Segmented Multi-Channel RF Transmitter for MRI Homogeneity

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Solution Overview

Problem

Conventional MRI systems face increasing image inhomogeneity issues at higher field strengths due to signal intensity variations and specific absorption rate (SAR) limitations, which compromise patient safety and image quality.

Innovation Solution

A multi-channel RF transmit system with segmented RF transmitter elements, driven by independent RF waveform generators and amplifiers, allowing for precise control of RF field patterns to correct for inhomogeneities and reduce SAR, particularly by segmenting coils in the z-direction and using 2D or 3D arrangements of transmitter elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If higher field strength is used to improve image quality, then image quality improves, but image inhomogeneity increases due to signal intensity variations and dielectric resonance effects

Engineering Contradiction:

Improveimage qualityVSAvoidimage homogeneity

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The RF transmitter elements are segmented into multiple independently controllable segments along the z-direction and longitudinal direction. This segmentation allows different segments to be driven with different RF signals, enabling spatially selective RF pulses that can compensate for inhomogeneities in different regions of the examination object, thereby maintaining image homogeneity at higher field strengths

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different segments of the RF transmitter elements are assigned different RF signals with varying phases and amplitudes. This local quality approach allows each segment to be optimized for its specific spatial location, correcting for local inhomogeneities caused by dielectric resonance effects while maintaining overall image quality

Inventive Principle:

Principle #3Local quality

2Measurement precision

If higher RF power is used to improve image quality, then image quality improves, but SAR rate increases compromising patient safety

Engineering Contradiction:

Improveimage qualityVSAvoidSAR rate

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

By segmenting the RF transmitter elements and enabling independent control of each segment, the system can distribute the RF power across multiple segments rather than concentrating it in a single element. This reduces the peak SAR rate in any one location while maintaining the overall image quality through coordinated operation of all segments

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system applies RF power partially and selectively to only those segments that are needed for the specific imaging task, rather than activating all segments at full power. This partial action approach reduces the total SAR rate while still achieving the required image quality for the examination

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If conventional single-channel RF transmission is used to maintain system simplicity, then device complexity remains low, but flexibility in applying spatial RF field patterns is limited

Engineering Contradiction:

Improvesystem simplicityVSAvoidflexibility of spatial RF field pattern

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The RF transmitter is divided into multiple independently controllable segments, each capable of receiving and transmitting RF signals with different characteristics. This segmentation provides the flexibility to generate complex spatial RF field patterns while maintaining a modular system architecture that manages complexity through standardized segment design

Inventive Principle:

Principle #1Segmentation

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 compensates for wave propagation and dielectric resonance effects, improving image homogeneity, reducing SAR, and enabling higher acceleration factors for spatially selective RF pulses, thus enhancing MRI image quality and patient safety at higher field strengths.

Implementation Method 1

a plurality of elements for generating an RF field for exciting nuclear magnetic resonances

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

wave propagation or dielectric resonance effects within the examination object

Methodology Applied

Scientific EffectWave propagation:

Implementation Method 3

wave propagation or dielectric resonance effects within the examination object

Methodology Applied

Scientific EffectDielectric resonance:

Data Source

PatentUS8390288B2Method and RF transmitter arrangement for generating RF fields

Publication Date: 2013.03.05 KONINKLIJKE PHILIPS NV

AI summary

A multi-channel RF transmitter arrangement comprising a plurality of RF transmitter elements like RE antennas, antenna elements, coils or coil elements, for generating an RF field, especially for use in a magnetic resonance imaging system for exciting nuclear magnetic resonances, and a method for generating such an RF field wherein the RF transmitter elements are segmented in a plurality of segments at least along the direction of one or more of the main magnetic field of the MRI system, the z-direction or the longitudinal direction.