MRI Intensity Correction via Multi-Channel Coil Shimming
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Solution Overview
Problem
Magnetic resonance imaging (MRI) techniques, such as SENSE, face issues with signal voids and ghosting due to coil non-uniformity, especially at higher magnetic fields, which are not adequately addressed by existing intensity level correction methods like CLEAR correction.
Innovation Solution
Shimming a multi-channel transmit coil system to optimize its operating parameters, acquiring a coil sensitivity map, and reconstructing MRI images using the shimmed system to perform intensity level correction, thereby reducing artifacts and improving image uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CLEAR correction is applied to correct coil non-uniformity, then image uniformity is improved, but signal voids and ghosting artifacts appear
Solution Approach 1:
The patent applies preliminary shimming to the multi-channel transmit coil system before acquiring the coil sensitivity map and performing CLEAR correction. This preliminary optimization of the transmit coil's magnetic field uniformity prevents the generation of severe non-uniformity that would otherwise be squared and amplified during CLEAR correction, thereby avoiding signal voids and ghosting artifacts while still achieving image uniformity
Solution Approach 2:
The patent changes the operating parameters of the multi-channel transmit coil system through shimming, which optimizes the transmit coil's magnetic field distribution. This parameter optimization ensures that the transmit coil non-uniformity is minimized before the CLEAR correction process, preventing the amplification of artifacts that would occur with conventional single-channel coils
2Device complexity
If conventional single-channel transmit coil is used, then device complexity is low, but transmit coil non-uniformity causes severe artifacts after CLEAR correction
Solution Approach 1:
The patent divides the transmit coil system into multiple independent channels, each with its own sensitivity profile. This segmentation allows for optimized shimming of each channel and enables the system to achieve uniform transmit field through coordinated operation of multiple channels, thereby eliminating the non-uniformity artifacts that plague conventional single-channel systems
Solution Approach 2:
The patent employs a composite multi-channel coil system that combines multiple transmit coil elements with different sensitivity characteristics. Through shimming and coordinated operation, this composite system achieves superior field uniformity compared to any single channel, while the diversity of the composite channels provides redundancy and artifact reduction
Data Source
AI summary
A magnetic resonance system includes a magnetic resonance scanner having a multi-channel transmit coil or coil system and a magnetic resonance receive element; and a digital processor configured to perform an imaging process. The image process includes shimming the multi-channel transmit coil or coil system, acquiring a coil sensitivity map for the magnetic resonance receive element using the multi-channel transmit coil or coil system, acquiring a magnetic resonance image using the magnetic resonance receive element and the shimmed multi-channel transmit coil or coil system, and performing an intensity level correction on the acquired magnetic resonance image using the coil sensitivity map to generate a corrected magnetic resonance image.