NMR Spectroscopy Using Intermittently Blipped Phase Gradients
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Solution Overview
Problem
Current nuclear magnetic resonance spectroscopy (NMR) methods face challenges in achieving short acquisition times while maintaining a good signal-to-noise ratio (SNR) and reducing motion artifacts, often resulting in longer acquisition and processing times, especially in chemical shift imaging (CSI) techniques.
Innovation Solution
A method involving intermittently blipped phase gradient pulses is applied during NMR signal sensing, allowing for incremental shifting in k-space without frequency encoding magnetic field gradients, enabling efficient spectroscopic imaging with reduced acquisition times and motion artifacts, and allowing for multiple voxel locations to be acquired from a single NMR signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional chemical shift imaging (CSI) with phase-encoding gradients is used, then spatial encoding and metabolite maps are achieved, but acquisition time becomes long
Solution Approach 1:
The k-space data collection is segmented into multiple segments, with each segment collected during a different echo train. This allows parallel acquisition of spatial encoding information across multiple echoes, significantly reducing the total number of phase-encoding steps required and thus reducing acquisition time while maintaining spatial encoding precision
Solution Approach 2:
Multiple echoes are prepared in advance using a multi-echo pulse sequence, with each echo containing phase-encoded spatial information. By preparing these echoes beforehand and collecting them in parallel, the method eliminates the need for sequential acquisition of each phase-encoding step, thereby reducing acquisition time without sacrificing measurement precision
2Productivity
If fast acquisition methods like echo planar spectroscopic imaging (EPI) are used, then acquisition time is reduced, but signal-to-noise ratio (SNR) deteriorates
Solution Approach 1:
The method uses multiple continuous echo trains to collect k-space data segments, maximizing the utilization of the available signal throughout the echo train. By continuously acquiring useful signal data across multiple echoes rather than relying on a single fast readout, the method maintains high SNR while achieving fast acquisition through parallel processing of the continuous signal
Solution Approach 2:
Multiple k-space data segments from different echo trains are merged and combined during reconstruction. This combining process integrates the signal information from multiple echoes, effectively increasing the total signal accumulated while distributing the acquisition time, thereby maintaining high SNR while achieving fast overall acquisition
3Productivity
If high-speed imaging techniques are used, then acquisition time is reduced, but image artifacts increase
Solution Approach 1:
The method dynamically assigns different segments of k-space to different echo trains based on the signal characteristics and decay patterns. By adaptively distributing the data collection across multiple echoes with different temporal characteristics, the method avoids the artifacts that arise from attempting to capture all data in a single static readout, thereby reducing artifacts while maintaining high acquisition speed
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 data acquisition with improved SNR and reduced image artifacts, allowing for efficient 2D or 3D imaging with shorter acquisition times, enhancing patient comfort and maintaining spectral resolution.
Implementation Method 1
positioning a sample in a homogeneous stationary magnetic field directed along an axis
Implementation Method 2
preparing nuclei in at least a predetermined volume of the sample for resonant emission of an NMR signal and creating this NMR signal, in which this preparing and creating comprises irradiating the sample with at least one radio-frequency excitation pulse
Implementation Method 3
During this sensing, a plurality of intermittently blipped phase gradient pulses are applied to incrementally shift a position in k-space
Data Source
AI summary
A method is provided for performing NMR spectroscopy. The method comprises positioning a sample in a homogeneous stationary magnetic field directed along an axis, preparing nuclei in at least a predetermined volume of the sample for resonant emission of an NMR signal and creating this NMR signal. This comprises irradiating the sample with at least one RF excitation pulse in accordance with an MRI sequence preparation and/or evolution module. The method also comprises sensing the NMR signal in the absence of frequency encoding magnetic field gradients such that analysis of the NMR signal yields a chemical shift spectrum from the nuclei. During this sensing, a plurality of intermittently blipped phase gradient pulses are applied to incrementally shift a position in k-space such that different time segments of the NMR signal, demarcated by the blipped phase gradient pulses, correspond to different predetermined locations in k-space.