Clock Signal Shifting for MRI-Nuclear Interference Reduction
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Solution Overview
Problem
Combined-modality imaging assemblies face interoperability issues due to electrical interference between nuclear imaging systems and MR imaging systems, particularly in simultaneous-acquisition setups, which degrades MR image quality and requires further reduction of interference to improve diagnostic accuracy.
Innovation Solution
A combined imaging assembly that shifts clock signals for nuclear imaging system modules in phase or frequency to reduce RF interference within the MR imaging system's sensitive frequency interval, using a timing control unit with a reference clock and phase or frequency shifting units to generate shifted clock signals, and optimizing module orientations and sub-module phase relationships to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If electrical screening materials are used to reduce RF interference from the nuclear imaging system, then interference with the MR imaging system is reduced, but the MR magnetic field is distorted and MR image quality degrades
Solution Approach 1:
The patent introduces an intermediary material with intermediate magnetic properties positioned between the nuclear imaging system and the MR imaging system. This intermediary material acts as a buffer that reduces RF interference transmission while maintaining magnetic field integrity, thereby protecting MR image quality without requiring conductive screening materials that would distort the magnetic field.
2Adaptability or versatility
If the nuclear imaging system is positioned close to the MR imaging system for simultaneous acquisition, then integrated imaging capability is improved, but RF interference within the MR sensitive frequency bandwidth increases
Solution Approach 1:
The patent applies local quality by positioning the nuclear imaging system in a specific location within the MR bore where the local RF field strength and interference characteristics are optimized. This strategic positioning exploits the spatial variation of the RF field to minimize interference with the MR sensitive frequency bandwidth while maintaining simultaneous acquisition capability.
Solution Approach 2:
The patent modifies operational parameters of the nuclear imaging system, such as clock frequency and timing, to shift its RF emissions outside the MR sensitive frequency bandwidth. This parameter adjustment allows both systems to operate simultaneously without significant RF interference.
3Manufacturing precision
If electrical screening is applied to reduce interference, then MR image quality is improved, but eddy currents are induced that soften gradient switching and distort k space
Solution Approach 1:
The patent uses an intermediary material with non-conductive or low-conductive properties that reduces RF interference without inducing significant eddy currents. This intermediary maintains the stability of the gradient field and k space integrity while still providing interference reduction, unlike traditional conductive screening materials.
4Productivity
If clock frequencies of nuclear imaging modules are within the MR sensitive frequency interval, then nuclear imaging performance is optimized, but RF interference with the MR system occurs
Solution Approach 1:
The patent adjusts the clock frequency parameter of the nuclear imaging modules to fall within the MR sensitive frequency interval while using phase modulation or timing adjustments to ensure that the actual RF emissions do not occur at frequencies that interfere with MR imaging. This allows optimal nuclear imaging performance without significant RF interference.
Solution Approach 2:
The patent employs periodic modulation of the clock signals in the nuclear imaging system, where the RF emissions are pulsed or modulated in a periodic manner that avoids continuous interference with the MR frequency band. This periodic action allows nuclear imaging to operate at optimal frequencies while minimizing sustained RF interference.
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
The solution significantly reduces RF interference between the nuclear and MR imaging systems, enhancing MR image quality by spreading interference frequencies across a broader range and shifting them outside the MR system's sensitive frequencies, thereby improving diagnostic capabilities.
Implementation Method 1
at least one of the phase shifting unit and the frequency shifting unit is configured to receive a reference clock signal from the reference clock unit and to generate a plurality of (M) shifted clock signals for clocking the (M) modules such that at least one of the (M) shifted clock signals is shifted respective the reference clock signal in at least one of frequency or phase
Implementation Method 2
at least one of the phase shifting unit and the frequency shifting unit is configured to receive a reference clock signal from the reference clock unit and to generate a plurality of (M) shifted clock signals for clocking the (M) modules such that at least one of the (M) shifted clock signals is shifted respective the reference clock signal in at least one of frequency or phase
Implementation Method 3
electrical currents flowing in the circuits of the nuclear imaging system produce electromagnetic radiation which risks being detected by the sensitive RF sense coils in the MR imaging system
Data Source
AI summary
A combined-modality imaging assembly includes a Magnetic Resonance (MR) imaging system and a nuclear imaging system. The nuclear imaging system has a plurality of (M) modules; and the combined imaging assembly includes a timing control unit having a reference clock unit; and at least one of a phase shifting unit and a frequency shifting unit. At least one of the phase shifting unit and the frequency shifting unit is configured to receive a reference clock signal from the reference clock unit and to generate a plurality of (M) shifted clock signals for clocking the (M) modules such that at least one of the (M) shifted clock signals is shifted respective the reference clock signal in at least one of frequency or phase. In so doing, reduced interference between the modules of the nuclear imaging system and the MR imaging system is obtained.