Circuit arrangement for transferring signals from local MR coils to evaluation units

• US 20060055409A1
• Filed: 09/13/2005
• Published: 03/16/2006
• Est. Priority Date: 09/14/2004
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Kess, Helmut
• Granted Patent: US 7,170,293 B2
• Time in Patent Office: Days
• US Class Current: 324/322
• CPC Class Codes: G01R 33/341 comprising surface coils
• CPC Class Codes: G01R 33/3685 Means for reducing sheath currents, e.g. RF traps, baluns

Abstract

A circuit arrangement for connection of at least two local coils of a magnetic resonance apparatus with at least two evaluation units has at least two sheath wave barriers arranged so that magnetic fields caused by them substantially cancel one another.

Claims

1. A circuit arrangement comprising:

at least a first input and a second input, said first and second inputs being adapted for connection to respective MR local coils;

at least a first output and a second output, said first and second outputs being adapted for connection to respective evaluation units;

a first signal line between said first input and said first output and a second line between said second input and said second output;

at least one first sheath wave barrier connected in said first signal line and at least one second sheath wave barrier connected in said second signal line, each of said at least one first sheath wave barrier and said at least one second sheath wave barrier producing a magnetic field, and said at least one first sheath wave barrier and said at least one second sheath wave barrier being configured relative to each other so that the respective magnetic fields produced thereby substantially cancel each other.

2. A circuit arrangement as claimed in claim 1 comprising a plurality of first sheath wave barriers and a plurality of second sheath wave barriers with each first sheath wave barrier forming a pair with one second sheath wave barrier.

3. A circuit arrangement as claimed in claim 2 wherein each of said at least one first sheath wave barrier and said at least one second sheath wave barrier comprises a shielded cable wound to form a coil.

4. A circuit arrangement as claimed in claim 3 comprising a capacitive element connected in parallel with each coil.

5. A circuit arrangement as claimed in claim 2 wherein the respective coils of each first sheath wave barrier and each second sheath wave barrier in a pair have respectively different winding directions.

6. A circuit arrangement as claimed in claim 1 wherein each of said at least one first sheath wave barrier and said at least one second sheath wave barrier comprises a shielded cable wound to form a coil.

7. A circuit arrangement as claimed in claim 6 comprising a capacitive element connected in parallel with each coil.

8. A circuit arrangement as claimed in claim 1 wherein each of said first line and said second line comprises a shielded cable.

9. A circuit arrangement as claimed in claim 8 wherein each shielded cable comprises a plurality of inner conductors surrounded by a shield conductor.

10. A circuit arrangement as claimed in claim 9 comprising a plurality of first sheath wave barriers and a plurality of second sheath wave barriers with each first sheath wave barrier forming a pair with one second sheath wave barrier, and comprising an inductive element and a capacitor connecting the shield conductors of the respective coils of the first and second sheath wave barriers in said pair.

11. A circuit arrangement as claimed in claim 10 comprising a further inductive element and a further capacitor connecting the shield conductors of the respective coils of said first sheath wave barrier and said sheath wave barrier in said pair.