Orthogonal Sub-Volume Navigators for MRI Motion Correction
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Solution Overview
Problem
Conventional prospective motion correction methods in magnetic resonance imaging (MRI) face challenges in accurately compensating for patient motion, particularly in regions like the neck, jaw, and nasal cavities, due to non-rigid body motion assumptions, leading to incomplete motion correction and image artifacts.
Innovation Solution
The method employs multiple orthogonal sub-volume navigator slices acquired using simultaneous multi-slice (SMS) blipped CAIPI acceleration, with lower resolution than diagnostic data, to detect motion quickly and minimize non-rigid motion effects, avoiding susceptible regions and using anatomical information for optimal navigator placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional prospective motion correction methods use full-volume navigators, then motion detection coverage is complete, but scan time and computational load increase
Solution Approach 1:
The patent divides the full navigator volume into multiple orthogonal sub-volume slices (e.g., three orthogonal slices through the center of the volume). Each slice is acquired separately and used for motion detection in specific anatomical regions. This segmentation reduces the total data acquisition time and computational load while maintaining effective motion correction coverage through the use of multiple orthogonal orientations.
2Productivity
If rigid body model assumption is used for motion correction, then processing speed increases, but accuracy decreases in regions with non-rigid motion
Solution Approach 1:
The patent applies different motion correction strategies to different anatomical regions by using orthogonal sub-volume slices. Each slice can be independently processed with appropriate motion correction parameters. This allows rigid body model to be applied where appropriate while minimizing the impact of non-rigid motion in specific regions through selective slice placement and independent processing.
3Reliability
If motion correction is applied in real-time during acquisition, then motion artifacts are reduced, but system complexity increases
Solution Approach 1:
The patent performs motion detection and correction parameter calculation during the acquisition process itself using the orthogonal sub-volume slices. The motion parameters derived from each slice are immediately applied to correct the diagnostic image data. This preliminary action during acquisition reduces the need for complex post-processing while maintaining image quality.
4Productivity
If low resolution navigators are used, then acquisition speed increases, but motion detection precision decreases
Solution Approach 1:
The patent uses multiple orthogonal sub-volume slices instead of a single low-resolution full-volume navigator. By distributing the motion detection task across multiple orthogonal dimensions (x, y, z orientations), the system achieves both speed and precision. Each slice can be acquired quickly at low resolution, but the combination of multiple orthogonal slices provides comprehensive and accurate motion detection coverage.
Data Source
AI summary
In a method and apparatus for motion-corrected magnetic resonance (MR) imaging, MR data are acquired in a diagnostic scan in respective portions, and between each portion of acquired diagnostic data, a navigator scan is implemented wherein navigator data are acquired simultaneously in multiple slices in a navigator sub-volume that is less than the volume of the acquisition volume. A reference scan is acquired before beginning the diagnostic scan, and the navigator data in the sub-volumes are acquired between the acquisition of the portions of the MR data in the diagnostic scan. Between each acquisition portion, a motion-correction algorithm is executed, wherein the navigator data of the sub-volume is compared only to corresponding image data in the reference scan, and, if necessary, a motion-correction instruction is generated that is used for the acquisition of the next diagnostic data portion.