PET Attenuation Correction via CT Segmentation and Motion Phase Alignment
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Solution Overview
Problem
Respiratory motion during PET imaging leads to inaccuracies in attenuation correction due to mismatch between CT and PET data, as CT scans are brief and capture varying motion phases, causing discomfort and limitations in breath-hold methods for patients.
Innovation Solution
A system and method that segment CT images into axial sub-images, align PET data with corresponding motion phases, and construct a PET reference image aligned with CT images for accurate attenuation correction, using rigid or affine transformations to determine the best matching PET data for each CT sub-image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If CT scan is performed quickly to reduce patient discomfort, then patient comfort is improved, but motion phase mismatch between CT and PET data increases
Solution Approach 1:
The patent segments the CT image into multiple axial sub-images and segments PET data into multiple gates corresponding to different motion phases. For each CT sub-image, a corresponding PET gate is identified and used for attenuation correction, ensuring motion phase consistency without requiring long scan times or breath-hold maneuvers.
2Measurement precision
If CT scan duration is extended to capture consistent motion phases, then attenuation correction accuracy is improved, but patient discomfort increases
Solution Approach 1:
The patent performs preliminary segmentation of both CT and PET data into motion-phase-specific subsets before attenuation correction. This allows the system to match corresponding motion phases without requiring the patient to maintain a fixed position or hold breath during the scan.
3Measurement precision
If breath-hold method is used to eliminate motion, then motion phase mismatch is reduced, but patient limitations and discomfort increase
Solution Approach 1:
The patent dynamically matches CT and PET data based on their respective motion phases without requiring the patient to staticize their breathing. The system adapts to natural respiratory motion by identifying corresponding gates for each CT sub-image, making the method applicable to all patients regardless of breath-hold capability.
4Productivity
If CT scanner moves through multiple slices quickly, then scan time is reduced, but motion phase varies along z-direction causing mismatch
Solution Approach 1:
The patent divides the volumetric CT data into multiple axial sub-images and segments PET data into temporal gates. Each CT sub-image is then matched with the corresponding PET gate based on motion phase, ensuring spatial alignment accuracy is maintained despite rapid scanner movement through multiple slices.
Data Source
AI summary
The invention relates to a system and a method for assisting in attenuation correction of gated PET data of a moving object (2). In the system, an evaluation unit (15) is configured to (i) receive a CT image of the object (2) and to segment the CT image into a plurality of CT sub-images, each CT sub-image correspond to an axial segment of an imaged volume, (ii) to determine for each CT sub-image a gate including PET data having a greatest correspondence with the CT sub-image, (iii) to construct, for each CT sub-image, a PET sub-image from the PET data included in the gate determined for the CT sub-image, the PET sub-image substantially corresponding to the same axial segment of the imaged volume as the CT sub-image, and (iv) to combine the PET sub-images to form a PET reference image of the object (2).