Cost effective and quality assurance friendly magnetic resonance imaging thermometer using non-encapsulated liquid c1ystals to be incorporated in standard reference objects for magnetic resonance imaging.
The invention is liquid crystals with phase change from cholesteric state to isotropic liquid state at a particular temperature. In the MRI, the cholesteric state has dark signal (similar to a solid) due to sho1t T2 and the isotropic liquid state has a bright signal (similar to liquids). In the preferred invention, the temperatures are in the range of MRI bore temperatures (e.g., I5°C-25°C). To determine the temperature of the phantom environment, one can use a line scan of the liquid crystal array to determine the temperature. Liquid crystals have not previously been used commercially to measure temperature in MRI. The invention allows measurement of temperature using a simple and sh01t time duration Tl weighted gradient-recalled echo sequence. If possible, we will use non-encapsulated liquid crystals to have a temperature accuracy of 0.1°C rather than 0.4-0.5°C with encapsulated liquid crystals, but the latter is sufficient for current commercial applications. We are still determining the accuracy of the thermometer. This work is based on magnetic resonance images, not on N1v1R spectra. Some previous work has been done with liquid c1ystals and NlV1R spectra, but it was not adopted. The intended use is within an MR standard reference object (known as a phantom).
Commercial problem it solves: need a way to quickly and noninvasively measure temperature to enable the phantom's use in quality control (QC) systems-quick temperature assessment as part of the MR exam (not an additional step) will speed the QC test, allow for it to be run overnight, reduce user induced error, and provide more accurate standardization of the MRI scanner.
Current practice does not have an ability to accurately determine a temperature using a simple MRI scan. Current practice uses an external temperature probe to determine exact temperature or uses MRI to determine a relative temperature, both of which can contribute to significant error. Currently, when using phantoms (standard reference objects) it is a cumbersome process to determine the temperature, and it cannot be done at the time of scanning. After scanning is complete, the phantom is opened and a temperature probe is inse1ted into the phantom. Opening the phantom can compromise the stability of its reference objects and its shelf-life. To implement quality control on MR systems, we need non-invasive, rapid assessment of phantom temperature.