MRI Cable Filtering for RF-Induced Heating Reduction
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Solution Overview
Problem
Current medical cables used in MRI environments suffer from insufficient attenuation of RF-induced heating, leading to potential tissue damage and equipment failure, as existing solutions like high impedance cables, resonant LC filters, and coiled cables either limit functionality or fail to adequately block RF currents over longer lengths.
Innovation Solution
A novel cable construction incorporating a combination of resonant and non-resonant filters, where a resonant LC filter is placed at the cable/patient interface to block RF currents and non-resonant filters along the cable length to attenuate induced currents, ensuring effective blocking and reducing heating, while maintaining flexibility and maneuverability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high impedance cables are used to reduce RF induced current, then RF induced heating is reduced, but cable functionality is limited
Solution Approach 1:
The cable is divided into multiple segments with different impedance characteristics. A first portion has high impedance to block RF currents, while a second portion has low impedance to maintain signal transmission functionality. This segmentation allows the cable to simultaneously reduce RF induced heating and preserve cable functionality for medical procedures.
2Object-affected harmful factors
If resonant LC filters are placed at cable/patient interface to block RF currents, then RF induced heating is reduced, but cable length is limited
Solution Approach 1:
The cable is divided into a first portion with resonant LC filters for RF blocking and a second portion without filters for signal transmission. This segmentation allows the filtered portion to be relatively short while the unfiltered portion can extend to required lengths, enabling both RF protection and adequate cable length for various procedural needs.
Solution Approach 2:
RF filtering is applied locally at the cable/patient interface where RF induced heating is most problematic, rather than along the entire cable length. This localized approach blocks RF currents at the critical interface while leaving the rest of the cable functional for signal transmission over longer distances.
3Object-affected harmful factors
If coiled cables are used to provide distributed reactance, then RF induced current is reduced, but cable flexibility is reduced
Solution Approach 1:
The cable is segmented into a first portion with coiled configuration for RF protection and a second portion in straight configuration for flexibility. The coiled first portion provides distributed reactance to reduce RF induced current, while the straight second portion maintains cable flexibility and maneuverability for procedural manipulation.
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 proposed cable construct significantly reduces RF-induced heating by effectively blocking RF currents and preventing excessive heating of the cable and surrounding tissue, ensuring safety and functionality during MRI procedures.
Implementation Method 1
a resonant LC filter is placed at the cable/patient interface to block RF currents
Implementation Method 2
non-resonant filters along the cable length to attenuate induced currents
Implementation Method 3
RF induced currents in the cable may result in increased local exposure to RF energy in nearby skin or other tissue, thus increasing the tissue's temperature. The foregoing phenomenon may be experienced as dielectric heating.
Data Source
AI summary
An MRI compatible cable construct is provided. The cable is adapted to be used with a medical device in direct electrical contact with a patient. Each cable or cable set includes a plurality of filter components. The filter component comprises at least two filter components. One filter component may be a resonant filter at a distal end that resolves the issue of insufficient attenuation by effectively blocking the RF induced current on the cable from exiting the cable at the distal. The second filter component may comprise one or more non-resonant filter(s) or inductors positioned along the length of the cable that resolve(s) the issue of excessive heating of the resonant LC filter by significantly attenuating the current induced on the cable before it reaches the resonant LC filter.