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QUADRATURE PROBE FOR SURFACE COIL UNIFORMITY MEASUREMENT

IP.com Disclosure Number: IPCOM000228569D
Publication Date: 2013-Jun-19
Document File: 5 page(s) / 859K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention proposes a quadrature probe for surface coil uniformity measurements. The quadrature probe includes two transmitters arranged orthogonally to each other, a 90-degree coupler/isolator, balun circuit and an insulated stripline circuit board to operate as one antenna. The invention maximizes support of data and provides sensitivity mapping technique. Sensitivity mapping technique for multi-channel coils provides additional way in data collection to understand uniformity of coil product.

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QUADRATURE PROBE FOR SURFACE COIL UNIFORMITY MEASUREMENT

FIELD OF INVENTION

The invention generally relates to multi-channel magnetic resonance (MR) coils and more particularly to a quadrature probe for MR surface coil uniformity measurements.

BACKGROUND OF THE INVENTION

During construction of a radio frequency (RF) coil, sensitivity measurements are currently achieved with linear sensitivity probes and network analyzers.  The test results with this method do not provide ideal uniformity of the coil product. As a result, for further examination of uniformity the coils need to be tested with a magnetic resonance imaging (MRI) system. The test results are achieved by various techniques during an MRI scan with loading and non-loading phantoms. These further confirm need and adjustment required in the RF coil. The conventional techniques have limitations due to complexity and /or lack of resource and use of MRI system.

A conventional technique involves use of a semi-rigid coaxial cable structure to form a magnetic flux probe to provide surface coil uniformity measurements. The technique does not provide optimal result due to losses from improper combination of transmission lines and inconsistent loop shape structure. The combined transmission lines and inconsistent loop structure prevents repeatable and reproducible results.

Therefore, there is a need in the art for an efficient method for surface coil uniformity measurements.

BRIEF DESCRIPTION OF THE INVENTION

The invention includes a quadrature probe for surface coil uniformity measurements. The invention saves time in test and measurement. The invention maximizes support of data and provides a repeatable and reproducible sensitivity mapping technique. Sensitivity mapping technique for multi-channel coils provides additional and ideal way in data collection to understand uniformity of coil product.

DETAILED DESCRIPTION OF THE INVENTION

The invention includes a quadrature probe for surface coil uniformity measurements. The quadrature probe includes two transmitters arranged orthogonally to each other, a 90-degree coupler/isolator, balun circuit and an insulated stripline circuit board to operate as one antenna. For surface coil uniformity measurement, two orthogonally arranged circular probes are required to be decoupled. To achieve effective decoupling tolerance it is required to have small errors in fabrication and design structure. Tuning of probes is also required to attain full performance.  

FIG .1 depicts a quadrature probe.

                                                             FIG .1

The probe uses impedance controlled transmission lines for isolation and effective signal propagation. The source signal needs to be separated into two signals phase shifted by 90 degrees from each other to drive the two loops. At the operating frequency of the probe, it is necessary to maintain high isolation between the output ports drivi...