Magnetic Resonance Thermometry Using PRF and Spectroscopy
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Solution Overview
Problem
Current magnetic resonance imaging (MRI) techniques for temperature measurement in thermal therapies, such as HIFU, face challenges in achieving real-time, high spatial resolution with sufficient signal-to-noise ratio (SNR) for reliable temperature monitoring, as existing methods either provide relative temperature changes or are too slow for continuous imaging.
Innovation Solution
Combining proton resonance frequency (PRF) based temperature mapping with proton spectroscopic imaging to leverage the strengths of both methods, using PRF for continuous measurement and spectroscopic imaging for initial state estimation and sanity checks, enabling more accurate and reliable temperature monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PRF based temperature mapping is used, then real-time temperature monitoring with high spatial resolution is achieved, but absolute temperature measurement is not provided
Solution Approach 1:
The patent combines PRF-based temperature mapping with spectroscopic imaging by processing both signal types through a unified temperature calculation system. The PRF method provides real-time relative temperature changes while spectroscopic imaging provides absolute temperature calibration, and these are merged to produce temperature maps that include both relative changes and absolute temperature values.
Solution Approach 2:
The patent introduces a reference substance or reference region as an intermediary to bridge the gap between relative and absolute temperature measurement. This reference provides a known temperature baseline that allows conversion of PRF-based relative temperature changes into absolute temperature measurements while maintaining the real-time monitoring capability.
2Measurement precision
If spectroscopic imaging is used, then absolute temperature measurement is achieved, but imaging speed is too slow for continuous monitoring
Solution Approach 1:
The patent performs spectroscopic imaging at specific time points (e.g., baseline before heating, and periodically during/after treatment) to establish absolute temperature calibration. These preliminary measurements are then used to calibrate and validate the continuous PRF-based temperature monitoring, allowing the system to maintain high imaging speed while providing absolute temperature information.
Solution Approach 2:
The patent maintains continuous PRF-based temperature monitoring as the primary measurement method, using spectroscopic imaging only as a periodic calibration reference. This ensures that the useful action of continuous real-time temperature monitoring is maintained, while absolute temperature accuracy is periodically refreshed through spectroscopic measurements.
3Productivity
If fast imaging is used for HIFU therapy, then real-time temperature monitoring is achieved, but spatial resolution and SNR are insufficient for reliable temperature measurement
Solution Approach 1:
The patent applies different imaging techniques to different spatial regions or different measurement objectives. High-resolution spectroscopic imaging is used for absolute temperature calibration in specific regions, while faster PRF-based imaging is used for continuous monitoring across the entire treatment area. This local differentiation allows optimization of both speed and precision where needed.
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
This combination allows for precise, real-time temperature monitoring with high spatial resolution and absolute temperature measurements, reducing errors and improving the reliability of thermal damage assessment during HIFU therapy.
Implementation Method 1
Water proton resonance frequency based temperature mapping method is based on the property of the water proton nuclei that the local magnetic field experienced by the nuclei depends linearly on the temperature at least in the temperature range 20-80° C. This causes the phase of the nuclei to depend linearly on their temperature on the RF-spoiled gradient echo images.
Implementation Method 2
acquire spectroscopic magnetic resonance data and calculate a calibration thermal map using the spectroscopic method
Implementation Method 3
acquire magnetic resonance thermometry data and calculate a temperature map using the PRF method
Data Source
AI summary
A medical apparatus (300, 400, 500, 600) comprising a magnetic resonance imaging system (302). The medical apparatus further comprises a memory (332) storing machine readable instructions (352, 354, 356, 358, 470, 472, 474) for execution by a processor (326). Execution of the instructions causes the processor to acquire (100, 202) spectroscopic magnetic resonance data (334). Execution of the instructions further cause the processor to calculate (102, 204) a calibration thermal map (336) using the spectroscopic magnetic resonance data. Execution of the instructions further causes the processor to acquire (104, 206) baseline magnetic resonance thermometry data (338). Execution of the instructions further causes the processor to repeatedly acquire (106, 212) magnetic resonance thermometry data (340). Execution of the instructions further cause the processor to calculate (108, 214) a temperature map (351) using the magnetic resonance thermometry data, the calibration thermal map, and the baseline magnetic resonance thermometry data.