Magnetic Resonance Signal Correction Using Receiver Maps
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Solution Overview
Problem
In magnetic resonance imaging, particularly in breast imaging, artifacts such as uneven signal intensities occur due to eddy currents and location-dependent flip angles, making diagnosis difficult, despite efforts to homogenize the B1 field for transmission.
Innovation Solution
A method that accounts for the receiver characteristics of the coil arrangement, specifically using B1− receiving maps to correct signal intensity data, ensuring homogenized signal intensities by compensating for location-dependent sensitivity, which can be measured or calculated, and applied before or after data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If B1+ transmission field homogenization is applied, then transmission field uniformity is improved, but receiver sensitivity inhomogeneity remains causing signal intensity artifacts
Solution Approach 1:
Instead of only homogenizing the transmission field B1+, the patent inverts the approach by measuring and correcting based on the receiver field B1− characteristics. B1− maps are acquired and used to calculate correction factors that compensate for receiver sensitivity variations, thereby correcting signal intensity inhomogeneities at the reception stage rather than only at transmission.
Solution Approach 2:
The patent changes the parameter being corrected from transmission field uniformity (B1+) to receiver sensitivity distribution (B1−). By measuring B1− maps and deriving correction factors from these measurements, the system adapts the correction parameters to match the actual receiver characteristics, improving signal intensity accuracy according to the formula: corrected signal intensity = measured signal intensity × correction factor.
2Stability of the object's composition
If conventional B1+ homogenization methods are used, then transmission pulse uniformity is improved, but location-dependent signal intensities due to eddy currents persist
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual receiver sensitivity distribution through B1− maps and using these measurements to calculate correction factors. This measured feedback information is then applied to correct the signal intensity data, creating a closed-loop system that accounts for eddy current effects and receiver characteristics rather than relying solely on theoretical transmission field models.
Solution Approach 2:
The patent performs preliminary measurement of B1− maps before acquiring the actual signal intensity data. These pre-acquired receiver characteristic maps are used to calculate correction factors in advance, which are then applied during or after signal acquisition to prevent location-dependent signal intensity artifacts rather than attempting to correct them afterward.
3Manufacturing precision
If B1+ field correction is applied during transmission, then flip angle homogeneity is improved, but receiver coil sensitivity variations cause remaining artifacts
Solution Approach 1:
The patent extracts and separates the receiver sensitivity component from the overall signal intensity variation problem. By specifically measuring B1− maps that represent only receiver coil sensitivity characteristics, the method isolates the receiver-related artifacts from other sources of signal variation, allowing targeted correction of only the receiver sensitivity component while preserving other signal characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces or eliminates artifacts by ensuring equal signal intensities across the examination region, improving diagnostic accuracy by accounting for the receiver coil's sensitivity distribution, resulting in homogeneous signal intensities even in the presence of eddy currents.
Implementation Method 1
one or a plurality of transmission coils is/are supplied with current. The flip angle achieved is dependent on the duration of the HF pulse and on the pulse profile. An interaction exists here between the B1 field of the high frequency pulse and the tissue that is being examined.
Implementation Method 2
In the patient, eddy currents occur due to the tissue in the examination region. These currents lead to a phase shift to the inducing current.
Data Source
AI summary
A method for generating a spatially resolved magnetic resonance dataset using a coil arrangement includes providing at least one correction datum based on receiver characteristics of the coil arrangement. The method also includes providing a magnetic resonance dataset with spatially resolved signal intensity data, and correcting the at least one signal intensity datum in the magnetic resonance dataset by the correction datum before or after providing the magnetic resonance dataset.