MR Thermometry for Fat Layer Cooling in Thermal Treatment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current MR guided thermal treatment systems face challenges in accurately regulating the cool-down period, particularly in fat layers, due to the insulating properties of fat and limitations in temperature measurement techniques, which can lead to thermal build-up and potential burns.
Innovation Solution
The system employs relaxation constant based thermometry (T1, T2, or T2* based) for accurate temperature monitoring in fat layers, allowing for spatially differentiated cooling and reducing unnecessary delays, enabling active cooling and efficient use of MR data acquisition time during the cool-down period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed cool-down period is used based on predetermined energy density, then the treatment planning is simplified, but thermal build-up in fat layers cannot be accurately prevented leading to potential burns
Solution Approach 1:
The system implements real-time temperature monitoring during the cool-down period using MR thermometry to detect when fat layer temperatures have sufficiently decreased. This feedback mechanism allows dynamic adjustment of the cool-down period duration based on actual temperature conditions rather than using a fixed predetermined time, thereby preventing thermal build-up and burns while maintaining operational simplicity through automated control.
2Measurement precision
If PRF thermometry is used for temperature monitoring, then temperature measurement is straightforward in aqueous tissues, but it cannot measure temperature in fat layers due to absence of hydrogen bonds
Solution Approach 1:
The system switches from PRF thermometry (which relies on hydrogen bond dynamics in aqueous tissues) to relaxation time constant thermometry (T1, T2, or T2*) that measures different magnetic resonance parameters. These relaxation times are sensitive to temperature changes in fat layers where hydrogen bonds are absent, thereby extending temperature measurement capability to previously unmonitable tissues while maintaining measurement precision through established MR thermometry techniques.
3Reliability
If the cool-down period is extended to ensure fat layer cooling, then thermal safety is improved, but treatment time increases unnecessarily
Solution Approach 1:
The system uses real-time MR thermometry feedback during the cool-down period to monitor fat layer temperature evolution. The cool-down period is terminated as soon as the temperature drops below a predetermined safe threshold, rather than waiting for a fixed extended period. This feedback-controlled approach ensures thermal safety by preventing burns while minimizing unnecessary delays by ending cooling exactly when safe to proceed.
Solution Approach 2:
The cool-down period duration is made dynamic rather than static. The system continuously adjusts the timing based on real-time temperature measurements in the fat layer, allowing the cool-down period to be shorter when cooling is rapid and longer when cooling is slow, thereby optimizing treatment time while maintaining thermal safety across different patient anatomies and treatment conditions.
4Reliability
If temperature monitoring is performed continuously throughout the cool-down period, then thermal safety is maximized, but MR data acquisition time is wasted and treatment efficiency decreases
Solution Approach 1:
Instead of continuous monitoring throughout the entire cool-down period, the system performs temperature measurements at periodic intervals. The monitoring frequency is adjusted based on the cooling phase: more frequent measurements are taken when temperatures are critical, and less frequent measurements are performed when temperatures are already well below safety thresholds. This periodic approach maintains thermal safety while maximizing treatment efficiency by reducing unnecessary MR data acquisition time.
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 approach prevents thermal build-up, reduces treatment time, and allows for safer continuation of sonications by accurately determining when fat layers have cooled sufficiently, thereby preventing burns and optimizing the thermal treatment process.
Implementation Method 1
temperature measurements in fat are performed by using relaxation constant based thermometry
Implementation Method 2
energy is deposited into a target zone. Energy can be delivered as sonications in the form of focused ultrasound waves
Implementation Method 3
The linear dependence appears to be valid when the temperature decrease due to diffusion of heat can be neglected
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a system in the field of MR guided thermal treatment and more specifically to the temperature control. In the invention an MR and a thermal treatment system are combined. The thermal treatment system is configured to apply thermal treatment pulses to a subject. The prevent overheating of healthy tissue, the thermal treatment pulses are spaced by a cool-down period. The end of the cool-down period is determined by temperature measurements performed during the cool-down period.