MRI Apparatus Suppressing MT Effect via Dual IR Pulse Sequences
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Solution Overview
Problem
Perfusion techniques using Arterial Spin Labeling (ASL) methods, such as FAIR and pCASL, face challenges in suppressing the Magnetization Transfer (MT) effect, especially in brain imaging, where the perfusion curve fails to return to baseline after repeated spatially selective IR pulse applications, and achieving high Signal-to-Noise Ratio (SNR) is hindered.
Innovation Solution
A magnetic resonance imaging apparatus executes two pulse sequences: one with a spatially non-selective IR pulse and another with both spatially selective and non-selective IR pulses, followed by Cartesian and radial acquisitions, to calculate and generate images that suppress the MT effect, allowing for 4D non-contrast-enhanced ASL imaging in regions like the brain, muscle, or kidney.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spatially selective IR pulse is repeatedly applied in FAIR or pCASL methods, then high SNR is achieved, but the perfusion curve fails to return to baseline and MT effect is not suppressed
Solution Approach 1:
The patent divides the IR pulse application into two separate sequences: one with spatially selective IR pulse and another with spatially non-selective IR pulse. This segmentation allows independent optimization of each sequence's function, where the selective pulse provides high SNR while the non-selective pulse suppresses MT effect, resolving the contradiction between SNR and baseline return.
Solution Approach 2:
The patent combines two different IR pulse sequences (spatially selective and spatially non-selective) into a unified imaging approach. By merging these sequences and processing their data separately, the system achieves both high SNR from the selective pulse and MT suppression from the non-selective pulse, eliminating the baseline drift problem.
2Measurement precision
If a spatially selective IR pulse is continuously applied, then high SNR is achieved, but the MT effect needs to be suppressed especially in brain imaging
Solution Approach 1:
The patent segments the IR pulse application into two distinct sequences: one with spatially selective IR pulse for high SNR acquisition, and another with spatially non-selective IR pulse for MT effect suppression. This segmentation allows each sequence to address its specific function without interference, resolving the contradiction between SNR and MT suppression.
Solution Approach 2:
The spatially non-selective IR pulse sequence acts as an intermediary mechanism to suppress the MT effect. By applying this non-selective pulse separately and processing its data independently, the system effectively suppresses MT effect without compromising the high SNR achieved by the spatially selective pulse sequence.
3Reliability
If multiple pulse sequences with different TI periods are executed, then MT effect is suppressed, but examination time increases
Solution Approach 1:
The patent performs preliminary actions by executing multiple pulse sequences with different TI periods to suppress MT effect before the main imaging process. By pre-calculating and pre-executing these sequences, the system optimizes MT suppression while managing examination time through efficient sequence design and data processing.
Solution Approach 2:
The patent utilizes parameter changes by varying the inversion time (TI) period across multiple pulse sequences. By systematically changing the TI parameter and processing the resulting data separately, the system achieves effective MT suppression while controlling examination time through optimized parameter selection and efficient data handling.
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 effectively suppresses the MT effect, enabling precise 4D non-contrast-enhanced ASL imaging and improving medical examination throughput, and when combined with MRA, allows for accurate prediction of blood vessel stenosis or occlusion.
Implementation Method 1
how to suppress the MT effect is important
Implementation Method 2
a spatially non-selective IR pulse and a spatially selective IR pulse are applied
Implementation Method 3
by using an Arterial Spin Labeling (ASL) method by which a Radio Frequency (RF) pulse is radiated onto blood vessels so as to invert blood spins
Implementation Method 4
a spatially non-selective IR pulse and a spatially selective IR pulse are applied
Implementation Method 5
a gradient coil and a gradient power supply, a couch, couch controlling circuitry
Implementation Method 6
a reception coil and a receiver circuitry, sequence controlling circuitry and processing circuitry are configured to generate a magnetic resonance image
Data Source
AI summary
A magnetic resonance imaging apparatus includes sequence controlling circuitry and processing circuitry. The sequence controlling circuitry executes (i) a first pulse sequence in which a spatially selective Inversion recovery (IR) pulse and a spatially non-selective IR pulse are applied, and (ii) a second pulse sequence in which the spatially non-selective IR pulse is applied without applying the spatially selective IR pulse, while varying the first TI period, with respect to a plurality of first TI periods. The sequence controlling circuitry executes (iii) the third pulse sequence in which the spatially selective IR pulse and the spatially non-selective IR pulse are applied, and (iv) the fourth pulse sequence in which the spatially non-selective IR pulse is applied without applying the spatially selective IR pulse. The processing circuitry generates a magnetic resonance image of an imaged region based on data obtained from the third pulse sequence and the fourth pulse sequence.