Multi-Contrast Brain MRI via Cyclic K-Space Acquisition
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Solution Overview
Problem
Conventional MRI techniques require multiple scans to achieve multiple tissue contrasts, increasing exam time and sensitivity to motion, as only one tissue type can be nulled at a time during inversion recovery imaging.
Innovation Solution
A method involving k-space data acquisition using radial or spiral sectors with dithering to create incoherent point spread functions, allowing for the rapid generation of multiple TI contrast images in a single scan by dividing Cartesian points into groups and subgroups, and acquiring k-space data sequentially and cyclically to minimize artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRI techniques are used to achieve multiple tissue contrasts, then multiple scans are required, but this increases exam time and sensitivity to motion
Solution Approach 1:
The patent combines multiple inversion recovery scans with different inversion times into a single scan by acquiring k-space data for multiple TI values sequentially. The k-space is divided into sectors, and data from different TI periods are interleaved within the same scan, allowing reconstruction of multiple contrast images without performing separate scans for each contrast type.
Solution Approach 2:
The patent employs periodic inversion pulses with different inversion times within a single scan sequence. The scan alternates between acquiring data at different TI periods, creating a periodic pattern of inversion and acquisition that enables multiple contrasts to be obtained efficiently in one continuous scan.
2Adaptability or versatility
If multiple scans are performed to achieve multiple tissue contrasts, then comprehensive contrast coverage is obtained, but motion sensitivity increases
Solution Approach 1:
Multiple contrast acquisitions are merged into a single scan sequence, eliminating gaps between scans where motion can occur. The continuous acquisition process reduces the opportunity for patient motion between separate scans, improving reliability while maintaining comprehensive contrast coverage.
Solution Approach 2:
The patent performs preliminary division of k-space into sectors and establishes the acquisition pattern before the scan begins. This pre-planned structure allows seamless transition between different TI acquisitions without requiring repositioning or re-alignment, reducing motion artifacts.
3Measurement precision
If k-space data is acquired for all Cartesian points at each time period, then complete image data is obtained, but scan time increases significantly
Solution Approach 1:
The k-space is segmented into multiple sectors, and the Cartesian points are divided into groups based on their radial distance from the center. Different groups are acquired at different time periods within the same scan, allowing efficient utilization of the inversion recovery curve while maintaining complete image data through subsequent reconstruction.
Solution Approach 2:
The patent acquires only a subset of k-space points at each time period rather than all points, using the temporal information from multiple TI periods to reconstruct complete images. This partial acquisition approach significantly reduces scan time while maintaining image quality through the use of multiple contrast time points.
4Productivity
If Cartesian points are divided into groups with different kr values, then rapid multi-contrast imaging is enabled, but artifact generation may increase
Solution Approach 1:
Different regions of k-space (central and peripheral) are assigned different acquisition priorities and timing. The central points with lower kr values are acquired at specific TI periods optimized for their contrast requirements, while peripheral points are acquired at other time periods, creating locally optimized acquisition patterns that reduce artifacts while maintaining fast imaging.
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
Enables the generation of multiple TI contrast images in short scan times comparable to conventional single-contrast 3D scans, reducing artifacts and motion sensitivity, and allowing for efficient image reconstruction without the need for new reconstruction engines.
Implementation Method 1
A radio frequency inversion pulse is applied to the subject such that a net longitudinal magnetization in the subject is substantially inverted and begins to relax back to equilibrium
Implementation Method 2
K-space data for the first group of Cartesian points for M different time periods is acquired
Data Source
AI summary
A method for providing an image of a subject is provided. The plurality of Cartesian points is divided into a first group and a second group, wherein all of the Cartesian points in the first group have a kr that is less than or equal to kr of all of the Cartesian points in the second group. The second group is divided into N subgroups. An inversion recovery radio frequency is applied to the subject. K-space data for the first group of Cartesian points for M different time periods is acquired, wherein k-space data is acquired for only one sub-group sequentially and cyclically for the M different time periods. For each time period i of the M different time periods, acquired k-space data for the first group of Cartesian points at time period i and k-space data from N consecutive subgroups of Cartesian points.