MRI B0 and B1 Map Acquisition Using Dual Flip Angle RF Pulses
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Solution Overview
Problem
Current MRI systems require multiple scans to obtain B0 and B1 maps, which is time-consuming and only provide amplitude information, lacking accurate phase information and efficient signal-to-noise ratio (SNR) for improved image quality.
Innovation Solution
Transmitting pulses with different flip angles at varying repetition times to simultaneously obtain B0 and B1 maps by combining response signals, allowing for accurate intensity and phase information retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple scans are performed to obtain B0 and B1 maps separately, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent combines the acquisition of B0 map information and B1 map information into a single scan by transmitting RF pulses with different flip angles (first and second flip angles) and acquiring both sets of information from the same response signals, rather than performing separate scans for each map
Solution Approach 2:
The patent uses periodic RF pulse transmission with different flip angles at predetermined time intervals (repetition times) to systematically acquire both B0 and B1 map information through multiple measurements that can be combined
2Loss of time
If conventional scanning methods are used, then scanning time is reduced, but measurement precision deteriorates due to lack of phase information
Solution Approach 1:
The patent uses response signals acquired at different flip angles as intermediary measurements that enable extraction of both amplitude and phase information through signal combination and mathematical processing
Solution Approach 2:
The patent changes the flip angle parameter of RF pulses to different values (first and second flip angles) to acquire multiple measurements that contain different combinations of amplitude and phase information, enabling complete characterization
3Device complexity
If conventional single flip angle scanning is used, then device complexity is minimized, but measurement precision deteriorates due to insufficient signal-to-noise ratio
Solution Approach 1:
The patent acquires more measurements than the minimum single scan by performing multiple acquisitions with different flip angles, where the excess measurements provide redundant information that improves signal-to-noise ratio through averaging and combination
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 method reduces scanning time, enhances SNR, and provides both amplitude and phase information, improving the accuracy of MRI images by optimizing flip angle ratios.
Implementation Method 1
Magnetic resonance imaging (MRI) refers to a technique of acquiring an image of a target object by locating the target object in a large area where a magnetic field is generated, generating radio frequency (RF) pulses to cause nuclei in the target object to resonate
Data Source
AI summary
A method obtains main magnetic field information and radio frequency (RF) pulse related information in a magnetic resonance imaging (MRI) system, in which a pulse having a first flip angle and a pulse having a second flip angle are transmitted to a target object at predetermined time intervals. The method includes: obtaining at least one first response signal with respect to the pulse, having the first flip angle, from the target object; obtaining at least one second response signal, with respect to the pulse having the second flip angle, from the target object; and combining the at least one first response signal and the at least one second response signal to obtain the main magnetic field information and the RF pulse related information.