Parallel MR Imaging RF Coil Sensitivity Mapping via Stimulated Echo
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Solution Overview
Problem
Current MR imaging techniques require multiple preparation scans to determine RF coil sensitivity profiles and B1/B0 mapping, leading to increased scan times and inefficiencies, especially at high magnetic field strengths.
Innovation Solution
A stimulated echo sequence is used to acquire both direct and conjugated stimulated echo signals via RF receiving antennas with different sensitivity profiles and a body RF coil, allowing for simultaneous sensitivity mapping and B1/B0 mapping in a single scan, leveraging the DREAM B1 mapping approach to accelerate data acquisition and reduce phase wrapping effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple preparation scans are performed to determine RF coil sensitivity profiles and B1/B0 mapping, then measurement precision is improved, but scan time increases
Solution Approach 1:
The patent combines multiple preparation scans (RF coil sensitivity mapping and B1/B0 mapping) into a single integrated stimulated echo sequence. The system acquires signals from both array RF coils and body RF coil simultaneously within one scan, merging functions that traditionally required separate scans. This is achieved by implementing a unified pulse sequence that collects data for both sensitivity profiles and magnetic field mapping in parallel, directly resolving the time penalty associated with multiple sequential scans while maintaining measurement precision.
Solution Approach 2:
The stimulated echo sequence is designed to serve multiple functions simultaneously: it performs RF coil sensitivity mapping, B1 mapping, and B0 mapping all within a single scan protocol. The sequence structure allows it to extract multiple types of information from the same acquired signals, making the imaging system more versatile and efficient. This multi-functionality eliminates the need for separate dedicated scans for each mapping type, directly addressing the time consumption issue.
2Measurement precision
If multiple separate scans are used for sensitivity mapping and B1/B0 mapping, then measurement accuracy is maintained, but productivity decreases
Solution Approach 1:
The patent merges sensitivity mapping and B1/B0 mapping into a single integrated workflow. The stimulated echo sequence acquires all necessary data for both types of mapping simultaneously, combining what were previously separate productivity-reducing scans into one efficient operation. This maintains measurement accuracy while doubling the effective productivity by eliminating the sequential execution overhead.
Solution Approach 2:
The imaging system maintains continuous useful action throughout the single scan by simultaneously acquiring data for multiple mapping purposes. Rather than interrupting the scan sequence to perform separate sensitivity and B1/B0 mapping scans, the system continuously collects all necessary information in an uninterrupted flow, maximizing productivity while preserving measurement quality.
3Device complexity
If conventional separate scanning methods are used, then device complexity is low, but scan time increases
Solution Approach 1:
The patent implements a merged scanning protocol where the stimulated echo sequence integrates multiple mapping functions. While the internal sequence structure is more complex than simple sequential scans, the user-facing protocol remains simple - a single scan replaces multiple scans. This approach reduces the effective time loss without requiring the user to manage multiple separate scanning procedures, balancing device complexity with time efficiency.
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 enables fast and robust determination of RF coil sensitivity profiles and B1/B0 maps, reducing scan time and making the technique suitable for real-time applications by integrating sensitivity mapping and B1/B0 mapping into a single pre-scan, thus enhancing the efficiency of MR imaging.
Implementation Method 1
Image-forming MR methods which utilize the interaction between magnetic fields and nuclear spins in order to form two-dimensional or three-dimensional images
Implementation Method 2
The variation of the magnetization can be detected by means of one or more receiving RF coils which are arranged and oriented within an examination volume of the MR device in such a manner that the variation of the magnetization is measured in the direction perpendicular to the z-axis
Implementation Method 3
These energy levels can be excited (spin resonance) by application of an electromagnetic alternating field (RF field, also referred to as B1 field) of defined frequency
Data Source
AI summary
The invention relates to a method of MR imaging of an object (10). The problem of the invention is to provide an improved MR imaging technique that enables fast and robust determination of spatial sensitivity profiles of RF receiving antennas (11, 12, 13) used in parallel imaging as well as B1 and/or B0 mapping. The method of the invention comprises subjecting the object (10) to a stimulated echo sequence. Two or more stimulated echo signals (STE, STE*) are acquired, namely a direct stimulated echo signal (STE) and a conjugated stimulated echo signal (STE*), wherein at least one of the stimulated echo signals (STE, STE*) is received in parallel via an array of two or more RF receiving antennas (11, 12, 13) having different spatial sensitivity profiles, and wherein at least another one of the stimulated echo signals (STE, STE*) is received via a body RF coil (9) having an essentially homogeneous spatial sensitivity profile. Sensitivity maps indicating the spatial sensitivity profiles of the individual RF receiving antennas (11, 12, 13) of the array are derived by comparing the stimulated echo signals (STE, STE*) received via the array of RF receiving antennas (11, 12, 13) with the stimulated echo signals (STE, STE*) received via the body RF coil (9). Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).