MRI-Guided Cryoablation System RF Heating Mitigation
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Solution Overview
Problem
Cryosurgical systems face challenges in operating within MRI environments due to reactive effects such as RF heating and induced currents in metallic and electrical components, which can lead to component failure and corruption of fault detection circuits by high amplitude gradient and RF fields, making it difficult to determine if the MRI system is operational and mitigate these effects.
Innovation Solution
A magnetic resonance imaging (MRI) guided cryosurgical system that includes a control system capable of determining if the MRI system is operational and mitigating reactive effects by initiating cooling operations, disconnecting electrical components, and ignoring signals from temperature sensors and heaters when exposed to MR signals, using detectors to sense RF and magnetic fields and controlling the supply of cryofluid to counteract radiofrequency heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If surgical tools with metallic and electrical components are positioned in the MRI room for MRI-guided surgery, then imaging guidance is improved, but radiofrequency heating and induced currents cause harmful reactive effects on the surgical components
Solution Approach 1:
The control system proactively monitors MRI system operational status through detectors and preemptively mitigates reactive effects by initiating cooling operations and disconnecting electrical components before harmful heating and induced currents can occur, rather than reacting after damage occurs
Solution Approach 2:
A control system acts as an intermediary between the MRI system and surgical tools, using detectors to sense MRI operational status and automatically implementing mitigation strategies (cooling fluid delivery, electrical disconnection) to protect surgical components from harmful effects
2Measurement precision
If fault detection circuits are exposed to high amplitude gradient and RF fields during MRI operation, then MRI imaging is improved, but the fault detection circuits become corrupted and vulnerable to failure
Solution Approach 1:
The control system detects MRI operational status in advance and preemptively disconnects electrical components and ignores fault detection signals during MRI operation, preventing circuit corruption before it occurs
Solution Approach 2:
The system electrically disconnects vulnerable components (heaters, temperature sensors) from the circuit during MRI operation, removing them from the harmful electromagnetic environment to prevent signal corruption and circuit failure
3Reliability
If the control system continuously monitors and mitigates reactive effects during MRI operation, then component safety is improved, but system complexity and operational overhead increase
Solution Approach 1:
The control system automatically monitors MRI operational status through detectors and autonomously implements mitigation strategies (cooling fluid delivery, electrical disconnection, signal ignoring) without requiring manual intervention, making the complex safety management transparent to the user
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 system effectively reduces reactive effects on cryosurgical components, allowing safe operation within MRI environments by cooling components, disconnecting electrical components, and managing signal processing to prevent corruption, thereby ensuring reliable operation and patient safety.
Implementation Method 1
a cryofluid can be delivered from a cryofluid source to one or more cryoprobes. The cryoprobe can be cooled as a result of expansion of the cryofluid, thereby freezing tissue in the vicinity of a tip of the cryoprobe.
Implementation Method 2
Some such systems include an electrical heater (in the form of a high resistance wire) positioned within the probe shaft of each cryoprobe to thaw tissue after freezing to facilitate removal of the cryoprobe.
Implementation Method 3
a magnetic resonance (MR) system positioned in an MR room configured to produce MR signals, such as magnetic fields and radiofrequency signals. The magnetic and radiofrequency fields permit imaging of a region of patient tissue.
Implementation Method 4
placement of surgical system having metallic and/or electrical components (e.g., probe shaft or heater wire and so on) adjacent to a MRI system may result in heating due to radiofrequency fields (radiofrequency heating), or induced current flow therethrough caused by the presence of the MRI magnet.
Data Source
AI summary
A magnetic resonance imaging (MRI) guided surgical system is provided that includes one or more surgical tools having components configured to develop reactive effects when exposed to MR signals generated by the MRI system. The system includes a control system that can determine whether the MR system is generating MR signals, and if the control system determines that the MR system is generating MR signals, mitigates the reactive effects of MR signals on components of the surgical tools. The system can include a cryoablation system with a cryoprobe having a probe shaft being made of a metallic material. If the control system determines that the MR system is generating MR signals, the control system can electrically disconnect the cryoprobe and/or ignore electrical signals generated by the electric heater in response to exposure to MR signals, and/or initiate a cooling operation of the probe shaft, whereby the cooling operation.