Single-Sided MRI Frequency-Sweep DEFT Pulses for Inhomogeneous Fields
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Solution Overview
Problem
Single-sided magnetic resonance imaging (MRI) systems face challenges with inadequate contrast and Signal-to-Noise ratio (SNR) due to inhomogeneous magnetic fields, leading to poor image quality.
Innovation Solution
Implementing a DEFT pulse sequence with frequency sweep RF pulses, including a 90-degree excitation pulse, two 180-degree refocusing pulses, and a 90-degree final excitation pulse, each with specific durations and sweep rates to manage phase dispersion and improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single-sided MRI is used to enable easier patient access and shorter scan time, then productivity and ease of operation are improved, but image quality and SNR deteriorate due to inhomogeneous magnetic fields
Solution Approach 1:
The patent applies parameter changes by using frequency-swept RF pulses instead of conventional fixed-frequency pulses. The frequency sweep rate is specifically optimized to match the magnetic field inhomogeneity characteristics of single-sided MRI systems, allowing effective refocusing of magnetization across the inhomogeneous field and improving image quality while maintaining fast scan times
Solution Approach 2:
The patent implements dynamics by using time-varying frequency pulses (frequency sweeps) rather than static frequency pulses. The frequency of the RF pulses changes dynamically during the pulse duration according to a predetermined sweep rate, enabling the system to adapt to the spatially varying magnetic field strengths in single-sided MRI and achieve uniform image quality across the field of view
2Reliability
If conventional RF pulse sequences are used in inhomogeneous fields, then device complexity is low, but SNR and image quality deteriorate
Solution Approach 1:
The patent changes the temporal frequency parameter of the RF pulses by implementing frequency sweeps with optimized sweep rates. This parameter modification allows the pulse sequence to effectively refocus magnetization in the presence of magnetic field inhomogeneity, significantly improving SNR and image quality while adding only moderate complexity to the pulse sequence design
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 DEFT pulse sequence enhances image quality and SNR in inhomogeneous magnetic fields by effectively refocusing magnetization, allowing for higher quality images to be collected in less time.
Implementation Method 1
single-sided magnetic resonance imaging (MRI) scans
Implementation Method 2
the magnetic field generated by the magnet is inhomogeneous in the field of view
Implementation Method 3
applying a first sweeping frequency pulse having a first duration and a first sweep rate
Implementation Method 4
Driven Equilibrium Fourier Transform (DEFT) is a radio frequency (RF) pulse sequence in which the equilibrium magnetization of nuclei with long T1 is restored rapidly by recycling transverse magnetization
Data Source
AI summary
Single-sided MRI scanners, systems, and methods are disclosed. A method can include applying a first sweeping frequency pulse defining an X axis; applying a second sweeping frequency pulse defining a Y axis; applying a third sweeping frequency pulse defining the Y axis; and applying a fourth sweeping frequency pulse defines a −X axis. The sweep rate of the fourth sweeping frequency pulse can be less than the sweep rate of the third and/or second sweeping frequency pulse. The sweeping frequency pulses can be chirp pulses. Frequency sweep DEFT pulse sequences can provide the benefits of a broader bandwidth and less sensitivity to the inhomogeneity of a single-sided MRI scanner.