DANTE Pulse Trains for Flowing Spin Suppression in MRI
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MRI techniques face challenges in effectively suppressing flowing spin signals, particularly in multi-slice and multi-slab imaging, due to issues like signal loss, eddy currents, and specific absorption rate (SAR) problems, limiting their adaptability for high-quality black blood and CSF suppression.
Innovation Solution
The use of modified DANTE pulse trains in combination with gradient pulses to differentiate and suppress moving spins, such as flowing blood or CSF, while preserving static tissue signal, through a non-selective unbalanced steady-state free precession module that manipulates both static and moving spins via their steady-state behaviors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DIR technique is used for flowing spin suppression, then reasonable flowing spin suppression is achieved, but imaging acquisition efficiency is compromised due to single-slice sequential acquisition requirement
Solution Approach 1:
The patent divides the imaging process into multiple segments by implementing multi-slice and multi-slab acquisitions. The DANTE pulse train preparation module is applied independently to each slice or slab, allowing parallel processing and significantly improving acquisition efficiency compared to sequential single-slice methods while maintaining flow suppression quality.
Solution Approach 2:
The patent employs periodic DANTE pulse train sequences applied before each imaging readout. This periodic preparation module is repeated for each slice and slab acquisition, enabling efficient multi-slice and multi-slab imaging while maintaining consistent flow suppression performance across all segments.
2Reliability
If MSDE preparation module is used for flowing spin suppression, then robust flowing spin suppression is achieved, but SAR problems due to multiple 90° and 180° pulses compromise multi-slice acquisition at high static field
Solution Approach 1:
The patent changes the RF pulse parameters by using low flip-angle DANTE pulses instead of high flip-angle 90° and 180° pulses. This parameter modification significantly reduces the specific absorption rate while maintaining effective flow suppression, enabling safe multi-slice acquisition at high static field strengths.
Solution Approach 2:
The patent replaces the expensive and SAR-intensive MSDE preparation with a simpler, lower-cost DANTE pulse train approach. The DANTE module achieves comparable or superior flow suppression with much lower energy consumption, making it suitable for multi-slice and multi-slab acquisitions at high fields.
3Illumination intensity
If standard SSFP readout imaging sequences are used, then inflow signal enhancement is strong, but flowing spin signal attenuation effects are overwhelmed and cannot be fully utilized
Solution Approach 1:
The patent applies preliminary flow suppression using the DANTE preparation module before the SSFP readout. This preliminary anti-action attenuates the flowing spin signal in advance, allowing the SSFP sequence to provide sufficient inflow enhancement for static tissues while the DANTE module ensures flowing spins are suppressed, achieving both objectives simultaneously.
4Reliability
If DIR imaging is used for multi-slab 3D imaging, then flowing spin suppression is achieved, but outflow volume required for effective blood nulling is substantially increased compared to 2D imaging
Solution Approach 1:
The patent applies local flow suppression by using slice-selective or slab-selective DANTE preparation modules that target specific regions of interest. This local approach suppresses flow in the desired areas without requiring large outflow volumes, making multi-slab 3D imaging efficient and effective.
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 provides superior signal suppression of flowing spins, is insensitive to spin velocity, and allows for high-quality black blood imaging with reduced SAR, enabling efficient multi-slice and multi-slab acquisitions, and improved diagnostic imaging.
Implementation Method 1
Delay Alternating with Nutation for Tailored Excitation (DANTE) pulse trains are a method used for frequency-selective excitation of a narrow frequency region in high-resolution NMR spectroscopy
Implementation Method 2
flow crushing gradients
Data Source
AI summary
Systems and methods for motion sensitized and motion suppressed quantitative imaging of a subject are provided as a train of interlaced radio frequency (RF) and magnetic field gradient pulses. Non-selective Delay Alternating with Nutation for Tailored Excitation (DANTE) pulse trains may be used in combination with gradient pulses and short repetition times as motion-sensitive preparation modules. In one or more embodiments, the systems and methods may use a train of low flip angle radio frequency (RF) pulses in combination with a blipped field gradient pulse between each RF pulse, repeated regularly. While the longitudinal magnetization of static tissue is mostly preserved, moving spins are largely (or fully) suppressed since they fail to establish transverse steady state due to a spoiling effect caused by flow along the applied gradient. The present systems and methods can be incorporated into any existing imaging readout for applications in vessel wall imaging, angiography, high resolution structural MRI, and also functional MRI.