Magnetic Particle Imaging with Narrowband Harmonic Detection
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Solution Overview
Problem
Current magnetic particle imaging (MPI) techniques face challenges in creating high-resolution images with minimal noise amplification due to broad frequency range detection and inefficient sampling methods, particularly with sparse magnetic particle contrast agents.
Innovation Solution
The use of permanent magnets to create a gradient magnetic field with a field-free region, combined with excitation and receiving coils, and signal processing circuitry that includes intermodulation techniques to produce a single composite image from multiple intermodulation signals, optimized for narrowband detection and efficient sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional MPI techniques use broad frequency range detection to capture multiple harmonics, then the imaging coverage is improved, but noise amplification increases and measurement precision deteriorates
Solution Approach 1:
The patent segments the broad frequency spectrum into multiple narrowband channels, each tuned to detect specific harmonic frequencies separately. This segmentation allows the system to maintain comprehensive imaging coverage while reducing noise amplification in each individual channel, as each narrowband detector operates with optimized signal-to-noise ratio rather than attempting to capture the entire broad spectrum simultaneously.
2Loss of information
If MPI techniques sample all high resolution pixels across the imaging region, then complete image coverage is achieved, but sampling efficiency deteriorates due to the large number of pixels
Solution Approach 1:
The patent implements partial sampling by strategically selecting a subset of pixels for detection rather than sampling every high-resolution pixel. This partial action approach maintains sufficient image coverage and diagnostic information while dramatically improving sampling efficiency and reducing the total number of measurements required, thereby solving the contradiction between complete coverage and sampling efficiency.
3Adaptability or versatility
If an un-tuned receiver coil is used to detect signals over large bandwidth, then detection versatility is improved, but the ability to optimally match the preamplifier is lost
Solution Approach 1:
The patent divides the broad bandwidth detection task into multiple narrowband receiver coils, each tuned to a specific frequency range. This segmentation enables each receiver to optimally match its associated preamplifier for maximum signal detection quality within its narrow band, while the collective array of segmented receivers covers the entire broad spectrum required for comprehensive MPI imaging.
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 the creation of high-resolution images with reduced noise amplification and improved efficiency in MPI, allowing for more effective detection of magnetic particles while minimizing sampling inefficiencies.
Implementation Method 1
permanent magnets that produce a gradient magnetic field having a field free region (FFR)
Implementation Method 2
excitation field electromagnets and associated excitation circuitry that produce a radiofrequency magnetic field within the field free region
Implementation Method 3
receiving coils and associated receiving circuitry that detect a response of magnetic particles in the field free region to the excitation field
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A magnetic particle imaging apparatus includes magnets [106,107] that produce a gradient magnetic field having a field free region (FFR), excitation field electromagnets [102,114] that produce a radiofrequency magnetic field within the field free region, high-Q receiving coils [112] that detect a response of magnetic particles in the field free region to the excitation field. Field translation electromagnets create a homogeneous magnetic field displacing the field-free region through the field of view (FOV) allowing the imaging region to be scanned to optimize scan time, scanning power, amplifier heating, SAR, dB/dt, and/or slew rate. Efficient multi-resolution scanning techniques are also provided. Intermodulated low and radio-frequency excitation signals are processed to produce an image of a distribution of the magnetic nanoparticles within the imaging region. A single composite image is computed using deconvolution of multiple signals at different harmonics.