Magnetic Resonance Imaging Device with Phase-Modulated Slice Excitation

Solution Overview

Problem

Magnetic resonance spectroscopy (MRS) measurements face challenges in accurately acquiring data from multiple regions due to differences in axes alignment between measurement regions and positioning images, leading to low signal-to-noise ratio and inefficient measurement times, especially when regions share common slices.

Innovation Solution

A technique where a radio frequency magnetic field of different phases is used to excite slices not common to the region of interest, allowing for simultaneous thermal equilibration of other regions during measurement, enabling efficient acquisition of highly accurate results by aligning measurement axes with positioning axes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If three slices are used to localize a measurement region in the PRESS method, then the measurement precision is improved, but the measurement time increases due to thermal equilibrium restoration requirements

Engineering Contradiction:

Improvelocalization precisionVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The invention applies a preparatory radio frequency magnetic field pulse with a specific phase before the main excitation pulse. This preliminary action pre-conditions the nuclear magnetization in regions that will share common slices, allowing them to be rapidly switched between measurement and equilibrium states without waiting for full thermal recovery, thereby reducing measurement time while maintaining localization precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention implements periodic alternation between measuring a target region and allowing a comparison region to reach thermal equilibrium. By rhythmically switching which region is actively measured and which is recovering, the system optimizes the use of shared slices and reduces idle waiting time, effectively halving the total measurement time compared to conventional sequential measurement

Inventive Principle:

Principle #19Periodic action

2Device complexity

If the same slice is used for both target and comparison regions, then the device complexity is reduced, but the productivity decreases due to sequential measurement requirements

Engineering Contradiction:

Improveslice configurationVSAvoidmeasurement efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The invention implements periodic alternation between measuring a target region and allowing a comparison region to reach thermal equilibrium. By rhythmically switching which region is actively measured and which is recovering, the system optimizes the use of shared slices and reduces idle waiting time, effectively halving the total measurement time compared to conventional sequential measurement

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The invention changes the phase parameter of the radio frequency magnetic field pulse to differentiate between target and comparison regions. By applying pulses with different phases (0° for target region, 180° for comparison region), the system can selectively manipulate nuclear magnetization in overlapping slice regions, enabling efficient alternating measurement without requiring additional hardware complexity

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If measurements are repeated to secure signal-to-noise ratio, then the measurement precision is improved, but the loss of time increases due to inability to use waiting time for other measurements

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidtotal measurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The invention eliminates idle waiting time by continuously performing useful measurements. While one region is being measured, the other region is simultaneously allowed to reach thermal equilibrium in preparation for its measurement. This continuous utilization of measurement time for productive purposes rather than idle waiting doubles the measurement throughput while maintaining the required signal-to-noise ratio through repeated measurements

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The invention implements periodic alternation between measuring a target region and allowing a comparison region to reach thermal equilibrium. By rhythmically switching which region is actively measured and which is recovering, the system optimizes the use of shared slices and reduces idle waiting time, effectively halving the total measurement time compared to conventional sequential measurement

Inventive Principle:

Principle #19Periodic action

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 allows for efficient and accurate measurement of multiple regions with improved signal-to-noise ratio and reduced measurement time, as regions can be measured alternately without waiting for thermal equilibrium restoration.

Implementation Method 1

irradiate a radio frequency magnetic field of a specific frequency to a subject placed in a static magnetic field to excite nuclear magnetization of atomic nuclei

Methodology Applied

Scientific EffectNuclear magnetization excitation: Electromagnetic Induction

Implementation Method 2

a gradient magnetic field pulse for selection of a predetermined slice is applied

Methodology Applied

Scientific EffectMagnetic field gradient: Magnetic Field

Implementation Method 3

magnetic resonance signals acquired from one to several regions are separated into groups of signals for each molecule on the basis of difference of resonance frequency (henceforth referred to as chemical shift) due to difference in chemical bonds of various molecules

Methodology Applied

Scientific EffectChemical shift:

Implementation Method 4

the measured magnetic resonance signals are subjected to Fourier transform in the time axis direction to acquire magnetic resonance spectrum signals

Methodology Applied

Scientific EffectFourier transform:

Data Source

PatentUS8547101B2Magnetic resonance imaging device

Publication Date: 2013.10.01 FUJIFILM CORP

AI summary

In MRS measurement using magnetic resonance highly precise results are efficiently obtained with coincidence of axes with axes in positioning image. In measurement according to the PRESS method for a plurality of regions each localized (specified) with a set of perpendicularly intersecting three slices, wherein one or two slices are common to the sets of three slices localizing the regions, and slices not common do not intersect, a slice not common to those of a region to be selectively excited is excited with a radio frequency magnetic field of which phase is different by 180 degrees from that of a radio frequency magnetic field used for exciting the region to be selectively excited a number of times equal to the number of common slices, and during the measurement of the region to be selectively excited, a group of regions other than the region to be selectively excited are thermally equilibrated.