Intracardiac MRI Receiving Antenna With External Detuning Switch
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Solution Overview
Problem
Conventional intracardiac MRI systems face risks of patient harm due to high-intensity currents induced in receiving antennas during transmission, magnetic field inhomogeneity, and hardware deterioration, necessitating safe and efficient switching between tuned and detuned states.
Innovation Solution
A receiving device with an intracardiac resonant antenna and a switch that alternates between open and closed states using different direct current intensities, located outside the body, coupled with a transmission line and optional negative resistance circuit to ensure safe and efficient decoupling, minimizing bulk and risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the receiving antenna is supplied with direct current to detune it during transmission phase, then the frequency switching is achieved, but high-intensity currents may be induced causing patient harm
Solution Approach 1:
The patent extracts the dangerous direct current supply from the intracardiac environment by placing the switching equipment outside the body. The receiving antenna remains inside the heart for optimal imaging, while the PIN diode switch and current supply are positioned externally through the sheath, eliminating the risk of cardiac arrest from internal current induction.
Solution Approach 2:
The patent introduces an intermediary switching mechanism (PIN diode switch) that mediates between the external control system and the internal receiving antenna. This intermediary component enables frequency switching without requiring direct current to flow through the intracardiac tissue, thus preventing patient harm while achieving the desired frequency adaptation.
2Adaptability or versatility
If active decoupling equipment is used to switch between tuned and detuned states, then frequency switching is achieved, but device complexity increases
Solution Approach 1:
The patent employs a simple PIN diode switch, which is a relatively simple and inexpensive component compared to complex active decoupling systems. This simple switching element achieves the required frequency switching functionality without introducing significant complexity, maintaining system simplicity while providing necessary adaptability.
3Object-affected harmful factors
If the receiving antenna is detuned during transmission phase, then high-intensity current induction is prevented, but magnetic field inhomogeneity is created
Solution Approach 1:
The patent applies preliminary action by detuning the receiving antenna before the transmission phase begins. The PIN diode switch is activated in advance to open the circuit, preventing any current induction during the subsequent transmission phase. This preliminary detuning ensures safety while the magnetic field homogeneity is maintained through proper positioning and design of the antenna system.
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
Ensures patient safety by avoiding high-intensity currents, maintains magnetic field homogeneity, and improves image quality by optimizing decoupling efficiency and signal-to-noise ratio, particularly suitable for intracardiac imaging.
Implementation Method 1
The receiving antenna is a resonant circuit of R, L, C type, the resonance frequency fR of which must be equal to the Larmor frequency f0 of the MRI system
Implementation Method 2
an antenna for receiving RF signals resulting from the excitation of an organ of interest by the RF excitation signals
Implementation Method 3
The active decoupling equipment conventionally comprises a PIN diode that is supplied with direct current during the transmission phase so that the PIN diode is ON and the frequency of the receiving antenna is detuned
Implementation Method 4
The receiving antenna is connected to a receiver of the MRI device by a transmission line integrated within a sheath and intended to convey the radio frequency signals received by the antenna to the receiver
Data Source
AI summary
A device for receiving radio frequency signals for a magnetic resonance imaging/spectroscopy system including an intracardiac receiving resonant loop and a switch capable of being alternately in an open state such that the frequency of the receiving antenna is tuned to an operating frequency of the magnetic resonance imaging system, and in a closed state such that the frequency of the receiving resonant loop is detuned, the receiving device including a first transmission line having a conductor with a distal end electrically connected to the receiving resonant loop and a proximal end electrically connected to the switch such that the switch is intended to be located outside the human body when the receiving resonant loop is located inside a patient's heart.