are for reasons of simplicity not shown in FIG. 11.

[0092] FIG. 12 shows an antenna unit 144 according to an eleventh embodiment. The antenna unit 144 of the eleventh embodiment can substitute any of the previously described antenna units 144. If not otherwise stated, principles of the antenna units 144 of the first to tenth embodiment also apply to the antenna unit 144 of the eleventh embodiment.

[0093] The antenna unit 144 according to the eleventh embodiment comprises a coil element 146 sensitive to magnetic resonance signals, i.e. sensitive to B-field signals, and an E-field antenna 148 sensitive to E-field signals. The E-field antenna 148 and the coil element 146 are decoupled, as described above.

[0094] As can be seen in FIG. 12, the coil element 146 is provided as an essentially planar loop 147, and the E-field antenna 148 is embedded in the coil element 146. As can be further seen in FIG. 12, the E-field antenna 148 is located in the plane of the coil element 146 and within the coil element 146. In an alternative embodiment, the E-field antenna 148 is oriented at some angle with respect to the coil element 146.

[0095] The E-field antenna 148 of the eleventh embodiment is provided as a dipole antenna with two connections 164. The coil element 146 is provided with coupling capacitors 174 within the planar loop 147. Furthermore, the coil element 146 is provided with connections 176 for connection to a preamplifier in accordance with the description of the first embodiment. The E-field antenna 148 of the eleventh embodiment comprises wires 178, which are wound on a planar surface.

[0096] ADCs 156, pre-amplifiers 150, de-noising units 152 and further signal processing components of the antenna unit 144 are for reasons of simplicity not shown in FIG. 12.

[0097] FIG. 13 shows an antenna unit 144 according to a twelfth embodiment. The antenna unit 144 of the twelfth embodiment can substitute any of the previously described antenna units 144. If not otherwise stated, principles of the antenna units 144 of the first to eleventh embodiment also apply to the antenna unit 144 of the twelfth embodiment.

[0098] The antenna unit 144 according to the twelfth embodiment comprises a coil element 146 sensitive to magnetic resonance signals, i.e. sensitive to B-field signals, and an E-field antenna 148 sensitive to E-field signals. The E-field antenna 148 and the coil element 146 are decoupled, as described above.

[0099] The E-field antenna 148 of the twelfth embodiment is provided as a dipole antenna with two connections 164. The coil element 146 is provided with connections 176 for connection to a preamplifier in accordance with the description of the first embodiment. As can be seen in FIG. 13, the coil element 146 and the E-field antenna 148 are decoupled by a decoupling circuit 180.

[0100] ADCs 156, pre-amplifiers 150, de-noising units 152 and further signal processing components of the antenna unit 144 are for reasons of simplicity not shown in FIG. 12.

[0101] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

REFERENCE SYMBOL LIST

[0102] 110 magnetic resonance (MR) imaging system [0103] 112 magnetic resonance (MR) scanner [0104] 114 main magnet [0105] 116 RF examination space, bore [0106] 118 center axis [0107] 120 subject of interest [0108] 122 magnetic gradient coil system [0109] 124 RF screen [0110] 126 MR imaging system control unit [0111] 128 monitor unit [0112] 130 MR image reconstruction unit [0113] 132 control line [0114] 134 RF transmitter unit [0115] 136 RF switching unit [0116] 138 control line [0117] 140 radio frequency (RF) antenna device, receive coil unit [0118] 142 receive coil array [0119] 144 antenna unit [0120] 146 coil element [0121] 147 planar loop [0122] 148 E-field antenna [0123] 150 pre-amplifier [0124] 152 de-noising unit [0125] 154 optical output [0126] 156 analog-to-digital converter, ADC [0127] 158 local RF screen [0128] 160 cover [0129] 162 coupling element, inductivity [0130] 164 connection (E-field antenna) [0131] 166 diversity switch [0132] 168 balun filter [0133] 170 impedance matching unit [0134] 172 segment [0135] 174 coupling capacitor [0136] 176 connection (coil element) [0137] 178 wire [0138] 180 decoupling circuit