Motion Correction for CT Images Using Concurrent MR Data
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Solution Overview
Problem
Combining CT and MRI imaging data acquired sequentially poses challenges due to patient or organ motion, particularly in applications like cardiac imaging, where motion artifacts degrade image quality and make it difficult to align anatomical structures across different imaging modalities.
Innovation Solution
Concurrent acquisition of CT and MRI data allows for motion correction using MR imaging information, where MR data is used to estimate motion fields and guide the reconstruction of CT images, reducing motion artifacts and improving image quality by aligning the data sets effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CT scanning rotational speed is increased to minimize motion effects, then motion artifacts are reduced, but image quality (signal-to-noise ratio) decreases
Solution Approach 1:
The patent introduces MR imaging data as an intermediary to measure and characterize organ motion independently. This motion information from MR serves as a mediator to guide CT reconstruction, allowing the CT system to operate at lower rotational speeds without suffering from motion artifacts, thus resolving the contradiction between speed and image quality
Solution Approach 2:
The system implements feedback by using MR imaging to continuously monitor organ motion and feeding this motion information back to the CT reconstruction process. This feedback loop enables dynamic adjustment of reconstruction parameters based on actual motion, allowing slower CT rotation while maintaining image quality through motion-compensated reconstruction
2Ease of operation
If CT and MRI scanning are performed sequentially to facilitate patient repositioning, then patient comfort is improved, but motion between scans degrades alignment accuracy
Solution Approach 1:
The patent applies preliminary action by acquiring MR imaging data before and during the CT scan to establish motion characteristics in advance. This preliminary MR data is used to predict and compensate for motion during CT reconstruction, ensuring accurate anatomical alignment even though scanning is performed sequentially
Solution Approach 2:
The patent replaces the mechanical approach of physical immobilization and table registration with a computational approach using MR-derived motion fields. Instead of mechanically constraining patient motion or precisely repositioning the table, the system uses software-based motion correction substituting mechanical alignment requirements with computational registration
3Reliability
If CT scanning time is reduced to minimize motion effects, then motion artifacts are reduced, but image quality (signal-to-noise ratio) decreases
Solution Approach 1:
MR imaging serves as an intermediary that decouples the relationship between scanning time and motion artifact reduction. By independently measuring motion through MR, the system can afford longer CT scanning times without proportionally increasing motion artifacts, as the MR-derived motion compensation corrects for the extended acquisition period
Data Source
AI summary
A method of generating an image in one embodiment includes acquiring, with a computed tomography (CT) acquisition unit, CT projection data from at least a region of interest (ROI), and concurrently acquiring, with a magnetic resonance (MR) acquisition unit, MR imaging information of at least a portion of the ROI. The method also includes determining a motion of the at least a portion of the ROI using the MR imaging information, and reconstructing the image using the CT projection data. Reconstructing the image includes motion correcting the CT projection data based on the motion determined using the MR imaging information.