Movement-Corrected B1 Field Mapping After Contrast Injection
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Solution Overview
Problem
Existing magnetic resonance fingerprinting (MRF) methods fail to generate accurate B1 field maps in regions of interest with high dynamic levels due to T1 time shortening caused by contrast medium injection, preventing the evaluation of physiological parameter maps.
Innovation Solution
A method involving multiple scan portions to record MR signals before and after contrast medium administration, correcting the B1 field map for movement changes, allowing accurate B1 field maps to be used despite contrast medium injection, enabling the generation of quantitative physiological MR parameter maps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If contrast medium is injected into the person under examination, then dynamic contrast medium distribution information can be acquired, but the T1 time is shortened at certain locations making B1 determination no longer possible
Solution Approach 1:
The examination is divided into two separate scan portions: a first scan portion performed before contrast medium administration to acquire the B1 field map, and a second scan portion performed after contrast medium administration to acquire dynamic contrast medium distribution information. This segmentation allows each scan to be optimized for its specific purpose without interference from the other.
Solution Approach 2:
The B1 field map is determined in advance, before the contrast medium is administered. This preliminary acquisition of the B1 field map ensures that the data is obtained when T1 times are not shortened by the contrast medium, while still being available for use in analyzing the subsequent dynamic contrast medium distribution scans.
2Measurement precision
If a B1 field map is recorded before the MRF scan with contrast medium, then accurate B1 field map can be obtained, but the regions of interest with high dynamic level cannot be evaluated
Solution Approach 1:
The examination protocol is segmented into distinct phases: (1) B1 field map acquisition before contrast administration, (2) dynamic contrast medium distribution imaging after administration, and (3) physiological parameter map generation using both the pre-acquired B1 field map and the dynamic contrast data. This segmentation resolves the contradiction by allowing each phase to serve its specific function.
Solution Approach 2:
The B1 field map acquired before contrast administration serves as an intermediary data set that can be applied to the subsequent dynamic contrast medium distribution scans. This intermediary B1 field map enables the evaluation of physiological parameter maps from the contrast-enhanced scans without requiring a new B1 map after contrast administration.
3Measurement precision
If multiple scan portions are performed to correct for movement changes, then accurate B1 field map can be determined, but the examination time increases
Solution Approach 1:
The B1 field map is acquired in advance during the first scan portion, and movement corrections are applied to this pre-acquired data rather than requiring repeated B1 field map acquisitions. This preliminary acquisition approach reduces the total examination time while maintaining accuracy through post-processing corrections.
Solution Approach 2:
Instead of re-acquiring the B1 field map after contrast administration, the patent uses the pre-acquired B1 field map as a template or copy, which is then corrected for movement changes by comparing positions from the first and second scan portions. This copying approach is more time-efficient than repeated acquisitions.
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
Enables the calculation of accurate B1 field maps over the whole object, allowing for precise determination of physiological parameters despite contrast medium administration, by correcting for movement-related changes using a movement-corrected B1 field map.
Implementation Method 1
Magnetic resonance fingerprinting (MRF) is a technology for operating quantitative imaging by MR systems
Implementation Method 2
an important parameter in the simulation is the trajectory of the magnetic field gradients and the high frequency (HF) pulses that are used in the signal recording
Data Source
AI summary
A method is provided for determining a movement-corrected B1 field map on contrast medium injection, wherein before the injection, a B1 field map is determined. Following the contrast medium administration, a position change is determined at the position at which the B1 field map was determined. With the position change and the B1 field map, the movement-corrected B1 field map is determined.