MRI Bone Visualization via Phase Ramp and Dataset Subtraction

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Solution Overview

Problem

Current magnetic resonance imaging (MRI) technologies are inadequate for effective three-dimensional bone imaging, as they struggle to provide clear visualization of bone structures, relying on computed tomography (CT) for bone imaging, and existing MRI methods for bone detection and segmentation are not sufficient.

Innovation Solution

A system and method for bone imaging using MRI that involves generating an echo MRI dataset with a radial sampling scheme and an echo time greater than or equal to the T2 value of bone, applying a phase ramp to enhance bone signal intensity, and combining datasets to suppress background structures, thereby improving bone visualization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional MRI methods are used for bone imaging, then soft tissue visualization is improved, but bone structure visualization deteriorates

Engineering Contradiction:
Improvesoft tissue signal intensityVSAvoidbone structure visualization quality
Core Design Contradiction:
Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent applies different processing strategies to different tissue types by using tissue-specific T2 relaxation time thresholds. Bone tissue (with T2 ≤ 1 ms) is selectively enhanced using the long TE sequence, while soft tissues are imaged using conventional short TE sequences, allowing each tissue type to be optimized independently

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the echo time parameter to be greater than or equal to the T2 relaxation time of bone tissue (TE ≥ T2_bone). This parameter change causes bone signal to decay to near zero while soft tissue signal remains, enabling selective bone suppression and improved bone margin visualization through subtraction imaging

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If ultrashort echo time sequences are used for bone imaging, then bone signal is improved, but imaging complexity and noise increase

Engineering Contradiction:
Improvebone signal intensityVSAvoidimaging sequence complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of trying to preserve bone signal using ultrashort TE, the patent inverts the approach by using a long TE that allows bone signal to decay completely. This inversion transforms the problem from bone signal preservation to bone signal suppression, simplifying the sequence design and reducing noise

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts and removes the bone signal from the imaging process by allowing it to decay to zero through appropriate TE selection. This extraction of the problematic bone signal eliminates the need for complex ultrashort TE sequences and reduces overall image noise

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If long echo time sequences are used for bone imaging, then bone signal suppression is improved, but signal-to-noise ratio deteriorates

Engineering Contradiction:
Improvebone tissue differentiationVSAvoidsignal-to-noise ratio
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent employs periodic action by acquiring two separate MRI sequences with different echo times (one with TE ≥ T2_bone for bone suppression and one with short TE for high SNR), then combining them through subtraction. This periodic acquisition strategy allows optimal imaging conditions for different tissue types to be alternated and then integrated

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The final image is created as a composite by subtracting the long TE image (with suppressed bone signal) from the short TE image (with high SNR). This composite imaging approach combines the advantages of both sequences: bone suppression from the long TE sequence and high signal-to-noise ratio from the short TE sequence

Inventive Principle:
Principle #40Composite materials

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 enhances bone tissue visualization with improved signal-to-noise ratio and efficient data processing, allowing for effective bone imaging without the need for ultrashort echo times, reducing complexity and noise, and facilitating real-time imaging and diagnostic quality.

Implementation Method 1

the processing unit is configured to apply a phase ramp to the radial sampling lines of the complex data according to the radial sampling scheme to obtain a bone-enhanced image dataset

Methodology Applied
Scientific EffectPhase ramp:

Implementation Method 2

wherein the echo time is greater than or equal to a predetermined T 2 value of a bone

Methodology Applied
Scientific EffectT2 relaxation:

Implementation Method 3

magnetic resonance imaging system and a computer system

Methodology Applied
Scientific EffectMagnetic resonance:

Implementation Method 4

The combining unit may help to remove the non-bone structures, using e.g. comparison techniques and/or susceptibility induced phenomena

Methodology Applied
Scientific EffectBackground suppression:

Data Source

PatentEP3201643B1Magnetic resonance imaging with enhanced bone visualization
Publication Date: 2021.01.27 MRIGUIDANCE BV
  • EP3201643B1 patent drawingFigure 1A~2A
  • EP3201643B1 patent drawingFigure 2B~3
  • EP3201643B1 patent drawingFigure 4

AI summary

A system for bone imaging is disclosed. A processing unit is provided for processing an echo MRI dataset. The processing unit is configured to apply a phase ramp to the radial sampling lines of the complex data according to the radial sampling scheme to obtain a bone-enhanced image dataset, wherein a single phase ramp is applied to a radial sampling line of the sampling scheme, which radial sampling line extends on both sides of an origin defined by the echo time, and wherein the phase ramp is based on an equation. A combining unit is provided for combining the MRI dataset with the bone-enhanced image dataset to obtain a background suppressed image dataset.