MRgFUS Focus Correction via Chemical and K-Space Shift Compensation
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Solution Overview
Problem
Current methods for correcting focus location in magnetic resonance guided focused ultrasound (MRgFUS) surgery are slow and prone to errors due to image artifacts in MRI thermal images, leading to misalignment of the ultrasound focus with the actual target tissue, which can result in treatment failure, especially in procedures requiring high accuracy like Essential Tremor treatment.
Innovation Solution
A method and system that corrects chemical shift and k-space shift errors in MRI thermal images to accurately align the ultrasound focus with the actual focus location, using formulas to calculate temperature and echo time errors, allowing for real-time adjustments during the treatment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low power sonication is used for alignment confirmation, then patient safety is improved, but treatment time is prolonged and alignment precision is insufficient
Solution Approach 1:
The system performs preliminary calculation of focus location offsets based on temperature field distribution and chemical shift effects before the actual treatment begins. By pre-computing the correction values using the temperature map and known physical constants, the system eliminates the need for repeated low-power sonication trials during alignment confirmation.
Solution Approach 2:
The patent replaces the mechanical trial-and-error alignment process (repeated low-power sonication) with a computational approach using MRI thermal image analysis. The system substitutes physical alignment adjustments with mathematical calculations based on temperature field models and chemical shift corrections, achieving both speed and accuracy.
2Measurement precision
If chemical shift correction is applied, then focus location accuracy is improved, but spatial displacement due to heating effects remains
Solution Approach 1:
The system dynamically adjusts multiple parameters simultaneously: it corrects for chemical shift effects, compensates for heating-induced spatial displacement, and accounts for k-space shift variations. By changing multiple parameters in the correction model rather than relying on a single correction type, the system achieves both improved precision and maintained reliability.
Solution Approach 2:
The system uses real-time temperature field feedback from MRI thermal imaging to continuously update the focus location correction calculations. The temperature map provides feedback about heating effects, which are then used to adjust the correction values, creating a closed-loop system that maintains accuracy throughout the treatment process.
3Manufacturing precision
If multiple low power sonication processes are performed for alignment, then focus location alignment is improved, but treatment complexity and time are increased
Solution Approach 1:
The system creates a computational copy of the physical alignment process by calculating the expected focus location offsets based on temperature field distribution. Instead of physically adjusting the ultrasound focus multiple times, the system copies the alignment process into the digital domain using MRI image analysis and mathematical models, achieving the same precision with far less complexity.
Solution Approach 2:
The correction process is segmented into distinct computational steps: temperature field extraction, chemical shift calculation, k-space shift correction, and focus location adjustment. By breaking down the complex alignment problem into separate calculable components, the system reduces overall complexity while maintaining precision.
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 enables precise and rapid alignment of the ultrasound focus with the target tissue, reducing spatial errors and improving the accuracy of MRgFUS treatments by correcting for both chemical shift and k-space shift effects, thereby enhancing the effectiveness of the surgery.
Implementation Method 1
correcting a chemical shift and a k-space shift of a monitored ultrasound focus location in the magnetic resonance thermal image such that the monitored ultrasound focus location is aligned with a real physical ultrasound focus location; wherein correcting the chemical shift comprises correcting a first spatial error of the monitored ultrasound focus location caused by resonance frequency changes of hydrogen nuclei due to environmental differences of water molecules
Implementation Method 2
correcting the k-space shift comprises correcting a second spatial error of the monitored ultrasound focus location caused by temperature error due to spatial variations of a primary magnetic field
Implementation Method 3
a focused ultrasound device configured to generate focused ultrasound so as to heat a target tissue at an actual ultrasound focus location of the focused ultrasound
Implementation Method 4
a magnetic resonance imaging device configured to generate a magnetic resonance imaging data of the target tissue
Data Source
AI summary
The present disclosure provides a method for determining an ultrasound focus location in a thermal image. In one aspect, the method includes obtaining a magnetic resonance thermal image of a tissue heated by a focused ultrasound and correcting a chemical shift and a k-space shift of a monitored ultrasound focus location in the magnetic resonance thermal image such that the monitored ultrasound focus location is aligned with a real physical ultrasound focus location. Correcting the chemical shift includes correcting a first spatial error of the monitored ultrasound focus location caused by resonance frequency changes of hydrogen nuclei due to environmental differences of water molecules. Correcting the k-space shift includes correcting a second spatial error of the monitored ultrasound focus location caused by temperature error due to spatial variations of a primary magnetic field.