SAR Focusing Algorithm Using MR Thermometry Feedback
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Solution Overview
Problem
Current methods for achieving specific absorption rate (SAR) focusing in hyperthermia treatments are inefficient in aligning hotspots with targets and optimizing pulse delivery, particularly in magnetic resonance imaging (MRI) systems, leading to suboptimal temperature control and therapeutic outcomes.
Innovation Solution
An algorithm and apparatus for determining optimal channel weightings of an array of transmitters to achieve SAR focusing, using MR thermometry for real-time temperature mapping and pulse refinement, along with computational software for electromagnetic modeling and optimization, to ensure precise hotspot alignment and maximum SAR at the target while constraining peak local SAR in non-target voxels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current methods for achieving SAR focusing in hyperthermia treatments are used, then treatment can be performed, but hotspot alignment with targets is inefficient and temperature control is suboptimal
Solution Approach 1:
The patent implements an iterative feedback loop where MR thermometry measures the actual temperature distribution, compares it to the desired target, and uses this information to refine the computed pulse for improved hotspot alignment. This closed-loop feedback system continuously optimizes the SAR focusing to achieve precise temperature control at the target while minimizing heating in non-target regions.
Solution Approach 2:
The patent performs preliminary MR thermometry measurements and hotspot alignment optimization before delivering the full therapeutic power. By pre-characterizing the temperature distribution and refining the pulse computation at lower powers, the system establishes an optimized focusing pattern that is then applied at therapeutic power levels, improving overall treatment efficiency.
2Measurement precision
If iterative pulse refinement using MR thermometry is performed, then hotspot alignment with target is improved, but treatment time increases
Solution Approach 1:
The patent performs a limited number of iterative refinement cycles at lower power levels to achieve sufficient hotspot alignment, rather than attempting perfect optimization at full therapeutic power. This partial action approach achieves clinically adequate alignment precision while minimizing the time penalty of iterative refinement.
3Power
If higher power is applied to achieve therapeutic effect, then treatment effectiveness increases, but temperature monitoring becomes more critical
Solution Approach 1:
The patent implements continuous temperature monitoring via MR thermometry during high-power therapeutic delivery, with real-time feedback used to verify that the pre-optimized hotspot alignment remains accurate and that target temperature reaches therapeutic thresholds while non-target regions remain below safety limits.
Solution Approach 2:
The patent performs preliminary optimization and alignment verification at lower power levels before escalating to full therapeutic power. This preparatory step cushions against potential temperature control failures by ensuring the focusing pattern is already optimized, reducing the risk of off-target heating when higher powers are applied.
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
The solution enables efficient and precise SAR focusing, allowing for effective hyperthermia treatments by iteratively refining the computed pulse to align hotspots with targets, ensuring therapeutic temperatures are reached while adhering to safety and hardware constraints, thereby improving the spatial selectivity and efficiency of treatments.
Implementation Method 1
An efficient algorithm for determining the optimal channel weightings of an array of transmitters to achieve specific absorption rate (SAR) focusing
Implementation Method 2
MR thermometry is performed using the MRI system
Data Source
AI summary
A method for providing SAR focusing at a target in a body using an MRI system is provided. A computed pulse is provided at a lower power to the body. A MR thermometry is performed. A map is created from the MR thermometry to determine if a hotspot aligns with the target. If the target does not align with the hotspot, then the steps are performed comprising, recomputing the computed pulse, providing the computed pulse at a lower power to the body, performing MR thermometry, creating a map from the MR thermometry to determine if a hotspot aligns with the target, and repeating these steps until the hotspot aligns with the target. The computed pulse is applied at a higher power to the body to provide the desired SAR at the target. Temperature change is monitored with MR thermometry the previous two steps are repeated until desired temperature is achieved.