LOCATING AN ERROR IN A SUPPLY OR SIGNAL LINE OF A MAGNETIC RESONANCE SYSTEM

Abstract

The invention relates to the field of magnetic resonance, and in particular to determining a location of an error in a supply or signal line (12). Due to the rugged environment for MR systems (10) in hospitals supply or signal lines (12) of MR systems (10) are error prone. For serviceability and part replacement it is important to locate the error in the supply or signal line (12) or to identify the subunit (14, 16, 18, 20) of the supply or signal line (12) in which the error occurred. The basic idea of the invention is to use an additional impedance (24), that is coupled to the supply or signal line (12) of the MR system (10) in the region of interconnection (22) for locating the error in the supply or signal line (12). The additional impedance provides a reference impedance value. By measuring the impedance and comparing the measured impedance to the reference impedance value, the error in the supply or signal line (12) can be located. In one embodiment the additional impedance (24) is realized as additional capacitance and provided as a capacitor (28).

Claims

1. A magnetic resonance system comprising: a supply or signal line, wherein the supply or signal line includes several interconnected subunits, and wherein in respective regions on of interconnection respective additional impedances are coupled to the supply or signal line, wherein the additional impedances provide defined reference impedance values and is configured to add the reference impedance value for locating an error in the supply or signal.

2. The magnetic resonance system according to claim 1 wherein the subunit comprises a connector and the additional impedance are integrated in the connector.

3. The magnetic resonance system according claim 1 wherein the additional impedance are provided as capacitor, resistor, inductor and/or resonant circuit.

4. The magnetic resonance system according to claim 1 wherein in the region of interconnection the additional impedance are connected in parallel to the supply or signal line.

5. The magnetic resonance system according to claim 1 wherein in the region of interconnection the additional impedance are connected in series to the supply or signal line.

6. The magnetic resonance system according to claim 1 wherein in each region of interconnection at least one said additional impedance coupled to the supply or signal line.

7. The magnetic resonance system according to claim 1 wherein the magnetic resonance system comprises a power supply and an impedance measurement device that is integrated in the power supply.

8. The magnetic resonance system, according to claim 1 wherein in the region of interconnection the additional impedance is provided as a highly resistive sensing wire coupled to the supply or signal line or as a network of highly resistive sensing wires coupled to the supply or signal line.

9. A method for locating an error in a supply or signal line a magnetic resonance system, wherein the supply or signal line consists of several interconnected subunits, and wherein in respective regions of interconnection resistive additional impedances are coupled to the supply or signal line, and wherein the additional impedance provides a reference impedance value, comprising: a) measuring an impedance, and b) determining a location of the error by comparing the measured impedance to the reference impedance value.

10. The method according to claim 9 wherein the method further comprises the step of coupling additional impedance to the supply or signal line in a region of interconnection.

11. The method according to claim 9 wherein the step of measuring an impedance comprises measuring an impedance of the supply or signal line.

12. The method according to claim 9 wherein the step of measuring an impedance comprises measuring an impedance between a highly resistive sensing wire and the supply or signal line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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.

[0028] In the drawings:

[0029] FIG. 1 schematically depicts one possible embodiment of a magnetic resonance system comprising a supply line, wherein the additional impedance is provided as capacitor;

[0030] FIG. 2 schematically depicts another possible embodiment of a magnetic resonance system comprising a supply line, wherein the additional impedance is provided as a highly resistive sensing wire; and

[0031] FIG. 3 schematically depicts another possible embodiment of a magnetic resonance system comprising a signal line, wherein the additional impedance is provided as a network of highly resistive sensing wires.

DETAILED DESCRIPTION OF EMBODIMENTS

[0032] FIG. 1 depicts one possible embodiment of the magnetic resonance system 10 as disclosed herein. The MR system 10 comprises a supply line 12, used for transmitting power to coil electronics 20 inside the coil that provide the MR specific functions such as signal amplification, coil detuning, A/D conversion, signal processing, and digital transmission. The supply line 12 consist of several subunits 14, 16, 18, 20. In this embodiment, the subunits are a power supply 14, a coil connector cable 16, a coil cable 18, and coil electronics 20.

[0033] The subunits 14, 16, 18, 20 are interconnected, i.e. the power supply 14 is connected to the coil connector cable 16, the coil connector cable 16 is connected to the coil cable 18, and the coil cable 18 is connected to the coil electronics 20. In the regions of interconnection 22 of two subunits, i.e. in the region 22 where the power supply 14 is connected to the coil connector cable 16, in the region 22 where the coil connector cable 16 is connected to the coil cable 18, and in the region 22 where the coil cable 18 is connected to the coil electronics 20, additional impedances 24 are coupled to the supply line 12.

[0034] In the embodiment depicted in FIG. 1, the additional impedances 24 are realized as additional capacitance and are provided as capacitors 28. The capacitors 28 are connected to the supply line 12 in parallel in the regions of interconnection 22. In this embodiment the subunits 14, 16, 18, 20 comprise connectors 26 for interconnecting the subunits 14, 16, 18, 20 with each other. The capacitors 12 are integrated in the connectors 26. The capacitors 28 each have a capacitance in the order of 100 pF to 1 nF; a capacitance small enough not to disturb the functions of the supply line 12 and MR system 10 and a capacitance high enough for a reliable location of the error.

