k-space Sampling for Combined MRI Angiography and Perfusion
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Solution Overview
Problem
Current MRI systems face challenges in acquiring both angiographic and perfusion images simultaneously without extending acquisition times or requiring data collection during undesirable contrast enhancement phases, leading to limitations in spatial and temporal resolution and increased acquisition times.
Innovation Solution
A system and method that samples k-space in a Cartesian acquisition pattern with features similar to projection reconstruction, dividing k-space into a central region and radially-extending sectors, allowing for time-resolved image data acquisition and reconstruction of both MRA and perfusion images using a single MRI acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRI systems acquire both angiographic and perfusion images using separate pulse sequences, then both types of images can be obtained, but the acquisition time is extended and spatial/temporal resolution is compromised
Solution Approach 1:
The patent combines angiographic and perfusion imaging into a single pulse sequence by integrating k-space sampling strategies. The method samples the central region of k-space during a first period and radially-extending sectors during a second period, then combines these data to reconstruct both MRA and perfusion images simultaneously, eliminating the need for separate acquisitions and reducing total scan time while maintaining high spatial and temporal resolution
Solution Approach 2:
The patent segments the k-space acquisition into distinct temporal periods: a first period for sampling the central region of k-space and a second period for sampling radially-extending sectors. This segmentation allows optimized sampling strategies for different image types within a unified acquisition, enabling both angiographic and perfusion information to be captured efficiently without compromising resolution
2Reliability
If timing boluses are used to coordinate contrast agent injection with image acquisition, then optimal contrast enhancement can be achieved, but the system complexity increases and acquisition timing becomes more constrained
Solution Approach 1:
The patent eliminates the need for timing boluses by using a unified pulse sequence that inherently captures both angiographic and perfusion phases. The method acquires data from the central region of k-space and radially-extending sectors in a coordinated manner without requiring external triggering or synchronization devices, thereby reducing system complexity while maintaining reliable contrast enhancement through optimized k-space sampling timing
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 efficient acquisition of high-quality angiographic and perfusion images without the need for timing boluses, reducing patient contrast dose and acquisition time, while maintaining high spatial and temporal resolution and minimizing artifacts.
Implementation Method 1
magnetic field gradients (Gx, Gy, and Gz) are employed
Implementation Method 2
the individual magnetic moments of the nuclei in the tissue attempt to align with this polarizing field, but process about it in random order at their characteristic Larmor frequency
Implementation Method 3
the net aligned moment, Mz, may be rotated, or 'tipped', into the x-y plane to produce a net transverse magnetic moment Mxy
Data Source
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AI summary
A method for performing magnetic resonance angiography and perfusion imaging using the same pulse sequence is provided. Time-resolved image data is acquired as a contrast agent passes through a subject. This image data is acquired by sampling Cartesian points in k-space that are contained within either a central region of k-space, or one of a plurality of different sets of radial sectors extending outwards from the central region. The image data is combined to form individual image frame data sets that are then reconstructed to produce a time series of image frames. From this time series, MR angiograms and perfusion maps are produced. With the added acquisition of calibration data, T1 relaxation parameters are estimated and quantitative perfusion maps produced.