Switchable Segmented MRI Transmission Line Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
RF-induced common mode currents in transmission lines for interventional devices used in MRI systems can cause tissue heating and potential burns, as existing methods lack a reliable means to verify decoupling of transmission line segments during RF exposure.
Innovation Solution
A segmented transmission line with conductive bridges that can switch between open and closed states, accompanied by impedance bridges to suppress RF-induced currents, and a measurement unit to ensure all bridges are in the open state before MRI protocols commence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transmission line segments are segmented and mechanically disconnected during imaging, then RF-induced common mode currents are reduced, but there is no means to verify that the line segments are decoupled to ensure safety
Solution Approach 1:
The patent implements a measurement unit that measures the impedance across the transmission line segments to verify the state of the conductive bridge. This feedback mechanism allows the system to confirm whether the segments are properly decoupled, providing reliability verification for the safety mechanism.
Solution Approach 2:
The patent introduces an impedance bridge as an intermediary element connected in parallel to the conductive bridge. This impedance bridge serves as a mediator that allows measurement of the decoupling state without directly interfering with the primary function of the conductive bridge in blocking RF-induced currents.
2Reliability
If a conductive bridge is used to connect transmission line segments, then electrical connection is achieved, but RF-induced currents can still flow causing tissue heating
Solution Approach 1:
The conductive bridge is designed to be switchable between open and closed states. During MRI imaging, the bridge is opened to prevent RF-induced currents, while during other operations it can be closed to maintain electrical connection. This dynamic switching allows the system to adapt its electrical connectivity based on the operational context.
Solution Approach 2:
The transmission line is divided into multiple segments separated by non-conductive gaps that can be bridged by the switchable conductive bridge. This segmentation allows the line to be electrically disconnected at specific points to prevent current flow while maintaining the physical integrity and continuity of the transmission line structure.
3Object-affected harmful factors
If impedance bridge is added to suppress RF-induced currents, then safety is improved, but device complexity increases
Solution Approach 1:
The measurement unit serves multiple functions: it measures the impedance across the transmission line segments to verify decoupling, and it can also detect the state of the conductive bridge. This multi-functionality reduces the need for separate verification components, thereby limiting the increase in device complexity.
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 effectively decouples transmission line segments during MRI procedures, reducing the risk of RF-induced tissue heating and ensuring patient and equipment safety by reliably suppressing common mode currents.
Implementation Method 1
each impedance bridge has an impedance which is chosen to suppress radiofrequency (RF) induced current between the line segments
Implementation Method 2
A measurement unit measures the impedance across the line segments and the impedance bridge while the conductive bridge controlled to be in the open state
Data Source
AI summary
A magnetic resonance imaging (MRI) system includes an interventional instrument and a switched, segmented transmission (Tx) line which ensures safety during an MRI protocol while the interventional instrument is located in the system. The transmission line includes at least two electrically conductive Tx line segments separated by a non-conductive gap. An electrically conductive bridge, having an open and a closed state, and a parallel connected impedance bridge, having a known impedance which suppresses RF current between the line segments, bridge the non-conductive gap. A measurement unit measures the impedance across the Tx line while the conductive bridges are open. The line segments are verified to be decoupled if the measured impedance of the line is substantially equal to that of the impedance bridge.