Single Point MRI Gradient Timing for Nanoparticle Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional single point imaging techniques in magnetic resonance imaging face challenges with long imaging times and signal dephasing due to continuously active encoding gradients, which is exacerbated by the presence of magnetic nanoparticles with short T2* decay times.
Innovation Solution
The use of a polarization magnet and gradient coils that apply phase-encoding gradients only after the RF excitation pulse and before signal acquisition, with high magnitude and short rise/fall times, to minimize additional phase dispersion and allow for faster imaging of species with short T2 decay times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If encoding gradients are continuously active during signal acquisition, then spatial encoding is maintained, but signal dephasing increases and imaging time extends
Solution Approach 1:
The patent applies periodic gradient pulses instead of continuous gradients. The gradient is applied in discrete bursts during specific time windows (TE1 and TE2) rather than continuously throughout the acquisition, allowing the signal to be encoded spatially while minimizing dephasing during the acquisition period. This periodic application resolves the contradiction by maintaining encoding accuracy when needed while reducing time loss when not needed.
2Measurement precision
If gradient magnitude is increased to improve spatial resolution, then encoding precision improves, but signal dephasing increases due to longer gradient application time
Solution Approach 1:
The gradient is applied periodically in short bursts rather than continuously, allowing high gradient magnitudes to be used for precise spatial encoding while the periodic nature limits the total duration of gradient application, thereby reducing cumulative dephasing and maintaining signal stability.
Solution Approach 2:
The gradient encoding is performed preliminarily during specific time windows before the signal acquisition completes. By applying the gradient pulses at predetermined intervals (TE1 and TE2) before the full acquisition is complete, the spatial encoding is established early, allowing the remaining acquisition time to be used for signal detection without additional dephasing from continuous gradients.
3Measurement precision
If conventional imaging sequences are used to image magnetic nanoparticles, then anatomical imaging is achieved, but T2* decay causes signal loss before data acquisition completes
Solution Approach 1:
The patent uses a single-point imaging approach that acquires one k-space point per excitation rather than filling entire k-space. This copying strategy samples only the necessary information (magnitude and phase at specific time points) to reconstruct images, dramatically reducing the time required for data acquisition and allowing imaging of rapidly decaying signals from magnetic nanoparticles before T2* decay completes.
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 enables faster imaging with constant voxel size and higher signal-to-noise ratios by halting phase encoding during signal acquisition, effectively capturing the spatial distribution and effect of magnetic particles on anatomical images without significant signal decay.
Implementation Method 1
at least one polarizing magnet controlled and positioned to polarize electron spins in a first region of interest
Implementation Method 2
at least one gradient coil controlled and positioned to generate phase-encoding gradient pulses within a second region of interest
Implementation Method 3
an acquisition window that measures radio frequencies near to the Lamour frequencies of the excited sample
Data Source
AI summary
Apparatuses and methodologies are provided that utilize at least one polarizing magnet controlled and positioned to polarize spins in a first region of interest, at least one gradient coil controlled and positioned to generate phase-encoding gradient pulses within a second region of interest, and at least one radiofrequency coil controlled and positioned to acquire radiofrequency signals from the second region of interest, wherein the at least one gradient coil and at least one radiofrequency coil may be controlled such that application of phase-encoding gradient pulses stops before acquisition of radiofrequency signals.