Attenuation Correction in PET Using MR Phase Field Segmentation
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Solution Overview
Problem
Current PET imaging systems face degraded image quality and reduced quantitative accuracy due to photon attenuation, which is often corrected using X-ray CT imaging, exposing patients to additional radiation.
Innovation Solution
A hybrid PET/MR imaging system employs magnetic resonance (MR) imaging to generate attenuation maps, allowing for attenuation correction of PET images without the need for X-ray CT, by using phase field algorithms to segment anatomies and correlate attenuation information, thereby modifying PET images based on MR-derived attenuation data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If X-ray CT imaging is used to correct attenuation in PET imaging, then attenuation correction accuracy is improved, but patient radiation exposure increases
Solution Approach 1:
The patent introduces MR imaging as an intermediary modality to obtain attenuation information without using X-rays. The MR images serve as a mediator between the PET data and the attenuation correction process, allowing accurate attenuation mapping while avoiding additional ionizing radiation exposure to patients.
Solution Approach 2:
The patent replaces the X-ray based CT imaging system with an MR imaging system that uses magnetic fields and radio waves. This substitution eliminates the harmful ionizing radiation while maintaining the capability to generate attenuation maps for PET correction through tissue segmentation and classification.
2Object-affected harmful factors
If MR imaging is used to generate attenuation maps instead of CT, then radiation exposure is reduced, but image quality and quantitative accuracy may deteriorate
Solution Approach 1:
The patent applies segmentation to divide the MR images into distinct tissue regions (e.g., bone, soft tissue, air, fat). By segmenting the anatomy into discrete classes and assigning appropriate attenuation coefficients to each class, the system reconstructs accurate attenuation maps from MR data, maintaining quantitative accuracy while avoiding radiation.
Solution Approach 2:
The patent assigns different attenuation coefficients to different tissue types based on their local properties. Each segmented region receives attenuation values specific to its tissue characteristics (bone has higher attenuation than soft tissue), thereby preserving the local quality and accuracy of attenuation correction throughout the image volume.
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 enhances image quality and accuracy by reducing radiation exposure while providing attenuation-corrected PET images, applicable to PET/MR and other imaging modalities like SPECT, facilitating simultaneous or sequential acquisition of PET and MR data for improved spatial and functional imaging.
Implementation Method 1
perform a magnetic resonance (MR) imaging sequence to acquire MR image slices or volumes
Implementation Method 2
a radionuclide is injected into a subject of interest. As the radionuclide decays, positrons are emitted that collide with electrons, resulting in an annihilation event that emits pairs of gamma particles. The pairs of gamma particles impact a detector array
Data Source
AI summary
In one embodiment, a method includes performing a magnetic resonance (MR) imaging sequence to acquire MR image slices or volumes of a first station representative of a portion of a patient; applying a first phase field algorithm to the first station to determine a body contour of the patient in the first station; identifying a contour of a first anatomy of interest within the body contour of the first station using the first phase field algorithm or a second phase field algorithm; segmenting the first anatomy of interest based on the identified contour of the first anatomy of interest; correlating first attenuation information to the segmented first anatomy of interest; and modifying a positron emission tomography (PET) image based at least on the first correlated attenuation information.