MRI Pulse Sequence Slice Thickness Adjustment for CSF Contrast
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Solution Overview
Problem
Conventional magnetic resonance imaging (MRI) techniques using the fast spin echo (FSE) method often fail to achieve sufficient contrast for cerebrospinal fluid (CSF) in T1-weighted and T2-weighted images of the cervical vertebra, leading to inadequate luminance values.
Innovation Solution
The MRI apparatus sets a pulse sequence where the slice thickness for the refocusing pulse is larger than that for the excitation pulse, adjusting the gradient magnetic field intensity to enhance contrast, and collects data on slices without consecutively imaging adjacent slices to reduce interference and improve CSF visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the slice thickness for the refocusing pulse is increased to be larger than that for the excitation pulse, then the CSF contrast is enhanced, but the interference between adjacent slices increases
Solution Approach 1:
The patent divides the imaging process into separate acquisitions for adjacent slices. Instead of simultaneously imaging all slices, the system acquires data from non-adjacent slices in alternating sequences (e.g., slice 1, then slice 3, then slice 2, then slice 4), which segments the interference problem and allows each slice to be imaged with optimized refocusing pulse parameters without contaminating adjacent slices.
Solution Approach 2:
The patent implements periodic acquisition of slice data by alternating between different slice groups in a systematic sequence. This periodic action allows the system to apply larger refocusing pulse slice thickness for improved CSF contrast while maintaining temporal separation between adjacent slice acquisitions, thereby reducing interference effects.
2Device complexity
If conventional FSE method is used with equal slice thickness for excitation and refocusing pulses, then the imaging process is simple, but the CSF contrast is insufficient
Solution Approach 1:
The patent applies different slice thickness parameters locally to different pulses within the FSE sequence. Specifically, the refocusing pulses are configured with a larger slice thickness than the excitation pulse, creating local parameter differentiation that enhances CSF contrast. This local quality change allows optimization of specific image contrast properties without fundamentally altering the overall FSE imaging approach.
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 configuration effectively decreases luminance in T1-weighted images and increases luminance in T2-weighted images, enhancing CSF contrast without extending the echo train space or increasing specific absorption rate (SAR).
Implementation Method 1
magnetic resonance imaging (MRI) apparatus
Implementation Method 2
adjusting the gradient magnetic field intensity
Data Source
AI summary
A magnetic resonance imaging apparatus according to an embodiment includes processing circuitry. The processing circuitry sets a pulse sequence to collect plural echo signals by application of a refocusing pulse more than once after application of an excitation pulse once, and collects data on plural slices that are parallel to each other by executing the pulse sequence more than once. The processing circuitry sets the pulse sequence such that a slice thickness for the refocusing pulse becomes larger than a slice thickness for the excitation pulse, and collects the data on the plural slices by executing the pulse sequence without consecutively collecting data on adjacent ones of the plural slices.