Multiband RF Encoding for Simultaneous MRI Slice Acquisition
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Solution Overview
Problem
Conventional magnetic resonance imaging (MRI) techniques require serial acquisition of signals from multiple slices, leading to prolonged scan times and increased difficulty in characterizing tissue properties due to the need for skilled interpretation of qualitative images across different machines and configurations.
Innovation Solution
The method employs simultaneous multislice acquisition using multiband radio frequency (RF) pulses with RF-encoding, allowing for the simultaneous production of magnetic resonance signals from multiple slices, which are then separated and compared to a dictionary of signal evolutions to determine quantitative parameters, thereby generating quantitative images efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If serial acquisition of signals from multiple slices is used, then signal separation and interpretation are simplified, but scan time is prolonged
Solution Approach 1:
The patent combines multiple slice acquisitions into a single simultaneous measurement using multiband RF pulses. Multiple slices are excited and acquired at the same time rather than sequentially, merging what were previously separate acquisition processes into one unified operation, thereby reducing scan time while managing complexity through structured signal separation techniques
Solution Approach 2:
The patent introduces RF encoding as an additional dimension for signal differentiation. By applying unique RF encoding patterns to each slice, the system adds a new degree of freedom for signal separation, allowing simultaneous multi-slice acquisition to be resolved through encoding/decoding operations in the RF domain rather than relying solely on temporal separation
2Productivity
If simultaneous multislice acquisition is used, then scan time is reduced, but signal separation becomes more difficult
Solution Approach 1:
The patent applies RF encoding to each slice before the actual signal acquisition takes place. This preliminary encoding step tags each slice's signal with unique identifiers, so that when signals are acquired simultaneously, they can be easily separated by decoding the RF encoding patterns. The preliminary action of encoding simplifies the subsequent signal separation task
Solution Approach 2:
The RF encoding acts as an intermediary mechanism between the simultaneous multi-slice acquisition and the signal separation process. Rather than directly trying to separate mixed signals from multiple slices, the system uses RF encoding/decoding as an intermediate step that transforms the separation problem into a more manageable signal processing task
3Adaptability or versatility
If conventional MRI pulse sequences are used, then qualitative images with various weightings are produced, but skilled interpretation is required for consistent assessment
Solution Approach 1:
The patent transitions from qualitative imaging parameters (different weightings and contrasts) to quantitative parameter measurement (T1, T2, proton density values). By changing the measurement approach from subjective image interpretation to objective quantitative parameter extraction, the system maintains versatile tissue characterization capability while significantly improving interpretation consistency across different machines and configurations
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 scan time by acquiring data from multiple slices simultaneously, enabling efficient characterization of tissue properties and improving the accuracy and consistency of MRI results across different machines and configurations.
Implementation Method 1
The multiband RF pulse provides an RF encoding of the magnetic resonance signals
Implementation Method 2
Characterizing tissue species using nuclear magnetic resonance (NMR) can include identifying different properties of a resonant species
Data Source
AI summary
A magnetic resonance fingerprinting (“MRF”) framework that implements simultaneous multislice acquisition techniques with a Hadamard RF-encoding to simultaneously acquire magnetic resonance data from multiple slices simultaneously is described. As one non-limiting example, magnetic resonance data can be simultaneously acquired from four different slices. In other embodiments, however, the Hadamard encoding can be condensed into one or two acquisitions, rather than four.