Attenuation Correction for Emission Tomography with MR Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Combined magnetic resonance emission tomography devices face challenges in accurately correcting emission tomography scan data due to magnetic interference fields caused by objects with different magnetic susceptibilities, leading to signal cancellations and artifacts in the vicinity of interference objects like metal implants.
Innovation Solution
The method involves acquiring magnetic resonance scan data using a sequence designed to compensate for magnetic interference fields, generating an attenuation map, and using this map for correction of emission tomography scan data to reduce signal cancellations and improve image quality near interference objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard magnetic resonance sequence is used to acquire scan data, then the acquisition process is simple and fast, but signal cancellations and artifacts occur in the vicinity of interference objects like metal implants
Solution Approach 1:
The patent applies preliminary action by identifying and segmenting interference objects (like metal implants) before acquiring magnetic resonance scan data. By预先 creating a mask of the interference object based on emission tomography data, the system can then use this mask to guide the magnetic resonance sequence acquisition, focusing resources on areas affected by interference while maintaining overall scan efficiency.
Solution Approach 2:
The patent implements local quality by applying different processing strategies to different regions of the scan data. Specifically, it generates an attenuation map that accounts for the presence of interference objects, applying localized corrections only where needed rather than uniformly across the entire dataset. This allows high-quality imaging in affected regions while maintaining efficiency elsewhere.
2Measurement precision
If attenuation correction is performed using conventional methods, then the process is straightforward, but accurate attenuation correction cannot be achieved in regions with magnetic interference fields
Solution Approach 1:
The patent uses an intermediary approach by introducing a specialized attenuation map generation process that acts as a mediator between the raw emission tomography data and the final corrected images. This intermediate step creates a customized attenuation map that accounts for interference object geometry and material properties, which then serves as the basis for accurate attenuation correction in subsequent processing.
Solution Approach 2:
The patent applies parameter changes by modifying the attenuation correction parameters based on the detected interference object characteristics. Instead of using uniform attenuation coefficients, the system adjusts these parameters locally according to the interference object's geometry, composition, and position, thereby achieving accurate correction in regions that would otherwise be corrupted by magnetic interference.
3Reliability
If the magnetic resonance sequence is optimized to reduce artifacts, then image quality improves, but the sequence design becomes more complex
Solution Approach 1:
The patent implements feedback by using the initially acquired emission tomography data to inform and optimize the subsequent magnetic resonance sequence design. The system analyzes the emission data to identify interference object locations and characteristics, then feeds this information back into the magnetic resonance sequence configuration to adjust parameters such as readout bandwidth, echo time, and spatial encoding strategies, thereby reducing artifacts while maintaining sequence manageability.
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 accurate and reliable attenuation correction of emission tomography scan data, reducing artifacts and improving image quality in the presence of interference objects by compensating for magnetic interference fields, thereby ensuring more precise imaging.
Implementation Method 1
Radio-frequency pulses, for example excitation pulses, are then emitted by a radio-frequency antenna unit by suitable antenna devices, and this leads to the nuclear spins of specific atoms, which are excited in a resonant manner by these radio-frequency pulses
Implementation Method 2
an interference object, which causes a magnetic interference field during combined magnetic resonance emission tomography imaging
Implementation Method 3
The attenuation values are typically stored in the form of linear attenuation coefficients with the unit 1/cm. The tissue of the examination object, which is located between the point of origin of the photons and the emission tomography detector, is especially relevant with respect to the attenuation correction
Data Source
AI summary
In a method for attenuation correction of emission tomography scan data acquired from an examination object in a combined magnetic resonance emission tomography apparatus, wherein an interference object is situated in the examination region, which causes a magnetic interference field during combined magnetic resonance emission tomography imaging, magnetic resonance scan data of the examination object are acquired by executing a magnetic resonance sequence designed to at least partially compensate inference due to the magnetic interference field. Emission tomography scan data are acquired and an attenuation map is generated using the acquired magnetic resonance scan data. Attenuation correction of the emission tomography scan data is implemented using the generated attenuation map.