MRI Safe Tissue Expander Port Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional tissue expanders are contraindicated for use with MRI due to interactions between the strong magnet and metal structure, leading to heating, dislodgement, rupture, and unwanted artifacts, which pose risks to patients and hinder breast reconstruction procedures.
Innovation Solution
A tissue expander with a non-reactive MRI-compatible access port constructed from non-metallic materials and a smaller, magnetometer-detectable magnet that is not detectable by external dangle-magnets, allowing safe MRI use while maintaining precise location capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a strong magnet and metal structure are used in the access port, then the port can be located using an external dangle-magnet, but the tissue expander becomes incompatible with MRI due to heating, dislodgement, and artifacts
Solution Approach 1:
The patent removes the strong magnet from the access port structure, extracting the harmful magnetic component that caused MRI incompatibility. Instead, a smaller magnet is placed within the port body, detectable only by specialized magnetometer sensors, not by external dangle-magnets. This separation eliminates the contradiction between port detectability and MRI safety.
Solution Approach 2:
The patent introduces an intermediary detection system consisting of a magnetometer sensor and associated electronics that can detect the small magnet within the port without requiring strong external magnets. This intermediary system enables port location while maintaining MRI compatibility, as the detection mechanism does not rely on strong magnetic fields that would cause heating or artifacts during MRI procedures.
2Ease of operation
If a strong magnet is used in the access port, then the port can be located externally, but the magnet can move or dislodge the tissue expander during MRI procedures
Solution Approach 1:
The strong magnet is extracted from the access port, eliminating the source of magnetic attraction forces that could cause dislodgement or movement during MRI. The remaining small magnet within the port body generates insufficient magnetic force to affect the tissue expander's position, ensuring stability while still allowing detection through specialized sensors.
Solution Approach 2:
The magnetic field strength parameter is dramatically reduced from strong magnet levels to weak magnet levels. This parameter change ensures that the magnet's field is sufficient for detection by magnetometer sensors but too weak to cause movement or dislodgement of the tissue expander during MRI procedures, thus maintaining reliability.
3Strength
If metal structure is used in the access port, then the port provides structural support, but the metal causes unwanted artifacts in MRI output
Solution Approach 1:
The material composition parameter of the access port is changed from metal to non-metallic materials. This parameter change eliminates the harmful magnetic susceptibility differences that cause artifacts in MRI images, while the non-metallic materials still provide sufficient structural support for the port's function.
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 enables safe MRI compatibility and precise localization of the tissue expander, reducing the risk of complications and improving the safety and effectiveness of breast reconstruction procedures.
Implementation Method 1
a magnetic sensor configured to detect a direction and a strength of a magnetic field of a magnet in the implanted tissue expander
Implementation Method 2
the MRI may cause heating of the strong magnet included in the structure of the port and this heating can lead to pain for the patient. The interaction between the MRI and the strong magnet can also cause movement of the strong magnet
Data Source
AI summary
Improvements for use with tissue expanders are provided. A tissue expander includes: a selectively inflatable and deflatable shell that is configured to be implanted; and an access port for selectively inflating and deflating the shell, the access port comprising a sidewall, a base at a first end, and a membrane at a second end opposite the first end, wherein the sidewall and the base of the access port are constructed of a material that is non-reactive with a magnetic resonance imaging (MRI) machine. In embodiments, the tissue expander includes a magnet at the access port. In embodiments, the magnet is configured with a physical size and magnetic force such that, when the tissue expander is implanted, the magnet is detectable by an external magnetometer sensor but is not detectable by an external dangle-magnet.