Steady State Magnetic Resonance Fingerprinting Dictionary
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Solution Overview
Problem
Magnetic resonance fingerprinting techniques face challenges in acquiring data rapidly due to residual magnetization, which requires long delays before subsequent data acquisition, limiting the efficiency of methods like SENSE and complicating the calculation of substance abundance.
Innovation Solution
The implementation of a steady state magnetic resonance fingerprinting dictionary allows for the acquisition of magnetic resonance data after a predetermined number of RF-pulse trains, enabling continuous data acquisition and minimizing delays by using a dictionary calculated through methods such as Bloch equations or extended phase graph calculations, facilitating faster data acquisition and more complex techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional magnetic resonance fingerprinting is used with residual magnetization, then data acquisition can be performed, but long delays are required before subsequent acquisition which limits efficiency
Solution Approach 1:
The patent applies parameter changes by transitioning from traditional transient MRF to steady-state MRF, where the dictionary is calculated based on steady-state magnetization conditions rather than transient relaxation. This fundamental parameter change in the physical model allows continuous data acquisition without long delays, as the steady-state assumption accounts for residual magnetization effects inherently, eliminating the need for waiting periods between acquisitions.
2Loss of time
If steady state magnetic resonance fingerprinting dictionary is used, then acquisition time is reduced, but the dictionary calculation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the steady-state MRF dictionary offline using Bloch equations or extended phase graph calculations. This preliminary computation of the dictionary, which captures the steady-state signal evolution for various tissue parameters, is performed beforehand and stored. During actual scanning, this pre-computed dictionary is simply compared with acquired signals, dramatically reducing scan time while the computational complexity is confined to the offline dictionary generation phase.
3Productivity
If continuous data acquisition is performed, then productivity increases, but measurement precision may be affected by subject motion
Solution Approach 1:
The patent applies continuity of useful action by implementing continuous data acquisition using steady-state MRF, where the magnetization is maintained in a steady state through optimized RF pulse sequences and timing. This continuous acquisition mode eliminates gaps between scans, improving productivity. The steady-state model inherently accounts for the continuous nature of the signal, and when combined with motion correction techniques, maintains measurement precision despite the accelerated acquisition pace.
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
This approach significantly reduces acquisition time and enhances the accuracy of substance abundance calculation, allowing for more rapid and reliable data acquisition while reducing the impact of subject motion, as demonstrated by accelerated data acquisition in examples using PROPELLER and SENSE protocols.
Implementation Method 1
Magnetic Resonance (MR) data is defined herein as being the recorded measurements of radio frequency signals emitted by atomic spins using the antenna of a Magnetic resonance apparatus during a magnetic resonance imaging scan
Implementation Method 2
The steady state magnetic resonance fingerprinting dictionary contains a listing of the calculated magnetic resonance signals in response to the RF-pulse train for a set of predetermined substances
Implementation Method 3
using a dictionary calculated through methods such as Bloch equations or extended phase graph calculations
Data Source
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AI summary
The invention provides for a magnetic resonance imaging system (100) for acquiring magnetic resonance data (142) from a subject (118) within a measurement zone (108), wherein the magnetic resonance imaging system comprises: a processor (130) for controlling the magnetic resonance imaging system and a memory (136) for storing machine executable instructions (150, 152, 154) and pulse sequence commands (140). The pulse sequence commands for controlling the magnetic resonance imaging system to acquire the magnetic resonance data according to a magnetic resonance fingerprinting protocol. The pulse sequence commands are configured for controlling the magnetic resonance imaging system to generate an RF pulse train (300). The pulse sequence commands are configured for controlling the magnetic resonance imaging system to acquire the magnetic resonance data as multiple k-space traces. The pulse sequence commands are configured for controlling the RF pulse train to be repeated for the acquisition of each of the multiple k-space traces. The machine executable instructions causes the processor to: sequentially acquire (200) the multiple k-space traces of magnetic resonance data by controlling the magnetic resonance imaging system with pulse sequence commands and calculate (202) the abundance of each of a set of predetermined substances for k-space traces that are acquired after a predetermined number of k-space traces of the multiple k-space traces has been acquired. The abundance of each of a set of predetermined substances is determined by comparing the magnetic resonance data with a steady state magnetic resonance fingerprinting dictionary (144). The steady state magnetic resonance fingerprinting dictionary contains a listing of calculated magnetic resonance signals in response to the RF pulse train for a set of predetermined substances.