[0035] Furthermore, the MR system 10 comprises an impedance measurement device 34 that is integrated in the power supply 14. For example, the impedance measurement device can be an LCR meter (Inductance (L), Capacitance (C), and Resistance (R)). An LCR meter can measure the inductance, resistance and capacitance of a component and from these values, the impedance at any frequency can be determined. For example, for measuring the impedance of the supply line 12 the voltage and current of the supply line 12 as a function of time can be measured. By measuring the impedance of the supply line 12 the location of the error in the supply line 12 can be determined. For the MR system 10 depicted in FIG. 1 the relation between the location of the error in the supply line 12 and the measured capacitance is for example as follows, assuming ideal (lossless) components:

TABLE-US-00001 Measured Location Possible capacitance of error service action 5 C + residual No error in supply In case of errors replace cable capacitance chain 12 power supply 14 or coil electronics 20 4 C + residual No connection between Check connector 26 for cable capacitance coil electronics 20 obvious issues between and coil cable 18 subunit 20 and subunit 18, replace coil electronics 20 3 C + residual Error in coil cable 18 Replace coil cable 18 cable capacitance 2 C No connection between Check connector 26 for coil cable 18 an coil obvious issues between connector cable 16 subunit 18 and subunit 16 1 C Error in coil connector Replace coil connector cable 16 cable 16 No C No connection between Check connector 26 for power supply 14 and obvious issues between the coil connector subunit 16 and subunit 14, cable 16 replace coil connector cable 16

[0036] FIG. 2 depicts another possible embodiment of the magnetic resonance system 10 as disclosed herein. The MR system 10 comprises a supply line 12, used for transmitting power to coil electronics 20 inside the coil that provide the MR specific functions such as signal amplification, coil detuning, A/D conversion, signal processing, and digital transmission. The supply line 12 consist of several subunits 14, 16, 18, 20, in this embodiment, the subunits are the power supply 14, the coil connector cable 16, the coil cable 18, and the coil electronics 20.

[0037] The subunits 14, 16, 18, 20 are interconnected, i.e. the power supply 14 is connected to the coil connector cable 16, the coil connector cable 16 is connected to the coil cable 18, and the coil cable 18 is connected to the coil electronics 20. In the regions of interconnection 22 of two subunits, i.e. in the region 22 where the power supply 14 is connected to the coil connector cable 16, in the region 22 where the coil connector cable 16 is connected to the coil cable 18, and in the region 22 where the coil cable 18 is connected to the coil electronics 20, additional impedances 24 are coupled to the supply line 12.

[0038] In the embodiment depicted in FIG. 2, the additional impedance 24 is realized as additional resistance and is provided as highly resistive sensing wire 30. In this embodiment one highly resistive sensing wire 30 is coupled to each region of interconnection 22, hence three highly resistive sensing wires 30 are used for locating the error in the supply line 12. The highly resistive sensing wires 30 are coupled to one path of the supply line 12. However, it is possible that each path of the supply line 12 is equipped with highly resistive sensing wires 30. An error analysis of the MR system 10 may show that the likelihood for errors is different for one path of the supply line 12 to the other, especially when asymmetric supply lines 12 such as coaxial cables are used.

[0039] Furthermore, in the embodiment depicted in FIG. 2 additional resistors are connected in series to the highly resistive sensing wire 30, to further add additional impedance. This increases the difference in the measured impedances for different locations of the error in the supply line 12. The resistance of the highly resistive sensing wires 30 is preferably >1 kΩ/m for ensuring that no excessive currents are induced in the highly resistive sensing wire 30 by the magnetic field of the coils of the MR system 10. For determining the location of the error the impedance between the highly resistive sensing wire 30 and the supply line 12 can be measured. For example the voltage can be sensed via the highly resistive sensing wire 30 and the supply line 12, ensuring that the input impedance of the impedance measurement device is sufficiently high. If there is an error in the supply line 12, allocated in one of the subunits 14, 16, 18, 20 different impedances are measured for the different error allocations. Thus, the location of the error in the supply line 12 can be determined. Hence, no cumbersome additional tests have to be performed by exchanging one or the other subunit 14, 16, 18, 20 of the supply line 12 to see if the error persists or not.

[0040] In a further embodiment, depicted in FIG. 3, the MR system 10 comprises a signal line 12, used for transmitting MR signals from the coil electronics 20 inside the coil. The signal line 12 consist of several subunits 14, 16, 18, 20, in this embodiment, the subunits are a first signal transmission line 14, a second signal transmission line 16 inside the patient table, a third signal transmission line 18, and the coil electronics 20. As well as in the embodiment depicted in FIG. 2, the subunits 14, 16, 18, 20 are interconnected. In the regions of interconnection 22 of two subunits 14, 16, 18, 20 additional impedances 24 are coupled to the signal line 12.

[0041] In the embodiment depicted in FIG. 3, the additional impedance 24 is realized as additional resistance and is provided as a network of highly resistive sensing wires 30. In this embodiment the network of highly resistive sensing wire 30 is coupled to each region of interconnection 22 for locating the error in the signal line 12. The network of highly resistive sensing wires 30 is coupled to one path of the signal line 12 and additional resistors are connected to the network of highly resistive sensing wire 30 to further add additional impedance. This increases the difference in the measured impedances for different locations of the error in the signal line. For determining the location of the error the impedance between the highly resistive sensing wire 30 and the signal line 12 can be measured.

[0042] 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. Further, for the sake of clearness, not all elements in the drawings may have been supplied with reference signs.

REFERENCE SYMBOL LIST

[0043] Magnetic resonance system 10 [0044] Supply or signal line 12 [0045] Subunit, power supply, first signal transmission line 14 [0046] Subunit, coil connector cable, second signal transmission line 16 [0047] Subunit, coil cable, third signal transmission line 18 [0048] Subunit, coil electronics 20 [0049] Region of interconnection 22 [0050] Additional impedance 24 [0051] Connector 26 [0052] Capacitor 28 [0053] Resistor, highly resistive sensing wire 30 [0054] Power supply 32 [0055] Impedance measurement device