Second-Order Concomitant Field Correction in 3D MRI
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Solution Overview
Problem
Current methods for correcting concomitant fields in 3D magnetic resonance (MR) imaging are inadequate, particularly for high-order concomitant phase errors, which cause artifacts such as pixel shifts and blurring, and are not effectively addressed in existing systems, especially at low field strengths and high gradient amplitudes.
Innovation Solution
A system and method that includes a gradient coil assembly and a concomitant field correction computing device programmed to adjust MR signals with second-order or higher concomitant phases, allowing for the reconstruction of MR images by accounting for the spatial and temporal variations of these phases, thereby correcting high-order concomitant field effects without modifying the MR system hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gradient fields are applied in 3D MRI to improve imaging capability, then image quality and diagnostic accuracy are improved, but concomitant field errors cause pixel shifts and blurring artifacts
Solution Approach 1:
The patent applies preliminary anti-action by calculating and applying correction phases before image reconstruction to counteract the concomitant field errors. The correction phase is computed based on the gradient waveforms and applied to the k-space data prior to reconstruction, preventing the artifacts from appearing in the final image rather than attempting to correct them after they occur.
Solution Approach 2:
The patent introduces an intermediary correction phase that mediates between the raw k-space data and the final reconstructed image. This correction phase acts as a mediator that transforms the erroneous k-space data into corrected data by applying phase adjustments that compensate for the concomitant field effects, enabling accurate image reconstruction without modifying the gradient hardware.
2Reliability
If known correction methods are used, then some concomitant field effects are addressed, but high-order concomitant phase errors remain uncorrected
Solution Approach 1:
The patent applies parameter changes by extending the correction approach from traditional first-order concomitant field correction to include second-order and higher-order terms. This is achieved by modifying the correction phase calculation to incorporate additional gradient waveform parameters and their interactions, thereby capturing and correcting high-order phase errors that were previously neglected in standard correction methods.
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
The solution effectively corrects high-order concomitant field effects, improving image quality by reducing artifacts like pixel shifts and blurring, enabling full utilization of gradient coil capabilities without compromising image quality, and facilitating accurate diagnosis.
Implementation Method 1
a gradient coil assembly including an x gradient coil, a y gradient coil, and a z gradient coil. The x gradient coil, the y gradient coil, or the z gradient coil is configured to apply a gradient field along an x direction (Gx), a gradient field along a y direction (Gy), or a gradient field along a z direction (Gz), respectively
Implementation Method 2
The at least one processor is further programmed to correct effects of concomitant fields generated by gradient fields applied by the gradient coil assembly by adjusting the MR signals with second-order concomitant phases accumulated from second-order concomitant fields
Data Source
AI summary
A magnetic resonance (MR) system is provided. The MR system includes a gradient coil assembly and a concomitant field correction computing device. The at least one processor of the computing device is programmed to receive MR signals acquired with the MR system using a three-dimensional (3D) pulse sequence, wherein a kx dimension and a ky dimension in k-space are sampled along non-Cartesian trajectories. The at least one processor is further programmed to correct effects of concomitant fields generated by gradient fields applied by the gradient coil assembly by adjusting the MR signals with second-order concomitant phases accumulated from second-order concomitant fields, and reconstructing MR images based on the adjusted MR signals. The second-order concomitant phases vary as functions of time and spatial locations. The at least one processor is also programmed to output the MR images.