MRI Gradient Field Error Correction via Parallel Echo Signal Measurement
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Solution Overview
Problem
The radial sampling method in MRI imaging is prone to artifacts due to gradient magnetic field non-linearity, requiring additional measurements to correct, which extends imaging time.
Innovation Solution
An MRI apparatus with a measurement controller, correcting processor, and calculation processor that measures parallel echo signals to detect and correct shifts in the peak position of echo signals, reducing artifacts without extending imaging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radial sampling method is used to reduce body movement artifacts, then robustness to body movement is improved, but artifacts due to gradient magnetic field non-linearity increase
Solution Approach 1:
The patent applies preliminary action by measuring the gradient magnetic field distribution before actual imaging and using this pre-acquired information to correct sampling data. The system measures the actual gradient field values at multiple positions, calculates correction values, and applies these corrections during the radial sampling process to eliminate artifacts caused by non-linearity.
2Object-generated harmful factors
If additional measurement is performed to measure gradient magnetic field non-linearity, then artifact correction is improved, but imaging time is extended
Solution Approach 1:
The patent merges the gradient field measurement process with the actual imaging process. Instead of performing separate measurements, the system acquires sampling data that serves dual purposes: both for image reconstruction and for characterizing the gradient field non-linearity. This integration allows correction data to be obtained without extending imaging time.
Solution Approach 2:
The sampling data acquired during imaging serves multiple functions simultaneously. The same data is used for both reconstructing the image and for measuring the gradient magnetic field distribution. This multi-functionality eliminates the need for dedicated measurement time while still providing accurate correction information.
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 effectively reduces artifacts caused by gradient magnetic field errors in non-orthogonal sampling methods while maintaining efficient imaging time.
Implementation Method 1
the effects of non-uniformity of a magnetostatic field distribution and non-linearity of the gradient magnetic field are different among echo signals
Implementation Method 2
obtaining a tomogram of an examination site of an examinee by utilizing a nuclear magnetic resonance (hereinafter referred to as 'NMR') phenomenon
Data Source
AI summary
In a non-cartesian sampling method, in order to reduce an artifact on an image caused by an error of a gradient magnetic field, data for correcting the error caused by the gradient magnetic field are obtained when data used for image reconstruction are obtained, and the data used for the image reconstruction are corrected by using the obtained data for the correction. In order to obtain the data for correcting the error, a block having plural parallel echo signals is measured.