CT Motion Estimation and Compensation via Fourier Modulation
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Solution Overview
Problem
Conventional CT image reconstruction methods fail to effectively address motion artifacts in cardiac imaging due to the heart's movement, leading to image blurring and incorrect diagnoses, especially for small features like coronary artery plaques, and existing techniques are costly or mechanically restrictive.
Innovation Solution
A CT imaging system and method that includes data acquisition and image processing to identify regions of interest, apply directional filters to estimate motion paths, and compensate for motion by modulating the Fourier space with motion vectors, reducing the need for extensive scan data and minimizing radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CT image reconstruction methods are used, then the imaging process is simple and fast, but motion artifacts cause image blurring and reduce diagnostic accuracy
Solution Approach 1:
The patent applies preliminary action by estimating motion parameters before the actual image reconstruction. The motion estimation is performed on the raw projection data or initial reconstructions, and then these motion parameters are used to guide the reconstruction process, allowing the system to compensate for motion effects proactively rather than reactively
Solution Approach 2:
The patent introduces motion parameter estimation as an intermediary step between data acquisition and final image reconstruction. This intermediary process extracts motion information that serves as a mediator to adjust and optimize the reconstruction, enabling the system to handle motion artifacts without fundamentally changing the reconstruction algorithm
2Measurement precision
If brute force approaches like employing two X-ray tubes or higher power tubes are used, then motion artifacts are reduced, but the cost and mechanical complexity increase significantly
Solution Approach 1:
The patent replaces mechanical solutions (additional X-ray tubes, higher power tubes, faster gantry spinning) with a computational approach. Instead of physically changing the hardware to handle motion, the system uses software-based motion estimation and compensation algorithms to achieve the same goal, thereby reducing mechanical complexity while maintaining image quality
Solution Approach 2:
The patent changes the parameters of the reconstruction process by introducing motion parameter estimation. Rather than changing the physical parameters of the scanner (X-ray power, gantry speed), the system adjusts reconstruction parameters based on estimated motion, achieving motion compensation through parameter optimization rather than hardware modification
3Measurement precision
If multiple phase reconstructions are performed to select quiescent phase images, then motion artifacts are reduced, but temporal resolution becomes insufficient for high heart rates
Solution Approach 1:
The patent applies dynamics by making the reconstruction process adaptive to the actual motion characteristics. Instead of using fixed multiple phase reconstructions, the system dynamically estimates motion parameters and adjusts the reconstruction strategy accordingly, allowing it to handle varying heart rates and motion patterns effectively
Solution Approach 2:
The patent implements feedback by using the estimated motion parameters to guide and optimize the reconstruction process. The motion estimation provides feedback about the actual motion occurring during the scan, which is then used to adjust reconstruction parameters and select optimal images, creating a closed-loop system that adapts to real-time conditions
4Measurement precision
If model-based estimation requiring several cardiac phase reconstructions is used, then motion compensation improves, but X-ray exposure time increases and computational challenges arise
Solution Approach 1:
The patent applies partial action by estimating motion parameters using only a subset of the available data or a simplified approach rather than requiring complete multi-phase reconstructions. This partial estimation is sufficient to achieve effective motion compensation while significantly reducing the total X-ray exposure time and computational burden
Data Source
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AI summary
A method and system (10) for motion estimation and compensation are disclosed. Initially, a set of one or more initial images is reconstructed using acquired imaging data. Further, one or more regions of interest are identified in this set of reconstructed initial images. At least a set of filters (402, 404, 406) is applied to the identified regions of interest to generate a sequence of filtered images. Particularly, each of the filtered images in the generated sequence of filtered images includes data acquired near a different reference point. Subsequently, a motion path corresponding to each region of interest is determined based on one or more correspondences in the sequence of filtered images.