3D-3D MRI CT Registration for Real-Time Image Guidance
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Solution Overview
Problem
Current image guidance technologies face challenges in accurately and rapidly registering MRI images with X-ray transmission images in real-time, making it difficult to apply MRI effectively in real-time image guidance due to the time-consuming nature of MRI imaging and the inability to perform fast image registration with digital projection images.
Innovation Solution
A method involving 3D-3D registration between MRI and CT images, where a 3D MR image is acquired and a reference 3D CT image is used to characterize the initial position state, allowing for accurate marking of object regions of interest and correction of setup errors, with the option to reacquire CT images if registration precision is insufficient, and further incorporating 2D-3D registration with X-ray transmission images to correct positional deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MRI imaging is used for image guidance, then soft tissue contrast resolution is improved, but imaging time increases and real-time registration with X-ray images becomes difficult
Solution Approach 1:
The patent segments the imaging process into two distinct phases: (1) a pre-treatment planning phase where a detailed 3D MR image is acquired offline to establish high-precision soft tissue anatomy and objects of interest, and (2) a real-time treatment execution phase where only fast 2D X-ray transmission images are acquired. This segmentation allows MRI's superior soft tissue contrast to be utilized without compromising real-time imaging requirements during treatment delivery.
Solution Approach 2:
The patent performs preliminary 3D MR image acquisition and 3D-3D registration with the treatment planning CT image before the actual radiotherapy treatment begins. All complex 3D image processing, object segmentation, and registration calculations are completed in advance during the planning phase, so that during real-time treatment only simple 2D-3D registration of X-ray images with the pre-processed 3D MR image is required, enabling real-time guidance without the time penalty of repeated 3D MR scanning.
2Measurement precision
If 3D MR images are registered with X-ray transmission images in real-time, then image guidance accuracy is improved, but registration time increases making real-time application difficult
Solution Approach 1:
The patent segments the registration process into two stages: (1) a 3D-3D registration stage between the pre-acquired 3D MR image and the treatment planning CT image that establishes accurate 3D anatomical correspondence and objects of interest, and (2) a 2D-3D registration stage where real-time 2D X-ray transmission images are registered with the pre-processed 3D MR image using the previously established 3D spatial relationships. This segmentation reduces real-time computational burden while maintaining high registration accuracy.
Solution Approach 2:
The patent performs preliminary 3D-3D registration between the 3D MR image and the CT planning image before treatment, pre-calculating transformation matrices and identifying objects of interest in 3D space. During real-time treatment, this preliminary registration framework is reused, and only lightweight 2D-3D registration of X-ray images is performed, dramatically reducing registration time while preserving the high accuracy benefits of 3D MR imaging.
3Measurement precision
If 3D-3D registration is performed between MR and CT images, then setup error correction is improved, but processing complexity increases
Solution Approach 1:
The patent performs the complex 3D-3D registration between MR and CT images during the pre-treatment planning phase, when time and computational resources are abundant. This preliminary registration establishes the spatial transformation relationships and identifies objects of interest in the 3D MR image that correspond to anatomical structures in the CT image. By completing this complex processing beforehand, the actual treatment delivery becomes simpler and faster.
Solution Approach 2:
The patent creates a 3D copy of the treatment planning CT image space using the pre-acquired 3D MR image through 3D-3D registration. This registered 3D MR image with overlaid objects of interest serves as a virtual reference model that can be rapidly compared with real-time 2D X-ray images during treatment without requiring repeated complex 3D-3D registration operations, thereby reducing processing complexity during real-time execution.
Data Source
AI summary
Provided is a method for performing image guidance, including: acquiring a 3D magnetic resonance (MR) image of a target individual, wherein at least one region range of an object of interest is marked in the 3D MR image; acquiring a reference 3D image of the target individual, wherein the reference 3D image is a 3D-reconstructed computed tomography (CT) image; performing a 3D-3D registration on the 3D MR image and the reference 3D image, so as to mark each region range of the object of interest in the reference 3D image; and performing image guidance on the basis that the reference 3D image is adopted to characterize an initial position state.