T-WASSR MRI Temperature Mapping Fat Interference
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Solution Overview
Problem
Current MRI techniques for temperature mapping, such as Water PRF-based methods, face limitations in spatial and temporal resolution, especially in the presence of fat, and require additional data processing steps or prior knowledge of fat composition.
Innovation Solution
The Temperature-Responsive Water Saturated Shift Referencing (T-WASSR) method uses MRI to measure chemical shifts of water protons, separates water peaks from lipid peaks, and assesses proton resonance frequency, allowing for high-resolution temperature mapping without prior knowledge of fat composition and additional data processing, using a Lorentzian line shape to determine temperature-induced shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Water PRF-based methods are used for temperature mapping, then temperature measurement sensitivity is improved, but spatial and temporal resolution deteriorate
Solution Approach 1:
The patent changes the measurement parameter from conventional phase-based PRF imaging to direct water saturation spectrum analysis. By using a weak radiofrequency saturation pulse and analyzing the resulting saturation spectrum, the method achieves both high temperature sensitivity and high spatial/temporal resolution simultaneously, resolving the contradiction between measurement precision and resolution.
Solution Approach 2:
The patent replaces the traditional phase-based mechanical imaging approach with a spectral analysis approach. Instead of relying on phase shifts that suffer from spatial and temporal limitations, the method uses direct spectral measurement of water protons, substituting a more efficient measurement mechanism that achieves both high resolution and high precision.
2Productivity
If conventional PRF imaging is used, then temperature monitoring capability is improved, but accuracy deteriorates in the presence of fat
Solution Approach 1:
The patent segments the spectral signal into distinct water and fat components. By analyzing the water saturation spectrum separately from the fat signal, the method eliminates the interference caused by fat protons, thereby maintaining temperature monitoring capability while improving measurement accuracy in fat-containing tissues.
Solution Approach 2:
The patent introduces a water-specific saturation spectrum as an intermediary measurement. This water-only spectral signature acts as a mediator that allows temperature measurement without being contaminated by fat protons, enabling accurate temperature monitoring even in tissues with significant fat content.
3Measurement precision
If additional data processing steps are required for fat composition knowledge, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent enables the MRI system to self-characterize the tissue composition automatically. By analyzing the saturation spectrum, the system can identify and separate water and fat contributions without requiring external input or complex preprocessing. This self-service approach maintains measurement accuracy while minimizing device complexity and user intervention requirements.
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
T-WASSR provides high temporal and spatial resolution for temperature mapping, accurately measuring temperature changes in both water and fat-containing tissues, correlating well with traditional phase-based PRF imaging and MR spectroscopy, and is robust for fat-containing tissues, enabling real-time monitoring.
Implementation Method 1
Water PRF shifts are sensitive to temperature because it strongly affects the chemical shift of water protons by altering their hydrogen bonding state
Implementation Method 2
assessing the chemical shift of water protons
Implementation Method 3
a powerful magnetic field is used to align the magnetization of atomic nuclei in the body, and radio frequency is used to alter the alignment of the magnetization
Implementation Method 4
The nuclei then produce a rotating magnetic field that is detectable by an MRI scanner
Implementation Method 5
radio frequency is used to alter the alignment of the magnetization
Implementation Method 6
The steady-state direct saturation spectrum can be described exactly by a Lorentzian line shape
Data Source
AI summary
An embodiment in accordance with the present invention provides a method of non-invasively detecting and imaging temperature or temperature changes by assessing the temperature induced shifts in the saturation spectrum of water using MRI, namely saturation shift referencing. This procedure includes the MRI procedures to assess water saturation spectrum and the data processing steps to determine the temperature induced shifts of water resonance frequency and consequently to estimate the temperature change. This procedure also includes the procedure of assessing fat saturation spectrum and estimating fat resonance frequency. This method can be used as a clinical procedure for temperature mapping in multiple applications, especially where a significant amount of fat is present. One application is to monitor the temperature of the targeted tumor and its surrounding tissues during the procedure of hyperthermia. Such local hyperthermia can be applied, using high-intensity focus-ultrasound for deep-seated tissues or heating supplies for superficial tissues.