Respiratory Phase-Gated PET Image Reconstruction
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Solution Overview
Problem
Respiratory motion causes mismatches between PET and CT data in PET/CT imaging systems, leading to artifacts in PET images, which affect diagnosis and image quality due to differences in scanning times and phases.
Innovation Solution
A method that gates PET data into respiratory phases, determines a motion vector field to match anatomical images with PET data, and reconstructs attenuation-corrected PET images by transforming anatomical images based on the motion vector field to align with target respiratory phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PET scan is performed for a relatively long duration to achieve high sensitivity detection, then measurement precision is improved, but respiratory motion causes mismatch between PET and CT data leading to image artifacts
Solution Approach 1:
The PET data is segmented into multiple respiratory phase bins (e.g., inspiration phase, mid-inspiration phase, mid-expiration phase, expiration phase) based on respiratory cycle timing. This segmentation allows separate reconstruction of PET images for each phase, enabling accurate matching with corresponding phase CT data and eliminating motion-induced artifacts.
Solution Approach 2:
The patent changes the temporal parameter by introducing respiratory phase timing information into the image reconstruction process. By assigning each PET event to a specific respiratory phase bin based on timing, the system transforms the mismatch problem into a phase-matched reconstruction problem, improving both detection precision and image quality.
2Productivity
If CT scan is performed quickly to capture anatomical structure, then productivity is improved, but the CT data corresponds to a specific respiratory phase that may not match the PET data
Solution Approach 1:
The patent segments the PET data into multiple respiratory phase bins that correspond to different portions of the respiratory cycle. The CT data is then matched to the appropriate PET phase bin based on respiratory phase information, allowing quick CT scanning without sacrificing data matching accuracy.
Solution Approach 2:
Respiratory phase timing information serves as an intermediary that links the quickly acquired CT data with the PET data. By using this intermediary parameter, the system can match CT and PET data from different respiratory phases, maintaining measurement precision while preserving the productivity benefit of rapid CT scanning.
3Measurement precision
If PET data is collected over multiple respiratory phases to improve signal detection, then measurement precision is improved, but mismatch with CT data causes artifacts
Solution Approach 1:
The patent segments PET data into distinct respiratory phase bins (inspiration, mid-inspiration, mid-expiration, expiration phases) and reconstructs separate images for each phase. This segmentation eliminates artifacts by ensuring that each phase-specific PET image is matched with corresponding phase-specific CT attenuation correction data.
Solution Approach 2:
The patent introduces respiratory phase timing as a new parameter for organizing and reconstructing PET data. By changing the reconstruction approach from a single averaged image to phase-specific images, the system maintains high tracer detection sensitivity while eliminating motion-induced artifacts through proper phase matching.
Data Source
AI summary
The disclosure relates to PET imaging systems and methods. The systems may obtain a plurality of PET images of a subject and a CT image acquired by performing a spiral CT scan on the subject. Each gated PET image may include a plurality of sub-gated PET images. The CT image may include a plurality of sub-CT images each of which corresponds to one of the plurality of sub-gated PET images. The systems may determine a target motion vector field between a target physiological phase and a physiological phase of the CT image based on the plurality of sub-gated PET images and the plurality of sub-CT images. The systems may reconstruct an attenuation corrected PET image corresponding to the target physiological phase based on the target motion vector field, the CT image, and PET data used for the plurality of gated PET images reconstruction.