Interleaved MR Sequence for Quantification
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Solution Overview
Problem
Current MRI methods require multiple scans to measure T1, T2, and PD, leading to excessive scan time and limited clinical application, and rely on conventional contrast images for diagnosis, which are not directly meaningful.
Innovation Solution
A method that simultaneously measures T1, T2, PD, and B1 in a single MR sequence using a multi-slice, multi-echo, and multi-delay acquisition, with a slice-selective pre-pulse and multi-echo acquisition technique, allowing for absolute quantification of these parameters within a clinically acceptable time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple scans are used to measure T1, T2, and PD, then measurement precision is improved, but scan time increases excessively
Solution Approach 1:
The patent combines multiple measurement sequences (T1, T2, PD) into a single integrated MR sequence. The method uses an interleaved sequence structure where different slice selections and echo times are combined in one scan, allowing simultaneous acquisition of multiple parameters without requiring separate scans for each parameter.
Solution Approach 2:
The patent introduces a multi-dimensional acquisition approach by using multiple echo times and multiple slice selections within a single sequence. This dimensional expansion allows the system to capture multiple relaxation parameters from different temporal and spatial dimensions simultaneously, transforming a sequential measurement process into a parallel one.
2Ease of operation
If conventional contrast images are used for diagnosis, then ease of operation is maintained, but measurement precision for absolute quantification is lost
Solution Approach 1:
The patent creates synthetic contrast images by copying and transforming the measured physical parameters (T1, T2, PD, B1) into image formats that resemble conventional MR images. This allows the system to provide both absolute quantitative data and visually intuitive contrast images derived from the same single scan, eliminating the need for multiple separate scans.
3Loss of time
If a single sequence measures all parameters, then scan time is reduced, but device complexity increases
Solution Approach 1:
The patent segments the single MR sequence into distinct functional phases: a preparation phase with slice-selective pre-pulses, an acquisition phase with multi-echo readouts, and a processing phase for parameter extraction. This segmentation allows the complex sequence to be managed through modular, well-defined stages, making the overall system more controllable and easier to implement despite the integrated nature of the measurement.
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
Enables rapid and accurate measurement of T1, T2, PD, and B1, reducing scan time and providing absolute quantification for improved diagnostic capabilities, with the ability to synthesize conventional contrast images from these parameters, enhancing clinical utility.
Implementation Method 1
The RF excitation of the MR scanner is performed by a rotating B1 field inside an RF transmission coil
Implementation Method 2
The realignment of nuclear spins with the magnetic field is termed longitudinal relaxation and the time (typically about 1 sec) required for a certain percentage of the tissue nuclei to realign is termed 'Time 1' or T1
Implementation Method 3
T2-weighted imaging relies upon local dephasing of spins following the application of the transverse energy pulse; the transverse relaxation time (typically about 100-200 ms) is termed 'Time 2' or T2
Implementation Method 4
When the object to be imaged is placed in a powerful, uniform magnetic field the spins of the atomic nuclei with non-integer spin numbers within the tissue all align either parallel to the magnetic field or anti-parallel
Data Source
AI summary
A magnetic resonance sequence includes an interleaved slice-selective pre-pulse and a slice-selective multi-echo acquisition. This sequence is repeated with different delays between the pre-pulse and the acquisition resulting in a matrix of complex images. Based on this matrix T1 and T2 relaxations, proton density and the B1 field can be estimated. These quantified parameters enable synthetic magnetic resonance imaging (MRI) and form a robust input for tissue segmentation in computer aided diagnosis for MRI.