Liquid crystal thermometer for MRI
Inventors
Mirowski, Elizabeth • Snow, Michael • Keenan, Kathryn
Assignees
Qalibremd Inc • Qalibremd • United States Department of Commerce
Publication Number
US-10809331-B2
Publication Date
2020-10-20
Expiration Date
2038-03-05
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Abstract
Provided herein are novel liquid crystal based devices for the facile measurement of temperature in an MRI system. The thermometers comprise a plurality of vessels wherein each vessel contains a liquid crystal composition having a unique phase transition temperature. By scanning with appropriate techniques, the state of the liquid crystals in each vessel can be assessed, and the temperature at the time of the scan can be determined by the state of the liquid crystal compositions. Also provided are novel vessels and assemblies of vessels that can be used as MRI thermometers and which are compatible with MRI phantoms.
Core Innovation
The invention provides novel liquid crystal based devices for facile temperature measurement in an MRI system. The thermometers comprise multiple vessels, each containing a liquid crystal composition with a unique phase transition temperature. MRI scans assess the state of the liquid crystals in each vessel, allowing determination of the temperature at the time of the scan based on the phase state of the liquid crystals. Assemblies of vessels compatible with MRI phantoms are also provided.
The problem addressed is that obtaining consistent MRI measurement protocols across different MRI systems is challenging due to variability caused by differences in hardware, software, user implementation, and temperature fluctuations within the MRI bore. Temperature affects MRI parameters such as T1, T2 relaxation times, and Apparent Diffusion Coefficient. Existing temperature measurement techniques, like fiber-optic or digital thermometers, have drawbacks including invasiveness, high cost, laborious setup, and potential phantom contamination.
Previous methods using chemical shift NMR thermometers or microencapsulated liquid crystals for hyperthermia treatment monitoring are inadequate for MRI phantom calibration. These existing methods require specialized spectroscopic capabilities, are time-consuming, have insufficient signal under MRI conditions, demand toxic or expensive materials, and produce broad transition temperatures insufficient for the accuracy needed.
The invention addresses these limitations by employing liquid crystal temperature sensing techniques that enable inexpensive and facile methods for accurate temperature measurement, facilitating the consistent use of ground state standards in MRI system characterization.
Claims Coverage
The patent includes two independent claims related to a liquid crystal thermometer and a method of assessing MRI bore temperature, each featuring multiple inventive aspects described below.
Thermometer comprising multiple liquid crystal compositions in separate containers
The thermometer includes two or more liquid crystal compositions each enclosed in separate containers. Each has a unique phase transition temperature between ordered and liquid states, producing distinct signals in MRI scans.
Use of cholesteric liquid crystals and specific phase transition temperature range
The liquid crystal compositions comprise cholesteric liquid crystals with phase transition temperatures typically between 15 and 25° C., varying by fixed increments such as 0.1, 0.5, or 1.0° C.
Containers made of MRI-compatible materials with interlocking features
Each container is made from materials that do not generate substantial MRI signal, including polychlorotrifluoroethylene and other fluoropolymers, and includes complementary interlocking features allowing assembly into linear or other configurations.
Sealing mechanism using a sphere in container opening
Containers have an opening sealed by a hard plastic or glass sphere that creates an airtight, liquid-proof seal without adhesive joints, improving durability and MRI compatibility.
Use of selected MRI scan techniques providing differential signals from liquid crystal states
The thermometer is imaged with scan techniques such as spin echo, gradient echo, and spoiled gradient echo, which produce distinct MRI signals from liquid crystals in ordered versus liquid states.
Method for assessing MRI bore temperature by imaging liquid crystal state transitions
The method involves acquiring an MRI image of the thermometer in the bore, assessing the break point between the lowest transition temperature liquid crystal in liquid state and the highest transition temperature liquid crystal in ordered state, thereby determining the bore temperature range.
Automated or manual assessment of liquid crystal phase break point
The break point between liquid and ordered phases in the series of liquid crystal compositions can be determined either by visual inspection or by automated computer-aided detection algorithms.
The claims cover a liquid crystal thermometer assembly with multiple uniquely transitioning compositions in MRI-compatible containers, use of specific MRI imaging techniques to detect phase states, and methods for accurate MRI bore temperature determination based on the solid-liquid transition break point, allowing practical, accurate, and compatible temperature measurement in MRI phantoms and systems.
Stated Advantages
Provides an inexpensive and facile means for accurate temperature measurement during MRI system characterization.
Enables consistent temperature assessment facilitating accurate use of ground state standards in MRI measurements.
Non-invasive and compatible with MRI phantoms, avoiding contamination and complexity associated with traditional thermometers.
Fast temperature measurement integration into MRI scanning protocols, without requiring specialized spectroscopic analysis.
Improved robustness and seal integrity of containers due to novel sealing method eliminating adhesive joints.
Documented Applications
Measurement of temperature within the bore of an MRI system to characterize and standardize MRI equipment using ground truth standards.
Integration of the liquid crystal thermometer in MRI calibration phantoms for non-invasive, real-time temperature monitoring during MRI quality control procedures.
Use of temperature data obtained from the liquid crystal thermometer to correct or adjust temperature-dependent MRI parameters of ground state standards, enhancing diagnostic consistency.
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