Phase Correction Reference Data Acquisition in MRI
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current phase correction methods in magnetic resonance technology either extend the minimum echo time or fail to adequately correct dynamic faults like B0 drifts, leading to ghost artifacts, especially in diffusion-weighted imaging.
Innovation Solution
A method for acquiring reference data for phase correction by recording echo signals with alternating readout gradients before and after the RF refocusing pulse, allowing for dynamic fault correction and matching phase evolution with measurement data, without extending the echo time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase correction recording is integrated into the pulse sequence diagram, then phase correction can be performed, but the minimum echo time is extended
Solution Approach 1:
The reference data for phase correction is acquired in advance, between the RF excitation pulse and the measurement data acquisition, rather than being integrated into the measurement pulse sequence. This preliminary acquisition of reference data allows phase correction to be performed without extending the minimum echo time of the actual measurement.
2Loss of time
If separate phase correction recording is performed outside the pulse sequence, then echo time is not extended, but dynamic faults like B0 drifts cannot be corrected
Solution Approach 1:
The reference data is acquired in a preliminary manner immediately before the measurement data, in the time window between the RF excitation pulse and the echo signal recording. This timing ensures that the reference data reflects the current magnetic field conditions, allowing correction of dynamic faults like B0 drifts while not extending the minimum echo time.
Solution Approach 2:
The system uses the newly acquired reference data to dynamically correct phase errors in the measurement data through complex multiplication. This feedback mechanism ensures that phase corrections adapt to changing magnetic field conditions, effectively correcting dynamic faults like B0 drifts.
3Measurement precision
If reference data is acquired before measurement data, then phase evolution matches measurement data, but additional time for reference acquisition is required
Solution Approach 1:
The reference data acquisition is performed in the idle time window between the RF excitation pulse and the measurement data acquisition, utilizing otherwise unused time. This preliminary action ensures phase evolution matching without adding to the overall measurement time, as it occurs during the preparation phase rather than extending the echo time.
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 effectively corrects phase errors and dynamic faults, reducing ghost artifacts and ensuring accurate image reconstruction without increasing the minimum echo time or echo time extension.
Implementation Method 1
to trigger nuclear spin resonances that can be measured as signals, radio-frequency excitation pulses (RF pulses) are beamed into the object under examination
Implementation Method 2
For position encoding of the measurement data, rapidly switched magnetic gradient fields, called gradients for short, are overlaid on the constant magnetic field
Implementation Method 3
acquisition of reference data by recording at least two echo signals while switching readout gradients with different polarity
Data Source
AI summary
In a method and system for acquiring measurement data reference data for a phase correction of the measurement data, a RF excitation pulse is provided to excite spins in the object under examination, one or more RF refocusing pulses are provided to refocus the spins excited by the RF excitation pulse, measurement data is acquired by recording echo signals of refocused spins excited by the RF excitation pulse by switching readout gradients that alternate in their polarity, at least two echo signals are recorded while switching readout gradients with different polarity acquire reference data, chronologically between the providing of the RF excitation pulse and the acquisition of the measurement data, and correction data is determined for phase correction of phase errors contained in the measurement data based on the acquired reference data.