Simultaneous B0 and B1 Mapping for Faster MRI Field Correction
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Solution Overview
Problem
Existing MRI methods for B0 and B1 mapping are sequential, taking over one minute and increasing scan time, while separate B0 and B1 mapping sequences lead to signal intensity variations and quantitative measurement errors due to inhomogeneous magnetic fields.
Innovation Solution
A simultaneous B0 and B1 mapping method using the satTFL B1 mapping method with two passes of pre-saturation RF pulses and gradient echo trains, allowing for rapid determination of both B0 and B1 fields within 20 seconds, utilizing a single gradient echo routine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential B0 and B1 mapping methods are used, then measurement precision can be maintained, but scan time increases to over one minute
Solution Approach 1:
The patent combines B0 and B1 mapping into a single simultaneous measurement process using a unified pulse sequence that acquires both field maps together, eliminating the need for separate sequential mapping scans and reducing total scan time to under 20 seconds
Solution Approach 2:
The patent applies pre-saturation RF pulses before the gradient echo acquisition to prepare the magnetization state, enabling both B0 and B1 information to be extracted from the same echo train through carefully designed flip angles and timing
2Measurement precision
If separate B0 and B1 mapping sequences are used, then measurement precision is maintained, but signal intensity variations and quantitative measurement errors occur due to inhomogeneous magnetic fields
Solution Approach 1:
By acquiring B0 and B1 information simultaneously from the same gradient echo train, the method eliminates signal intensity variations that would occur between separate sequential scans, as both field maps are obtained under identical magnetization conditions
Solution Approach 2:
The patent uses the phase information from the gradient echo signals to calculate both B0 and B1 fields, with the B1 calculation incorporating feedback from the pre-saturation pulse effects to correct for inhomogeneous field distortions
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
The method achieves accurate B0 and B1 maps in a fraction of the time of traditional methods, maintaining image quality and accuracy, with B0 maps consistent with dual TE methods and B1 maps similar to Bloch-Siegert standards, reducing patient scan duration.
Implementation Method 1
Magnetic resonance (MR) imaging is often used to obtain internal physiological information of a patient
Implementation Method 2
the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field, but precess about it in random order at their characteristic Larmor frequency
Implementation Method 3
magnetic field gradients (Gx, Gy, and Gz) are employed. Typically, the region to be imaged is scanned by a sequence of measurement cycles in which these gradients vary according to the particular localization method being used
Data Source
AI summary
A method for acquiring magnetic resonance (MR) data from a subject with a magnetic resonance imaging (MRI) system includes generating a first pre-saturation RF pulse having a first flip angle for each of at least one slice in the subject, generating a series of first gradient echo sequences following each first pre-saturation RF pulse, and calculating a B0 value for each of the at least one slice. A second pre-saturation RF pulse having a second flip angle is generated for each of the at least one slice in the subject, followed by a series of second gradient echo sequences, and a B1 is calculated for each of the at least one slice based on the first gradient echo sequences and the second gradient echo sequences.