Wireless RF Coil Clock Synchronization via Larmor Frequency Transmission

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Solution Overview

Problem

MRI systems face challenges in maintaining clock synchronization between the control side and wireless RF coils across different countries due to varying radio wave regulations, which complicates the transmission of synchronization signals within the Larmor frequency band.

Innovation Solution

An MRI apparatus with a wireless RF coil and a control side oscillator that continuously transmits a synchronization signal within the Larmor frequency band, except during MR signal detection periods, ensuring clock synchronization regardless of country-specific radio regulations, using a whole body coil to transmit the synchronization signal and a phase locked loop to synchronize the coil-side clock with the control-side clock.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a synchronization signal is wirelessly transmitted from the control side to the wireless RF coil, then clock synchronization between the control side and coil side is achieved, but the transmission may violate country-specific radio wave regulations

Engineering Contradiction:

Improveclock synchronizationVSAvoidcompliance with radio regulations

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The whole body coil is designed to perform multiple functions: it serves as both the imaging RF coil and the transmission antenna for the synchronization signal. This eliminates the need for a separate transmission coil, reducing hardware complexity while ensuring that the transmission frequency can be chosen within the Larmor frequency band, which is generally permitted under radio regulations across different countries.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The synchronization signal is transmitted at a frequency within the Larmor frequency band rather than using arbitrary high-frequency carriers. This parameter change ensures compliance with radio regulations in different countries, as the Larmor frequency band is typically allocated for MRI operations and is legally permitted for use during imaging procedures.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the Larmor frequency band is used for transmitting the synchronization signal, then compliance with radio regulations is improved, but interference with MR signal detection may occur

Engineering Contradiction:

Improvecompliance with radio regulationsVSAvoidMR signal detection

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The synchronization signal is transmitted periodically at specific time points during the pulse sequence execution, specifically at moments when no MR signal acquisition is occurring. This periodic transmission ensures that the synchronization function is maintained while avoiding interference with the sensitive MR signal detection periods.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The synchronization signal is transmitted in advance of the MR signal acquisition phases, allowing the coil-side clock to be synchronized before the actual imaging data collection begins. This preliminary action ensures that any phase drift is corrected before it can affect the quality of the MR signal detection.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If wireless RF coils are used to reduce cable complexity, then ease of operation is improved, but maintaining clock synchronization across different countries becomes difficult

Engineering Contradiction:

Improvereduction of cable complexityVSAvoidclock synchronization across countries

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The system uses the existing whole body coil for both imaging and synchronization signal transmission, eliminating the need for additional dedicated transmission hardware. This universal use of existing components maintains ease of operation while enabling adaptable synchronization across different countries through frequency selection within the permitted Larmor band.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution allows for reliable clock synchronization in digital radio communication of MR signals across different countries, ensuring compliance with local radio regulations and maintaining efficient data transmission without the need for additional hardware components.

Implementation Method 1

a phase locked loop to synchronize the coil-side clock with the control-side clock

Methodology Applied

Scientific EffectPhase locked loop:

Implementation Method 2

a whole body coil to transmit the synchronization signal

Methodology Applied

Scientific EffectElectromagnetic wave transmission:

Data Source

PatentUS10416250B2Magnetic resonance imaging apparatus

Publication Date: 2019.09.17 CANON MEDICAL SYST CORP

AI summary

In one embodiment, an MRI apparatus includes a wireless RF coil; a control side oscillator configured to output a control-side clock signal used for executing a pulse sequence; and a synchronization signal transmission circuit configured to wirelessly transmit a synchronization signal to the wireless RF coil in an executing period of the pulse sequence, except an MR-signal detection period during which the wireless RF coil detects a magnetic resonance signal, wherein the synchronization signal is within a frequency band of a Larmor frequency and reflects a phase of the control-side clock signal.